Join the MRA | Member Login
Find a Professional
Sign Up Log In Add New Topic

TOPIC: Installation Process

Moisture barrier--Visqueen or red rosin paper

Return to Installation Process

Return to Archive

Return to Forum

I am preparing to put a standing seam roof over single layer of shingle roof and plan to put 30# felt over the shingles and would like to know if black visqueen would be as good or better than red rosin paper over the felt to prevent it sticking to back of the metal?
Guest User

1/17/2006
Generally speaking the undrlayment is a moistiure barrier biut it needs to breathe so felt will do the trick and poly should not be used. In critical areas such as valleys and eaves where ice damming etc, a self sealing ice and water shield is recommended. If you are worried about sticking, an old trick is to get some powdered chalk and sprinkle it on the felts as you lay the sheets.
Allan Reid
Dura-Loc Roofing Systems, Inc.

1/17/2006
We are about to put a metal roof on top of existing composite shingles. Would red rosin paper help with moisture buildup if you live in a fairly humid environment?
Guest User

10/8/2008
I would suggest 30 pound felt or a synthetic underlayment. Red rosin paper will not be helpful in this case. Todd Miller
Todd Miller
Isaiah Industries, Inc.

10/9/2008
I sell metal roofing products. I speak for my company, as well as for many of my competitors when it comes to the use of red rosin paper under a standing seam metal roof. DON'T DO IT. Red Rosin paper has sponge-like qualities. It entraps moisture. It subsequently can lead to back-side corrosion of metal roofing. The use of it under my standing seam metal roof voids any and all warranties. With respect to metal roofing, the only acceptable use for red rosin paper would be under a copper roof, due to the high rate of expansion/contraction exhibited by copper. Roofing felt is perfectly acceptable under a standing seam metal roof, although a good high-temperature, non-granulated ice and water shield is ideal.
Guest User

1/19/2009
Thanks for weighing in, Chris. Todd Miller
Todd Miller
Isaiah Industries, Inc.

1/21/2009
I installed a metal roof over asphalt shingles thinking that the moisture barrier of the original roof should be sufficient. Two years later i see evidence of moisture on the top of the interior center wall. Is there something I could insert between the original roof and the metal overlay that would act as a wick to draw the moisture?
Guest User

4/20/2009
This actually sounds to me like a ventilation issue. Todd Miller
Todd Miller
Isaiah Industries, Inc.

4/22/2009
So, I should install vents in the crawl-attic?
Guest User

6/12/2009
Yes, is there opportunity to add intake and exhaust vents in order to get some air movement in the attic? Todd Miller
Todd Miller
Isaiah Industries, Inc.

6/12/2009
There is no power up there, but it is just an open space with both gable ends on outside walls, so a non electric vent on both ends might provise intake and outflow, I think, or would a single vent be enough?
Guest User

6/14/2009