Expert: Daniel Humphrey - 1/22/2008

Question
I know that our garage has a truss system supporting it, so in order to add a room, that would have to change, and the roof itself is not tall enough to support a bedroom. Do you have any idea how difficult and costly it is to take on such a feat? We would be accessing the new room through a bathroom, but the whole project could be done without disturbing anything except the garage and the empty attic space above the attached garage until the project was almost complete.

Answer
Betsy,

Projects like this are as expensive as (and more intrusive than) starting from scratch at ground level, given good access and benign terrain. Adding a floor over the garage makes the most sense for a house already having two stories. Maybe yours is two floors, and the new roofline will match.

There is a major expense in tearing the old roof apart, or alternatively cutting it free and raising it with a crane. You will be needing an engineered wood I- beam system for a floor support, and possibly some new trusses even if you can save your old ones. All the rest is normal platform framing, but done above ground level, which makes it a little more expensive, as usual for second stories.

You will also have a fair amount of repair needed for the garage when it's all done. Converting a bath to a stairwell also may have some hidden expenses and repairs.

Maybe you have already ruled out the possiblity of a ground-floor addition--or converting the garage to a living area and building a new garage--which would involve a lot fewer surprises.

If you do this second-story project, you need to do some very thorough cost planning. If you get a builder, he may not want to commit to a fixed lump sum because of hidden expenses that inevitably come up. You will probably be asked for a lot of change orders if you do have a lump sum contract. The other way to go is cost-plus, which puts a lot of the responsibility on you to stay in budget and make sure you have enough to finish it.

Anyway, its' all fun at this stage, envisioning something cool to improve your home!

Happy planning.

Dan