How to Inspect for Basement Leaks or Moisture - a Step in Detecting & Correcting Attic Condensation, Ice Dam Leaks, & Indoor Mold
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How to Inspect for Basement Leaks or Moisture as a Step in Detecting and Correcting Attic Condensation, Ice Dam Leaks, and Indoor Mold Contamination
Photo guide to clues indicating foundation leaks, basement leaks, water entry, high moisture
This article describes visual inspection methods and clues to detect basement leaks, water entry, flooding, or just high moisture problems. Finding where basement or crawl space water is coming from is the first step in fixing foundation leaks and wet basements. Here we illustrate common basement water entry leak points and signs.
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Wet Basement Diagnosis: a Guide to Inspecting for Basement Moisture, Leaks, Flood History, or Chronic Water Entry
Our opinion is that an expert inspection for a building basement or crawl space water entry problem begins outdoors with an inspection of the site, roof drainage, and similar features (see EXTERIOR WATER SOURCE ELIMINATION). But there are plenty of indoor clues of water leakage problems in buildings, and they can be found on every level of the structure. Here we begin with a catalog of basement or crawl space water entry signs seen from inside the structure.
This article explains procedures for inspecting in the building basement for signs of leaks and for sources of building soisture that could even be appearing as attic condensation or building mold.
The photograph at page top shows a very wet basement with water stains high on the foundation walls - telling us that the cause of this water entry is obviously not "rising damp" nor "construction over an underground stream".
The photo at left shows the author (DF) as a much younger man, pointing out that water stains on the foundation wall were originating at the very top of the foundation .
We describe common water entry or leak points in basements and crawl spaces as part of our discussion of both ATTIC LEAKS Moisture or Mold (where did that moisture originate?) and also WATER ENTRY in buildings (how to keep a building dry and at proper moisture levels).
These basement water entry inspection recommendations are based on 35 years of
building inspections, on the observation of the locations of moisture, mold, ice dams, condensation stains, Efflorescence & white or brown deposits and other clues in buildings,
and on the correlation of these clues with the roof venting conditions at those properties as well as frequent literature review and discussion among professionals.
Carson Dunlop Associates' sketch (left) shows some clues that easily indicate a history of wet basement troubles.
Readers should see WATER ENTRY in buildings and also see WET BASEMENT PREVENTION where we describe the basics of preventing basement or crawl space water entry, report a foundation collapse case study, and describe some simple steps that may cure a wet basement without major expense.
Cute Little Stuffed Animals Hiding Water Stains on Basement Floor and Door Trim
Basement trim water stains can be a good indicator of a history of wet basement floors. In our photos below we illustrate a cute attempt by someone to "hide" the water stains on basement door trim by placing little stuffed animals in the doorway. First the skunk, then the little squirrel happened to tip over, disclosing that the little rascals had been hiding water stains.
Moisture from a wet building basement or crawl space travels up through
the building where it can often condense in an attic, causing mold, frost, and even rot in a building if proper under-roof ventilation
is missing.
In the case of the basement shown at page top, we also need to correct the cause of basement water entry - in this case almost certainly it's a
roof spillage or gutter problem since we see water stains so high on the foundation walls.
In the basement shown at left there has been flooding, a mold problem, and perhaps other moisture damage in the building. But further investigation, both outside and indoors, will be needed to fully explain why water is on the basement floor.
Inspecting in the Basement for Sources of Building Leaks or Moisture Appearing as Attic Condensation
Because building leaks, water entry, and flooding and their related damage, ranging from structural damage to costly mold damage are such a large topic, we divide our building water problem inspection, discussion, and advice into these major categories:
Three Degrees of Building Wetness
We divide our wet building thinking into these degrees of severity: Damp, Wet, and Flooding. Here are our definitions of each of these levels of building water entry:
1. Damp or moist conditions in a building: in most areas basements and crawl spaces are damp; certainly anywhere that we have masonry construction below ground level we can expect higher humidity and dampness; depending on the degree of moisture and other building conditions, damp or moist conditions can cause mold or other building problems.
Watch out: as we demonstrate at MOISTURE METER STUDY, using infrared scanners will not reliably detect old or historic water entry leakage if the leak area happens to be dry at the time of the scan. A similar limitation applies to use of moisture meters. Evidence of moisture is a reliable indicator, but absence of moisture is not - moisture may be present but beyond the ability of the instrument to reach, such as a wet inner surface of exterior wall sheathing.
2. Wet conditions in a building: some limited areas of a basement or crawl space floor have been or are regularly wet or showing puddles in some weather conditions, but water does not extend over the entire building floor.
As our photo shows, water seeps up through cracks in this Staatsburg NY basement floor. Staatsburg is built on a wet swampy flat area in Dutchess County. If your basement is dry, you probably don't live in Staatsburg.
3. Flood conditions in a building: water extends over the entire building floor, extending from a fraction of an inch to virtually filling the building and even flooding upper floor levels if a building is located in a flood plain or flooded area.
At below left our client points out that basement flooding had reached at least this far up from the basement floor - leaving mud on the bottom of an expansion tank. In this neighborhood we also found flood-deposited mud atop sill plates at foundation wall tops.
Our second photo, at above right, is really an outdoor clue, though you might see this from the inside: it's a foundation flood vent, indicating that the builder thinks the building is in a flood prone area.
Photographs of Signs of Basement Water Entry
Another important observation about the causes of and cures for attic moisture condensation
is that buildings with an attic moisture condensation problem very often have
wet basement or crawl space water entry problems.
In fact even before entering an attic to inspect for moisture, while still outside
I often look at excessively curled asphalt shingle roofs and suspect a basement water entry problem.
In the photograph shown here our client points to moisture stains originating high on a masonry block
basement wall. The presence of moisture staining high on the wall confirm that the water source is
either roof runoff spillage against the foundation or a surface water runoff problem.
This is not
a case of "rising groundwater" or "a buried stream".
A careful study of the pattern and location
of moisture stains gives important diagnostic information about the probable source of basement water entry
and of leaks or building moisture problems in general.
Sump Pumps As Basement Water Entry Indicators
Carson Dunlop Associates' sketches (left and below) show some additional clues that easily indicate a history of wet basement troubles as well as how people may be dealing with recurrent basement flooding by an interior perimeter drain, exterior drainage, or sump pumps.
Watch out: basement leaks and high moisture travel throughout the building
Actual basement flooding or simply high basement moisture forms a moisture source in a building that
affects the entire structure.
An attic inspection that discovers attic condensation should direct you to go back to inspect the basement for leaks. See ATTIC CONDENSATION CAUSE & CURE
Our photos show part of a collection of basement sump pumps found in a single location - a strong indicator of a history of basement water entry trouble.
Moist air rises through the building by natural convection, eventually
finding its way into the attic or roof cavity. If the roof cavity is not adequately vented, moisture
will condense there leading to building damage and perhaps an attic mold problem.
Simply cleaning up or removing
attic mold such as moldy roof plywood, framing, or mold contaminated attic insulation
may not provide a lasting cure for attic mold.
In fact even correcting the inadequate attic venting (as we describe below),
will be insufficient if a basement or crawl space source of attic moisture was also present and
if it remains un remediated.
Signs of Basement Water Entry and Leakage: rot, stains, water marks
Actual
Carson Dunlop Associates' sketch (left) shows additional clues that easily indicate a history of wet basement: rot at floro joist ends and sill plates atop the foundation wall.
On occasion we find mud in this location, indicating perhaps that the home was previously flooded.
This photo shows strong evidence of a history of water entry through the foundation wall at right: stains on the bottom stair riser appear to emanate right out of the foundation wall.
And that projection of concrete poured along the wall bottom is often a sign of an attempt to retrofit a water seal at a point of water seepage at the wall/floor juncture. If that guess is correct, that might explain why the stair riser is water stained - the concrete "seal" couldn't extend between the stairs and wall without demolishing and rebuilding the stairs themselves, so behind the first stair tread a leak point remained un-sealed.
Rusted Metal Beams or Lally Columns Can Indicate Basement Water Entry or High Moisture
Carson Dunlop Associates' sketch (left) shows places to look for rust as an indicator of basement leaks or high moisture levels:
Rust stains at drywall nails or screws
Rusted or stained carpet tack strips
Heavy rust especially at the base of steel Lally columns or on steel beams (see our photo, below).
Rusted metal screws, nails, and structural connectors connected to the foundation wall
Rusted feet on a basement-located oil tank
Rust or water stains on the bottom of heating equipment that rests on or close to floor level, or if you see that heating equipment has been installed on concrete blocks to lift it above floor level that may also indicate a concer for a history of leaks and water entry.
An example of Carson Dunlop's tip to look for rust or water stains on metal beams is shown in our photograph (below left). This steel girder was supporting a modular home that had been driven in rain and received extensive highway-blown water inside the structure.
Our second structural rust photo (above right) was very exciting. We were inspecting a house on Long Island when the owner mentioned that she had pumps running 24/7 in the basement to keep the bay at bay. All of the Lally columns (some were just hollow pipes not real Lallys) were badly rusted. Details are at COLUMNS & POSTS, DEFECTS. Also see FLOOD DAMAGE TO FOUNDATIONS. For problems with settlement of piers below Lally columns see Settlement Cracks in Slabs.
Flood lines on Basement Furnishings or Equipment or Flood Vents indicate Flooding
Our photos below are clear examples of a severe basement flood. If you inspect closely you may find multiple apparent high-water lines on basement surfaces or contents. Don't assume this is necessarily multiple flooding events. The lines may be multiple separate events, or they may be stages in lowering of the water level in a flooded basement. Additional clues (such as rotted floor trim) can distinguish between a one-time basement flood and recurrent water entry.
Our second photo shows our inspection client taking a break next to flood lines on a warm air furnace base.
More basement water entry clues: details on walls
Carson Dunlop Associates' sketch (left) shows additional clues that may point out a history of wet basements:
Concrete block or poured concrete foundation wall spalling
Patches in finished drywall
Deterioration of drywall at or close to floor level
Stains or rotted floor baseboard trim
Where plaster is applied directly to the foundation walls look for soft spots or effloresence.
Still More Signs of Basement Water Entry & Moisture Sources
Concrete Foundation Wall Leak Points - Leaks at Cold Pour Joints
At Cold Pour Joints we discuss the cause and possible significance of cold pour joints on a poured concrete foundation wall. Usually a cold pour joint in a concrete wall is only of cosmetic import. But if sufficient time elapsed between successive concrete pours into an individual foundation wall, the lower wall concrete "sets up" enough that there is a poor bond between that layer and the next pour of concrete into the wall forms.
The result can be not only a visible "crack" in the poured concrete wall, but this cold pour joint may leak surface water or ground water into the building. Our photo (above left) shows white efflorescence stains left by a long history of building foundation leaks at a cold pour joint on this building.
Also notice that in the corner there was some efflorescence above the cold pour joint, while at the second photo (above right) there was efflorescence and leakage only below the cold pour joint. At both of these locations a roof drainage downspout had spilled water against the building wall for many years.
Often, including at this building, the leaks at the concrete wall cold pour joint occurred primarily, or in this case only, where there was a concentration of water spillage outside the building. In our two photos above, the two areas of leakage, at the cold pour joint in the building corner, and further along to the right of that corner in a lower cold pour joint leak, you can see that water leakage was concentrated (shown by the white efflorescence on the wall).
Our photo at left shows a closeup of white mineral salts (efflorescence is discussed at Efflorescence & white or brown deposits) left on the concrete foundation wall below a leaky cold pour joint.
So routing downspouts well away from the building and terminating the downspout at a location where water will continue to run away from the building rather than back towards it would probably have prevented most or all of this basement water entry problem as well as the mold contamination that it led to.
Concrete Foundation Leak Points - at Form Ties
Form ties are usually steel wires or rods that secure the front and back foundation wall forms in place during a concrete foundation wall pour. After the wall has cured the ties are cut or broken off.
On (usually rare) occasions we find water leaks through the poured foundation wall at the form ties, as shown by the stains in this photo.
The significant volume of leakage along this basement wall suggests that there was an outdoor problem with surface runoff or mis-handling of roof runoff around the building.
Concrete Foundation Leak Points - at Wall Cracks
Our photo (left) shows stains at a poured concrete foundation wall crack that had been covered by insulation, drywall, and paneling in a finished basement.
Episodic water leaks through this crack sent water into the wall cavity and below a raised floor in the basement where it was un-noticed until a severe rainfall and leak quantity brought enough water into the basement for water to appear above the finished floor level.
The exact location of the leak was apparent once we removed the basement wall and floor coverings - a step that was necessitated by a mold-contamination problem that originated in basement water leakage.
Concrete Foundation Leak Points - at Floor Slab Shrinkage Gaps & Cold Pour Joints
Our photo (below left) shows a normal concrete floor slab shrinkage gap where the floor (under our pen) abuts a poured concrete foundation wall.
The brown material on the floor is mud which we suspect rose up from below the slab when surface runoff or ground water saturated the soils around and under the floor slab.
Our second photo, above right, shows minor seepage through the concrete foundation wall at cold pour joints. Most cold pour joints are not leaky, but this one was.
Concrete Block Foundation Leakage at Footing Drains
There are two common explanations for the water seepage pattern shown here:
1. The footing drain is absent or clogged - notice that the wall at right looks pretty dry except along that first course of block. This might suggest that water is not running down this foundation wall from above.
2. Sometimes a serious water source along one foundation wall will enter the block walls and travel around to other sides of the foundation through the hollow cores of the masonry blocks. This circumnavigation of the foundation wall interior through the hollow core concrete blocks is particularly mobile if the basement floor slab is poured half-way up the first course of block, forming a dam that raises water level inside the wall and encouraging water travel in the wall interior.
EIFS Synethetic Stucco Wall or Window Sill Exterior Leaks Show Up in Basement or Garage
Our photo (left) shows water stains down a poured concrete foundation below an EIFS-clad new home.
Leaks at window sills and other exterior EIFS wall penetrations allowed wind-blown rain (or spray from a garden hose) to soak the wall cavity, wall insulation, and to appear as streams down the foundation wall beginning at a height several feet above ground level - compelling evidence that this is not a roof spillage nor ground water leak. It's an exterior wall leak showing up in the basement.
Basement floor tiles indicate building leak history
Water-damaged, curling, lifting floor tiles are a likely indicator of a basement flood or recurrent wet basement floors. In this basement, all of the floor tiles had come loose, but the rectangular marks show where they had previously been located.
The use of plastic floor baseboard trim (plastic cove molding) in an older home may indicate that water-damaged wood trim or even water-damaged lower portion of drywall close to the floor have been covered with this wider, water-resistant material.
Buckling laminate or wood flooring may indicate high moisture or basement leakage
High moisture, even without actual flooding, can cause wood flooring and some laminate floors to buckle.
This laminate engineered wood floor was badly buckled and eventually just popped up after water had leaked under the floor installation.
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Alan Carson Carson Dunlop Associates, Toronto, Ontario. Mr. Carson is a home inspection professional, educator, researcher, writer, and a principal of Carson Dunlop Associates, a Toronto home inspection and education firm. Mr. Carson is a past president of ASHI, the American Society of Home Inspectors
Some great illustrations of the proper under-roof ventilation pathways are offered by Carson Dunlop.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06 & 12/08
John Annunziata, P.E. - NY Metro ASHI during informal chapter discussions about roof and attic ventilation options (1986-1996).
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
"The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
"Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
Access Ramp building codes:
UBC 1003.3.4.3
BOCA 1016.3
ADA 4.8.2
IBC 1010.2
Access Ramp Standards:
ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standards)
American Plywood Association, APA, "Portland Manufacturing Company, No. 1, a series of monographs on the history of plywood manufacturing",Plywood Pioneers Association, 31 March, 1967, www.apawood.org
Asbestos: How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials
Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print).
Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
Building Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ... In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
How could homes be designed and built more efficiently?
What kinds of construction and production techniques worked well and which did not?
How did people use different kinds of spaces in their homes?
What roles did community planning, zoning, and interior design play in how neighborhoods worked
"An Example of Colonial Paneling", Norman Morrison Isham, The Metropolitan Museum of Art Bulletin, Vol. 6, No. 5 (May, 1911), pp. 112-116, available by JSTOR.
Dust from the World Trade Center collapse following the 9/11/01 attack: the lower floors of this building contained spray-on fire-proofing asbestos materials.
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438 "Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "
Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
Lighting, proper use of: proper aiming of a good flashlight can disclose hard to see but toxic light or white mold colonies on walls.
Pergo AB, division of Perstorp AB, is a Swedish manufacturer or modern laminate flooring products. Information about the U.S. company can be found at http://www.pergo.com where we obtained historical data used in our discussion of the age of flooring materials in buildings.
Plank House Construction: weblog from plankhouse.wordpress.com/2009/01/25/plank-house-construction/ and where plank houses were built by native Americans, see
Large 1:6 Scale Plank House Construction / P8094228,
Photographer: Mike Meuser
06/12/2007 documented at yurokplankhouse.com where scale model Museum quality Yurok Plank Houses are being sold to raise money for the Blue Creek - Ah Pah Traditional Yurok Village project.
Re-Bath, tub lining products is a bath tub relining manufacturer and distributor located in Tempe, Arizona - see rebath.com
Slips, Trips, Missteps and Their Consequences, Second Edition, Gary M. Bakken, H. Harvey Cohen,A. S. Hyde, Jon R. Abele, ISBN-13: 978-1-933264-01-1 or
ISBN 10: 1-933264-01-2,
available from the publisher, Lawyers ^ Judges Publishing Company,Inc., www.lawyersandjudges.com sales@lawyersandjudges.com and also from the InspectAPedia Bookstore (Amazon.com)
The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
How to Clean Moldy Wood Framing & Sheathing How to clean/seal mold from/on exposed lumber or plywood subfloor or roof sheathing indoors - some suggestions based on our field and laboratory research
Lighting, proper use of: proper aiming of a good flashlight can disclose hard to see but toxic light or white mold colonies on walls.
Manufactured & Modular Homes: Modular Building Systems Association, MBSA, modularhousing.com, is a trade association promoting and providing links to contact modular builders in North America. Also see the Manufactured Home Owners Association, MHOAA, at www.mhoaa.us. The Manufactured Home Owners Association of America is a National Organization dedicated to the protection of the rights of all people living in Manufactured Housing in the United States.
Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
Mold-Resistant Building Practices, advice from an expert on how to prevent mold after a building flood and how to prevent mold growth in buildings by selection of building materials and by anti-mold construction details.
Slips, Trips, Missteps and Their Consequences, Gary M. Bakken, H. Harvey Cohen, Jon R. Abele, Alvin S. Hyde, Cindy A. LaRue, Lawyers and Judges Publishing; 2 edition (April 2006), ISBN-10: 1933264012 ISBN-13: 978-1933264011
Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
"The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
Weaver: Beaver Board and Upson Board:
Beaver Board and Upson Board: History and Conservation of Early Wallboard, Shelby Weaver,
APT Bulletin, Vol. 28, No. 2/3 (1997), pp. 71-78, Association for Preservation Technology International (APT), available online at JSTOR.