Sarking membrane roof on the cheap
Hello,
Almost done with the roof framing on my 1000 square foot PGH 3-12 single slope pitch in coastal Maine. I have an idea for this sarking membrane assembly that won’t break the bank. Feedback please.
I will apply 9 foot rolls of typar across the rafters and tape the seams and edges with 4 inch Rissan tape. Before I fasten my 2×4 sleepers to the rafters, I will cut ice and water shield into 3 inch strips and apply it to the typar, on top of the rafters to act as nailing tape. I will then deck it with 5/8 zip and tape the seams before laying down metal roofing (non-standing seam).
Questions:
1. Will the ice and water shield seal around my fasteners in this application? Using a framing nailer with 2 and 3/8 ring shank nails.
2. Should I strap the deck before applying the metal roof? (I am hoping not to).
3. Would the typar tape be better than the rissan?
All told, I am looking at 4 rolls of rissan, 2 rolls of typar, 1 roll of ice and water shield ( plus zip, 2×4’s and, metal roof). A good deal less expensive than the high performance stuff and I think i can get it to air seal just as well…
Thanks,
Stephen.
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Replies
A hole with a nail in it is not an air leak. I don't think the I&W strips are needed. Try to lay out the house wrap in a way that seams land over rafters. Much easier to tape plus the strapping now clamps that joint tight.
Otherwise what you propose will work. The hard part is installing the membrane without stepping through it.
Thanks Akos,
I am surprised that a batten held down by a nail without nailing tape would be air tight. Something to consider. I will be dense packing my roof and imagine some upward pressure that might tug on the typar and create air leakage. The I and W strips might act as insurance against that.
The stepping through the membrane thing is a challenge, you are right. Laying the typar perpindicular to the rafters helps solve this as I can build it up from the bottom (membrane, tape, sleepers, decking) and it would be safer and easier to control (by laying the sheathing down as you go to have a working/kneeling surface). The 9 foot rolls and 8 feet of sheathing (2 courses) place the taping seam in an easily workable location.
Thanks, Stephen
Stephen,
Akos is right about air-leakage, but even if he wasn't, that sarking membrane isn't your primary air-barrier, and a bit of air-leakage would make very little difference.
Hi Malcolm,
thanks for chiming in.
The sarking membrane, in my case, is my primary air barrier. I am taping it to the zip wall sheathing to cap the whole thing. That is why I am a little concerned about the nail holes. Bearing that in mind, would you still forgo the nailing tape?
I am doing monopoly framing and adding my overhangs after I tape my sarking membrane.