FAQs on the proper way to clean up mold-contaminated wood or wood surfaces:

Questions & answers about how to remove mold from wood or wood surfaces in or on buildings.

This article series offers advice on cleaning mold found on surfaces of un-finished wooden building materials such as framing lumber (rafters, floor joists, wall studs), and building roof, wall, and floor sheathing such as plywood, tongue-and groove pine boards, and other structural wood surfaces in buildings.

How to remove mold from wood framing, plywood sheathing, tongue and groove subfloor or roof decking

These questions & answers about the proper procedures & methods to clean moldy wood surfaces in, on or around buildings were posted originally

at MOLD CLEANUP - WOOD FRAMING & PLYWOOD - be sure to review the advice given there.

The object in cleaning mold from a wood surface is to remove all fungal material from the surface of the wood: fungal spores, hyphae, and conidiophores (the spore producing structures of mold). It is not necessary to remove all stains from wood.

[Click to enlarge any image]

On 2015-12-01 by (mod) how to safely get rid of mold contamination in a fixer-upper house

Anon:

Use any household cleaner - or if there is more than 30 sqft of contiguous moldy surface, hire a professional mold cleaning company; the proper approach is to remove the mold and fix the leak or moisture problem that caused its growth.

If you cannot afford a professional you may be tempted to do the cleanup yourself - there are several articles here on how to clean up or remove mold from building surfaces; but keep in mind that if you don't proceed properly (containment of airborne dust, personal protective gear, proper cleaning procedures) the risk is that you make yourself sick or spread moldy dust to other house areas - if those problems occur the ultimate cost is greater than if a pro did the work properly the first time.

Check with your local community aid associations to see if you can get some financial help.

I would NOT move into a moldy home before I knew if I were risking not just health issues but contamination of my stuff; If the mold is ONLY in the basement, keeping that area under negative air pressure with respect to the rest of the home (fans blowing out) can help.

On 2015-11-30 by Anonymous

I just bought a fixer upper house and there is white mold well it appears as white mold on the support beams in the basement/crawlspace

i need help i dont know if its safe or how to get rid of it. I have 2 kids and i have to be able to move in very soon. Help please. I cant call a professional because i dont have money and i dont know if my house would get condemned.

On 2015-11-18 by (mod) clean white mold off of cabin floor joists over a crawl area

Thank you for the question, Ann.

Use the page bottom CONTACT link to send some pictures of the problem if you can, including a sharp closeup.

If the area is now dry and the mold light and cleaning difficult and no IAQ complaints are voiced in the living area I would cover the wood surfaces in the crawl with a fungicidal sealant. A pro might spray a sanitizing treatment furst, then let that dry before sealing.

On 2015-11-17 by Ann F

have spent quite a bit of time reading articles and can't seem to find the specific answer I am looking for. We have a cabin in upper penninsula Michigan and have noticed white mold growing on the floor joists in the crawl space. I believe this used to be very damp in the past but with the efforts of a past owner as well as ourselves, it is very dry.

We installed thick plastic over the sand floor to stop moisture evaporating upward and that has worked very well. It is an uninsulated cabin with no drywall. There is no moldy smell even when in close proximity to the "white Mold". The floor joists are made of rough cut wood, so wiping them is out of the question. I noticed that the mold is growing along the grain lines of the wood.

I fear that disturbing it in the attempt to remove it will make a bigger mess than just leaving it alone. The cabin was built in the 1950/60's era as a summer resort cabin. It has been observed that it may not have even been on a foundation when first constructed. As I said there is no moldy smell when entering the crawl space and it is a very dry space at this time.

So, white mold on rough cut floor joists-should we worry about it? This cabin is closed down/no heat for the winter.Thank you so much!

On 2015-11-17 by (mod) clean or remove mold on upholstered furniture? doubtful

Upholstered furniture is just about impossible to clean of mold if it was actually supporting mold growth. It'd have to be stripped to the frame; no vacuuming or treatment can get into multi-inch-thick padding &c.

If mold was on a wood surface, clean it with any household cleaner; If you like you can then seal the cleaned but non-visible surfaces with a clear lacquer.

On 2015-11-17 by Joyce

We had a roof leak that left mold on the wall and floor of the bedroom. My wood furniture and bed smells musty.
I can wipe off the tops of the furniture but the backs and underneath are made of a porous wood that I'm not sure what to clean them with.

On 2015-10-23 by (mod) wet or moldy plywood under leaky bath tub - mold killing primer?

If the plywood doesn't need to be replaced for structural reasons, physically clean the surfaces, don't worry about stains that remain (They're of cosmetic import), or for extra confidence seal the cleaned dry surfaces with a fungicidal sealant paint. Search inspectapedia for fungicidal sealant to read details.

See FUNGICIDAL SEALANT USE GUIDE - sprays and sealants used after proper cleaning reduce further risks

On 2015-10-23 by Amelia

I found a leak in front of my tub, where the access panel is. It's coming from the drain. My concern is the wet plywood underneath.

I have had a fan blowing on it for about 1 day and have wiped off the surface with bleach ( before I read these articles). Any suggestions on what to do next? I hope to avoid having to replace the plywood as there is little damage. My main concern is to get rid of the mold. Leak has been fixed.

On 2015-10-08 by sharon

I am having some mold issue on the plywood flooring. can I use mold killing primer.

On 2015-08-21 by Pierre

We pulled cupboards and wall paneling off the main(lower) floor and found an old leak in the ABS drain.

The horizontal wood boards nailed across the studs look like charred wood! They actually look and feel like they were totally charred with at least a few inches of wood partially burned away.

What kind of mould would make the wood look like that? Is there a danger of it being black mold?
Thanks for your help!

On 2015-10-23 by (mod) - moldy attic rafters, black and white - is there a difference in removal methods?

Nope. The mold genera/species does not change the appropriate mold cleanup and prevention methods, with the exceptions that

1. some dark colored mold is harmless, only cosmetic, and that case is easy to identify -

see BLACK COSMETIC MOLD

2. large areas of mold should be cleaned up by a professional, typically that's more than 30 sq.ft. of contiguous moldy surface

while

3. small areas of mold can be cleaned by most people using ordinary household cleaners

On 2015-07-18 by Anonymous

Excellent information on this site. My question is: I have mold in my attic on several rafters. The leak has been repaired, but the mold hasn't been dealt with. I see black and white mold. Is there a difference in removing this, and can I use a cleaning solution on both? I do plan on using a fungicide sealer after wiping down.

Question: mold on heat pump stand

(Feb 13, 2014) Karen Gunderson said:

Question: The heat pump is on a wood stand. Some water leaked and the wood got wet. There is black color on the wood around the bottom. It has been tested for mold, and mold was found. Have cleaned the wet carpet out, scrubbed cement with Clorox bleach. removed most everything that was in the storage area.

Am replacing the material around the wood stand, but wonder if I should do something more, like seal the bottom of the four boards. Do not want mold inspection to come back positive.

Should I try to get all the black stuff off the boards. Could I spray the foam on the boards so nothing could get through from boards?

Reply:

Karen,

If water ran beneath an enclosed wood base it's possible that the hidden underside is mold contaminated. If that area is inaccessible, I'd leave it alone, arguing that the total size of moldy area is trivial; but I agree that after cleaning, when the stained wood surfaces are dry,

if you seal those with a paint (or if you prefer a fungicidal sealant paint) you'll reduce the moisture uptake of the wood and thus improve its mold-resistance in the future.

Spray foam on exposed wood outdoors sounds like a mess and one that may trap water; and indoors we don't like to leave foam exposed - that's a fire hazard.

see MOLD CLEANUP, BLEACH - not an adequate mold remediation approach

Question: best way to kill mold or remove moldy studs?

(Aug 16, 2014) E H said:
I have a interior 2 x 4 stud walls that have mold spots on them. What is the best way to kill it or do I need to remove the studs?

Reply:

EH

You do not need to replace moldy wood framing studs.

If you want to deal with mold on the studs, physically clean the surfaces and to be thorough, when dry, paint them with a lacquer primer sealer.

The object when dealing with mold contamination is to remove it, not "kill it" - some dead spores remain harmful.

You also want to identify and fix the cause of mold growth.

Question: leaks into building walls at flashing errors

(Sept 20, 2014) Kirt said:

We have recently discovered that the builder of our home did not use window sill flashing, and the installation Tyvek was done in such a manner that it does not shed water - it catches it. As a result, there is dry rot and what appears to be black mold in the sheathing. How much sheathing ought to be removed - a 12" band all around, or what? thanks,

(Sept 29, 2014) Stacey said:
We are replacing the laminate flooring in our bathroom and noticed black mold near our tub on the plywood underneath the laminate we pulled up.

First, what is the best way to clean this mold if we can do it ourselves and second, should we be concerned about any thing growing under the tub?

Oct 6, 2014) Nancy Collins said:
I went into attic and noticed at top of attic stairs on rafters on each side it looks like white paint spayed. It's hard like paint and doesn't flake or and it's not fluffy. Could this be mold. Thanks

Reply:

Nancy use our email found at CONTACT found at page bottom to send us some photos and we can comment on what you are seeing

Question: mold on roof underside above bath

(Dec 11, 2014) James said:
I had a new roof put onto the house. I had them remove a sky-light over the bathroom. My contractor was supposed to have close off the area in the ceiling to the new sheeting, but he bailed on me.

Now I have what appears to be mold on the sheeting from moisture from showering. I have inspected the attic and the mold is contained to only the area where the sky-light was removed. the opening is framed and drywalled to the rafters. What would be my best solution for cleaning this before I close it up? Thank you

Reply:

James

Fix any leaks

Physically clean the wood surfaces using any household cleaner and a scrubby sponge - don't get moldy water or cleaners in your face or eyes.

Optionally: after the cleaned surfaces are thoroughly dry use a fungicidal sealant

Question: sanding to remove mold

(Mar 27, 2015) Denis said:
I had a roof leak that allowed water into the attic affecting the an area of insulation, roof rafters along with a 12x18 bedroom ceiling.

My question is, does sanding the affected roof rafters and removing all of the attic insulation the correct process? Why sand? Why not wipe down the affected wood structures.
Thanks,
Denis

Reply:

Denis

There is no requirement for sanding to remove mold; you can scrub or wipe off moldy surfaces with cleaning products but you will probably want to treat the dried surfaces with a fungicidal sealant as well. In fact the cost of sanding for mold remediation is rather questionable except where it is needed for cosmetic reasons such as perhaps leaving an exposed beam in a living space.

Question: rotten joist treatment for mold?

(May 21, 2015) Mr.justincox said:

Recently noticed my floor and sub floor in my bathroom are completely saturated and black(some black mold as well), very easily removable,

my question is one of the joist is visible rotten on the surface and a Flathead screw driver easily penetrates about 1/4 of the surface.

Can the rot be removed and reused or does it need to be removed and replaced? Along that same line the plywood sub floor that's leading under the wall is also noticeable rotten and needs to be addressed, how do I asses this and what can been done?

I have pictures if that would help?

Reply:

Yes I'll comment when I've seen the photos.

On 2013-04-08 by Linda Lewis

We are building a new home, the wood framing has mold, the walls are still open. How should the builder clean or remove the mold?

On 2012-09-27 by (mod) -

Clean the srrfaces thoroughly, apply a fungicidal sealant, and find and fix the moisture source and your camper mold may not reappear on that surface.

On 2012-08-13 by Bev Williams

As part of a construction project (total rebuild of vintage camper) we purchased plywood from a local "bargain warehouse" that deals mostly in South American varieties of lumber. We are incorporating several different types of lumber from several different sources---ie. 2X4's, paneling, OSB, etc. The plywood I referenced first is fast becoming covered with a dark green/black mold; and is the ONLY surface to do so. No sign of mold on any other wood. What the heck is going on and how do we fix it?

I should mention we live in Western NC and the rain and heat have combined for ultra high humidity this summer. Such a bummer to see this adorable old Scotty camper off to such a depressing start. Thanks in advance!

On 2012-08-11 by (mod) - when is moldy roof plyood replacement justified

Jim:

I'm not sure that roof decking replacement is always justified when mold is detected thereon;

Depending on the mold genera/species as well as air movement through the attic and more - between the attic and occupied space, the actual level of risk to building occupants can vary enormously.

Often it may make the most sense to dry out the attic, fix the moisture source, perhaps do what you can to clean the exposed surfaces, consider a sealant on the cleaned surfaces, check the insulation for evidence of mold contamination, replace any insulation that has been wet or that is visibly suspect;

All of that would cost a fraction of tearing off and replacing a roof.

On 2012-08-11 by (mod) -

Bill from Hawaii:

please remember that the object is not to "KILL" mold but to remove it and fix its cause. Some dead mold spores are still toxic.

On 2012-08-0 by Jim

Hi -About a year after our home was build (2000), we discovered that mold was growing in the attic space on the underside of a few pieced or roofing plywood.

The contractor had vented the bathroom fan into the eaves where moist exhaust would then back into the attic. The contractor moved the fan exhaust port and installed a power roof vent. He determined that the plywood's structural integrity was fine, which it is. The mold has not spread. With hindsight, I should have had sued to have the builder replace the (around 8) pieces of discolored plywood roofing.

The discolored (black/grey) appearance of the plywood in question is a concern. My concern now is that when it comes to selling our home, an inspector may balk at the mold he sees in the attic. My attic is filled with blown insulation and movement is limited. What is the "least gruesome" and "least investment of time" method for a DIYer to remove the "mold color" from the areas that I described? I don't want to spend a lot of time in my attic. My only interest is that a home inspector not cite/site mold in the attic. How's that for a play on words? - Thanks for your input.

On 2011-11-04 by (mod) -

Bill, take a look at MOLD KILLING GUIDE in the ARTICLE INDEX and you'll see that there are a number of sanitizers, biocides, and simple bleach that will somewhat "kill" mold, but you'll also read that we consider this approach basically a mistake.

Even "dead" mold spores can be harmful depending on the species of mold present

Killing mold does not correct the original reason for its growth - find and fix the leak or moisture problem - so eventually the problem is likely to recur in the same building if not immediately on the same surface

What's recommended is physical cleaning off of moldy surfaces, correcting the cause of mold growth, and optionally you can use a fungicidal sealer that can reduce the moisture uptake of the wood and thus increase the wood's resistance to future mold growth even after the biocidal chemicals may have deteriorated.

I don't recommend WD 40 for mold control, though indeed that lightweight oil has found uses for hundreds of applications, but it is interesting that you've found it seems to work in your application. I suppose that the oil coating in the wood helps resist moisture.

On 2011-11-03 by Bill

I have searched all over the internet and haven't found a chemical or god method that kills white mold on wood. I tried acetone, paint thiner, alcohol, mold removers like x-14, etc. Thru trial and error I found something that seems to work, guess what, it was WD-40 either sprayed or wiped on, and it seems to have killed the mold completely. It does leave a smell for a few days and may need another coat or two, but two weeks later and the mold has not come back.

On 2011-11-01 by (mod) -

Chris, we discuss mold sprays, biocides, sanitizers, disinfectants, and sealers in details at MOLD SPRAYS, SEALANTS, PAINTS (see the ARTICLE INDEX on this page)

In general, sprays are not usually necessary but can offer some advantages in knocking down a few remaining particles and sealants can reduce the tendency of surfaces to pick up moisture in the future, increasing their mold resistance even after any chemical biocidal effects may have worn off.

Watch out: We warn that using sprays of any sort as a substitute for actual cleaning and for finding and fixing the mold cause is not a good idea and not likely to be effective.

On 2011-10-31 by Chris

In your opinion, which is the best mold disinfectant? I'm familiar with Shockwave and Microban, but know there are others. One article said Microban provides a residue to discourage future growth (and Shockwave doesn't), but one supplier says both are about the same, but they sell more Microban (which is a bit cheaper).

There is mold on many floor joists in basement, likely caused by humidity from plumbing leak. There is a lot to clean. Mold is not on bottom surface of plywood subfloor. Should I wipe the mold down, remove it first with HEPA vacuum, or spray/fog it first with Microban or Shockwave, then vacuum/wipe down?

On 2011-09-06 by (mod) -

Cheryl take a look at MOLD EXPERT, WHEN TO HIRE in the ARTICLE INDEX for help in deciding how far you need to go in addressing your mold worry. Also MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD gives some succinct advice about dealing with mold in buildings.

On 2011-09-06 by Cheryl

Not sure if I have bad mold and how to get rid of it. Help

On 2011-07-19 by (mod) - Terminix pest inspection does not include risk of mold contamination

Steve,

I've observed that many pest control companies have added a disclaimer about mold to their contracts to avoid a liability concern that arose when they inspected homes under the aegis of "pest inspection" though in my OPINION it ought not have been necessary: mold may be a pestilence but it's not an insect, nor a raccoon that are traditional scope of pest control companies.

Take a look at MOLD EXPERT, WHEN TO HIRE in the ARTICLE INDEX for help in deciding if your home has conditions that merit an expert opinion about mold contamination and the need for a mold cleanup. There are legitimate mold concerns in some buildings while in others there are opportunities for folks to overreact and sometimes to perform work that was unnecessary, or worse, to perform work that was needed but ineffectively done.

On 2011-07-17 by Steve

One year ago, we hired a professional inspector to inspect our house before buying it. In October 2010, we had Terminix treat with the 20-year guranteed barrier against termites. Neither of these visits prompted any mention of fungus (mold) in the crawl space under the house.

But now, the Terminix one-year inspection cites we have fungus on the joists under the house. Is Terminix trying to stampede us into hiring them to treat mold, when we don't have a mold problem?

On 2011-04-23 by Very interesting!

This the most complete instructions I found. Thank you
Gene

...

Continue reading at MOLD CLEANUP - WOOD FRAMING & PLYWOOD, topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see MOLD CLEANUP of WOOD, FAQs-2 - more-recent questions & answers about how to clean off moldy wood surfaces.

Or see these

Mold Cleanup Articles

• MOLD CLEANUP - WOOD FLOORING
• BLACK COSMETIC MOLD - not all black mold is harmful
• FUNGICIDAL SEALANT USE GUIDE - sprays and sealants used after proper cleaning reduce further risks
• MOLD CLEANUP, BLEACH - not an adequate mold remediation approach
• MOLD CLEANUP - WOOD FLOORING - how to remove mold from wood flooring surfaces
• MOLD REMOVAL, MEDIA BLASTING - good approach for irregular or hard-to-clean surfaces
• SIDING, WOOD CLEANERS, STAINS, PAINTS how to remove stains on siding & how to choose the proper paint or stain coating

Suggested citation for this web page

MOLD CLEANUP of WOOD, FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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