Adding Story Over Flat Roof Residence

gust0261

Adding Story over flat roof residence:
Has anyone ever done this?
It seems that I would have to remove all the existing tar which means all the existing plywood which means separating the plywood from the trusses/joists. If they are glued down (which they probably are) how the heck am I going to get it off? Am I just in for two full length cuts through the plywood along the whole length of every joist?

neolitic

That seems to be a plan
Question: How do you eat an elephant?
Answer: One bite at a time!

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thom

The roof framing will be inadequate to support a floor load. You can't double them up without rewiring the area below. You will probably need to rework plumbing and hvac ducting as well. That means you are likely to be working in every room of the existing house.

OR

You could tear off the existing roofing (or leave it in place as a sloppy job), tear off the parapets or pig-troughs, run 2X4 plates around the perimeter of the house, then install floor trusses that will span to the plates. Leave the existing house alone, add new hvac for the upstairs. Will be much quicker and cleaner for the lived-in portion of the house.

OR

If you lack confidence in the existing wall/foundation structure, install columns at the perimeter of the existing residence supported on pier foundations and supporting girders that support the new floor trusses (or tji's) so the second story addition is independently supported.

There are a few ways to do this job, using the existing joists isn't one of them.

woodmagman

You may want to consult and engineer and General Contractor to confirm your design, but the process of building a parapet and transposing the load of a new floor to the existing exterior wall, can be a fast solution. It would allow you to construct the second level and enclose the structure prior to removing the existing roof and exposing the house to the elements.

neolitic

Wow, you got a lot of detailed advice by just asking how to tear off the roof deck!
If you do need some advice along the way, since no one else has seen it, you might post some more detail about the existing structure.
Personally my crystal ball is in for polishing right now.
Good luck

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woodmagman

Make sure you read the fine print when starting that tear off....

d-rez

I did this very thing last year on a remodel, adding a master suite on top of a flat roofed section of a house. I agree wih Thom, demo the whole roof structure down to top plate. Start over fresh and do it right. As mentioned by others, without knowing more, it's hard to give any more accurate advice. You probably have ducts and wiring, and depending on span it might be easier to go with open web, I am using them more and more on projects. Chris

localtradesman

I just completed a second story addition to a whole house. There is alot to look at. Have HVAC, electric, Framer, check it all out first. Your supporting outside walls have much to do with this project. If you can't build on your existing outside walls your in trouble. Everything else can be done. It is pretty much the second story that matters at this point.