basement plan with slab for 20x30 plans

Started by metolent, August 27, 2010, 02:25:16 PM

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I've got the 20x30 1.5 story plans here in front of me.  I'm drawing up the plans for the foundation right now based on these plans and am staring back and forth at pages 2 (slab and floating slab foundations) and 3 (crawlspace foundation plan).  I've been looking at the composition of the concrete stem wall to use as a reference for the basement foundation wall on the one side as I'm building on a slight grade so the basement will actually be a daylight basement.  However, since I plan to have a slab poured within the basement, I've been looking at page 2.  Hence my questions:

For a daylight block basement, should I simply combine the basics of the stem wall (with the same J-bar ties at the footer to wall connection as well as at the block wall to sill connection) with the monopour slab floor detail?

Second question - is such information or examples available on the site?  I haven't joined that one, but will if it would help here...

The foundation is the part I feel least comfortable with at the moment.  I'm going to contract this part of the build out, but I need/want to understand the composition sufficiently well for the building plans I will submit, plus just for my own edification.  For reference I'm going to be building in Packwood, Washington.  I've already built a 12x16 based on the little house plans I bought last year to get my feet wet (been meaning to share on the forum), but am now ready to move on to the "big" cabin. 



I am in the process of building the 20x30 1 1/2 storey with a walk out basement and have just finished the footings and walls (although these are poured not block.) The floor will also be concrete. I have plans you are welcome to have a copy of if you think they would be of use to you. They have been stamped by an engineer in Nova Scotia though I suspect this may not carry any weight south of the border. Also they may not be suitable for your ground type and frost conditions.
Best of luck,

John Raabe

For a basement foundation you can use the basics of the crawlspace foundation (p. 3) but it will need to be upsized to an 8x16 footer for an 8" wall. For the slab floor this can be poured after the walls are up and it would be similar to the "floating slab" on p. 2 of the plans. You will want to step the foundation footings down on the low side to stay below frostline and there will be rebar and bond beams in the block wall that the contractor will probably have details for.

You will also want to make sure you have good drainage installed and an external membrane or coating before the backfill goes in. This is more important in a basement than a crawlspace.
None of us are as smart as all of us.

Devil Dog

@Alasdair I am looking to exactly what you are talking about. Could you send me a copy. So I can make sure I am on the right track. Thank you. Josh


@Alasdair I am also looking at something very near what you are talking about. Could you send me a copy. So I can make sure I am on the right track. Thank you. Steve