# Adding a pitch to a flat roof



## theRoofingLady (Oct 6, 2015)

I want to add a 0.25/12 pitch to a small flat 11 square residential roof. The cost to use a foam taper system with a coverboard is cost-prohibitive. I am wondering if I can use 2x4's and OSB to add a pitch. There is currently an old Modified Bitumen hot mop on the roof. I would leave the old roof and then make the pitch using the wood and then put a peel and stick modified bitumen over the wood and up the parapet walls (using cant strips in the junction between the roof and wall) and sealed under wall caps. I would advise a handyman-type homeowner to do this....I just want to know if this is advisable. Thanks!


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## llmotoll (Feb 27, 2015)

Would advise caution in making structural changes in slope or modifications to existing drainage details 
-Collateral weight load to the structure 
-Does this roof have a peripheral edge for drainage? If not than point loading the deck with a clogged drain/through wall scupper is a concern.
-When the first two concerns have been addressed and you intend to move forward. Recommend tearing off old roof prior to framing new deck over top. Years down the road the new roof could fail or be damaged allowing water into the structure. Where would it go? Pond on the underlying roof left in place? Now think snow load weather conditions with who knows how much standing water trapped underneath. Potential roof collapse? What if some kid is underneath getting ready for school one day and the roof collapses? 
At a minimum cut at base of all wall flashing and around all projections and cut 25 square foot or 100 square foot squares across entire roof to allow future roof leak water to pass through into the structure. This eliminates potential standing water on the old roof underneath the new framing, steeling collateral weight load, mold/mildew, eliminates the monolithic deck and allows for some sort of deck ventilation. 

There are several other options to accomplish the goal. But if you decide to go this direction the above items would be most critical for buildings structural integrity.


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## theRoofingLady (Oct 6, 2015)

*Thank you!*

Those are good points. Thank you for your comments and your insights! :thumbup1:

What are some other options to create positive drainage? Scuppers would not work with this building because there is no attic space.


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## johnmeto (Aug 30, 2015)

The dispenses with potential standing water on the old rooftop underneath the new confining, steeling guarantee weight burden, mold/buildup, kills the solid deck and takes into consideration some kind of deck ventilation.


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