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.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Wayne,
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.
Funny, seven years to the day of my original post above, I am finally getting around to painting our home!
So in looking more closely, we do have an overhang of about 6-8 inches with a drip edge on it.
Part of the home is already painted, so no going back on that now. Am planning to paint out the rest to match and repaint the originally painted part.
My question still remains, do I want permeable paint on the exterior to allow vapor to vent to the outside, given that i have closed cell on the inside OR do I want paint that is a vapor barrier to keep the moisture out of the wall system to begin with??? I think it is the former (which appears to be the opposite of the opinion I had in 2014!), but want to be sure.
And what do I do about the already painted brick? Is there any way to ascertain what was used originally... over a decade ago. Or does it not matter, and whatever I do on one, I do on all of the brick?
No offense to those who paint professionally, but closed cell on brick is no where as common as it should be in DC, given all the brick here, so want to come to the conversation with my own understanding/information.
Your insight is (still) much appreciated.
Still have the same question
You might want to investigate mineral paints made for masonry. Did you install the CC foam on the interior?
Yes, I should have made that clear. Interior is now all complete... just never painted.
Closed cell directly applied to the 100 year old brick on the interior.
Bumping back up to the top as I am still without an answer.
Hello Wayne, Any updates?