Old House New House Living

In this age, where energy efficiency and cost are at the forefront of our minds, we are considering ways that can improve our homes and achieve lower energy costs in return.

To achieve these goals, one of the ways we can address this issue is by improving our basic wall insulating value. However, this is sometimes easier said than done.  Most older brick homes have no insulation in the exterior walls and energy efficiency advocates are promoting filling the air space between your brick veneer and main wall of your home.  It is natural to think, wow, this would be great: its easy, it won't require repair of plaster walls and can easily be done without any visual evidence once complete, right? Well maybe not. Please consider the following:

Brick is naturally porous in nature as is the mortar that binds them. Standard construction techniques for decades have required this air space, for several reasons, but one of those reasons is to address the water that naturally permeates the wall.  Newer construction is not of concern because they have the appropriate wall insulation already included and actually have improved the wall veneer system by including flashing and weep holes in the veneer that were not included in older constructed homes. 

So, if the air space that naturally functions to address water permeation is filled with insulation, we have to ask ourselves where will the water go?

Some will naturally evaporate, as it does now, but the ability for the water to escape will be impeded as the brick will not be able to breath from both sides and the probability of water being trapped inside the brick will be increased if this air space is closed. 

What this means is that when we experience the natural freeze and thaw process of the seasons, this water will freeze within the body of the brick creating a potential for the brick to fracture.

Although there are no studies currently in place to determine the long term affects of this new insulating technique. Please ask the contractor you are working with about this specific concern.  I would also recommend that you ask them about warranties associated with any damage that may be attributable to eliminating this natural relief valve.  Not all air spaces are bad and they have a function in and of themselves.