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FAQ: Moisture Control

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What should I do about my leaking basement?
P.P. writes:
My wife owns a 5-room log house in Amherst, Mass. that was built about 10 years ago and is now rented. It is built of Maine white cedar with a full concrete basement. For most of the 10 years we had no trouble with water, except for minor leaks around the basement bulkhead which were fixed with caulking. But about a month ago, after a heavy wet snow followed by rain, our tenant called to inform us that there was about 2 inches of water in part of the cellar --the part where the oil fired furnace and fuel tank are located. A washing machine and dryer are also in this area, which our tenant uses to store excess furniture and miscellany. The washing machine drains its used water directly into the pipe to the septic tank.

The carpenter who built the house lives nearby. He came and looked at the basement, and reported that water seemed to be leaking in where the walls and floors meet. He had no suggestions on how to fix the immediate problem except to make a hole in the cellar floor and install a sump pump. After the place dries out, he thought perhaps we should install caulking along the joints of the walls and floor. He also speculated that perhaps the roof gutters were clogged and leaking water down the outside walls. But he checked them and said this was not the case. And he told us that drain tile was installed around the outside of the foundation when the house was built.

We live in Concord, Mass. and do not get to Amherst very often in the winter. Our tenant has been quite understanding about this problem, but has expressed unease about the water reappearing. Incidentally, after another fairly heavy rain a week or so ago, she reported that there was very little water except for dampness in the walls and a damp spot in the floor near the oil tank.

What could be going on here? And what could we do to prevent future problems of this kind? What kind of company could diagnose and fix it without requiring us to get a second mortgage? Would waterproof paint on the inside walls help?

Paul Fisette answers:
As with all problems involving leakage there are 3 components that you need to identify: 1) the source 2) the path 3) the driving force. If you successfully address one of these 3 components, you will have elimniated your problem.

1) Obviously, you have a source of water. But you have to identify what it is to craft a soulution. It could be run-off from the roof that is saturating the soil around the house. Added to the wet soil due to snow melt, your soils moisture-holding capacity could have been pushed over the edge. To deal with water from above, provide good gutters, cap the soil with an impermeable material like clay or plastic sheating and then cover it with soil that supports the growt of grass, provide good surface protection with overhangs and plantings, provide good positive drainage away from the house by grading the soil so it pitches consistently away from the house --- these are some suggestions. There are other ideas that work too, but the general idea is to reduce your home's exposure to water from above.

2) Pathway::: How is the source of water traveling to enter the house? if the soil is saturated then you could have water finding its way through any crack or pore or penetration in the foundaton. Any goop that you apply will not block the flow inward. It is only a matter of time before caulk or coatings applied to the inside of your wall will fail. It is most difficult to block all of the holes to eliminate liquid water penetration. Coatings work adequately as "dampproofing" but not as waterproofing. Blocing holes in a foundation works better if you block them with a continuous flexible membrane like EPDM that is placed on the outside surface of the foundaton wall. This means excavation and it is expensive. So blocking the cracks on the inside usually don't work to hold back serious leaks.

3) Driving force::: What force is acting to drive the source through the pathways into your house? If the water is leaking from the crack between the floor and the wall, it sounds like groundwater (source) is being forced through a seam (path) by hydrostatic pressure(force). So you can reduce the effects of the force by building a drainage envelope around the perimeter of the foundation. Provide a porous, well-draining area around the basement. YOu can do this using stone and gravel wrapped in filter fabric (so fines dont block the drainage path). Or you can purchase drainage mat materail and lay it against the outside of your foundation wall. Water that approaches your basement will enter the drainage envelope and find it easier to follow the influence of gravity and flow downward where you will position a drain pipe around the basement footing. So with this system water enters the soil, travels toward the foundation, enters the drainage envelope, drains downward, enters the peremeter drain pipe, and is carried away (preferably to daylight). This is expensive but extremely effective.

The other thing you might want to consider, is whether or not the existing drain pipe is clogged by roots or fines that have dislodged or filled the pipe.

This is the briefest of overviews that I have provided you with. Obviously it is a complicated process. I hope this stimulates some thinking on your part. And unfortunately, I do not know of a person who does this work in Amherst area. I also would be careful who I hired to do this work. There are not very many individuals who truly understand how to approach these types of problems beyond applying goop. One commercial system that I do like very much is called "Tuff-N-Dri Warm-N-Dry" This is a combination of applying an elastomeric coating to the outside surface of the wall and then covered with a rigid fibergall insulation/drainage blanket. This process is licensed and its intallation is somewhat controlled because of this fact.

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What about housewrap and vinyl siding?
E.V. writes:
My wife and I are building our first home in Columbus, Ohio. The house is being built by M/I, and is expected to be finished in December. I am somewhat familiar with construction, but not an expert by any means. I have several questions, so I hope that this is not an inconvenience. To put the questions in context, I am negotiating with the builder to allow me to housewrap the home, but they are very reluctant because they are worried about liability, warranties associated with vinyl siding, and the fact that my home will be the only one with housewrap, so others in the development will complain that they don't have the housewrap.
1). I have heard and read about the advantages of housewrap, including your article, and that one is foolish not to housewrap, but will the vinyl siding on a house, warp or degenerate as a result of heat build-up, if the house has been constructed with housewrap underneath the vinyl siding?
2). Do you have any references or cites to references that I could use to bolster my argument against the builder to allow me to housewrap my home?
3). Are all of the housewraping materials from the different manufacturers comparable? For example, is tyvek better than pinkwrap?
4). Finally, the basement of the new home uses a waterproofing system called warm-n-dry or tuf-n-dry, which if I am not mistaken, consists of a coating on the outside of the block foundation from the grade down, and a foil coated foam board that gets glued to the inside of the foundation walls except for the crawl space wall. The basement also has a sump pump. Should I coat the inside of the block foundation with a waterproof coating (i.e. thoroseal or the like) before attaching the foil-faom boards to the walls? The basement has a ten year warranty with their system, but I don't know how long that I will live there, so I want to ensure that my basement doesn't leak.

Paul Fisette answers:
1) I have never heard of and can't imagine that there could be an interaction between housewrap and vinyl. I strongly recommend the use of a redundant layer of protection beneath the siding, otherwise how can you protect the top of your flashing? How can you protect other leakage points? Certainly, noone in their right mind will tell you that vinyl siding is water tight!
2) As far as providing you with other documentation, I do not know of published information. My experience has been first-hand and also gathered from other inspectors and consultants who have witness wall system failures. It is not a topic that gets much press. You could contact the manufacturers of the siding to see how wrap affects the warranty. Contact DuPont and ask if their product adversely affects vinyl. This should give you a layer of comfort.
3) In my field inspections and in the laboratory testing, I have come by the strong opinion that DuPont's Tyvek is far more water repellant than any of the competing brands. Most of the other products leak water like a seive under a fairly low-pressure hydro-head. If I were building a house I would use either Tyvek or #15 pound felt.
4) This is not what I understnad to be the warm-n-dry or tuf-n-dry system. I thought this system was a combination of first applying a bituminous coating on the exterior surface of the wall, followed by a layer of rigid fiberglass (insulation-like material only the fibers are alligned vertically so water drains through the material which functions as a drainage mat). I have never heard of an interior layer being part of the "official" system as sold and promoted. I do think the warm-n-dry or tuf-n-dry system is very good. Adding Thoro-seal to the inside is an added bonus.

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What about insulation as a vapor barrier?
S.F. writes:
I have renovated 2 houses (additions, framing, plumbing, electrical, etc.) myself. I just purchased a fieldstone house on the Mass/Ct border. The house was built in 1929 using slipform (my guess) with walls 12 to 15 inches thick. The interior walls are 1 inch plaster over a product called "insul-lath", a pressboard type looking material. I'm thinking about blowing in insulation from the inside. Neither blown in fiberglass nor cellulose provide a vapor barrier. Would another product be more effective?. Also, I'm replacing the asbestos tile roof (after an abatement company removes them) this summer. My home is a gambrel style where the roof line to the front and back of the house are sort of the 2nd floors exterior walls. I've already insulated the kneewalls with R19 and installed Pro-vents down to the soffets and from above the knee wall into the attic. Behind the kneewall is a crawlspace that runs the length of the house.
Question: 1). I read on Mazenails web page about a nail that they have for nailing through roof insulation. Is this some kind of foam product?
Question: 2). I'm looking for an alternate to asphalt shingles without the cost of slate, copper or tile. Do you have any information on any of the alternatives?? (Cedarlite, etc..)

Paul Fisette answers:
Don't worry obsessively about the vapor barrier. Vapor DIFFUSION is a minor player in moisture transport. Air tansported moisture (vapor carried by air leakage) is an order of magnitude more significant. Bulk moisture is 2 orders of magnitude more significant. This does not mean to ignore vapor diffusion. It means: don't confuse diffusion with air leakage. BLown-in cellulose does a great job of blocking air. Fiberglass doesn't do as good of a job blocking air. I would be concerned about using cellulose insulaton in a stone-wall cavity. Cellulose is hygroscopic and will settle if it gets damp and wet. Fiberglass will shed water more readily. I am not familiar with your specific case, but you might want to keep this in mind. To provide an adequate vapor barrier all you have to do is prime your interior walls with bin or some other vapor barrier paint like glidden insulaid or 2 coats of oil-based paint. These all qualify as vapor barriers. You should be more concerned about air leakage into cold wall cavities. Warm indoor air leaking into these cavities will cause condensaton and susequent damage.
About the nails, I think what they are referring to is that they have nails designed to be used when plastic foam roof insualation boards are used on the roof.

About a good substitute for asphalt roof shingles...I don't know of any material that can compete performance vs cost with asphalt. Sorry.

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