Actually, we did precisely this project just last summer. We tore down an older wooden deck that was over a walk-out basement, enclosed the area below while accessing the older part of the basement by knocking out a wall, and then building a new bigger deck on top of that structure. It turned out beautifully, but there are certainly details that need to be attended to, and you need to deal with someone who knows how to build a deck on top of a rubber roof (which is what we did, but you could do it other ways as well). The basement expansion also turned out wonderfully.

We are doing something similar, starting construction in about a month. Our house has a first floor enclosed sun porch on wood posts. The area under the porch was sided at one point and it has been used as a shed. We are extending our daylight basement out under the porch to capture the area. It involves cutting into the original foundation, pouring new footings, installing a beam to replace the load bearing wall, etc. I can't really tell you how much it will cost because it's part of a MUCH larger project, but it's definitely not the most expensive part of the basement remodel. I would suggest you have an architect draw up plans for you -- they can arrange for the services of a structural engineer etc. Good luck!

You'll definitely a structural engineer's opinion, both for removing part of your existing back basement wall, and for supporting the deck above. I had one independent of the builder for my own peace of mind, and it wasn't too expensive. His guidance turned out to be very useful, and the builder was happy to work with him.

Your proposal involves excavation and pouring of new footings and stem wall (varies with how the terrain elevations may be), demolition of existing affected construction, new construction, insulation and finishing of new exterior walls and roof assembly, proper waterproofing of the new roof assembly, building the new deck and tieing everything into your existing building envelope properly. In addition, you may need to re-examine your electrical, lighting, plumbing and HAVC for sufficient cacpacity and distribution to accomodate the new space.

We don't know the situation and configuration of your existing house, so whether or not it's the most economical way to add new area to the house, and whether it's the most functional addition that could be added, is impossible to answer. For that you need a designer or experienced builder.

It's only a guess, but salvaging and reusing existing materials may be more costly and time-consuming than all new materials. This assumes that the existing materials will be compatible and appropriate for the new addition, which they may or may not be.

Sounds like you need a bit more study and analysis before making a final decision on your best course of action.

Good luck on your project.

We are trying to figure out how to do something like this. How did your project turn out

Hi Stacey, I ended up here wanting to do something similar, and yours is, by far, the most recent post! Are you still considering this? Have you talked to anyone? We have a meeting with a contractor tomorrow, and I have no idea what to expect!

Anyone has photos they can share? Looking to do the same soon and thinking of ideas when talking with a contractor.