The four things a report is not

A crawl space line in an inspection report is one of four separate pieces of information, and the trouble starts when a reader assumes it is all four. It is worth being pedantic about this, because every downstream frustration in the process traces back to it.

Stage What it is Who produces it What goes wrong when it is skipped
Observation A condition somebody saw and wrote down. "Standing water present in the northeast corner." "Vapor barrier torn and displaced." It is a description of what the crawl space looked like on the day, and it is what a home inspection is built to produce. The home inspector, whose job under Washington’s standards of practice is to report the condition of specific systems and components and to identify conditions that may need a specialist. Reading an observation as though it carried a cause and a price. The Washington standards of practice do not require the inspector to determine either.
Diagnosis Why the condition exists. Water in a crawl space can be groundwater rising through the soil, surface water entering through a foundation wall, a failed downspout discharging beside the footing, or a supply line leaking under the house. Those are four different problems that look identical in a photograph. A specialist evaluating the crawl space, often with the benefit of knowing what the weather has done recently. Sometimes a plumber before anyone else, because a plumbing leak is the cheapest cause to rule out and the most expensive one to fix by accident. Skipping it. A repair aimed at the wrong cause fails, and it fails a season later, when the contractor who sold it is no longer the one you are talking to.
Scope The specific work proposed to correct the diagnosed cause, written as line items. Not "encapsulation" — a list saying what goes in, what comes out, what is sealed to what, and what is not included. The contractor, in writing, before any number is attached to it. Comparing two quotes that name the same service and describe different work. Two crawl space bids for one house can differ by thousands for this reason alone, and it is invisible until the line items are set side by side.
Quote A price attached to a defined scope. Without the scope, it is a number attached to a word. The contractor, in writing, together with the disclosure statement Washington requires a contractor to hand over before starting all but the smallest jobs. Treating the lowest number as the best offer. A quote can only be compared against another quote for the same scope; otherwise the cheaper one is usually just the smaller one.

So “moisture present in crawl space” is an observation. It does not establish the cause, it does not establish the repair, it does not establish the severity, and it certainly does not establish the price. Every one of those is a separate question with a separate person answering it, and the gap between the cheapest and dearest published band on this site — Sump Pump Installation at $1,600 against Foundation Waterproofing reaching $40,050 — is roughly the range of outcomes that one line of a report can sit in front of.

What your inspector is and is not required to do

Washington has licensed home inspectors since 2009, and they work to standards of practice the Department of Licensing publishes as chapter 308-408C WAC, last amended effective August 7, 2026. Reading the relevant parts changes how the report looks, because most of what people treat as gaps in a report are things the standard deliberately puts outside it.

The rule What it means for your crawl space
Inspections are visual, not technically exhaustive, and do not find concealed conditions The report describes what could be seen on one visit with simple tools. The standards call the inspector a generalist who identifies conditions that may need to be referred to a specialist, and say plainly that an inspection does not identify concealed conditions or latent defects.
Inspectors are not required to determine the causes of any condition or deficiency This is the rule that produces the observation-without-diagnosis line. Your inspector is not withholding the cause; determining it is outside the scope you paid for.
Inspectors are not required to determine the methods, materials or estimated cost of repairs — but may specify the type of repair An inspector who declines to tell you what a repair will cost is following the standard, not being unhelpful. Washington adds that an inspector who is qualified and willing may specify the type of repair, so some reports carry a recommendation. Either way, the estimate in your head after reading the report has no source.
Inspectors enter and traverse crawl spaces where readily and safely accessible — but not flooded ones, ones behind an opening under 18 by 24 inches, or ones with under 18 inches of headroom beneath the joists or 12 inches beneath the girders A crawl space that is too wet, too tight or too full to enter goes unentered, and when something the standards cover is excluded, the report must say why. That note is information, not an omission.
Inspectors must inspect crawl spaces for indications of flooding and moisture penetration, probe where deterioration is suspected, and report all wood rot Water and rot findings are squarely inside the scope. If the report mentions water at all, treat it as deliberate. The standards also have the inspector report missing or inadequate vapor barriers over earth floors.
Inspectors are not required to comment on code compliance, or to report wood destroying insects or environmental hazards such as mold Which is why reports say “suspected fungal growth”, why “inadequate ventilation” is an opinion about the house rather than a code citation, and why insect findings read as “wood destroying insects”: unless the inspector is also a licensed structural pest inspector, Washington law limits them to general terms and a referral.
The inspection is for the client, under a written preinspection agreement The agreement must describe what will and will not be inspected and say that mold, asbestos, air quality and other environmental issues are not included unless agreed in writing, and the inspector may not share the report without the client's approval. A buyer reading a report the seller commissioned is reading a document scoped for someone else.

None of this makes the report less useful. It makes it a different kind of useful than most people assume. A generalist's description of what is under your house, produced by someone the standards bar from doing paid repair work on that building for a year afterward, is exactly the right thing to start from.

Findings, and what each one establishes

These are the crawl space lines that turn up most often. For each one: the observation, what could be causing it, what the finding alone does not establish, and what actually narrows it down. The last column is the one worth reading twice.

Standing water observed in crawl space

Liquid water was on the ground under the house at the time of the inspection.

Could be caused by

  • A plumbing supply or drain leak — the cheapest cause to rule out and the one that changes the whole scope
  • Surface water: downspouts discharging at the foundation, negative grade, a failed area drain
  • Groundwater rising into the crawl space through the soil during the wet season
  • A failed or absent perimeter drain, or a sump pump that has stopped working

What this alone does not establish

Where the water came from, whether it is there year-round or only after a storm, how long it has been happening, or whether anything under the house has been damaged by it.

What narrows it down

The date of the inspection against recent rainfall, whether the water is clean or silty, whether it is localized or general, and whether the meter moves with every fixture off.

Under the Washington standards: A Washington home inspector is not required to enter a flooded crawl space, or any area the inspector judges likely to be dangerous (WAC 308-408C-030(18)). Where the crawl space is entered, the standards have the inspector look for indications of flooding and moisture penetration (WAC 308-408C-070). A report that says less about a wet crawl space than a dry one is not a worse report.

usually structural or expensive DrainageWaterproofingSump Pump

Elevated moisture / high humidity noted in crawl space

Damp soil, condensation, or a moisture-meter reading the inspector considered elevated. Frequently no liquid water at all.

Could be caused by

  • Bare or inadequately covered soil evaporating moisture into the space year-round
  • Warm humid summer air entering through foundation vents and condensing on cool surfaces
  • A drainage problem that has not yet progressed to visible standing water
  • A dryer vent, bathroom fan or crawl space plumbing discharging under the house

What this alone does not establish

What "elevated" was measured against, whether the reading is seasonal or permanent, or whether it is high enough to support decay rather than just being uncomfortable.

What narrows it down

Wood moisture content readings rather than air humidity alone, taken at more than one point, and knowing whether the soil is covered.

depends entirely on the cause Vapor BarrierEncapsulation

Suspected fungal growth / possible mold observed on floor framing

Discoloration on joists, subfloor or rim board that the inspector thought looked like microbial growth.

Could be caused by

  • Active surface mold on wood that is currently wet enough to support it
  • Historic growth that is now dormant because the moisture source was corrected
  • Sapstain or mill-yard staining that arrived with the lumber and has never been a growth
  • Efflorescence or mineral deposit rather than anything biological

What this alone does not establish

Whether it is active or dormant, what species it is, whether it is affecting indoor air, or whether the wood underneath it has lost strength.

What narrows it down

Whether the wood is currently wet, whether the growth wipes off or is embedded, and whether there is a moisture source that would still be feeding it.

Under the Washington standards: Inspectors are not required to report the presence of environmental hazards including mold (WAC 308-408C-030(3)), and the pre-inspection agreement must state that the inspection does not include investigation of mold unless that was agreed in writing (WAC 308-408C-050). That is why a report can say "suspected fungal growth" and stop there. What the standards do require is a report of all wood rot discovered (WAC 308-408C-070).

depends entirely on the cause Mold RemediationEncapsulationVapor Barrier

Water staining observed on subfloor / joists

Discolored wood in a pattern consistent with water having been there.

Could be caused by

  • A past plumbing leak that has since been repaired
  • An ongoing leak that was not running during the inspection
  • Condensation dripping off cold water lines or ductwork
  • Historic flooding from a drainage problem that may or may not still exist

What this alone does not establish

Whether the source is active. This is the single most important open question in the whole report, and staining alone cannot answer it.

What narrows it down

Whether the stained wood is currently wet, whether the stain has a defined tide line, and whether anything above it could still be leaking.

depends entirely on the cause WaterproofingDrainage

Wood deterioration / decay / soft framing noted

Framing the inspector was able to probe or sound and found soft, or that showed visible decay.

Could be caused by

  • Long-term wetting from any of the water causes above
  • A localized leak that soaked one member for years
  • Ground contact or inadequate clearance between wood and soil

What this alone does not establish

How far it extends, whether load-carrying capacity is affected, or whether repair or replacement is needed. A home inspection is not technically exhaustive, and the inspector is not required to determine the strength or adequacy of a component.

What narrows it down

A structural evaluation. This is the finding most likely to warrant an engineer, or a registered contractor with a specific structural scope.

Under the Washington standards: The standards have the inspector probe structural components where deterioration is suspected, except where probing would damage a finished surface, and report all wood rot discovered (WAC 308-408C-070). They do not require the inspector to determine the strength or adequacy of any component (WAC 308-408C-030(1)).

usually structural or expensive WaterproofingDrainage

Vapor barrier damaged, displaced, or not installed

The ground cover is torn, has been pulled back, does not extend across the whole floor, or is absent.

Could be caused by

  • It was never installed
  • Foot traffic from HVAC, plumbing or pest-control work has torn it
  • Rodents have displaced it
  • It was installed loose and thin and has simply failed

What this alone does not establish

Whether replacing it is sufficient on its own, or whether it is the visible half of a drainage problem that has to be solved first.

What narrows it down

Whether there is liquid water under the house. A barrier over standing water hides the problem rather than fixing it.

Under the Washington standards: The standards have the inspector report missing or inadequate vapor barriers in crawl spaces with earth floors (WAC 308-408C-150). That duty covers subfloor areas that are viewable and accessible, so where the inspector did not enter the crawl space, the barrier was not assessed at all.

usually contained Vapor BarrierEncapsulation

Insulation wet, sagging, displaced, or missing

Batt insulation between the floor joists is fallen, compressed, damp, or absent in places.

Could be caused by

  • Moisture in the crawl space has saturated it and gravity has done the rest
  • Rodents have nested in it or pulled it down
  • Trades working under the house pulled it and did not replace it
  • It was never installed, or was installed without supports

What this alone does not establish

Why it fell. Insulation is almost never the underlying problem — it is the thing that visibly fails when something else has gone wrong, and replacing it without fixing that repeats the expense.

What narrows it down

Whether the crawl space is currently damp, and whether there is rodent evidence in the same area.

Under the Washington standards: The standards have the inspector describe the type of insulation in viewable, accessible unconditioned spaces and report its absence between conditioned and unconditioned space where visible. They do not require the inspector to determine the thickness or R-value of insulation below floors (WAC 308-408C-150).

usually contained Insulation

Rodent evidence observed (droppings, nesting material, runs)

Signs that rodents have been in the crawl space at some point.

Could be caused by

  • Open or damaged foundation vents, or vent covers with openings too large to exclude mice
  • Gaps at plumbing and utility penetrations
  • An unsealed crawl space access hatch

What this alone does not establish

Whether the activity is current or historic, how they are getting in, or whether the contamination needs professional cleanup. Washington’s standards do not require an inspector to report the presence of potentially hazardous animals.

What narrows it down

A pest control inspection, which is a separate trade from both home inspection and crawl space repair, and is the one that identifies entry points.

Under the Washington standards: A wood destroying organism report is a separate inspection, done by a structural pest inspector licensed by the Washington State Department of Agriculture. A home inspector who does not also hold that license reports rot and pest-conducive conditions, describes insect evidence only in general terms, and refers it to a structural pest inspector or pest control operator (WAC 308-408C-070; RCW 18.280.190).

depends entirely on the cause InsulationEncapsulation

Sump pump not operating / no discharge observed / drainage concerns noted

A sump pump present but not running, a basin with no visible discharge line, or grading and downspouts the inspector flagged.

Could be caused by

  • The pump has failed, or is fine and simply had nothing to pump on the day
  • The discharge is blocked, disconnected, or terminates against the foundation
  • There is a basin but no perimeter drain feeding it
  • Surface water is being delivered to the foundation by downspouts or grade

What this alone does not establish

Whether the system is adequate for the water this house actually gets, or whether the pump failing is a cause of the water or a symptom of how much of it there is.

What narrows it down

Following the discharge line to where it ends, and checking whether a perimeter drain exists at all.

Under the Washington standards: The standards have the inspector report the presence and functionality of sump pumps when visible (WAC 308-408C-100). They do not require inspecting exterior drain systems or underground drainage piping (WAC 308-408C-090 and 308-408C-100), so a report can describe the pump and say nothing about where the water goes.

depends entirely on the cause Sump PumpDrainage

Foundation vents blocked / inadequate ventilation noted

Vents obstructed by landscaping, stored material or insulation, or fewer of them than the inspector expected.

Could be caused by

  • Vents deliberately closed by a previous owner, sometimes seasonally
  • Vents blocked accidentally by grade, planting or storage
  • A part-converted crawl space where vents were sealed without the liner, radon system and exhaust ventilation Washington’s code asks of an unvented crawl space

What this alone does not establish

Whether the house is meant to be vented or sealed. Washington’s code makes a vented crawl space the default and permits an unvented one on stated conditions, so closed vents are not by themselves a defect.

What narrows it down

Whether there is a continuous sealed liner running up the stem wall, a radon vent, and continuously running exhaust ventilation, which is what Washington’s code asks of an unvented crawl space (WAC 51-51-0408, R408.3). Vents closed with none of those is the configuration to ask about.

Under the Washington standards: Ventilation of unfinished subfloor areas is within the inspection (WAC 308-408C-150). Inspectors are not required to comment on compliance with codes (WAC 308-408C-030(2)), so "inadequate ventilation" in a report is an opinion about the house, not a citation.

depends entirely on the cause EncapsulationVapor Barrier

Active leak / evidence of plumbing leak under floor

Water at or near a pipe, a dripping fitting, or wet ground in a line under plumbing.

Could be caused by

  • A supply line, drain line or fitting failure
  • A water heater or appliance drain discharging under the house
  • Condensation on uninsulated cold lines, which is not a leak but looks like one

What this alone does not establish

Which line, and how much of the crawl space condition it explains. A leak found alongside general dampness may be the whole story or a coincidence.

What narrows it down

A plumber. This is the one finding where the next call is usually not a crawl space contractor, and getting it wrong means paying for drainage that was never going to help.

depends entirely on the cause Waterproofing

For the findings you want to read about in depth rather than in a row of a table: water after rain, mold in a crawl space, musty smells, rodents, and whether the crawl space is meant to be vented or sealed.

The order to work through it

Every step here exists because skipping it is expensive. The sequence matters more than the speed, even inside a due diligence window.

  1. Read the finding as written, not as remembered. Note the exact wording, and note whether the inspector referred it to a specialist — the standards have the inspector identify conditions that may need one — or wrote “monitor”. The difference between “monitor” and “have evaluated” is a real signal.
  2. Look at the photographs. Is there liquid water or damp soil? Is the barrier torn or absent? Is staining bounded by a tide line? Photographs answer questions the text does not, and they are the thing to send a contractor before they visit.
  3. Check whether the crawl space was actually entered. If the report says access was restricted, the space has not been assessed and everything below is provisional.
  4. Decide whether the source is known. If the answer is yes and it is plumbing, call a plumber before anyone else. If the answer is no, the next step is an evaluation, not a quote.
  5. Get a specialist evaluation where the finding warrants it. The conditions that warrant it are in the next section. Ask specifically for a written assessment of the cause, not just a price.
  6. Get the proposed scope in writing, as line items. “Encapsulation” is not a scope. What goes in, what comes out, what is sealed to what, and what is excluded — that is a scope.
  7. Compare scopes before you compare prices. Set the line items side by side. Where one quote has a line the other does not, that gap is the whole explanation of the price difference more often than not.
  8. Verify the registration. Two minutes against the Department of Labor & Industries record, and it is the highest value check in the process. How to do it, and what it does and does not prove.
  9. Run the written quote through the bid checker. It checks the paperwork against what Washington asks of a contractor before work starts, checks the scope against what a bid for that service normally names, and puts the total in context. Open the bid checker — it works in the browser, nothing is sent anywhere, and it prints if you need to hand it to somebody.

When a finding warrants a specialist evaluation

The evaluation that follows a report line is a different visit from the one that produced it. What a crawl space inspection covers sets out how a pre-quote crawl space visit differs from the licensed home inspection above, and which one answers which question.

Not every crawl space note needs anyone else to look at it. A torn vapor barrier in an otherwise dry crawl space is a contained, well-understood repair. These are the situations where paying somebody to diagnose before anybody quotes is worth the delay:

  • Liquid water was present, or the report describes flooding or a water line on the foundation.
  • The crawl space could not be entered. Nothing has actually been assessed.
  • Wood rot or soft framing is noted. Determining structural adequacy is expressly outside a home inspection, and this is the finding most likely to warrant a structural opinion rather than a crawl space contractor alone. A floor that already gives underfoot is the version of this you can feel from upstairs, and what repairing failed framing involves covers the scope once somebody qualified has bounded the extent.
  • A plumbing leak is suspected. A plumber first, always — it is the cheapest cause to rule out and the most expensive one to fix by accident with a drainage system.
  • Findings contradict each other, such as high humidity noted alongside an intact barrier and no water. Something is producing that moisture and it has not been found yet.
  • Two contractors disagree about the cause, not just the price. That is a diagnosis dispute, and a third opinion from someone with nothing to sell resolves it faster than a third quote.

Before you compare any prices

Once you have a diagnosis and at least one written scope, the price question becomes answerable. Two things make it easier:

  • The cost guide publishes a modeled range for every service on this site, alongside the specific conditions that move a project up or down. The cost calculator adjusts those ranges for your square footage, clearance, moisture level and insulation state.
  • The bid checker is the one to use when you are holding an actual quote. It is built for exactly this moment and it is designed to be handed to somebody else — an agent, a client, a co-owner.

One honest caveat on every figure this site publishes. The ranges are modeled estimates for the Seattle metro, before sales tax, last reviewed November 10, 2026 — not a database of collected contractor quotes, because this site does not hold one. The methodology page sets out how they are built and what they cannot do. Use them to tell whether a number is unusual, not to decide whether it is correct.

Nothing here is legal advice, and your inspector, your contractor and your building department are the people whose reading of your specific house governs it. When you are ready for the diagnosis and the written scope, a free in-home inspection provides both, as a no-obligation quote you can run through the bid checker above.

Sources

Every statement on this page about what an inspection does or does not cover comes from Washington's home inspector standards of practice, chapter 308-408C WAC as amended effective August 7, 2026, read in the rule itself rather than in a summary of it, with RCW 18.280.190 and the Department of Agriculture's wood destroying organism rules for insect findings and WAC 51-51-0408 for the vented-or-sealed finding. RCW 64.06.020 is cited for the seller disclosure statement that runs alongside an inspection in a Washington sale, and the EPA, the state Department of Health and the Forest Products Laboratory for the two findings — suspected fungal growth and wood rot — where the useful question is a technical one rather than a procedural one.

  1. Washington State Department of Licensing (via Washington State Legislature), Chapter 308-408C WAC — Home inspectors: standards of practice (As amended by WSR 26-15-037, effective August 7, 2026) Checked

    What a Washington home inspection is required to cover at a crawl space, and what it is not. WAC 308-408C-010: an inspection uses visual observation, simple tools and normal controls, is not technically exhaustive, and the inspector is a generalist who identifies conditions that may need a specialist. WAC 308-408C-030(1): inspectors are not required to determine the strength, adequacy, effectiveness or efficiency of a system or component, the causes of any condition or deficiency, the methods, materials or estimated cost of repairs, or future conditions; (2) nor to comment on compliance with codes; (3) nor to report wood destroying insects or environmental hazards including mold; (18) nor to enter flooded crawl spaces. The same section says an inspector who is qualified and willing may specify the type of repairs to be made. WAC 308-408C-070: the inspector enters and traverses crawl spaces where readily and safely accessible, inspects visible foundations, posts, piers, beams, joists and subfloors and looks for signs of flooding and moisture penetration, probes where deterioration is suspected, and reports all wood rot and pest-conducive conditions, but need not enter a crawl space that requires excavation, has an access opening under 18 by 24 inches, or has less than 18 inches of headroom under joists or 12 inches under girders. WAC 308-408C-100: reports the presence and functionality of sump pumps when visible. WAC 308-408C-150: reports missing or inadequate vapor barriers in crawl spaces with earth floors and missing insulation where visible, and need not determine the thickness or R-value of insulation below floors. WAC 308-408C-050: the pre-inspection agreement must say the inspection does not include mold, asbestos, air quality or other environmental issues unless agreed in writing. WAC 308-408C-020(8): for one year after an inspection, the inspector and the inspector’s firm may not repair, replace or upgrade components of that building for pay. Also: the reason any item normally inspected is excluded must be stated in the report (030); the report may not be disclosed without the client’s approval (020(10)); and conditions beyond the inspection are referred to a specialist (070).

    Note: The Washington verb in 030(1) is “determine”, and the rule permits an inspector to specify repairs. It does not bar a repair recommendation; it makes one optional.

  2. Washington State Legislature, RCW 18.280.020 — Home inspectors: licensure required Checked

    That since September 1, 2009 nobody may work or advertise as a home inspector in Washington without a state license.

  3. Washington State Legislature, RCW 18.280.190 — Home inspectors: structural pest inspector Checked

    That a home inspector who is not also a licensed structural pest inspector may refer in the report only to rot or conditions conducive to wood destroying organisms, and must refer the identification of, or damage by, wood destroying insects to a licensed structural pest inspector.

  4. Washington State Department of Agriculture (via Washington State Legislature), Chapter 16-228 WAC, sections 2005 to 2060 — Wood destroying organism inspections Checked

    That a wood destroying organism (WDO) inspection done for the sale, exchange or refinancing of a property must be a complete WDO inspection by a licensed individual; that substructure crawl areas must be inspected when accessible, and where they are not the report must say why and state that the area may be vulnerable and should be made accessible; that a specific WDO inspection must accompany any proposal or estimate to prevent or control WDOs, may be done only by a licensed structural pest control operator or structural pest inspector, and may not stand in for a complete inspection in a sale.

  5. Washington State Legislature, WAC 51-51-0408 — Section R408, Under-floor space (Washington State Residential Code, amended by WSR 23-23-104) Checked

    What Washington requires under a house: ventilation at 1 square foot per 300 square feet of under-floor area; 6-mil black polyethylene ground cover with joints lapped 6 inches, extending to the foundation wall, which may be omitted where the crawl space has a concrete slab floor at least 2 inches thick; vent coverings with a least dimension of no more than 1/4 inch (corrosion-resistant wire mesh at 1/8 inch), and operational louvers permitted; ventilation reducible to 1/1,500 where a Class I vapor retarder covers the earth, with a radon vent built to Appendix AF required where ventilation is below 1/300 or operable louvers are installed. Vents may be omitted only where both numbered conditions of R408.3 are met: a continuous Class I vapor retarder lapped and sealed 6 inches, extending 6 inches up and sealed to the stem wall, with an Appendix AF radon system; and continuously operated mechanical exhaust at 1 cfm per 50 square feet. R408.8 is not adopted in Washington.

  6. Washington State Legislature, RCW 64.06.020, Improved residential real property — Seller’s duties — Format of disclosure statement Checked

    That the Washington seller disclosure statement (Form 17) asks whether the basement has flooded or leaked, and whether there are any flooding, standing water or drainage problems on the property; that the seller answers from actual knowledge; and that the statement is a disclosure, not a warranty. Re-read 2026-11-11 for the real-estate guides: that the form also asks about settling, slippage or sliding of the property or its improvements (4.E), whether a structural pest or “whole house” inspection was done and when and by whom (4.G), any wood destroying organism or pest infestation during the seller’s ownership (4.H), and defects in listed systems including the sump pump (5.A); that the buyer has three business days from delivery to rescind unless otherwise agreed in writing; that the form tells buyer and seller they may wish to obtain professional advice or inspections, naming building inspectors and structural pest inspectors among others; and that the seller of never-occupied new construction need not complete the structural and systems items.

    Note: The statute prints two versions, one effective until January 1, 2027 and one from that date; both carry the questions cited here. The form has no question that names a crawl space or mold.

  7. Washington State Department of Labor & Industries, Verify a Contractor, Tradesperson or Business Checked

    The official Washington register: registration status, bond, workers compensation account standing, and lawsuits filed against the bond.

  8. United States Environmental Protection Agency, A Brief Guide to Mold, Moisture and Your Home Checked

    Indoor humidity targets, EPA’s position on when sampling is and is not worth paying for, its position on biocides, the general health effects of damp indoor spaces, and the 24–48 hour drying window — which EPA states as a PREVENTION target ("dry water-damaged areas and items within 24-48 hours to prevent mold growth"), not as a time by which mold begins. Also that molds produce allergens, irritants and in some cases potentially toxic substances, can trigger asthma attacks in people allergic to mold, that it is impossible to get rid of all mold and spores indoors, that moldy surfaces should not be painted or caulked over, that a moldy area under about 10 square feet is in most cases a job a homeowner can handle, that larger growth sends the reader to EPA’s remediation guidance for schools and commercial buildings, and that damage from sewage or other contaminated water calls for a professional experienced with it.

  9. Washington State Department of Health, Mold Checked

    Washington’s homeowner guidance on mold: sampling is usually unnecessary; a small area is under about ten square feet, and above that a homeowner should consider hiring a professional, and should hire one where sewage is involved or the mold is hidden; and covering crawl space earth floors with heavy plastic is among the department’s moisture controls. Also that mold can cause allergic reactions and asthma and affect people with weakened immune systems, who should see a physician; that a musty odor is a sign of mold; that even dry, dead mold can still cause problems; that crawl spaces should be ventilated and insulated; that porous moldy materials should be bagged and removed; and that mold should not be painted or caulked over.

    Note: General guidance for homes, not a licensing rule. The page names no mold remediation credential and this site does not state whether Washington licenses mold work.

  10. USDA Forest Products Laboratory, Wood Handbook, Chapter 14: Biodeterioration of Wood (General Technical Report FPL-GTR-282 (2021 edition)) Checked

    The wood moisture content and temperature ranges at which decay fungi become active, which is what separates a surface mold problem from structural rot. Also, for the white-mold guide: mold shows as fuzzy or powdery surface growth in colors from light shades to black, and on softwoods can often be brushed off (p. 14-2); mold and stain fungi affect strength only slightly but make wood more absorbent, which can lead to decay (p. 14-2); fresh surface growth of decay fungi can look like fan-shaped patches, strands or root-like structures, usually white or brown (p. 14-3); white rot leaves wood bleached and spongy, brown rot darkens it and cracks it into cubes, and some brown-rot fungi form water-conducting strands that carry soil water into dry wood (p. 14-4); and that crawl-space condensation, whose primary source is soil moisture, can cause serious decay, while wood debris and concrete forms left under a building can seed it (p. 14-7). And, for the termite guide (pp. 14-11 to 14-15): anobiid powder-post beetles generally need wood at about 15% moisture or more, which inadequate ventilation can create and lower moisture through ventilation, insulation and vapor barriers can relieve; subterranean termites need a constant source of moisture, build mud shelter tubes that are a good sign of their activity, swarm usually in early spring or fall, and leave galleries along the grain under a shell of sound wood, so suspect wood is probed with a pick or knife; infestation hazard is greatest over a crawl space that is poorly drained and lacks a moisture barrier; in a crawl space, joists at least 18 inches and girders 12 inches from the earth, a polyethylene barrier over the soil running partly up the foundation wall, drainage away from the house with gutters, downspouts and grading, posts that bear on the ground made of concrete, and concrete forms, stakes, stumps and waste wood removed; control of termites already in a building means breaking the contact between the soil colony and the woodwork by blocking runways, treating the soil, repairing leaks such as plumbing leaks, or a combination, then inspecting often; carpenter ants use wood for shelter rather than food, prefer wood softened by decay and so can point to a moisture problem, and species such as Camponotus modoc can be particularly damaging.

Sources last checked between and ; the date beside each one is when it was last opened. Where a figure comes from a document that is revised on a schedule, the edition or version is named above so you can confirm it against the current one yourself.

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