cost of adding roof vs roof and upstairs living space (Portland: house, contractor)

[Fiddler2]

Who would build a house in Portland area with a flat roof? Well, we bought one to get a view, but now we're stuck with a 50's era sometimes leaking structure that takes constant babying to keep sound. Currently, the roof has been redone and is not leaking, but we'd like to get a new one. We've thought about adding an upstairs to the existing house when we add a new roof. For starters, it would be just empty space, but we'd need to be able to walk on it. Does anyone know what percentage of increase it costs to add walls, reinforce flooring, etc. plus add a pitched roof, vs. just adding a pitched roof? We're talking an area of about 1400 sq. ft. We were looking at one of those (I think) metal roofs (or are they plastic?). If that isn't considered "green," we'd probably want to do something green. Plus, we'd like to put some solar panels (yeah, dream on) over the part where the garage currently is.

[Nell Plotts]

Agree, flat roofs on residences in the northwest are nightmares.

What I would do:

First find a structural engineer who will take a look at the house to tell you what would need to be done structurally. There are a lot of architects (with licences - no "home designer") who need work these days. Ask friends and neighbors for names and call around. You want drawings adequate to obtain a building permit and that SPECIFY what a builder must do to, for example, flash windows properly. Find out what your jurisdiction charges for building permits.

The addition won't be cheap but there may be $$ out there for energy saving work, for example. Whether or not solar will be practical (return on investment) for your exposure is a question to ask. The panels themselves will be significantly cheaper in a couple years. If you have a suitable exposure install "legs" to support panel frames and a raceway for wiring this time, install panels later. Become your own expert on the subject.

Look for a roofing material now available that imitates the slate look, is comparatively light, made of recycled rubber and has a 50 year warranty. You can walk on it, no worry about a contractor stepping on a standing seam. PLEASE do not use plastic or vinyl, not good fire spread ratings. [Several homes burned in the Seattle area this week for that reason.]

For siding the cement fiber products are performing very well. I wouldn't use it on a roof only because I fear moss would love it.

[Nell Plotts]

I know you asked about cost but no one can estimate that at this time. Lumber is A LOT cheaper than it was a year ago, for example. Labor... maybe cheaper but more importantly the builder needn't settle for any carpenter who can lift a hammer. I don't think it will be a lot cheaper than a home with the same square footage you are adding.

Check with your local building department to see if there are any height limitations for your site. Also, if you are in a planned unit development check your deed for view easements.