Mold originates where there is moisture and food for it.

Three areas where most of the hidden mold problems originate are:

        In the crawlspace sill or exterior wall

        In the exterior walls of the living area

        At the top plate of exterior walls

    If the crawl space is wet then mold is going to happen somewhere in the home.

    The crawl must be free of standing water…this is accomplished by making sure the exterior grade and drainage are right and the guttering is correctly planned and installed.

    With a dry crawl mold is still possible (and occurs more frequently than most people are aware) because of air infiltration. Air leaks during sub freezing temperatures can meet up with warmer crawl space temperatures and cause condensation in the sill box and on the crawl space walls. Fiberglass in the sill box will not guarantee a cure for this because it allows air to move through and the moisture generated becomes a mold breeding ground.

    When blueboard is used on the crawl wall it is usually installed by using a tube adhesive applied to the wall and pressing the foamboard to the wall. Besides the occasional board which does not stay up the other opportunities for the cold block to get in touch with warmer air is at the seams and on the wall where the tube adhesive holds the board off the wall. As soon as the moisture appears in any of these circumstances there is the opportunity for mold growth.

    When spray applied closed cell foam is applied at levels yielding R-10 on the block wall and R-19 in the sill box the opportunity for cold air to enter the crawl is eliminated and there will be no condensation or mold in those areas. Spray foam is an upgrade and would cost about four to five hundred dollars more than the blueboard and fiberglass. The foam spray application also eliminates cold floors, loss of heat in the heat runs, and frozen water pipes.

    Exterior walls have many of the same problems when there is air infiltration into the stud cavity. While house wrap can be beneficial in reducing air infiltration there are many instances where seams are not overlapped to instruction or the material is not tacked down as the manufacturer recommends. Air that enters a wall cavity filled with fiberglass is free to move around the cavity.

    The cold air moving around the cavity may contact air from inside the home and cause condensation and give the risk of mold. Wall cavities that have been coated with even a skim coat of foam will defeat any air leaks in the cavity and allow the fiberglass laid over the foam to function to its rated R-value. This reduces the opportunity for moisture in the wall cavity to roof, window, or plumbing leaks. Because there are no wall air leaks the utility bills for this type wall are typically a third to a half less than might be expected from more conventional installations.

    One of the most common locations for mold is on the outside wall at the top near where the ceiling junction is made. This mold is the result of the top plate not being covered with insulation in a way to keep cold air from blowing over the room ceiling. In this case the ceiling gets cold enough that moisture is condensed on the drywall and provides the catalyst for forming mold. When the top plate of a home is covered with foam that fills in the space between the top plate and the air chute or roof deck the path for cold air to cause mold on the ceiling is blocked. Besides eliminating mold in this area the foam gives the highest possible "R" value to help prevent ice dams.

    Sealing a home’s exterior with foam probably offers the highest cost of any other insulation but the unique sealing quality of foam allows the investment in foam to be paid back to the homeowner quicker than any other product and it will continue to pay for itself over and over through the life of the home

    The only reason not to install a foam seal exterior in a home is if the homeowner knows that they will not be in the home longer than three years.

For more on mold, with pictures, CLICK HERE.


Copyright 2009 Hoosier Square, Inc.3/22/09
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