Published on December 4th, 2012 | by Henri


Insulation outside of foundation damaged

Q.    The foundation of my log home is poured concrete, which extends 32 inches above grade before the first course of logs. This foundation was tarred not only below grade but also sixteen inches above grade. The remaining sixteen inches are not tarred. Thirty two-inch sections of pink rigid Styrofoam insulation were attached to the above grade portion of the foundation and then a skim coat of gray cement was applied. Over the years the insulation has come off the foundation in a number of areas and this winter an entire section has buckled, split and fallen away from the foundation.

This spring I plan to remove all of the remaining insulation, which will leave me with an exposed foundation, the bottom half of which is tarred and the top half is not. As I do not want to restore the insulation as it was, having experienced this failure, I am seeking  a concrete paint that will adhere to both the tarred and the non-tarred portions of my foundation so that it will have a uniform appearance.

Do you know of such a paint and if so, where I might obtain it?

A.    First, to respect trademarks, the pink rigid insulation you have is FoamulaR by Owens Corning. Styrofoam is the proprietary name of Dow Chemical’s extruded foam insulation and comes in blue and grey.

It is not desirable to remove the rigid insulation as it does serve the purpose of reducing heat loss from your foundation. Consider that 8-inch-thick concrete walls have the same R-factor (resistance to heat loss) as a single pane of glass and that 1-inch rigid extruded polystyrene insulation can cut the heat loss through these walls by 84 percent. That should be enough to convince you that you should keep the foundation walls insulated.

Here is a better solution: Repair the insulation as needed, cover it with half-inch pressure-treated plywood, and attach the plywood to the concrete foundation with power studs. You can get these in any building supply store and rent the gun to apply them with; just be sure to get the right size fasteners by telling the store clerk what thickness materials it needs to go through.

Once you have done this, add soil to the foundation so only about eight inches of it shows. Slope the new soil at a rate of two inches per foot and plant grass on it. There is no reason to have so much foundation exposed.

If you are still determined to remove the insulation, tape black plastic to the concrete and add soil instead of painting the foundation. Cut off the excess plastic. This will cover the exposed tar and give you a better solution than painting by protecting the foundation from exposure to the cold and making your house look closer to the ground.

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