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Stephen Cutler
Stephen Cutler, General Contractor
Category: Home Improvement
Satisfied Customers: 2062
Experience:  35 years of troubleshooting construction, remodel, component & material failures. What to do next
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I have danosa material on my concrete roof. Recently it rained

Customer Question

I have danosa material on my concrete roof. Recently it rained extensively & a slight leak has begun in my livingroom. My husband went up to the roof & noticed thaqt the danosa has tiny punctures, when he steps on the danosa - water seeps out. Now my questions are how can my husband repair this problem? Also, can he place new material over the old material or does he have to remove the old material? Thank you for information.
Submitted: 8 years ago.
Category: Home Improvement
Expert:  Stephen Cutler replied 8 years ago.
Hi and thanks for using
The Danosa web site describes your roof material as Bituminous. They list the types of mastic (glue ) and most interesting is a self stick tape. From the sescription of the tape it is designed for direct exposure to UV. The pinholes you describe sound like the UV protectant wore away and the bituminous substrate became attacked by UV and degraded. These coverings are designed to be under tile, gravel, sand, or some other protection from UV rays from the sun.
The fact that water is oozing when you step on the roof suggest a cellulose pad under the roof membrane, and this pad is acting like a sponge. You need to get that soggy pad removed and dry out the roof deck. Then you can put down new pad and new danosa- glueing it to the old with the mastic. Here is the web site:

Asphaltic sheets
Bituminous sheets can be classified according to its finish (sand, polyethylene film, mineral slate or aluminium), as well as by its mastic (oxidised bitumen, modified SBS or modified APP bitumen) and by its reinforcement (fibreglass, polyester felt, etc).

Self-Adhesive Tapes Self-Dan
Self-adhesive tapes 10, 15 or 30 cm wide with metallic self-protection in natural, red or grey colour. Designed for sealing chimneys, pipes, skylights, cracks, etc.

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