What is the simplest way to add a pitched roof to a flat roofed garage.?

I'm looking at a 24' X 26' area of a house over a garage that has a flat roof. Water seams to be pooling in a few areas. We were thinking of adding a 2 x 6 ridge in the middle and sloping it in both directions. I'm a pretty handy guy nut I have not done this before so I'm looking for pointers.


The roof is strong. The waterproofing material ha some kind of fiberglass, I got it all over my arm, that's how I knew. Can I build right on top of this or do I have to remove the roofing material first, I really would hate to mess with that fiberglass. There are no current leaks.


What do I need to do for venting? Can I just cut a few holes in the existing roof to allow for ventilation and then add some roof vents.



Without a more exact description of the structure in relation to the house it is hard to advise. Are the ceiling joists 24' or 26' long? Is the garage attached to the house or separate? Do the joists run perpendicular or parallel to the house? Anyway, if possible, use a Reciprocating Saw and cut all the nails between the two boards of the double top plate on 3 sides. The front and two sides or the side by the house and the front and back. Jack up the roof joists in unison 6"to 12"to accomplish a shallow shed roof and fill the void created with two 2"x 6"or 2"x 12" on edge and blocked together to the necessary width to match the walls. Then make custom blocking to fill the triangular spaces over the other walls. It will be necessary to scab on extra length to the raised joist ends if you want any overhang or if you need them even with the wall under them.




You can buy roof trusses and anchor them to the existing flat roof then sheet it and shingle it. if you just want to get rid of the pooling, you can slope everything back one direction. You can do this by building a 2x4 frame then sloping it toward the back of the garage. after you do this put plywood sheeting on it and add shingles.




Sounds like you are right on track. Just build over the old roof. Your idea for venting is just fine. Build away.....