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posted: 5/18/2014 12:01 AM

Use of wrong type of lumber may have led to rotting, mold

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Q. I'm afraid I've got something really bad happening to the "knee wall" I built up under part of my house five or more years ago. Here's my situation:

I bought my home in 2005 as-is from a foreclosure sale. One-half of the house was originally a camp, built back in the '70s. This "camp" part has been nothing but trouble since I bought the place. I found that this side of the house was built on cedar posts, but had shifted off most of the posts and had significant rot on the sill on two sides. This was made worse by the previous owner piling dirt right up to the sill on these two sides (I believe in an effort to keep the wind from blowing under the crawl space). The other two sides of this half of the house were closed in with pressure-treated plywood and then sealed with spray foam.

Being more foolish than brave (and having little money), I proceeded to excavate by hand the two sides, which had rotten sills or rotten joists. After digging down as far as I could (I hit ledge after only two feet in one corner), I then poured an 8-inch wide footer, leaving myself 24 inches from the top of the footer to the newly repaired sill.

To keep the wind out, I copied the idea of building with PT 2-by-4-inch studs and 1/2-inch PT plywood up from the footer to the sill. This was not intended as a structural wall, just something to bridge the gap from house to footer, and give me something to insulate with extruded foam. On the outside, I coated the exposed footer and PT plywood with a black sealant that I brushed on, similar to tar (my apologies, I can't remember the exact name). Past that, in an effort to reduce the water that the PT wood would see, I piled up one inch of crushed stone with a drainpipe at the bottom.

It has been roughly five years since I put in the PT studs and plywood, and after just checking on things I find they are thoroughly rotten! I've also seen what looks like a white furry fungus growing all along one of the walls (mostly just below grade, but on the inside in the crawl space).

My first question is: What made my PT plywood and studs rot?

My second question: What can I do from the footer (below grade) up to the house that will not rot/fail? I am thinking cinder blocks, but after two courses I doubt there would be room for a full third, and I'm afraid they would wick moisture up to the sill itself.

I've seen PT lumber used for docks in swampy areas and it looks great after years. What did I do to ruin this installation? Was it the coating I put on the PT plywood, and if so, how did that lead to rotting the studs, which never saw any of the coating?

I've attached some pictures so you can see the inside of my crawl space and the rotten timber, plus a picture of an example of the outside above-grade portion of what I did. Please excuse the blurry photos!

A. You did all the right things, but you were sold the wrong material. There are several grades of pressure-treated wood, and the grade depends on the use. You must have bought wood labeled for above-grade use, which has a much lesser amount of the chemicals needed for contact with soil.

Some lumberyards and big-box stores sell two or more grades, and it is essential to buy the right one.

If you told the clerk what you intended to use the plywood and the 2-by-4-inch lumber for, he or she is at fault. Otherwise, count the experience as an unfortunate one.

Instead of coating the plywood with a tar-like substance, the best way to protect it is by applying a 6-mil black plastic sheet to it. Otherwise, do what you did before.

You should also cover the ground under the camp with 6-mil plastic to keep the soil's moisture under control. This would prevent the formation of the mold you now have.

Q. I've lived in my house in a northwest suburb of Chicago for 35 years and have only heard a certain noise twice last year and twice so far this winter. When it got bitterly cold, I heard a boom so loud that I thought something hit my house. I checked the rafters, walls, ceiling, etc. but saw no visible signs of damage. I did have two previously sealed foundation cracks leak again last spring and they had to be resealed. I read in the paper the following: "Residents of Toronto, when the temp hit minus 7, heard loud booms generated by underground water freezing and expanding."

I've never heard anyone around here even mention this before, and Chicago gets very cold. Could you tell me more about this, as I'm afraid of foundation and house damage that expanding water outside could do?

A. The loud bang may have been caused by underground water freezing, but it could also have been caused by your roof framing being affected by the extreme cold temperature. This can put so much stress on the fasteners that you hear the entire assembly groan or sound like a gunshot. This is a common problem in very cold climates. The noise is often heard again in the spring when the stress is relieved by moderating temperatures.

There is really nothing to worry about if you haven't seen any signs of separation at the joints of the different framing parts.

Q. Our granite countertops get hard water marks from the hard water we have. Is there any way to remove the hard water marks?

A. Clean the tops with a mixture of equal parts water and white vinegar. This will remove the hard water marks. You may also want to consider sealing the granite tops with a commercial sealer, such as Bulletproof, which you should be able to find in flooring supply stores and online.

You will need to reapply it periodically after a thorough cleaning with the same solution. You can tell when a new application is needed with the water test: If water beads on the counter, it is not yet time to reseal, but if water penetrates, it is.

Granite countertops need acidic cleaners, while marble countertops need alkaline cleaners. Using the wrong cleaners will etch the material and damage it.

Q. I read in the Grand Rapids Press that you are not a fan of the fiber cement siding (i.e., James Hardie, etc.). We too are looking for something more maintenance-free than the cedar we currently have and thought the fiber cement product was the ticket. We are still able enough to clean and re-stain the siding itself; but the awful job is what I call the overhang areas; cleaning and re-staining a ceiling type area is no fun (ditto the ceiling of our covered porch). Is there any wood compatible material you recommend for that area? Maybe the problem is the product we've used on the wood -- initially something called Penofin, and more recently a Cabot product.

A. I am not very fond of cement board (known in the trades as cem board) because I have seen too many problems with it. Some of these problems were due to installation, but the installations I checked were done according to the manufacturers' specifications, which were updated from time to time as the manufacturer became aware that the existing specs did not work and caused problems. To me, this is not a good recommendation for any product. I'd rather wait until all the bugs have been worked out.

Cedar is such a valuable and beautiful wood, I would hesitate to recommend that you cover it with either cem board or vinyl. Considering how difficult it is to work on a ceiling, why not hire a painter every few years to rejuvenate the soffits and the porch ceiling. That should be less expensive than covering them with a new material, which may also need cleaning from time to time.

You may want to try pressure-washing these areas. It may be enough to rejuvenate the surfaces. Pressure washers are quite reasonable in price, and have so many uses that it is worth investing in one. The choices are electric or gas-fired models. An electric one should be sufficient for what you need to do and it is easier to handle.

Q. I live in a 72-year-old house with a one-car attached garage that has a cement floor that is at times wet or damp. Is there something I can use to treat this condition, such as a special paint or coating? There are two downspouts draining six feet away from the foundation on a downslope near the garage.

A. I know of no paint or coating that will prevent condensation from forming on a concrete slab. Condensation happens on a cold slab, which mirrors the soil temperature below, when the relative humidity in the ambient air gets very high.

The condition is taken care of as the slab warms up or the air becomes drier.

VALUABLE INFORMATION FROM A READER: I received this email from a reader in response to my answer to another reader who had a noisy neighbor on how to build a soundproof wall between their units:

"I read your comment to the gentleman about the noisy neighbor in the newspaper and by no means should he have to go through the expense of another wall or the mess it will create. We have been in several condos, and yes, there's always a bad apple in the bushel, but he should go the association with a written complaint and the bylaws should be on his side. No one has to put up with that kind of aggravation. I hope he finds a little peace and quiet. People of that age have put up with enough noise in their life. Thank you."

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. Write to him in care of the Daily Herald, P.O. Box 280, Arlington Heights, IL 60006, or via email at

© 2014, United Feature Syndicate Inc.

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