Basement Walkout Addition

by richard
(woodbridge va)

Question

i want to build a 16 x 34 room addition from walkout basement,free standing with only a structural posts support on each end & one in the center & basicly the same against the house . we will install 14 or 15 foot sliding jeldren bifold glass doors. the space will be drywalled , insulated ,with mr slim heating & cooling. the space above will be accessed from kitchen - family room area. this will be a open deck with deckrite vinyl or rubber roof . we will install azek vast pavers over the entire area with shoreline vinyl railings around perrimeter with 6 x6 posts for railings. we will do another extension to the deck . a 14 x16 gazebo & a 8 x 13 out of wood construction . the paver look will cover all areas.my problem is how to construct the masonry project with only 14 inches of height including 1 3/4inches of paver. there will be 1/8 inch slope for drainage. thank you

ps there will be a new foundation with proper footers & insulated slab. i can make a drawing


Answer
Hi Richard,
I am not clear of your question. The 14 inches height you mentioned, are you talking about the height of the floor joists for your deck? The only way I can see it working is you will need floor joists such as TJI that can span 16 feet across. You will attach floor decking to the floor joists, waterproof before you lay your bricks on top. Those floor joists will be carried by beams that will sit on the posts you mentioned.

What I don’t get from this plan is whether or not you are going to have concrete or block walls at the perimeter of the new basement additions. These walls will not only retain the soils but they will also support the new structure you’re building. This is based on my assumption that basement addition is below ground level. Should you have the perimeter walls, you don’t need the posts you talked about, just lay the floor joists on top of the walls and that should work fine.

I hope you are not intending to cut 15 ft wide opening in your existing wall for your new bifold door. Should this is the case, you need to talk to a local structural engineer to investigate how feasible for your existing house for such a move. The walls in your house not only support your house vertically but they also prevent your house from collapsing due to side sway caused by wind or seismic load. Removing 15 ft from the wall can cause your house to be unstable.

Hope this answer your question. If not, shoot me a little more info and I'll try to bring the answer closer to your question.

Good luck
Tonga