My question concerns with a typical masonry wall construction, is this:
When the Air/Vapor barrier comes to a termination (i.e. at window opening, roof, or foundation),
1. at the window head, does the A/V barrier overlap on top of the metal thru wall flashing or goes behind it? some sources I looked at (i.e. graphic standard) they have a layer behind, but a note saying "membrane flashing over metal flashing) Does it mean a third (extra) membrane flashing over the mtl flashing which is the thru wall flashing?? it is always drawn muggy at that junction. What is the typical/best practice?
2. At the roof, if I have a metal clad parapet, my strata is something like this, from the exterior: metal cladding-> 'membrane flashing'-> exterior grade plywood-> wood blocking and insulation-> a/v barrier->concrete block parapet structure. But I've seen construction drawings with the same note however, is reversed, "mtl flashing OVER membrane flashing"
As far as I'm concern, the air/vapor barrier has to go over and around the parapet, but again, some sources has it turned up and ended very muggy.
3. finally, at the foundation, where the water proofing membrane starts seems to be always at the i.e. edge of slab-on-grade, or edge of slab. Where should the a/v barrier turn and stop?
Each of these conditions have different approaches.
For the wall / window it depends on the wall.
For parapet I wrap over the top of the wall and down. I have seen it terminate under the metal coping. Depends on the roof.
For the damp proofing - we never say water proof - the contractor normally stops it at grade. Depends on the wall either four or six inches below T/FDN.
May 11, 08 8:32 pm ·
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Learning my layers -thermal/moisture protection question
Hi all:
My question concerns with a typical masonry wall construction, is this:
When the Air/Vapor barrier comes to a termination (i.e. at window opening, roof, or foundation),
1. at the window head, does the A/V barrier overlap on top of the metal thru wall flashing or goes behind it? some sources I looked at (i.e. graphic standard) they have a layer behind, but a note saying "membrane flashing over metal flashing) Does it mean a third (extra) membrane flashing over the mtl flashing which is the thru wall flashing?? it is always drawn muggy at that junction. What is the typical/best practice?
2. At the roof, if I have a metal clad parapet, my strata is something like this, from the exterior: metal cladding-> 'membrane flashing'-> exterior grade plywood-> wood blocking and insulation-> a/v barrier->concrete block parapet structure. But I've seen construction drawings with the same note however, is reversed, "mtl flashing OVER membrane flashing"
As far as I'm concern, the air/vapor barrier has to go over and around the parapet, but again, some sources has it turned up and ended very muggy.
3. finally, at the foundation, where the water proofing membrane starts seems to be always at the i.e. edge of slab-on-grade, or edge of slab. Where should the a/v barrier turn and stop?
I'd greatly appreciate discussion/answers/comments. Thanks.
Maybe we should have a discussion category called 'construction details'
Each of these conditions have different approaches.
For the wall / window it depends on the wall.
For parapet I wrap over the top of the wall and down. I have seen it terminate under the metal coping. Depends on the roof.
For the damp proofing - we never say water proof - the contractor normally stops it at grade. Depends on the wall either four or six inches below T/FDN.
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