HomeMy WebLinkAboutHistorical preservation brochureConclusion
Providing temporary protection and stabilization for vacant
historic buildings can arrest deterioration and buy the
owner valuable time to raise money for preservation or to
find a compatible use for the property. A well planned
mothballing project involves documenting the history and
condition of the building, stabilizing the structure to slow
down its deterioration, and finally mothballing the
structure to secure it (See fig. 25). The three highest
priorities for the building while it is mothballed are 1) to
protect the building from sudden loss, 2) to weatherize and
maintain the property to stop moisture penetration, and 3)
to control the humidity levels inside once the building has
been secured. See Mothballing Checklist Figure 26.
While issues regarding mothballing may seem simple, the
variables and intricacies of possible solutions make the
decision -making process very important. Each building
must be individually evaluated prior to mothballing. In
addition, a variety of professional services as well as
volunteer assistance are needed for careful planning and
repair, sensitively designed protection measures, follow-up
security surveillance, and cyclical maintenance (see fig. 27).
In planning for the future of the building, complete and
systematic records must be kept and generous funds
allocated for mothballing. This will ensure that the historic
property will be in stable condition for its eventual
preservation, rehabilitation, or restoration.
Acknowledgements
This publication has been prepared pursuant to the National Historic
Preservation Act of 1966, as amended, which directs the Secretary of the Interior
to develop and make available information concerning historic properties.
Comments on the usefulness of this publication may be directed to H. Ward
Jandl, Deputy Chief, Preservation Assistance Division, National Park Service,
P.O. Box 37127, Washington, D.C. 20013-7127. This publication is not
copyrighted and can be reproduced without penalty. Normal procedures for
credit to the author and the National Park Service are appreciated.
The author, Sharon C. Park, Senior Historical Architect, Preservation Assistance
Division, National Park Service, would like to acknowledge the assistance of the
following individuals in the preparation and review of this publication. H. Ward
Jandl served as the technical editor and assisted with producing this
Preservation Brief. In addition the following persons have provided invaluable
information and illustrations: Ernest A. Conrad, PE; Doug Hicks, NPS
Williamsport Preservation Training Center; Thomas C. Taylor, Colonial
Williamsburg; Karen Gordon, Seattle Urban Conservation Office; Kevin B.
Stoops, Seattle Department of Parks and Recreation; Michael Mills, AIA;
Christine Henry, architect, Mary Beth Hirsch, Ohio Historical Society. Thanks
also to Preservation Assistance Division staff members Michael J. Auer, Anne E.
Grimmer, Kay D. Weeks, Timothy A. Buehner, and Jean Travers, and to the
numerous staff members of the NPS Regional offices who submitted comments.
All photographs and drawings are by the author unless otherwise noted.
Cover photograph: Mothballing of this historic house involved a new
membrane roof covering over the historic roof and slatted windmo covers
for security and ventilation, Photo: Williamsport Preservation Training
Center, NPS.
ISSN: 0885-7016
September 1993
Figure 27. 77ris residential building blends into its neighborhood even
though all the windows have been covered over and the front steps are
nxissisrg. The grounds are maintained and the special attention to
decoratavely painting the window pastels shows that the property is being
well cared for until it can be rehabilitated. Photo: Ohio Historical
Society.
Further Reading
Cotton, J. Randall. "Mothballing Buildings." The Old House
Journal. July/August,1993.
Fisher, Charles E. and Thomas A. Vitanza. "Temporary Window
Vents in Unoccupied Historic Buildings." Preservation Tech Note
(Windows, No. 10). Washington, DC: National Park Service, 1985.
Frazier Associates. "Mothballing Historic Buildings." Preserving
Prince William, 2. County of Prince William, VA, 1990.
Michell, Eleanor. Emergency Repairs for Historic Buildings. London:
Butterworth Architecture,1988.
"Mothballing Vacant Buildings," An Anti -Arson Kit for Preservation
and Neighborhood Action. Washington, DC: Federal Emergency
Management Agency, 1982.
Nelson, Lee H. Preservation Briefs 17. Architectural character -
Identifying the Visual Aspects of Historic Buildings as an Aid to
Preserving Their Character. Washington, DC: Government Printing
Office,1988.
Solon, Thomas E. "Security Panels for the Foster -Armstrong
House." Association for Preservation Technology Bulletin. Vol XVI
no. 3 & 4, 1984. (note the design of the panels, but be aware that
additional louvering may be needed on other projects).
31 PRESERVATION
BRIEFS
Mothballing Historic Buildings
Sharon C. Park, AIA
U.S. Department of the Interior
National Park Service
Cultural Resources
Preservation Assistance
When all means of finding a productive use for a historic
building have been exhausted or when funds are not
currently available to put a deteriorating structure into a
useable condition, it may be necessary to close up the
building temporarily to protect it from the weather as well
as to secure it from vandalism. This process, known as
mothballing, can be a necessary and effective means of
protecting the building while planning the property's future,
or raising money for a preservation, rehabilitation or
restoration project. If a vacant property has been declared
unsafe by building officials, stabilization and mothballing
may be the only way to protect it from demolition.
This Preservation Brief focuses on the steps needed to "de-
activate" a property for an extended period of time. The
project team will usually consist of an architect, historian,
preservation specialist, sometimes a structural engineer, and
a contractor. Mothballing should not be done without
careful planning to ensure that needed physical repairs are
made prior to securing the building. The steps discussed in
this Brief can protect buildings for periods of up to ten years;
long-term success will also depend on continued, although
somewhat limited, monitoring and maintenance. For all but
the simplest projects, hiring a team of preservation
specialists is recommended to assess the specific needs of the
structure and to develop an effective mothballing program.
A vacant historic building cannot survive indefinitely in a
boarded -up condition, and so even marginal interim uses
where there is regular activity and monitoring, such as a
caretaker residence or non-flammable storage, are generally
preferable to mothballing. In a few limited cases when the
vacant building is in good condition and in a location where
it can be watched and checked regularly, closing and locking
the door, setting heat levels at just
above freezing, and securing the
windows may provide sufficient
protection for a period of a few years.
But if long-term mothballing is the
only remaining option, it must be
done properly (see fig. 1 & 2). This
will require stabilization of the
exterior, properly designed security
protection, generally some form of
interior ventilation - either through
mechanical or natural air exchange
systems - and continued maintenance
and surveillance monitoring.
Figure 1. Proper ittothballing treatment: This building has been successfully mothballed for 10 years
because the roof and walls were repaired and structurally stabilized, ventilation louvers were added, and
the property is maintained. Photo: Charles E. Fisher, NPS.
Comprehensive mothballing
programs are generally expensive and
may cost 10% or more of a modest
rehabilitation budget. However, the
money spent on well -planned
protective measures will seem small
when amortized over the life of the
resource. Regardless of the location
and condition of the property or the
funding available, the following 9
steps are involved in properly
mothballing a building:
14
Figure 2. Improper treatment: Boarding up without adequate ventilation, lack of maintenance, and
neglect of this property have accelerated deterioration. Photo; NPS file.
Documentation
1. Document the architectural and historical significance of
the building.
2. Prepare a condition assessment of the building.
Stabilization
3. Structurally stabilize the building, based on a
professional condition assessment.
4. Exterminate or control pests, including termites and
rodents.
5. Protect the exterior from moisture penetration.
Mothballing
6. Secure the building and its component features to
reduce vandalism or break-ins.
7. Provide adequate ventilation to the interior.
8. Secure or modify utilities and mechanical systems.
9. Develop and implement a maintenance and
monitoring plan for protection.
These steps will be discussed in sequence below.
Documentation and stabilization are critical components
of the process and should not be skipped over.
Mothballing measures should not result in permanent
damage, and so each treatment should be weighed in
terms of its reversibility and its overall benefit.
Documentation
Documenting the historical significance and physical
condition of the property will provide information
necessary for setting priorities and allocating funds.
The project team should be cautious when first entering
the structure if it has been vacant or is deteriorated. It
may be advisable to shore temporarily areas appearing
to be structurally unsound until the
condition of the structure can be fully
assessed (see fig. 3). If pigeon or bat
droppings, friable asbestos or other
health hazards are present, precautions
must be taken to wear the appropriate
safety equipment when first inspecting
the building. Consideration should be
given to hiring a firm specializing in
hazardous waste removal if these
highly toxic elements are found in the
building.
Documenting and recording the
building. Documenting a building's
history is important because evidence
of its true age and architectural
significance may not be readily
evident. The owner should check with
the State Historic Preservation Office
or local preservation commission for
assistance in researching the building.
If the building has never been
researched for listing in the National
Register of Historic Places or other
historic registers, then, at a minimum,
the following should be determined:
a The overall historical significance of
the property and dates of construction;
the chronology of alterations or additions and their
approximate dates; and,
• types of building materials, construction techniques, and
any unusual detailing or regional variations of
craftsmanship.
Old photographs can be helpful in identifying early or
original features that might be hidden under modern
materials. On a walk-through, the architect, historian, or
preservation specialist should identify the architecturally
significant elements of the building, both inside and out
(see fig.4).
Figure 3. Buildings seriously damaged by storms or deterioration may need to be
braced before ardtifectural evaluations can be made. Jethro Coffin House. Photo:
John Milner Architects.
2
buildings to adequately ventilate without resorting to
extensive louvering and/or mechanical exhaust fan systems
are masonry buildings in humid climates. Even with
basement and attic vent grills, a masonry building many
not have more than one air exchange an hour. This is
generally unacceptable for summer conditions, For these
Depending on the size, plan configuration, and ceiling
heights of a building it is often necessary 10 have louvered
opening equivalent to 5` o-13% of the square footage of each
1.4
li.OJ.J vi
floor space and a typical number of windows, may need 30-
sq. tt.l'2./�sq.m- .3 sq. „i):3±;.:>u vei ea openings per 1——
With Each window measuring 3'x5'(.9m x 1.5 in) or 15 sq. ft.
(1.3 sq.m), ±he equivaeen± of 2 to 4 windows per floor may
need f li ;RTi '0;�; lou:iers.
Sir -11 pre -formed louvers set into a plywood panel or small
;;�+_t'.•=n rr^oic±^rc ^�4 {?-i,^ h1c� nC;-....ns .., �..,^1= `- -.�. :��--
cannot orovide enough venniation 1 1 n m St n7oLst cim ar_es to
offset condensation, but this approach is certainly better
than no louvers at all. Louvers should be located to give
cross ventilation, interior doors should be fixed ajar at least
4" (10cm) to allow air to circulate, and hatches to the attic
should be left open.
Monitoring devices which can record internal temperature
and humidity levels can be invaluable in determining if the
internal climate is remaining stable. These units can be
powered by portable battery packs or can be wired into
electric sei:tce ;;pith data dovmloade-d ' laptop
;i,io ,aapwp
computers periodically (see fig. 20). This can also give long-
term information throughout the mothbaLin_g years. If it is
determined that there are inadequate air exchanges to keep
interior moisture levels under control, additional passive
ventilation can be increased, or, if there is electric service,
mechanical exhaust fans can be installed. One fan in a
small to inedium sized building can reduce the amount of
louvering substantially.
Figure 20. Portable monitors used to record temperature and humidity
Conditions in historic buildings during mothballing can help identify
ventilation needs. This data can be downloaded directly into a Iap top
computer an site. These monitors are especially helpful over the long term
for buildings adflt sip dfrcanl historic Interiors or tohicls are remaining
fsrrnished. If interiors are remaining damp or humid, additionai
ventilation should be added or the source of moisture controlled.
If electric fans are used, study the environmental conditions
of each property and determine if the fans should be
controlled by thermostats or automatic timers.
Humidistats, designed for enclosed climate control systems,
generally are difficult to adapt for open mothballing
conditions. Hew the system will draw in or z l;aust air is
through lower basement windows (see fig. 21). If the
basement is damn; it may be best to zone i± from the rest of
the vu.,- ing and exna'�st its ai.r.separately. Additionally,
less humid day air is nreferresa over da-inver n; lit air. =nd
fan.
the type O± Veritildt. 11 stlOuid not undermine the security
of the building- The rni-Af secux is itallailc,i;_ ;oSe Custural-
made grills well anchored to the window frame, often set in
T vv✓:3/Jyi �Jec]2i7 i'yi _-,ei3, 3Z,i "ie :i i�{`C 5'� }Ii Y,Tl asi �l bIng
heavy millwork louvers set into existing window openings
(refer back to fig.18). For buildings where security is not a
there has been no heat for a long time, it may be possible to
use lightweight galvanized metal grills in the window
openings (refer back to fig.7). A cost effective grill can be
made from the expanded metal mesh lath used by
plasterers and installed so t'nat the mesh fins shed rainwater
to the exterior.
Securing mechanical systems and utilities. At the outset,
it is important to determine which utilities and services,
such as electrical or telephone .lines, are kept and which are
cut off. As long as these services will not constitute a fire
Figure 21. This electric thermos tat/humidistat mounted in the attic vent
controls a modified ducted air ffan system. The unit uses temporary
exposed sheet metal ducts to pill air through the building and exhaust it
out of the basement. For over test years this fan system in combination
with 18" x 18" preforn ed louvers in selective roiruiotos has kept the
interior dty and with good air exchanges.
F�gtsrr F. Dflrrrtcerrfiiig the building's hialory, prtJVrhg>t'itt'matir
plaiia,tic evlldilioll Uf the Im ldrng iuill provide necessary
info onatian ou which to set priorities for stabilization and repair prior to
securing the building. Photo: Frederick Lindstrom, NABS.
By understanding the History of the resource, significant
elements, even though deteriorated, may be spared the
trash pile. For that reason alone, any materials removed
from the building or site as part of the stabilization effort
should be carefully scrutinized and, if appearing historic,
should be photographed, tagged with a number,
inventioried, and safely stored, preferably in the building,
for later retrieval (see fig. 5).
A site plan and schematic building floor plans can be used
to note important information for use when the building is
eventually preserved, restored, or rehabilitated. Each room
should be given a number and notations added to the plans
regarding the removal of important features to storage or
recording physical treatments undertaken as part of the
stabilization or repair.
Because a mothballing project may extend over a long
period of time, with many different people involved, clear
records should be kept and a building file established_
Copies of all important data, plans, photographs, and lists
of consultants or contractors who have worked on the
property should be added to the file as the job progresses.
Figirre 5. Loose or detached elements should be identified, tagged and
stored, preferably on site. Photo: NPS files.
Recording all actions taker, on tie building will be helpful
in the future.
The project coordinator should keep the building file
updated and give duplicate copies to the owner. A list of
emergency numbers, including the number of the ken
- -
Preparing a condition assessment of the building.:?
Condition iti0i assessment can provide ilie OwiieT with an
accurate overview of the current condition of the property.
T} :lam ,
protection during the mothballing years, undertaking a
iOrraiiv n aSSessii:.r it i� riigitiy reCvi.l uiienllci:i, vui it it--d
not be ey-baustive.
A modified condition assessment prepared h,, an architect
, prepared �-i
or preseryatioii specialist, and in borne case a Structural
engineer, will help set priorities for repairs necessary to
v i_i e1-aIuate the age r ncl ccuidition W li,e io lolo tng r__'+a3ur
elements: foundations; structural systems; exterior
materials; roofs and gutters; exterior porches and steps;
interior finishes; staircases; plumbing, electrical, mechanical
systems; special features such as chimneys; and site
drainage.
To record existing conditions of the building and site, it
will be necessary to dean debris from the building and to
remove unwanted or overgrown vegetation to expose
foundations. The interior should be emptied of its
furnishing furless provisions are made .—or mothballing
these as well), all debris removed, and the interior swept
with a broom. Buil_di_ng materials too deteriorated to repair,
or which have come detached, such as moldings, balusters,
and decorative plaster, and which can be used to guide later
preservation work, should be tagged, labeled and saved.
Photographs or a videotape of the exterior and all interior
spaces of the resource will provide an invaluable record of
,as is" conditions. if a videotape is made, oral commentary
can be provided on the significance of each space and
architectural feature. If 35mm photographic prints or slides
are made, they should be numbered, dated, and
appropriately identified. Photographs should be cross-
referenced with the room numbers on the schematic plans.
A systematic method for photographing should be
developed; for example, photograph each wall in a room
and then take a corner shot to get floor and ceiling portions
in the picture. Photograph any unusual details as well as
examples of each window and door type.
For historic buildings, the great advantage of a condition
assessment is that architectural features, both on the
exterior as well as the interior, can be rated on a scale of
their importance to the ii-degiity dlid si�,iLlfil:aiICU of the
building. Those features of the highest priority should
receive preference when repairs or protection measures are
outlined as part of the mothballing process. Potential
problems with protecting these features should be
identified so that appropriate interim solutions can be
selected. For example, if a building has always been heated
and if murals, decorative plaster walls, or examples of
patterned wall paper are identified as highly significant,
then special care should be taken to regulate the interior
climate and to monitor it adequately during the
trio-uned out with mundn strips to give a shadow line-
siiitululii2g nu2lti lite �,vhtdwvs. This level of derail is a good
incl.ic:ali,_,,n lhil lho building it-: �:ruluclud _illd •.•ahacd by the
iiwner and the rominiynif.y-
U 11w uu!.ulli -'-' h. �liiiZiCi J, �7171�1, CiUJe L11 51Lu1Zers dll
a i')ntP t(_ _n._ew .I-mttr- P['Pl"1 in?
rr- r
mafpr,al, ann ;Pf'))rp tnl pm in Trip f if prl position. Louvered
propped open behind the shutters.
am
Figure ic'. Historic louvered shutters make excellent security closures
with passive ventilation.
There is some benefit from keeping windows unboarded if
security is not a problem. The building will appear to be
occupied, and the natural air leakage around the windows
will assist in ventilating the interior. The presence of
natural light will also help when periodic inspections are
made. Rigid polycarbonate clear storm glazing panels may
be placed on. the window exterior to protect against glass
breakage. Because the sun's ultraviolet rays can cause
fading of floor finishes and wall surfaces, filtering pull
shades or inexpensive curtains may be options for reducing
this type of deterioration for significant interiors. Some
acrylic sheeting comes with built-in ultraviolet filters.
Securing the building from catas Lophic destruction from
fire, lightning, or arson will require additional security
devices. Lightning rods properly grounded should be a
first consideration if the building is in an area susceptible to
lightning storms. A high security fence should also be
installed if the property cannot be monitored closely. These
interventions do not require a power source for operation.
Since many buildings will not maintain electrical power,
there are some devices available using battery packs, such
as intrusion alarms, security lighting, and smoke detectors
which through audible horn alarms can alert nearby
neighbors. These balleiy packs must be replaced every 3
months to 2 years, depending on type and usage. In
combination with a cellular phone, they can also provide
some level of direct communication with police and fire
departments.
If at all possible, new temporary electric service should be
provided to the building (see fig. 17). Generally a telephone
F2g!LYe 1%. Jnei�2•ii;,i . cre;;25 w. ~- :' ' important jor Y,:nc)^j;Giiz^!1 v'%Ildingq
if they are located where fire andsecurity services are available. A
temporary electric service with battery back-up has been installed in this
btaildin4. In tYUSi n nln7'ma and inni7n tiro _"Iolre/""rn rletncirrc rrn rnrsp l
y, : i
line is needed as well. A hard wired security system for
intrusion and a combination rate -of -rise and smoke detector
can send an immediate signal for help directly to the fire
department and security service. Depending on whether or
not heart will be maintained in the building, the security
system should be designed accordingly. Some systems
cannot work below 32°F (0°C). Exterior lighting set on a
timer, photo electric sensor, or a motion/infra-red detection
device provides additional security.
Providing adequate ventilation to the interior. Once the
exterior has been made weatt'iertigi,t and secure, it IS
essential to provide adequate air exchange throughout the
building. Without adequate air exchange, humidity may
rise to unsafe levels, and mold, rot, and insect infestation
are likely to thrive (see fig. 18). The needs of each historic
resource must be individually evaluated because there are
so many variables that affect the performance of each
interior space once the building has been secured. A
.p .. eeh en Ud N d
faxed
Inopemble
Lower .eash
a d sl'
1, secure fame
Mesh�bg
1!
Window 01
Extedor Imft
Figure 18. Heavy duty wooden slated louvers were custom fabricated to
replace the deteriorated lower sash. The upper sash were rebuilt to retain
the historic appearance and to allow light into this vacant historic
building. Refer back to Fig. 1 for a vieru of the buildir2g. Pholu: Charles E.
Fisher, NPS. Drawing by Thomas Vitanza.
Figure i. iNun-hi-,turic nuueruals are ar,:,uropr2ate for 2nor22hailing l%,o(,° ;, -1410 a 111,11; r:r,- _l..-r:
historicevideaux :entaim"X fur fulure preberuulivrr. This ligh-lweight uluminum channel frame and
roofing covers the historic wooden shingle roof. Galvanized mesh panels secure the window openings
from intrusion by raccoons and other unwanted guests. Photo: Williamsport Preservation Training
Center, NPS.
emergency repair because it is often blown off by the wind
in a subsequent storm.
If the existing historic roof needs moderate repairs to make
it last an additional ten years, then these repairs should be
undertaken as a first priority. Replacing cracked or missing
shingles and tiles, securing loose flashing, and reanchoring
gutters and downspouts can often be done by a local
roofing contractor. If the roof is in poor condition, but the
historic materials and configuration are important, a new
temporary roof, such as a lightweight aluminum channel
System over the existing, might be considered (see fig. 7). If
the roofing is so deteriorated that it must be replaced and a
lightweight aluminum system is not affordable, various
inexpensive options might be considered. These include
covering the existing deteriorated roof with galvanized
corrugated metal roofing panels, or 90 lb. rolled roofing, or
a rubberized membrane (refer back to cover photo). These
alternatives should leave as much of the historic sheathing
and roofing in place as evidence for later preservation
treatments.
For masonry repairs, appropriate preservation approaches
are essential. For example, if repointing deteriorated brick
chimneys or walls is necessary to prevent serious moisture
penetration while the building is mothballed, the mortar
should match the historic mortar in composition, color, and
tooling. The use of hard Portland cement mortars or vapor -
impermeable waterproof coatings are not appropriate
solutions as they can cause extensive damage and are not
reversible treatments (see fig. 8).
For wood siding that is deteriorated, repairs necessary to
keep out moisture should be made; repainting is generally
warranted. Cracks around windows and doors can be
beneficial in providing ventilation to the interior and so
should only be caulked if needed to keep out bugs and
moisture. For very deteriorated wall surfaces on wooden
frame structures, it may be necessary to sheathe in plywood
panels, but £arC Shoiiid be iakcn to minimize uistaiiativn
damage by planning the location of the nailing or screw
ll •�,L ,R.
i
Figure 8. Appropriate mortar mixes should be
infill brtza?cm the brief and ufooden elcn!euls.
When full repairs are made during the
restoration phase, this soft mortar can easily be
removed and missing bricks replaced.
patterns or by installing panels over a frame of battens (see
fig. 9). Generally, however, it is better to repair deteriorated
feaiures than to cover them over_
Foundation damage may occur if water does not drain
away from the building. Run-off from gutters and down-
spouts should be directed far away from the foundation
wail by using long flexible extender pipes equal in length to
twice the depth of the basement or crawl space. If under-
ground drains are susceptible to clogging, it is recommen-
ded that the downspouts be disconnected from the drain
boot and attached to flexible piping. If gutters and down-
spouts are in bad condition, replace them with inexpensive
aluminum units.
Figure 9. Severely deteriorated wooden siding on a farm building has been
covered over with painted plywood panels as a temporary measure to
eliminate moisture penetration to the interior. Foundation vents and loose
floor boards allow air to circulate inside.
6
If there are no significant landscape or exposed archeo-
logical elements around the foundation, consideration
should be given to regrading the site if there is a docu-
mented drainage problem (see fig. 10). If building up the
grade, use a fiber mesh membrane to separate the new soil
from the old and slope the new soil 6 to 8 feet (200 cm-266
cm) away from the foundation making sure not to cover up
the dampcourse layer or come into contact with skirting
boards. To keep vegetation under control, put down a layer
of 6 mil black polyethylene sheeting or fiber mesh matting
covered with a 2"-4" (5-10 cm.) of washed gravel. If .the
building suffers a serious rising damp problem, it may be
advisable to eliminate the plastic sheeting to avoid trapping
ground moisture against foundations.
Figure 10. Regrading around the Booker Tenementat Colonial Williams-
burg has protected the mosonart fontnndation wall from excessive damp.
This building has been success a ly inothballed for over 10 years. Note the
attic and basement vents, the temporary stairs, and the informative sign
interpreting the history of this building.
Mothballing
The actual mothballing effort involves controlling the long-
term deterioration of the building while it is unoccupied as
well as finding methods to protect it from sudden loss by
fire or vandalism. This requires securing the building from
unwanted entry, providing adequate ventilation to the
interior, and shutting down or modifying existing utilities.
Once the building is de -activated or secured, the long-term
success will depend on periodic maintenance and
surveillance monitoring.
Securing the building from vandals, break-ins, and
natural disasters. Securing the building from sudden loss
is a critical aspect of mothballing. Because historic
buildings are irreplaceable, it is vital that vulnerable entry
points are sealed. If the building is located where fire and
security service is available then it is highly recommeded
that some form of monitoring or alarm devices be used.
To protect decorative features, such as mantels, lighting
fixtures, copper downspouts, iron roof cresting, or stained
glass windows from theft or vandalism, it may be advisable
to temporarily remove them to a more secure location if
they cannot be adequately protected within the structure.
Mothballed buildings are usually boarded up, particularly
on the first floor and basement, to protect fragile glass
windows from breaking and to reinforce entry points (see
fig. 11). Infill materials for closing door and window
openings include plywood, corrugated panels, metal grates,
chain fencing, metal grills, and cinder or cement blocks (see
fig. 12). The method of installation should not result in the
destruction of the opening and all associated sash, doors,
and frames should be protected or stored for future reuse.
Figarre 11. Urban buildings often +teed additional protections froru
unwanted entry and graffiti. This cornniercial building uses painted
plywood panels to cover expansive glass storefronts and chain link Fencing
is applied on top of the panels. The upper windows on the street sides have
been covered and painted to resemble 19th cen[it ry sash. Photo: Thoi nas
fester, NPS.
Generally exterior doors are reinforced and provided with
strong locks, but if weak historic doors would be damaged
or disfigured by adding reinforcement or new locks, they
may be removed temporarily and replaced with secure
modern doors (see fig. 13). Alternatively, security gates in a
new metal frame can be installed within existing door
openings, much like a storm door, leaving the historic door
in place. If plywood panels are installed over door
openings, they should be screwed in place, as opposed to
nailed, to avoid crowbar damage each time the panel is
removed. This also reduces pounding vibrations from
hammers and eliminates new nail holes each time the panel
is replaced.
For windows, the most common security feature is the
closure of the openings, this may be achieved with wooden
or pre -formed panels or, as needed, with metal sheets or
concrete blocks. Plywood panels, properly installed to
protect wooden frames and properly ventilated, are the
preferred treatment from a preservation standpoint.
There are a number of ways to set insert plywood panels
into windows. openings to avoid damage to frame and sash
(see fig. 14). One common method is to bring the upper
and lower sash of a double hung unit to the mid -point of
the opening and then to install pre-cut plywood panels
using long carriage bolts anchored into horizontal wooden
bracing, or strong backs, on the inside face of the window.
Another means is to build new wooden blocking frames set
into deeply recessed openings, for example in an industrial
mill or warehouse, and then to affix the plywood panel to
the blocking frame. If sash must be removed prior to
installing panels, they should be labeled and stored safely
within the building.
Plywood panels are usually 1 /2"-3/4" (1.25-1.875 cm.)
thick and made of exterior grade stock, such as CDX, or
Figure 12. First floor openings have been filled with cinderblocks and
doors, window sash and frames have been reproved for safe keephx . Nate
the security light over the windows and the use of a security meta door
with heavy duty locks. Photo: H. Ward fandl, NPS.
i
•.
Figure 13. If historic doors would be damaged by adding extra locks, they
should be removed and stored and new security doors added. At this
liglithouse, the historic door has been replaced with a ueev door (seen both
inside and outside) with an inset vent and nets deadbolt locks. The heavy
historic hinges ]rage not been damaged. Photo: Williamsport Preservation
Training Cen ter, NPS.
marine grade plywood. They should be painted to protect
them from delamination and to provide a neater
appearance. These panels may be painted to resemble
operable windows or treated decoratively (see fig. 15). With
extra attention to detail, the plywood panels can be
".n.
Ifwdk�
NarizonLal
z z a wooden bm�e
f/4w 2 14 blocking frame
.fused to masonry w.,&g
owl
Figam 14. A: Plan detail showing plywood security panel anchored with.
carriage bolts through to the inside horizontal bracing, or strong backs
8: flan detail shoraiirg section of plywood window panel attached to a
new pressure treated wood frame set within the masonry opening.
Ventilation should be included whenever possible or necessanj.
Figure 15. Painting trompe !'veil scenes on plyeyood panels is a
neighborhood friendly device. In addition, tine small sign at the bottom left
corner gives information for contactin S the orgaiiizatton responsible for
rite Care of the mothballed building. Photo: Lee H. Nelson, FAIR.
I
mothballing years. This might require retaining electrical
service to provide minimal heat in winter, fan exhaust in
summer, and humidity controls for the interior.
Stabilization
Stabilization as part of a mothballing project involves
correcting deficiencies to slow down the deterioration of the
building while it is vacant. Weakened structural members
that might fail altogether in the forthcoming years must be
braced or reinforced; insects and other pests removed and
discouraged from returning; and the building protected
from moisture damage both by weatherizing the exterior
envelope and by handling water run-off on the site. Even if
a modified use or caretaker services can eventually be
found for the building, the following steps should be
addressed.
Structurally stabilizing the building. While bracing may
have been required to make the building temporarily safe
for inspection, the condition assessment may reveal areas of
hidden structural damage. Roofs, foundations, walls,
interior framing, porches and dormers all have structural
components that may need added reinforcement.
Structural stabilization by a qualified contractor should be
done under the direction of a structural engineer or a
preservation specialist to ensure that the added weight of
the reinforcement can be sustained by the building and that
the new members do not harm historic finishes (see fig. 6).
Any major vertical post added during the stabilization
should be properly supported and, if necessary, taken to the
ground and underpinned.
rim
Figure 6. Interior bracing which will last the duration of the mothballing
will protect weakened structural members. Jethro Coffin House. Photo:
John Milner Architects.
If the building is in a northern climate, then the roof
framing must be able to hold substantial snow loads.
Bracing the roof at the ridge and mid -points should be
considered if sagging is apparent. Likewise, interior
framing around stair openings or under long ceiling spans
should be investigated. Underpinning or bracing structural
piers weakened by poor drainage patterns may be a good
precaution as well. Damage caused by insects, moisture, or
from other causes should be repaired or reinforced and, if
possible, the source of the damage removed. If features
such as porches and dormers are so severely deteriorated
that they must be removed, they should be documented,
photographed, and portions salvaged for storage prior to
removal.
If the building is in a southern or humid climate and
termites or other insects are a particular problem, the
foundation and floor framing should be inspected to ensure
that there are no major structural weaknesses. This can
usually be done by observation from the crawl space or
basement. For those structures where this is not possible, it
may be advisable to lift selective floor boards to expose the
floor framing. If there is evidence of pest damage,
particularly termites, active colonies should be treated and
the structural members reinforced or replaced, if necessary.
Controlling pests. Pests can be numerous and include
squirrels, raccoons, bats, mice, rats, snakes, termites, moths,
beetles, ants, bees and wasps, pigeons, and other birds.
Termites, beetles, and carpenter ants destroy wood. Mice,
too, gnaw wood as well as plaster, insulation, and electrical
wires. Pigeon and bat droppings not only damage wood
finishes but create a serious and sometimes deadly health
hazard.
If the property is infested with animals or insects, it is
important to get them out and to seal off their access to the
building. If necessary, exterminate and remove any nests or
hatching colonies. Chimney Flues may be closed off with
exterior grade plywood caps, properly ventilated, or
protected, with framed wire screens. Existing vents, grills,
and louvers in attics and crawl spaces should be screened
with bug mesh or heavy duty wire, depending on the type
of pest being controlled. It may be advantageous to have
damp or infected wood treated with insecticides (as
permitted by each state) or preservatives, such as borate, to
slow the rate of deterioration during the time that the
building is not in use.
Securing the exterior envelope from moisture penetration.
It is important to protect the exterior envelope from
moisture penetration before securing the building_ Leaks
from deteriorated or damaged roofing, from around
windows and doors, or through deteriorated materials, as
well as ground moisture from improper site run-off or
rising damp at foundations, can cause long-term damage to
interior finishes and structural systems. Any serious
deficiencies on the exterior, identified in the condition
assessment, should be addressed.
To the greatest extent possible, these weatherization efforts
should not harm historic materials. The project budget may
not allow deteriorated features to be fully repaired or
replaced in -kind. Non -historic or modern materials may be
used to cover historic surfaces temporarily, but these
treatments should not destroy valuable evidence necessary
for future preservation work. Temporary modifications
should be as visually compatible as possible with the
historic building.
Roofs are often the most vulnerable elements on the
building exterior and yet in some ways they are the easiest
element to stabilize for the long term, if done correctly.
"Quick fix" solutions, such as tar patches on slate roofs,
should be avoided as they will generally fail within a year
or so and may accelerate damage by trapping moisture.
They are difficult to undo later when more permanent
repairs are undertaken. Use of a tarpaulin over a leaking
roof should be thought of only as a very temporary
mechanical engineer or a specialist in interior climates
should be consulted, particularly for buildings with intact
and significant interiors. In some circumstances, providing
heat during the winter, evert at a minimal MI5° F (7C), and
utilizing forced -fan ventilation in summer will be
recommended and will require retaining electrical service.
For masonry buildings it is often helpful to keep the
interior temperature above the spring dew point to avoid
damaging condensation. In most buildings it is the need
for summer ventilation that outweighs the winter
requirements.
Many old buildings are inherently leaky due to loose -fitting
windows and floorboards and the lack of insulation. The
level of air exchange needed for each building, however,
will vary according to geographic location, the building's
construction, and its general size and configuration.
There are four critical climate zones when looking at the
type and amount of interior ventilation needed for a closed
up building. hot and dry (southwestern states); cold and
damp (Pacific northwest and northeastern states);
temperate and. humid (Mid -Atlantic states, coastal areas);
and hot and humid (southern states and the tropics). (See
fig. 19 for a chart outlining guidance on ventilation.)
Once closed up, a building interior will still be affected by
the temperature and humidity of the exterior. Without
proper ventilation, moisture from condensation may occur
and cause damage by wetting plaster, peeling paint,
staining woodwork, warping floors, and in some cases even
causing freeze thaw damage to plaster. IF moist conditions
persist in a property, structural damage can result from rot
or returning insects attracted to moist conditions. Poorly
mothballed masonry buildings, particularly in damp and
humid zones have been so damaged on the interior with
just one year of unventilated closure that none of the
interior finishes were salvageable when the buildings were
rehabilitated.
The absolute minimum air exchange for most mothballed
buildings consists of one to four air exchanges every hour;
one or two air exchanges per hour in winter and often twice
that amount in summer. Even this minimal exchange may
foster mold and mildew in damp climates, and so
monitoring the property during the stabilization period and
after the building has been secured will provide useful
information on the effectiveness of the ventilation solution.
There is no exact science for how much ventilation should
be provided for each building. There are, however, some
general rules of thumb. Buildings, such as adobe
structures, located in hot and and climates may need no
additional ventilation if they have been well weatherized
and no moisture is penetrating the interior. Also frame
buildings with natural cracks and fissures for air infiltration
may have a natural air exchange rate of 3 or 4 per hour, and
so in and as well as temperate climates may need no
additional ventilation once secured. The most difficult
VENTILATION GUIDANCE CHART
CLIMATE
AIR EXCHANGES
VENTILATION
Temperature
Winter air Summer air
Frame Buildings Masonry Buildings
Masonry Buildings
and
exchange exchange
passive louvering passive louvering
fan combination
Humidity
per hour per hour
of openings % of openings
one fan +
louvered louvered
% louvered
winter summer winter summer
summer
hot and dry
less than 1 less than 1
N/A N/A N/A N/A
N/A
Southwestern
areas
cold and damp
1 2-3
5% 10% 10% 30%
20%
Northeastern &
Pacific northwestern
areas
temperate/humid
2 3-4
10% 20% 20% 40%
30%
Mid -Atlantic &
coastal areas
hot and humid
3 4
20% 30% 40% 80%
40%
Southern states &
or more
or more
or more
tropical areas
Figure 19. This is a general
guide for the amount of louvering
which might be expected for a medium size residential structure with art average amount of
tvindows, attic, and crawl
spare ventilation. There is currently
research being doge on effective air exchanges, but each
project should be evaluated
individually. it will be noticed
front the chart that saununer louvering rerluirentents can be reduced with the use of an exhflust fall. Masouury builds gs need
more ventilation than frame
braidings. Chart prepared by Sharon
C. Park, A[A and Ernest A. Conrad, PE.
4
hazard, it is advisable to retain those which will help
protect the property. Since the electrical needs will be
limited in a vacant building, it is best to install a new
temporary electric line and panel (100 amp) so that all the
wiring is new and exposed. This will be much safer for the
building, and allows easy access for reading the meter (see
fig. 22).
Most heating systems are shut down in long term
mothballing. For furnaces fueled by oil, there are two
choices for dealing with the tank. Either it must be filled to
the top with oil to eliminate condensation or it should be
drained. If it remains empty for more than a year, it will
likely rust and not be reusable. Most tanks are drained if a
newer type of system is envisioned when the building is
put back into service. Gas systems with open flames should
be turned off unless there is regular maintenance and
frequent surveillance of the property. Gas lines are shut off
by the utility company.
If a hot water radiator system is retained for low levels of
heat, it generally must be modified to be a self-contained
system and the water supply is capped at the meter. This
Figure 22. All systems except ternporary electric have been shut off at this
residence which has been amtlrballed over 20 years. An electric meter and
700 amp parcel box have been set on a plywood panel at the front of the
building. It is used for interior lightin and various alarm systents. The
building, however, is showing signs ofmoisture problems with effiou-
rescent stains on the masonry indicating the need forgutter maintenance
and additional ventilation for the interior. The vegetation on the walls,
although picturesque, traps moisture and is damaging to the masonry.
Photo: H. Ward Jandl, NPS.
recirculating system protects the property from extensive
damage from burst pipes. Water is replaced with a
water/glycol mix and the reserve tank must also be filled
with this mixture. This keeps the modified system from
freezing, if there is a power failure. If water service is cut
off, pipes should be drained. Sewerage systems will require
special care as sewer gas is explosive. Either the traps must
be filled with glycol or the sewer line should be capped off
at the building line.
Developing a maintenance and monitoring plan. While
every effort may have been made to stabilize the property
and to slow the deterioration of materials, natural disasters,
storms, undetected leaks, and unwanted intrusion can still
occur. A regular schedule for surveillance, maintenance,
and monitoring should be established: (See fig. 23 for
maintenance chart).
MAINTENANCE CRART
periodic
regular drive by surveillance
❑ check attic during storms if possible
monthly walk arounds
❑ check entrances
❑ check window panes for breakage
❑ mowing as required
❑ check for graffiti or Vandalism
enter every 3 months to air out
❑ check for :musty air
❑ check for moisture damage
❑ check battery parks and monitoring
equipment
❑ check light bulbs
❑ check for evidence of pest intrusion
every b months; spring and fall
❑ site clean-up; pruning and trimming
❑ gutter and downspout check
❑ check crawlspace for pests
❑ clean out storm drains
every 12 months
❑ maintenance contract inspections
for equipment/utilities
❑ check roof for loose or missing shingles
❑ termite and pest inspection/treatment
❑ exterior materials spot repair and touch up
painting
❑ remove bird droppings or other stains from
exterior
❑ check and update building file
Figure 23. Maintenance Chart. Many of the tasks on the maintenance
chart can be done by volunteer help or service contracts. Regular visits to
the site will help detect intrusion, storm damage, or poor water drainage.
The fire and police departments should be notified that the
property will be vacant. A walk-through visit to familiarize
these officials with the building's location, construction
materials, and overall plan may be invaluable if they are
called on in the future.
The optimum schedule for surveillance
visits to the property will depend on the
location of the property and the number
of people who can assist with these
activities. The more frequent the visits
to check the property, the sooner that
water leaks or break-ins will be noticed.
Also, the more frequently the building is
entered, the better the air exchange. By
keeping the site clear and the building in
good repair, the community will know
that the building has not been aband-
oned (see fig. 24 ). The involvement of
neighbors and community groups in
caring for the property can ensure its
protection from a variety of catastrophic
circumstances.
The owner may utilize volunteers and
service companies to undertake the
work outlined in the maintenance chart.
Service companies on a maintenance contract can provide
yard, maintenance, and inspection services, and their
reports or itemized bills reflecting work undertaken should
be added to update the building file.
Figure 24, Once mothballed, a property must still be monitored and maintained. The openings in this
historic barn has been modified with a combination of woad louvers and metal mesh panels which require
little maintenance. The grounds are regularly morved, even inside the chain link secrarity fence. Photo:
Williamsport Preservation Training Center, NPS.
Components of a Mothballing Project
Document: Brearley House, New Jersey; 2% story center
hall plan house contains a high degree of integrity of
circa 1761 materials and significant early 19th century
additions. Deterioration was attributable to leaking roof,
unstable masonry at gables and chimneys, deteriorating
attic windows, poor site drainage, and partially detached
gutters. Mothballing efforts are required for approxi-
mately 7-10 years.
Stabilize: Remove bat droppings from attic using great
caution. Secure historic chimneys and gable ends with
plywood panels. Do not take historic chimneys down.
Reroof with asphalt shingles and reattach or add new
gutters and downspouts. Add extenders to downspouts.
Add bug screens to any ventilation areas. Add soil
around foundation and slope to gain positive drain; do
not excavate as this will disturb archeological evidence.
Mothball: Install security fence around the property.
Secure doors and windows with plywood panels ff'
exterior grade). Install preformed metal grills in
basement and attic openings. Add surface mounted
wiring for ionization smoke and fire detection with direct
wire to police and fire departments. Shut off heat and
drain pipes. Add window exhaust fan set on a
thermostatic control. Provide for periodic monitoring
and maintenance of the property.
Figure 25. Above is a summary of the tasks that were necessary in
order to protect this significant property while restoration fronds are
raised. Photographs: IVlicluiel Mills, Ford Farewell Mills Gatsch
Architects.
a. A view showing the exterior of the house in its mothballed condition.
IL
b. Plywood panels stabilize the
chimneys. Note the gable vents.
c. The exhaust fan has tamper-
proof housing.
11
12
MOTHBALLING CHECKLIST
Mothballing Checklist
In reviewing mothballing plans, the following checklist may help to
ensure that work items are not inadvertently omitted.
Moisture
• Is the roof watertight?
• Do the gutters retain their proper pitch and are they clean?
• Are downspout joints intact?
• Are drains unobstructed?
• Are windows and doors and their frames in good condition?
• Are masonry walls in good condition to seal out moisture?
• Is wood siding in good condition?
• Is site properly graded for water run-off?
• Is vegetation cleared from around the building foundation to avoid
trapping moisture?
Pests
• Have nests/pests been removed from the building's interior and
eaves?
• Are adequate screens in place to guard against pests?
• Has the building been inspected and treated for termites, carpenter
ants, and rodents?
• If toxic droppings from bats and pigeons are present, has a special
company been brought in for its disposal?
Housekeeping
• Have the following been removed from the interior: trash, hazardous
materials such as inflammable liquids, poisons, and paints and
canned goods that could freeze and burst?
• Is the interior broom -clean?
• Have furnishings been removed to a safe location?
• If furnishings are remaining in the building, are they properly
protected from dust, pests, ultraviolet light, and other potentially
harmful problems?
• Have significant architectural elements that have become detached
from the building been labeled and stored in a safe place?
• Is there a building file?
Security
• Have fire and police departments been notified that the building will
be mothballed?
• Are smoke and fire detectors in working order?
• Are the exterior doors and windows securely fastened?
• Are plans in place to monitor the building on a regular basis?
• Are the keys to the building in a secure but accessible location?
• Are the grounds being kept from becoming overgrown?
Utilities
• Have utility companies disconnected/shut off or fully inspected
water, gas, and electric lines?
• If the building will not remain heated, have water pipes been drained
and glycol added?
• If the electricity is to be left on, is the wiring in safe condition?
Ventilation
• Have steps been taken to ensure proper ventilation of the building?
• Have interior doors been left open for ventilation purposes?
• Has the secured building been checked within the last 3 months for
interior dampness or excessive humidity?
Yes , No 1 Date of action or comment.
Figure 26.. MOTHBALL CHECKLIST. This checklist will give the building owner or manager a handy reference guiae to items that snouia ne aaaressea wriest
mothballing a historic building. Prepared by H. Ward Jandl, NPS.
13