I'm not aware of any industry standards or national building code restrictions regarding mold but some states have modified the state building code to require the building permit applicant to state in writing that the maximum moisture content of framing wood is 19% (eg Oregon in '08).

Normally it would be the specification in your contract that would set the maximum moisture content of the lumber used in the house (in the East it is usually Kiln-Dried) and how the lumber is to be stored on the site. The dryness of the wood would be stamped on the face of each member.

Given your health condition I would think the author of the specification, in addition to the terms listed above, would prohibit the use of any form of fiberglass insulation or any material that could produce airborne dust or fibers and would clearly describe what is unacceptable in terms of visible mold on material surfaces and would specify dehumidification of the building before mold-resistant drywall or vapor barriers were installed and would specify low VOC finishes. Forced air heating, if approved by your doctor, might need electrostatic filters, etc.

If you have a particular sensitivity to airborne elements you should hire an architect to design and document any modification to your home with the involvement of an air quality consultant.

Thanks, Renovator8. I called code enforcement for our area, and they said that the building code references international building code standards for how long wood can be left unprotected outside. So while the code does not prohibit wet or moldy wood from being used, the International Building Code does, and code says those standards apply.

We are planning to have the moldy wood treated rather than removed, and have told our contractor that we will pay for the treatment of any moldy wood that was already here. We are trying very hard not to make things unpleasant, but it is unfortunate that more care was not taken.

Did they give you the relevant code sections of the IRC and the IBC? I would be very surprised if your contractor owns a copy of the IBC.

"international building code standards for how long wood can be left unprotected outside. So while the code does not prohibit wet or moldy wood from being used, the International Building Code does,"

That is not what "how long wood can be left unprotected outside" says.
And surface wet (and surface mold) do not indicate moisture content, just surface moisture.

You are not going to get anywhere complaining about mold on framing lumber, and it will promptly die as soon as it is in a controlled environment and no addition moisture is available.

Mold needs a nutrient and water.
Since the wood itself is the nutrient (sometimes the actual cellulose of the wood, other times the dried out remains of wood cell contents, and other times just debris on the surface) removing the source of water is the only real option.

We just got the report back and the largest amount of mold is on plywood that was used to enclose the area. The level is a 4 on a scale of 1-5, and is not limited to spores. The presence of not just spores for all of the molds detected indicates active mold growth [i.e., conidiophores, hyphae & other growing parts of the molds]

Dead mold causes illness in people who are sensitive to it. The affected material needs to be cleaned even if the mold is dead. I completely agree that removing the source of moisture will stop the mold from continuing to grow. I suspect that in one case we are dealing with an unventilated area with no means of escape for the moisture. I'm thankful that the space hasn't been incorporated into our living space yet, or connected to the HVAC. The other 2 tests were done where there is plenty of ventilation, where the lumber has been in place for 2 months, and has no source of moisture other than what is in unheated air.

I am paraphrasing what the code enforcement official told me. I have not seen the wording myself yet. All I know is that there are standards concerning how wood used in construction is stored. Does anyone know more about it? I can call back and get the relevant codes.

I called the code enforcement person again, and they said that in section 3.14 of the UCC, there is a reference to Chapter 23 of the IBC, which concerns wood. According to the code enforcement official, that chapter, addresses storing wood outdoors.

I do not have access to the IBC. Does anyone know how to access a copy without buying it?

If you can't access it online, your local library or your building dept. should have copies.

Personally I think you are making too much of this situation. I would be more concerned with covering up the existing wood giving you problems such as warping and causing nail,(screw) popping in the wallboard as well as other concerns rather than focusing on code concerns.

Your entire house was built in the weather until it was dried in.

It rained in the house, it snowed in the house, the builder may even have used a garden hose in cleaning off the floors before drying in (and sometimes even after before insulation and wall coverings are installed).

The way drywall is bent to curved walls is by wetting it.

ANd then many gallons of water are introduced by plaster or drywall finishing, and using latex paint.

Thanks, everyone.

My interest in the code is only to establish whether a contractor has a duty to use clean, dry wood. My house is being remodeled, not built from scratch, so there wasn't much weather coming in during this project other than during roofing. We have found some old existing beams that have mold on them, but we also know that were some leaks over the years, and of course, the house was exposed to the weather when it was originally built 30 years ago.

Wet things that have a chance to dry out properly don't grow mold. I have no fear of water, or any process involving water as long as it can dry.

Wet things that are not dry within 72 hours can grow mold, and that is my concern. If I had not been so sick in the past, I would probably not be so worried, but in an area recently enclosed, the level of mold was a 4 on a scale of 1-5. That is a lot of mold! That mold was on a new sheet of plywood, so it must have been moldy when it was put in, or it had a very high moisture content.

There are other places where there is mold on new lumber, so my guess is that the wood had mold on it before it was installed. There isn't any water intrusion, so at some point the mold would die when the available moisture was used up, but even dead mold makes me very sick. If I had never had this experience, I would have a hard time imagining that this could be such a problem, but all I can say is, it is real.

I completely understand that my concern could seem overdone to many people. When I moved into this house, my health deteriorated to the point that I had constant infections, and I developed a productive cough that I never had before. My immune system was overwhelmed by mold that was fed by a small amount of water intrusion in a cold room under our front stoop. It was a perfect storm, with one of the ingredients was me, and I am the first to admit that I was born with a flawed immune system. Even people without my issues can get quite ill from mold. My husband's co-worker told him he didn't realize that cough lozenges were a part of the food pyramid until he knew my husband, who is never without one. My son had to have sinus surgery because all of his sinuses were chronically infected, and while he is allergic, he does not have the extent of immune issues that I do.

We have decided to pay for the remediation of the mold ourselves, but I was surprised that there are no regulations about using dry wood. I know it would be a nightmare to enforce, or even to agree on, but considering how mold has been in the news so much, and how people selling houses are held accountable for mold when they sell, I was still surprised.

I know that managing mold and dampness may seem impossible, and maybe it is! It is dose related, though, so for me, my quality of life goes up when I am not around mold. I respect and appreciate all of your opinions and input, so despite that I have taken a strong position, I totally get that to many of you it seems like much ado about nothing.

After being diagnosed with bronchiectasis and an immune deficiency in 2008, I was resigned to the idea that I would be hooked up to an IV of human plasma for 5 hours every three weeks for the rest of my life. Then in 2010 my son came home from college for spring break and asked to use my albuterol inhaler. He told me that he never needed his inhaler unless he was in our house. Even when working out at the gym he didn't need it, and of my three kids, he had the worst asthma. We then figured out that we had high levels of aspergillus in several rooms in our house, most of it coming from the problem with our stoop, as well as from improperly applied stucco that was crumbling and letting water in. Those situations have been addressed, and once that was done, I stopped coughing so much, and began sleeping better, sometimes all through the night. My son no longer needs his inhaler when he comes home for the summer, or for a visit. He hasn't been home since the remodeling began, so I don't know how he would be now. My cough has returned to being almost as bad as it was a few years ago, and to give you an idea of how intense it is, I come close to passing out sometimes, and I have pulled over while driving until it passes

For anyone who is interested, there is a link below to a World Health Organization document that speaks to the health effects of dampness in buildings. Dampness is harmful not just because of mold, but also because it attracts other living things like ants, mice and even snakes. For people who are allergic, the presence of these other critters cause other health problems, and carpenter ants are bad for the house itself.

http://www.euro.who.int/document/e92645.pdf

As I understand it, most molds,( the toxic types), are harmful when they dry out and you inhale the spores. On new lumber, there is a type of fungus that often is mistaken for mold and is harmless but of course how do you know unless it is tested. Sounds like you are on track by getting a remediation crew in there for the clean up. Sorry this is happening to you and your family but getting it professionally neutralized sounds like a great plan and hopefully no further problems in your future. Best of luck!

Thanks, Sierraeast. To your point about the dried mold, I have heard that molds of all kinds can blow around quite a bit on the first sunny dry day after a few days of rain, resulting in bad allergy days for susceptible folks.

Thanks for the good wishes, and I am confident we are on the right road. Now onto more fun things, like paint colors, floors, and moldings!

"My interest in the code is only to establish whether a contractor has a duty to use clean, dry wood."

Define clean and dry.

The dry is likely covered by the wood being kiln dried to a specified moisture level.
Unless you have evidence the wood no longer met its allowable moisture level after kiln drying (and it can sit in the rain a pretty long time and not abosrob enough water to be above the drying limit) it is 'dry.'

Clean is not defined.
Wood at a building site often has mud and debris on it.
Since it is normally concealed it is not much of an issue.

Finish wood is treated much more carefully then framing lumber since it WILL show after installation.
The smaller dimensions make it much more likely to absorb moisture and change shape, making it very hard to install.

It is normally not even delivered until the building is 'dried in' and the weather excluded to prevent damage to the finish wood.

If you have all these special needs, why did you not add additional conditions to your contract?

We have lived with molds for only a few million years without a whole lot of problems.

"We have lived with molds for only a few million years without a whole lot of problems. "

No, we really haven't. We lived in drafty places where air flow through the structure prevented most mold growth. Once we started sealing up "the envelop" we created living conditions that humans never experienced before. The tighter we build, the more important controlling contaminates becomes.

"We have decided to pay for the remediation of the mold ourselves, but I was surprised that there are no regulations about using dry wood".

Since you have already taken action to have mold remediation performed, you have wisely decided your health is more important than other concerns in this situation. If you spent an enormous amount of money for mold remediation and health treatment, you may wish to consult your attorney to see if the framer is liable to reimburse you for these costs.

The remaining long post below is for others who wonder what is all this hype about mold.

I am a licenced contractor who deals with mold issues in connection with water intrusion damage to homes.
In my years dealing with mold problems, I have come to understand mold from a different point of view than the average contractor or homeowner.

To start, some background about mold.
Mold is any of the thousands of kinds of fungus which inhabit the earth.
Most mold is parasitic, and feeds off wood or vegetable matter that is found in nature.
For various kinds of mold, there are different environmental conditions that promote their growth and survival.
We usually associate warm, damp conditions with mold, but mold can live in many conditions from very wet to nearly dry, cold or warm.
As partr of their reproductive cycle, molds create spores which are released into the air and settle on new surfaces where they can grow as new molds if conditions are favorable.
Mold spores are microscopic spheres which can become airborne.
But these airborne spheres usually have a coating on thier surface consisting of myotoxins -- (poisons that can cause allergic reactions or severe health problems when inhaled, or adhered to your skin).
However, some mold spores are more toxic than others, and some people are more sensitive to these myotoxins than other people are.
So we see a vast variation when we read reports from different people that mold is a health problem.

Also note that theses mold spores are in the air even when there is no known mold that can be seen growing nearby.
Mold spores are as common as dust in the air.
Most people are acclimated to the normal levels of mold spores that are suspended in the air that they breathe.
But if there are places that have a heavy mold growths, we often hear complaints from people that they can smell the mold, or they are experiencing allergic reactions.
Perhaps I am one of the lucky people who is more resistant.
I have been in areas with heavy mold growth which have caused homeowners to move out of their home because of their severe reactions, without returning until our crews removed the contaminated materials and treated the mold. On the other hand, I have seen most of the mold testing usually shows that penicillin is one of the most common molds found in most homes. This is known to be a kind of mold that is used as a medicine to fight bacterial infections.

Because of the undefined health risks of mold, there have been no laws that specifically determined what levels of mold are acceptable, or what methods must be used to treat the mold to make a home safe and habitable.
It seems to be more of a personal choice for each indiviual to determine what is acceptable or not. But there are certain established methods of mold abatement which are accepted in the industry.

Before we get into the mold abatement methods, let's take a look at the other side of mold problems with wood.
Some kinds of mold can attack the wood in a manner that makes the wood weak, so it does not serve its function as a structural member.
But other kinds of mold are relatively harmless to wood or to people who are near the mold.
As an example, some new lumber at the lumber yard has a spotty black coating on the surface when you buy it.
These black spots are mold, which is usually found on "green lumber" which may feel wet or damp to the touch.
But they are not generally harmful to the wood structure, because they are only growing on the surface, and they usually stop growing after the wood is nailed in place and has a chance to dry out.
But if wood is stacked so it does not dry, then other kinds of mold can grow which appear often as white webbed strands on the surface, that can weaken the wood so badly that you can break it by stomping on a board.
This usually takes some time for mold to penetrate that deep into the wood, so it is rarely seen home construction because the construction wood has a chance to dry from the time it is nailed in place.

A second kind of mold damage to wood is seen in exterior wood that is exposed to the weather, especially in decks and in outdoor patio covers and trellises.
It is usually called dryrot, but it is actually a mold which grows in wet conditions.
The dryrot mold grows when the wood is drying after becoming wet.
The mold likes the damp wood fibers, and will penetrate into the interior of beams and deck planks, especially in corners and seams where water is trapped so it cannot dry quickly.
Dryrot mold can destroy the fiber strength so it is so soft that you can push your finger into the surface of a board.
This is the reason why deck planks are usually spaced at least 1/4 inch apart, so the water can drain, and air can dry the space between planks.

So we see there are two problems with mold -- a health problem and a structural problem.
The structural problem can be solved by replacing the contaminated wood members.
But if the wood has not lost its strength (no soft spots), then there is no reason to replace it.
You can simply kill the mold so it cannot spread, then take precautions so new mold will not grow on the wood.

How to remediate mold that is causing health problems?
For the health problems, the usual method is to first remove all the mold from the surfaces that you can find.
Then kill the mold with a fungicide. Ordingary bleach (sodium hypochlorite) will do this (You can also buy a commercial fungicide to kill the mold instead of using bleach).
Dilute your bleach with half water or use your fungicide and spray all the surfaces that were contaminated, where you removed the mold from.
Be sure to scrub the surfaces with a green kitchen scrubber or brushes soaked in the bleach solution.
Then after everything dries for a day or two, paint it with primer paint like Kilz to encapsulate any microscopic mold spores that may be remaining on the surface.
The primer will coat these remaining spores so they cannot escape into the air where you can breathe them.
Note: These mold spores still contain the myotoxins even after you use the bleach or fungicide to kill the mold, so they are still a health threat.

If you are sensitive to mold, then be sure to wear a mask with a filter so you don't breath the spores while you are working.
Also wear rubber gloves, and even tyvex overalls taped at the wrists and feet to keep the spores from getting on your clothes.
You can throw the overalls and gloves away when you are done with the mold abatement.

This is the general procedure that people pay thousands of dollars to hire a professional mold abatement company to perform.

About the particular problem of mold from the porch header circulating through the house, here are my thoughts:
Generally speaking, there is no code that specifies when a piece of lumber has too much mold on it to be used for construction.
There may be some local codes, but I can not imagine how they could specify the exact dividing line where the amount of mold or type of mold is acceptable or not.
Ususally, if there is an ugly mold growth, a framer will discard the contaminated lumber and replace it.
But this seems to be a judgment call by the framer.
From the scenario above, I have visions of a framer who was thinking that its a whole lot of trouble to dig that header out and replace it, so it is good enough to leave it be.

If the mold was really bad, the building inspector could tell a framer that the wood he used is not in good enough condition to pass the inspection, and require that he must replace it.
I have never seen this done, but then I have never seen a framer use lumber that had mold actively growing on the lumber that he used for his remodeling other than that black spotty mold we often see on new lumber.
If your building inspector has no problem with the header, then the only remaining objection is the objection that you raise.
Your concern may be that you simply don't like the idea of using moldy wood to enclose inside your home -- (an objection which I agree with).
Or maybe someone in your home is having health problems because of the increased mold spore levels inside the home.
In any case, this is a problem you need to address with your framer, because there are no laws I know of that require him to remove it.
It is best to specify that all the moldy wood is to be removed before any work starts, and have the cost of remodeling include this work.
Otherwise, you are dealing with problems that could have been solved in the beginning instead of later.

Some other notes about remodeling and mold:
The mold from new lumber is not as toxic as some varieties which grow when persistent water is leaking onto surfaces in your home.
Any surface mold on the studs is contained within the walls, and will stop growing when the wood has fully dried (less than 90 days).
I doubt any of the spores will find a reason to move from the surface of the lumber past the drywall or to the ductwork where they can migrate to the interior of the home.
During the remodeling, there may be higher levels than normal for mold spores and dust levels.
But this will subside to normal levels after the construction is done.
Unless someone in the home is super-sensitive to the surface mold that sometimes is found on new lumber, it does not seem like it will be a problem after the construction is done.
You can take precautions if you are concerned, such as special air filters fitted to the furnace or even an electtrostatic collector to remove tiny particles suspended in the air stream.

To answer the question: Is the framer required to use new lumber instead of lumber that was weathered outdoor for years?
Probably not. It depends on local codes and what your local building inspectors will accept.
Hopefully your framer will replace old weathered lumber it to keep you as a happy client and reference for future work he does.

You can read here to learn a little more about residential mold problems: http://www.cdc.gov/mold/stachy.htm

con_j

Thank you, Billl and con_j for your comments. I'd like to add that sickness from mold can be insidious. It can start with colds you just don't get over, and fatigue that never goes away. In my case, I didn't wake up one day and feel stricken with an illness that kept me bedridden. Over time, though, I forgot that I used to feel better. Once the bronchiectasis came into play, I was quite ill, coughed like it was my job, & slept only a few hours per night, so there was no ignoring it then. Often people with mold illness are told it is all in their head. It is a lonely and scary place to be. Some people cannot afford to test for mold, or to fix what is wrong with their house. I feel blessed to have the means to protect myself, my family, and the future purchaser of our home (many years from now). I can't imagine how I would feel if I had never found out what was going on in my house, and that I was not just in some general decline, or just lazy. I cannot tell you how much I was beating myself up for not being able to accomplish more. I had to stop working, and I just couldn't keep up with life. It affected my self-esteem greatly, and although I know intellectually that my value transcends what I can accomplish, I still feel like a wuss a lot of the time because I can no longer paint a room, or be around most chemicals. My lungs are hypersensitive now, and every visit to a hotel is a roll of the dice. It is not unusual for me to cough like crazy, since the air quality can be poor in hotel, new or old. One indoor air quality person told me I should never vacuum again! I still do it, but I wear a mask, and we have a central vac which keeps the particulates from re-entering the house. We also have an electrostatic filter on our furnace to capture as much as possible. I am not reporting this to get sympathy, by the way. I just hope that my sharing might alert others to the danger. I know that I represent a minority of the population, but everyone in my household has suffered a decline in health, just not as serious as my case.

Here are the results of the recent analysis:

These were tape samples, we didn't do air samples this time. When we first tested for mold a few years ago, we had very high levels of aspergillus/penicillium in several rooms. There were some other more dangerous molds on a baseboard in the basement, but that was from water intrusion from a heavy storm as opposed to the ongoing water intrusion from the defects in the construction.

Just to clarify, the header in the area with the level 4 mold was ok. It looked funky to me but it was just mud. There was a lot of mold in the room, but it was on new plywood and on a couple of new studs. We will test the strength of the header for soft spots with a screwdriver to be sure it is sound, but it seems to be ok. The entire space was cleaned with Shockwave, and coated with Sentinel clear coat.

Con_j, I learned a few months ago that many molds can be removed by sanding the wood and removing as little as 1/32 or 1/16 of an inch. I had not known before that mold (other than dry rot), cannot bore into wood, but that it instead lives on the surface. I was encouraged by that, because that means that the problem is quite fixable in many cases. The ideal time to do it, of course, would be prior to installation. In some areas of our house, the wood with mold is being sanded, then cleaned, and then sealed. HEPA vacuums are being used at the same time. We have not found evidence of structural instability, so we are not removing the wood.

"Con_j, I learned a few months ago that many molds can be removed by sanding the wood and removing as little as 1/32 or 1/16 of an inch. I had not known before that mold (other than dry rot), cannot bore into wood, but that it instead lives on the surface. I was encouraged by that, because that means that the problem is quite fixable in many cases. The ideal time to do it, of course, would be prior to installation. In some areas of our house, the wood with mold is being sanded, then cleaned, and then sealed. HEPA vacuums are being used at the same time. We have not found evidence of structural instability, so we are not removing the wood".

Just to be clear, dryrot is not the only kind of mold that can penetrate deep into wood fibers and damage the structural integrity of the wood. There are several common kinds of mold found on wood that can destroy its structural strength. I recently opened a stack of 2x6 lumber that had been sitting in the weather for over a year. After removing the top weathered boards, the inside boards looked ok except for a layer of soft white mold that looked like a flattened spider web, and had the consisitency of christmas tree flocking. At first I thought it was only a harmless surface mold, but we found that if the 2x6 was placed on two benches at either end, we could stomp on the middle of the board and break it. The mold appears to have weakened the center enough to make it about the same strength as you expect to find from a 2x2 lumber piece. We threw out the entire load of weathered wood rather than to try to salvage any of it.

This was a special case where the wood was stacked tightly for over a year in the weather without any protection from the rain, and no way to dry between the boards.

But you are correct about mold that can be sanded off, or treated with a fungicide to kill it so it is no longer a threat. I expect this is the usual case for mold that is discovered shortly after it appears. It probably takes a longer time for mold to penetrate deeper into the wood.

It sounds like you are now in good shape since your wood checks out as structurally sound, and you have corrected the mold problem. With any luck, your health concerns could improve over time if there is no continued airborne mold aggravating the condition.

con_j

I have reviewed IBC chapter 23 and did not find any mention of wood storage outdoors on a construction site. However, pressure preservative treated wood that will be enclosed so that it cannot dry is required to have a moisture content of 19% or less. Elsewhere in the code there are requirements for storage of wood in lumberyards. It is unlikely that fungus would originate at the site unless wood was stored for an unusual length of time.

I recently took an NCARB course on mold & moisture prevention in buildings and in the 112 page text book site storage of materials was mentioned in a short paragraph the remedy was a specification requiring moisture field testing with hand held meters. Building codes and surface mold on wood was not mentioned in the book but proper construction sequence was recommended in order to minimize site storage of materials.

I suspect it might be a mistake to assume that all of your problems are the result of the way wood was stored on your site. The wood was stored elsewhere long before it arrived on site and there are many ways for excess moisture to occur in a building during and after construction.

"molds can be removed by sanding the wood and removing as little as 1/32 or 1/16 of an inch"

It is is that shallow you should be able to treat the wood with a liquid and kill anything present.

I'm currently remodeling my home as well and also have some new (and old) lumber that has some mold stains. I haven't had them tested for active mold since most of my research shows that they won't be a problem if the finished environment is dry and sealed. However, I did spray the questionable areas with Boracare with Moldcare for some extra peace of mind.

Hi everyone,

Renovator 8, thank you so much for reviewing the code! Good lessoned learn on how to specify that certain conditions are met. I don't think we can prove or disprove what the moisture content was of the wood used, unless it is stamped anywhere on the product.

I probably mis-spoke when I said the mold grew only since being on my property. I know that wood sits outside at lumber yards for long periods, so that would certainly be a factor. For that matter, perhaps the framing contractor had left-over materials from another job that was being stored in a mold-friendly environment.

In the area where the mold was the worst, however, there was no ventilation. It used to be a breezeway that had a header to support the roof but was otherwise open to the environment. We had it enclosed by a wall that is now sided on the exterior and has three windows. The old exterior wall (which is now inside) has not yet been removed. See link to picture below. Eventually the newly enclosed space will be incorporated into our kitchen, but right now it is a separate 3.5' by 15' space that can be entered by going through the original exterior french door. The three new windows have been closed for the most part, and has not air flow since It is not connected to our heating/ac system. so there has been no air flow. It was enclosed three months ago, so considering that mold loves dark moist conditions with no air flow, I don't think it is a huge stretch to believe that a pretty serious mold condition could arise, especially if the moisture content of the plywood was high. It faces west, and we have a lot of trees on our property, so the sun entering the space is less than in other areas of our house. If I remember to ask, I can check with the air quality person on how long it would take for mold to grow under those conditions. I am more of the belief that there was probably some mold on the wood to start, but one thing for sure is that I am not an expert.

Brickeyee, to your point that cleaning with an antimicrobial is as effective as sanding, I completely agree! I was just happy to know that sanding is an alternative to antimicrobial treatment. In the past, the remediation company we hired used an antimicrobial called Anabec, and my lungs did not like it at all! I wasn't at home when it was applied, but when I re-entered the house it was a problem for me for several days. Fewer chemicals= better breathing. :-). The product being used in our house now is called Shockwave, and doesn't bother me as much.

I think sanding could be an option in that someone concerned about mold could physically inspect & sand wood before building with it. If sanded outside, there would be no worry of the mold entering the house. I found out about this when we re-positioned some windows that had been replaced a couple of years ago, but were in their original frames. Before they were re-installed, I smelled a musty odor when I walked by them. The top boards of the frames had some mold on them, and the indoor air quality person we had used when our house was remediated told us that we could sand the boards and then polyurethane them. Apparently the FDA or EPA or whatever agency gets involved with this kind of thing has published that surface mold lives in a layer as thin as 1/16th or 1/32nd of an inch!

Thanks to all for weighing in. Newtoremodel, thanks for the information on Boracare with Moldcare.