Musty smell in a terraced house? Yes, it comes from the crawler area.


Q: We try to find the next step in dealing with a musty odor in our 1928 brick terraced house. It was originally built as a corner shop and has no full basement. The smell is most noticeable in the living room. When we bought the house, the inspector believed that the smell came from the damp earth under the living room, which was pulled in by the dehumidifier. We pulled it into the basement and started it only when it rained extensively, but that did not diminish the smell. We also tried to ventilate the house, scrub surfaces and use odor removal products. Nothing worked.

Friends have suggested installing a vapor barrier under the parquet flooring in the living room, but that would be expensive and difficult as the underlying crawl space is not really accessible. Would ceramic tiles or cork tiles provide a vapor barrier?

ON: The solution is probably to "encapsulate" the crawlspace – a treatment that involves sealing the dirt floor and outside edges of the room and then providing a way to keep the air temperature and humidity levels similar to those in your living space. There is no way to eliminate the mold problem by installing another flooring, as the problems creep in what's in the crawl space.

The construction workers felt that musty odors in and over a crawlspace should be avoided to ensure adequate ventilation under the house. And to keep a house warm, they isolated the floor from below, often with a vapor barrier to prevent moisture in the crawl space from entering the house.

The thinking has changed almost completely. Through the outer openings in a crawlspace, warm, moist air can actually flow in summer. If the air in the living room is cooled by an air conditioner, this moisture condenses on the bottom of the cold floor. Mildew grows, especially if there is a moisture barrier that protects the condensation from evaporation. In winter, the opposite happens with the same effect.

The solution is to eliminate the conditions that allow condensation.

Crawl space access is often quite close, but you can not assume you can not upgrade the crawl space. The image you sent shows what is probably just a foundation, and there is probably another access door, said Chris McLaughlin, Sales Manager at JES (877-537-9675; ), a Virginia Beach-based company that performs space encapsulation and other work throughout the DC area. "Sometimes there is a door in a closet and someone has put a rug over it so you do not even know it," he said. If there is really no opening, his company can cut one, either outside (with a steel lintel to support the bricks over the opening, in a case like yours), or in a secluded place, such as a cupboard, then equipped with a trap door. Call at least two companies specializing in encapsulation of crawler areas and request a local assessment and recommendation with a cost estimate.

Mohammed El-Ghoul, owner of Home Energy Saving Solutions, Rockville (301-842-8818; ), the encapsulation of a crawl space almost always indicates musty odors. The exception, he said, is when "mass water" flows into the room. So, the first step in solving your problem is to make sure that there is no obvious source of water, such as gutters that lie next to the foundation, or sprinklers that splash against the walls.

Then a company like El-Ghoul sends a crew to clear any debris in the crawlspace. This includes the removal of insulating materials, at the bottom of a moisture barrier is attached. The insulation without moisture barrier can remain in place as long as it does not mold or fall down in places.

When the room is tidied up, the crew spreads a moisture barrier, eg. B. thick, six millimeters thick plastic, over the dirt floor. They also install a moisture barrier on the walls and seal all seams. Fresh insulation goes against the walls, over the moisture barrier. The last steps include closing the external openings and adding a vent valve or a register for the heating and air conditioning. As a result, the crawl space is actually part of the heated and air-conditioned space of your home. Sometimes, said El-Ghoul, a dehumidifier in the crawl space replaces a register for heating and air conditioning.

This work is not cheap, but in addition to solving the odor problem, it should reduce drafts. Keeping the soil drier can also help to keep your house, as pests such as some types of powder beetles often attack moist wood. El-Ghoul estimated that for a typical Washington terraced house, the bill is often $ 1,700 or $ 1,800. But for complicated situations, including those with distended mildew that need to be cleaned up, it can go into the thousands.

McLaughlin said the minimum cost is more likely to be around $ 4,000 to $ 5,000, which includes a more robust dehumidifier than those normally sold to homeowners, and the electrical work required for operation. The cap could be tens of thousands of dollars if the soil structure rots and needs to be replaced, he said.

The retrofitting of a terraced house is usually similar to working on a single-family home, said El-Ghoul, because the crew treats the neighbor's crawlspace as an exterior wall. But rarely do terraced houses have common creepage areas. This brings additional problems – and costs.


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