Have a 20′ deepX24′ wide cabin with pier (5X6’s 42″ from footing to grade) and beam (3 sets of doubled treated 2X10’s) foundation. Resting on the beams is a floor platform composed of 2X8’s on 16″ centers with 3/4″ T&G on top and 1/2″ OSB on the bottom, fiberglass batts in the floor. Standard framing with rafters above that.
Grade slopes ~ 4′ in 20′ from back to front of cabin, leaving a crawl space from zero at the back to 4′ at the front.
The cabin will be added on to this fall…three wings, one on each side and one on the back….professionally installed pressure treated wood crawl space foundation topped with conventional framing and roof trusses. The back foundation wall will be protected from run-off via an additional drainage tiled retaining wall, which, in conjunction with the foundation wall, will form a swale diverting run-off away from the foundation. Also will excavate enough fill from underneath the back to get continuous VB down.
I’ll need to provide some sort of wall to seal off the front side of the original pier and beam crawl space from critters and to complete the insulation loop all around the cabin/additions. It’s this wall that I propose to use a homemade IP for. I’ll dig down 18″ from the current grade level between the piers, put some pea rock down, and then place a panel fabricated from 2″ (4″?) rigid foam sandwiched between 1/2″ .6 treated plywood. This panel then would be attached directly to the piers and backfilled. Alternate would be a PT 2X4 stud frost wall with PT ply on the outside and FG or rigid insulation. Seems to me a panel would be cheaper, lighter, and easier to handle. It’s certainly NOT structural….the piers handle that, and being on the down slope with run-off well off to both sides, should not be subjected to any run-off.
If you’re still with me here, what I need advice on is fabrication of the panel itself…I’ve thought of using PL400 and nails, screws, or maybe through-bolts to hold the thing together until the glue cures. It there a better adhesive for rigid foam-to-PT ply?
Also, please don’t hesitate to tell me I’m totally out to lunch on this…as long as you provide some other methods/ideas. Thanks alot for your advice and expertise…by the way I’ve already run this general IP idea by the guy I’m going to pay to frame this up, and he agrees it should work.
Edited 7/15/2003 10:29:30 AM ET by johnnyd
Replies
As long as you have plenty of peastone under it, and give the water someplace to go, you should be ok against heaving.
Don't use PL 400 though. It will disolve the foam. Get a poly foam glue like Enerfoam, PURfil, or one of the others. Buy the gun for it and keep it clean and it willl be cheaper and you can use it for other things.
If you want adhesive, the PL product for foam is 300 or 500, I forget which right now. Check the labels.
Excellence is its own reward!
Its 300 piff. Just bought some the other day. its blue in color and takes a day or so to cure.
Maybe I dont' have this pictured quite right, but if you backfill against 3 feet or so of your new panels won't you be putting a lot of lateral pressure on the existing piers that they weren't designed to handle?
I assume that the post to beam and the beam to floor joist connections are already tied together with metal framing ties and not just nailed. Did I get it right that the posts are buried more than 3 feet deep? That, of course, would help. Just seems that you'd want to take strong precautions to make sure that the posts didn't gradually slip back and tend to roll the beam.
Please ignore this if I've got the whole situation wrong. It's been a long day. :)
Any jackass can kick down a barn, but it takes a carpenter to build one.
#1...I won't be backfilling that much. Really only 18" on the outside and none on the indside. Wish I had some simple drawing software to make a simple sketch.
#2...The beams are through-bolted to the piers, which are buried 42" from grade.
Probably be fine. Especially if the panels you make go from the top of the beam down below grade in one piece (no lateral pressure on the joint between the post and the beam).Any jackass can kick down a barn, but it takes a carpenter to build one.