Air tight and breathable
We are building a small studio out of an old brick garage. The existing masonry walls are rough and definitely not air tight. In this design we want to leave the brick exposed on the exterior to match the house. So the air barrier has to happen on the interior side of the brick.
Since 90% of heat loss is through air infiltration, it's important to have a good air barrier. Since getting moisture stuck in the wall is very bad, having something waterproof to stop bulk water but vapour permeable to allow the walls to dry is a good thing. Remember, it's not if your building will get wet, it's when.
On a small personal project I had used STO Gold to paint on a vapour permeable air barrier over concrete block. You have to fill in the worst of the holes with mortar (lime render) prior to painting on the air barrier. This extra work is fine for the DIY person, but on the job site, this is costly labour. The process works well so I specified it on this studio job. The contractor from the Fourth Pig didn't agree and suggested that peel and stick would be better and less labour intensive
I was intrigued and yet skeptical. What if it is not sticky?? What if it is too sticky?? How hard is it to apply????
The contractor chose Delta Vent SA and are very happy with the results. It stuck well to everything. The workers felt it was easy to unroll and apply. The interior wall surface was entirely covered. Odd shapes were not a problem and it attaches to air sealing around windows and openings nicely. At the base of the wall, the product is stuck right to the concrete floor and for double protection a bead of SIGA adhesive is added between the floor and the air barrier.
The interior walls are inside the air barrier so that electrical and other holes in the wall are not an issue.