Bradley5
Mechanical
- Jun 18, 2024
- 11
We are working on designs of a couple buildings, mostly used for manufacturing so mostly no interior finishes other than the insulation facing. What is common is the "super saver" method, which is decent, but I am questioning the need and extra expense of the poly liner as opposed to just laying in the faced batts. I know we also want and need a product between the steel frame and steel sheathing to provide a thermal break. What is common is 2-4" of unfaced batts. This is where I am having most issue because in other buildings, we have identified a concern with all the overlap seams of all the steel panels that leak horribly. This leads to 'wind washing' of the batts right under it, effectively short circuiting the insulation.
For this reason, I have some consideration to having that outside layer of batts between the sheathing and frame to have a facing, but actually install it backwards so the facing is in contact with the sheathing. I believe it can help channel any condensate that could occur under the panels, and provide additional air seal.
Now, from a building science perspective, this may not make sense having effectively two vapor barriers, BUT that would assume something that is probably less true in these buildings, which is they leak by design. Ideally you want an air seal on both sides of glass batts, but that seems to rarely ever happen.
I'd be curious of any thoughts or alternative methods? Keeping in mind the level of complexity being up on a building, working in the elements.
For this reason, I have some consideration to having that outside layer of batts between the sheathing and frame to have a facing, but actually install it backwards so the facing is in contact with the sheathing. I believe it can help channel any condensate that could occur under the panels, and provide additional air seal.
Now, from a building science perspective, this may not make sense having effectively two vapor barriers, BUT that would assume something that is probably less true in these buildings, which is they leak by design. Ideally you want an air seal on both sides of glass batts, but that seems to rarely ever happen.
I'd be curious of any thoughts or alternative methods? Keeping in mind the level of complexity being up on a building, working in the elements.