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posted: 8/19/2012 4:58 AM

Energy audit can identify heat-loss culprits

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Q. First of all, I would like to thank you for suggesting Amteco TWP wood preservative. I just used the TWP 1500 series on my fence, and it turned out great. I hope it lasts for years to come.

My wife and I read your article every week. We are trying to find ways to make our house cooler in the summer and warmer in the winter. We live in a split-level home. Each year, icicles form on the gutters.

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Several years ago, we had an upstairs bathroom and the kitchen remodeled. During the work, I noticed some insulation dropping from the attic. It did not seem to be a lot, but we have noticed a difference. One of the walls in the bathroom is very hot to the touch on hot days and cold on cold days. The attic panels are located in my daughter's closet. Again, on really hot days, her closet is superhot. We had our roof replaced, and the workers replaced the old attic fan and roof louvers with new ones.

I am trying to figure out the most thorough and cheapest solution to the temperature swings. I think an energy audit might be our best solution. When is the best time of year to have an energy audit done on the house? Should certain tests be included in the audit? Can you recommend a specific company that does thorough energy audits in my area? I was looking at companies listed on www.resnet.us.

I am also interested in your thoughts about a company that inserts foam insulation into the home: www.usainsulation.net. It seems like it would be a great solution but might be rather pricey. Any suggestions are greatly appreciated.

A. Icicles indicate that the attic temperature is above freezing. This may be caused by insufficient insulation throughout the attic, poorly installed insulation, and uninsulated access panels or folding stairways. If your walls are insulated with cellulose, it may have settled, leaving voids at the top of the walls.

A warm attic also can be caused by convection of living-space air into the attic through any number of avenues: access panels or stairs with no weather stripping, bath and kitchen fans that discharge in the attic, ceiling light fixtures, separated drywall tape, holes through which plumbing pipes and electric wires are fed and any other cracks.

The icicles may indicate you have had ice dams that could have caused water to leak inside the walls, wetting the insulation and reducing its efficacy.

You may have read before that I am not a fan of attic fans; they draw conditioned air from the living space because there is seldom enough net free ventilation area (NFVA) from other louvers in the attic to satisfy a fan's CFM rating. And if the fan is installed in the ceiling, it is another convective path to the attic. It is unfortunate that you did not instead install continuous soffit and ridge vents when you replaced the roof.

I also hope the roofers installed an ice- and water-protective membrane at the eaves and at all roof perforations to prevent leakage in the house.

An energy audit will point out all potential sources of heat loss and gain. It consists of a blow-door test to identify the convective paths and of infrared imaging to find voids or improperly installed insulation in walls and ceiling. The best time to do an energy audit is when the temperature is below 50 degrees so that the infrared camera can spot the areas of heat loss.

I cannot recommend any particular energy auditing firm because I am not acquainted with any of them in your area, but you should be able to find out which ones have been registered as properly trained by calling your power company, fuel provider or state energy office.

As for foam insulation, it may not be appropriate in your case. If your walls are insulated with cellulose that has settled, it can be topped off with more cellulose. Once the convective paths have been identified and sealed off, more cellulose can be blown in the attic.

If you plan on replacing your siding, rigid foam insulation can be installed under the new siding.

Q. Since contracting my own house and living through the construction process, I wonder about everything. For example, I think about what could improve footings, what could improve drain tile and what could best prevent them from silting up. I also wonder a lot about how to prevent moisture accumulation in a basement.

I just heard about a new kind of concrete sold in California that is so porous that water runs through it. Its goal is to allow water to run into the ground to help replenish groundwater and reduce runoff.

I immediately thought: If there is a way to make concrete more porous to water, is there a way to make it impervious? Would a home's foundation be better if moisture was not able to wick up from the ground and add humidity to the basement? That is too deep of a question for me to think about, especially since you have warned so many readers about adding too much insulation to the inside of their basement walls. I assume that's because a basement wall is never supposed to get below 32 degrees for fear that moisture in the wall would freeze and crack it.

My assumption is that most homes have a certain amount of water that sits for a time in the trench that was dug for the footings, and that before it has a chance to work its way down into the earth, it could do a good job of saturating the footing and working its way up the wall. Is this a good assumption?

A. All water needs to be removed from the footing trench before the concrete is poured. If concrete were poured in a footing trench with standing water, the cement powder could be segregated from the aggregate and the sand, resulting in a weak mixture that would not cure properly.

Before installing a footing drain, geotextile fabric, wide enough to cover the stones that will cover the drainpipe, should be pinned to the earth bank.

A proper footing drain should be installed next to the exterior face of the footing on top of a 2-inch bed of stones. Several more inches (12 inches, preferably) of stones should be placed over the drainpipe. The fabric is then folded over the stones and at least 2 inches of coarse sand should be spread over the fabric to protect its filtering ability. If the native soil is silt or clay, it is best to backfill the trench to within a foot of the final grade with sand. This is particularly important if rigid insulation will be added, as it should be, to insulate the foundation.

The final grade should slope away from the foundation at the rate of 2 inches per horizontal foot, and carried as far as is practicable.

Pervious concrete is being used increasingly outside to allow water through instead of draining it away to other impervious surfaces such as asphalt roadways and to storm drains.

To prevent moisture from wicking from the soil into a basement, several inches of stones should be spread over the soil and covered with 6-mil plastic before pouring the slab.

To make concrete walls "impervious," it is best to tightly wrap a newly poured foundation with 6-mil plastic and leave it on until complete curing has taken place -- 28 days. The greatest enemy of concrete is premature evaporation of its moisture. Unfortunately, because the building process needs to move on, concrete contractors remove their forms a couple of days after the pour. It is up to the builder to quickly cover the foundation walls with plastic. Fully cured concrete becomes as tight as a rock, leaving few, if any voids, for moisture to seep through. There is no need to remove the plastic from the outside; it's another layer of protection against moisture in the soil.

The warning about insulating a basement wall when the texture of the backfill is unknown is not because the moisture in the wall will cause its failure, but because wet soil against it, allowed to freeze, can crack it.

Q. I am one of your biggest fans. I read your column, own your book, have given several copies of your book as gifts and think you are the greatest!

We live in the Chicago area. Our house is 46 years old (frame with aluminum siding). We have owned it for 43 years. In April, we had the second-floor master and hall baths remodeled to the studs. Everything was great; we were happy with the contractor and the finished bathrooms.

Two weeks ago, when I left the house at 8 a.m., everything was perfect. When I returned from work at 6 p.m., the floor in the upstairs hall at the top of the stairs "popped." The "pop" is about 3 to 4 inches high, and the floor slopes for about 12 inches on each side. The "pop" starts at the baseboard and goes out perpendicular for about 12 inches toward the top of the stairs. The baseboard is flat to the floor and to the wall -- it does not seem to have any involvement.

Nothing is wet in the bathrooms, the hall or the ceiling below. We keep the central air conditioning set between 74 and 75 degrees at all times and run a dehumidifier in our finished basement. The floor in the hall that has popped is wood parquet that is original to the house, with wall-to-wall carpet over it.

We waited about two weeks before we called our contractor, thinking it would just go back. It didn't. He said he had never seen anything like this without moisture being involved. He is coming back next week with a meter that measures dampness.

The toilets were removed and reset. The master bath shower backs to the hall. The floor under the shower was reinforced with two-by-fours, 2-by-6 or whatever. The whirlpool tub base was set in quickset. Twelve-inch-square porcelain tiles are on the shower enclosure to the ceiling and on the bathroom floor. I know the contractor used the correct cement board on the walls and good-quality underlayment on the floors. The custom shower door is half-inch glass, hinged, with a narrow stationary panel.

There doesn't seem to be an involvement with the hall bath, which does have a common wall with the master bath. The contractor has already checked for any obvious leaks -- all seems secure and dry. We are empty nesters, so there isn't a lot of excessive use or misuse.

May we have your thoughts?

A. Your contractor is right; flooring that expands and pops up is generally due to moisture absorption and a flooring material that has been installed tightly to the wall plate, leaving no room for normal expansion. Standard installation requires leaving at least a half-inch space between the wall plates and the flooring, space that is covered by the wall finish and the baseboard.

My guess is that either the carpeting on top of the parquet got wet and stayed damp long enough to cause the parquet to swell, or, more likely, a small amount of water has crept between the subfloor and the parquet, causing it to expand. Perhaps a slow leak through floor tile joints; a pinhole in the lead or composite pan, which is essential on shower floors; a leak at the shower drain; or a very slow leak in a pipe joint?

The span of time between April and July makes it improbable that the cause is moisture generated during the construction process, especially since you have central air conditioning.

I am curious to know what your contractor found with his moisture meter, and I assume that he has removed the carpeting and lifted the popped parquet tiles to see if the subfloor is wet. Please let me know.

• 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 henridemarne@gmavt.net. His book, "About the House," is available at www.upperaccess.com and in bookstores.

2012, United Feature Syndicate Inc.

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