Need suggestions for a foundation on a 10x18 building.

[deck99]

Hi everyone.  I am building a 10x18 woodworking studio/shop in my backyard.  It's the largest I can build with a post and pier foundation.

Please give me your suggestions on the wood foundation design I could use.  I would like to keep it as close to the ground as I can.

I was thinking about 6x6 posts in the ground sandwiched between two 2x8's or 2x10's.  Run two sets of these in parallel (18' long).  then run the floor joist across them.

Your suggestions would be helpful.

Thanks,
Deck99

[MountainDon]

Keep in mind that if low to the ground you should be using PT lumber. (girders closer than 12" and joists closer than 18" to the ground.)  My shed is low to the ground and uses PT including the plywood floor.

Rather than bolt or nail a 2xsomething to the side of the post (to make a sort of a beam or girder) and place the joists on top it would be better, IMO, to notch the 6x6 to make a ledge for the 2xsomethings to sit on. Then the fasteners will only have to keep the 2x's in lateral position, not support the weight of the entire structure. Or place the built up beam/girder on top of the 6x6. Either way, wood stacked on more wood is preferable to relying on only a fastener(s) to support the load. Fasteners are also only as strong as the wood they pass through, if you follow that.

[Squirl]

Don is right about the girder on top rather than on the side.  I built a shed with the sandwich method.  If you do go that route you need a few large lag bolts to secure them, but supported on top is always better.  I knew I wasn't going to load up my shed.  The sandwich method is very fast and easy to level, but the least sound.  It is an acceptable method by some books, but even they say it is the least desired.

On two 2x8's or 2x10's for girder sizing, it depends on the space between the posts.  A girder sizing chart can be found here:
http://publicecodes.citation.com/st/ny/st/b400v07/st_ny_st_b400v07_5_sec002_par013.htm