Crawl space Insulation & Heat Loss Inspection Guide
Crawl space mold inspection, detection, removal, prevention, testing
Questions & answers about diagnosing and fixing problems in building crawl spaces
This building crawl space article series explains how to inspect, diagnose problems in, and repair building crawl spaces, including crawl space insulation & leaks or moisture control. Information is provided about visual clues of crawl space problems, such as
evidence of a history of leaks, mold contamination, insect damage, structural damage, flooding, as well as evidence of hazardous materials and conditions such as the probable presence of animal allergens, asbestos, or mold.
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers nor with topics or services discussed at this website.
The sketch of the role of a dirt floor crawl space in building moisture and mold problems (above) is courtesy of Carson Dunlop.
Crawl Areas: Defect Recognition, Repair, Prevention for Building Crawl Space Leaks, Mold, Insulation & Ventilation
The list of concerns or problems in or due to building crawl spaces is long as would be a list of opinions about what to do with crawl spaces, wet crawl spaces, moldy crawl spaces, or crawl space insulation and ventilation. Good building science combined with a lot of experience has led to some good information on how to correct crawl space problems. Here we list crawl space problem inspection, diagnosis, and cure. Here are some things to watch out for in a building crawl space:
Crawl spaces may be unsafe to enter due to risk of asbestos, chemicals, collapse, hantavirus, mold, rodents, sewage, snakes or even electrical shock hazards. See CRAWL SPACE SAFETY ADVICE where we explain when you should not even enter a crawl space. Also see CRAWLSPACE MOLD ADVICE. Do not enter such an area without protective gear and appropriate training.
Crawl spaces may be a source of building water, moisture, leaks, mold - see CRAWL SPACE DRYOUT PROCEDURES - this is the key article on dealing with wet or damp crawl spaces and related problems in buildings. Also see CRAWL SPACE GROUND COVERS. For avoiding foundation collapse in areas prone to flooding, also see FLOOD VENTS & FLOOD PORTS. WATER ENTRY in BUILDINGS is the home page for our series of articles on the causes and cures of high indoor moisture, wet basements, wet crawl spaces, and moisture related problems like attic condensation and mold. Also see Mold in Fiberglass Insulation.
Crawl spaces may be a cause of building energy loss or increased heating bills, especially if the crawl space is improperly insulated and/or vented. See CRAWL SPACE DRYOUT PROCEDURES where we also discuss the change in thinking between the old-school idea of venting crawl spaces to the current best practice of converting crawl areas to a conditioned space, explained further at CRAWL SPACE GROUND COVERS.
Crawl spaces are often a reservoir of hidden structural, rot, insect, mold, water, contaminant, or other problems, largely because most crawl areas are difficult to enter and are rarely inspected. Rot, fungus, termites, carpenter ants, powder post beetles, & other wood destroying organisms are a special risk in crawl areas, especially if fiberglass insulation was run from crawl space floor right up the wall and onto building framing or flooring.
Key Crawl Space Inspection, Diagnosis, Repair articles
COMBUSTION AIR for TIGHT BUILDINGS - if you have heating equipment in a crawl space be sure there is adequate combustion air in and venting of exhaust gases out
EFFLORESCENCE, Salts & White / Brown Deposits - don't waste money testing white goop for crawl space mold if it is efflorescence, but efflorescence does indicate a source of crawl space moisture that needs attention
FIBERGLASS INSULATION - can become mold contaminated in a crawl area, leading to mold contamination in the occupied space above
Heat Loss in Buildings, how to determine and calculate heat loss from a building crawl space (or heat gain in a cooling climate), how to evaluate building insulation, & how to insulate buildings
Humidity: How Low Should You Keep the crawl space humidity to avoid a mold problem
Rot, fungus, termites, carpenter ants, powder post beetles, & other wood destroying organisms are a special risk in crawl areas
Thermal Tracking & Stains how to recognize thermal tracking or thermal bridging & how to diagnose Stains on Ceilings & Walls, Building Air Leaks & Insulation Defects, as well as other indoor air quality or building concerns
WATER ENTRY in BUILDINGS series of articles on the causes and cures of high indoor moisture, wet basements, wet crawl spaces, and moisture related problems like attic condensation and mold.
WINTERIZE A BUILDING - how to protect a building and its plumbing and mechanical systems from freeze damage, how to shut down a building to minimize damage; how to de-winterize a building.
Frequently-Asked Questions (FAQs) about wet or damp crawl spaces, crawl space mold, crawl space hazards
Question: What is the Best Approach to Drying out a Flooding Crawl Space?
I have been battling crawl-space moisture and puddling problems for about 2 years now and am desperately requesting your pro-bono assistance and consultations. I am living in a senior citizen retirement house that I inherited from my deceased parents. I am on total permanent Social Security Disability for almost 10 years now. This is my only income which is $1300 per month.
After many many hours, weeks, and months of calling people, searching the internet etc., I came across your excellent article and web-site. I knew from reading your material that you are the people I need to help me navigate properly through all the people and companies I have been in contact with. I didn't, (and still don't) know where to start first.
This house was built in a senior citizen community where the water-table is high and the ground gets soaked around the perimeter of the foundation and other areas of the property during heavy and even not-so-heavy rains. I have a dirt crawl-space that gets puddles in it and had a termite inspector put a not-so-good sump pump in it that the water never reaches.
Then another person told me I had mold in there and several other people told me I didn't. Had an excavator look and he told me the dirt needed to be pitched and leveled but he's never done that in a crawl space before. Even when the termite guy dug some trenches, the water just sat in the trenches.
I had water-proofing companies come and tell me differing things, all wanting thousands of dollars and none guaranteeing anything. Some say encapsulation and inside french drains, some say that's not good and outside french drains, some say putting more wall wells and vents in or digging the dirt out more so that water won't come in the vents. I consuted with a hydroscience company that also said to just clean the gutters (which I already had done and they have that netting over them so they weren't too bad) and clean or get new downspouts. And it goes on and on and on.
I want to get the right people to start at the right place but am thoroughly confused now. I got free weaherization from the state because I am on limited income and on medicare, paad, and food stamps. They wrapped the pipes down there and put in a cheap black moisture barrier and fiberglass insulation on top.
I have heard and read that may make the moisture and mold problems worse. Recently I have noticed a mildewy moldy smell coming from my forced-air gas baseboard registers and read when I put the heat on it will spread and contaminate the house even more with mold spores.
I know my carpeting needs to be removed and house painted but have been putting if off because I realize I need to get the water/moisture issues identified first as well as the mold problems corrected. I had the bathroom painted in April and shortly after I noticed the paint cracked on the ceiling which is near the attic where I suspect there may be water/mold damage.
This, I think is probably from a couple of years ago when my central air was dripping and we had a new a/c put in.
So I am asking you for your help in testing for molds and dust particle analysis as well as directing me to the correct professionals in the proper order to resolve all these issues.
Thank you very much for your kind consideration and assistance in advance,
- B.B., Toms River NJ
Reply: A Step by Step Approach to Wet Crawl Spaces
Thank you for the interesting or I should say challenging water entry question - it helps us realize where we need to work on making our text more clear or more complete.
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem.
That said, here are some things to consider,interspresed with your remarks from your own note:
I have a dirt crawl-space that gets puddles in it and had a termite inspector put a not-so-good sump pump in it that the water never reaches.
Puddles in a dirt crawl space below a home, even just wet soils, invite problems with building mold contamination and wood destroying insects such as termites and carpenter ants. It's certainly a problem that needs correction. Divide your wet crawl space solution thinking into these three main topics:
how to stop water from entering the crawl area
how to get rid of water and moisture therein
how to evaluate the building for related damage (mold, termites) that may need attention
Then another person told me I had mold in there and several other people told me I didn't.
If mold is not visible and there are no health complaints there might not be a big mold problem, or there may be one but as mold does not affect everyone to the same degree, you may not have noticed it.
See our article on MOLD EXPERT, WHEN TO HIRE, for help in deciding if it is cost justified or otherwise appropriate to perform some expert inspecting and testing for mold. Don't rely on mold tests without an inspection by an expert.
If your expert finds that there is a significant mold problem originating in the crawl area, also see CRAWLSPACE MOLD ADVICE.
Had an excavator look and he told me the dirt needed to be pitched and leveled but he's never done that in a crawl space before.
I agree with your excavator - if the crawl space is not sloped to a common drain point you cannot easily remove water therein. It's best not to have water enter the crawl in the first place since if we let water enter but then pump it out, we are still facing mold and insect troubles stemming from high moisture in the area.
Even when the termite guy dug some trenches, the water just sat in the trenches.
This means that the soil has a slow percolation rate. Trenches need to be pitched to a common drain point where a sump pump removes water.
I had water-proofing companies come and tell me differing things, all wanting thousands of dollars and none guaranteeing anything.
The number one water entry step is gutter and leader maintenance.
You think your gutters are "clean" but a mere handful of leaves can clog a downspout and lead to gutter overflow and spillage around the building so you will want to inspect the gutter and downspout system during a heavy rainfall. Make sure downspouts drain far enough from the building that water does not enter at those locations.
Some say encapsulation and inside french drains, some say that's not good and outside french drains, some say putting more wall wells and vents in or digging the dirt out more so that water won't come in the vents.
Simpler and less expensive are steps to stop water entry from outside, combined with a sloped crawl surface to a common sump pit (see SUMP PUMPS), combined with 6 mil poly over the dirt to stop pumping soil moisture into the area (see CRAWL SPACE VAPOR BARRIER).
I consuted with a hydroscience company that also said to just clean the gutters (which I already had done and they have that netting over them so they weren't too bad) and clean or get new downspouts.
Your hydroscience company was pointing to the number one cause of wet crawl spaces
Questions & Answers regarding this article
Questions & answers about diagnosing and fixing problems in building crawl spaces
Question: Problems with odors from poly vapor barriers on crawl space floors
I have a dirt crawl space under my bedroom floor which is causing me some health problems. I am extremely allergic to mold and my husband put 6 ply visqueen on dirt floor & 2 vents in block. I became extremely sick from visqueen order and I removed it, still feeling sick but not as bad. I am closing off the 2 vents to avoid anymore air flow in crawl space.
However, I want to put something down overtop the dirt floor and adhere it to the concrete walls to avoid any further allergy problems plus have cleaner air flow in our bedroom....but the plastic's are mostly made of polyurethene which might be sensitive too also or with the combinations and exposure to the dirt floor caused more airborne mold spores & allergies.
Even in the middle of the night I feel like something is crawling & biting me....and my husband is coughing something awful and we both have headaches & sinus, breathing problems too, nausea, disoriented and confusion. I am very worried about this and want it repaired ASAP before its too late. I am looking for something to cover & seal the dirtflooring but want something that is chemical free. I would also like to know if it would be wise to put insulation up underneath the bedroom floor to help prevent from coming up thru the floor into the bedroom? Any information, suggestions, ideas would be greatly appreciated. thank you! - Suzanne
Reply:
Suzanne, When choosing a poly vapor barrier for a crawl space beneath your home, indeed it makes sense to do a sniff test - some of the white 6-mil plastic vapor barriers I've seen used by building remediators were virtually odorless;
In other cases we placed the poly outdoors in the sun for a few days to help it complete its outgassing before putting it down in a crawl area. Indeed I've been bothered by horrible odor outgassing from some poly ground covers too.
You could also pour a concrete floor in the crawl area - a more costly solution that has its own concerns with temporary high moisture levels. More suggestions are at CRAWL SPACE GROUND COVERS where we describe ways to cover up dirt and stop moisture movement into the structure from the crawl space floor. Also see VAPOR BARRIERS & CONDENSATION in BUILDINGS.
But I wouldn't be too hasty to assume that plastic odors are the only concern, perhaps not even the main one, in your home. A damp dirt floor crawl space could have led to a mold problem or there could be other health and IAQ issues coming from that location or even elsewhere in the building. For example there could be hard-to-see mold contamination on wood surfaces or in fiberglass insulation if it has been exposed to wet or dampness. (See INSULATION MOLD).
At MOLD INFORMATION CENTER (article link at page left) you can find MOLD EXPERT, WHEN TO HIRE - that might help you decide if it's appropriate to bring in an expert for a more thorough building inspection and perhaps some tests. I'd be reluctant to ONLY blame the plastic odors (though those have bothered me too at times).
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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
Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
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
Brick Nogging, Historical Investigation and Contemporary Repair, Construction Specifier, April 2006. Historical use of brick in timber-framed buildings, drawing on the investigations of the Kent Tavern in Calais, VT.
"Brick nogging is a European method of construction which was brought to the new world in the early-nineteenth century. It was a common construction method that employed masonry as infill between the vertical uprights of wood framing." -- quoting the web article review.
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.
Piquet Wall Construction: See this photo of
piquet wall construction - involving timber-framed wall construction with long top girts, diagonal timber bracing, and small diameter logs
placed vertically along with concrete chinking to fill in the wall plane.
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
Rubblestone Wall Filler: See this Lartigue House using exterior-exposed rubblestone filler between vertical timbers of a post and beam-framed Canadian building.
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; ISBN-10: 1933264012 ISBN-13: 978-1933264011
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)
Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
"The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
"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
"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.
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