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Old brick with closed-cell foam on interior - Exterior paint?

I have read a considerable amount about the challenges of insulating brick homes. As I am in an historic district, interior insulation is my only option. From what I have read, closed cell foam is my best bet.

My question is how to best handle bulk water on the exterior of the home. It is a rowhouse with zero overhangs. Presently the front of the house is painted and the rear is exposed brick.

In my mind, I would want to ensure that the exterior of the brick is painted with a vapor barrier paint, thereby reducing the possibility of vapor and liquid coming into the brick structure from the outside. With the closed cell on the inside, there should be little vapor getting into the structure from the interior. Is that correct?

Location is in DC, mixed humid zone 4.

Asked by Wayne Weikel
Posted Fri, 03/28/2014 - 17:50
Edited Sun, 03/30/2014 - 06:06


1 Answer

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My first reaction is to advise you not to paint the exterior of your bricks. Most brick experts agree; it's rare to find a situation that is helped by exterior paint.

The best approach to exterior water management is the use of good flashings. Hopefully, your historic district commission is flexible enough to recognize that water management is essential to historic preservation. After all, if you can keep some of the rain off your bricks, the building will last longer.

If the building has parapets, it's a good idea to install wide flashing on top of the parapets, with drip edges that are extended as far as the historic preservationists will let you get away with.

It should also be possible to come up with an acceptable detail to install copper flashing above every window head.

In as many locations as possible, you want copper flashing with a drip-edge that is proud of your bricks. Even 2 inches can make a huge difference.

Answered by Martin Holladay, GBA Advisor
Posted Sat, 03/29/2014 - 06:08
Edited Sun, 03/30/2014 - 05:36.

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