12 x 12 Micro, then 16 X 24 Macro, Eufaula, Oklahoma- Chris & Julie

Don_P · December 01, 2012, 12:24:39 AM

The 2x8's are fine for full 40 lb LL+ 10lb DL @16"oc even if #2 SPF, from the codebook table. I've done it in true #2 Hem-Fir which is rated for right at 12', and it did feel like a minimal floor. In SYP it feels and is fine.

I'm not a fan of balancing a post on a pier, what about perimeter pony walls of some type in the pier saddles. Plywood sheathing walls is going to brace them better than trying to brace posts. I'd use treated for those parts but the would be above ground. Foundation grade might be sticks you can select out of the bundles already in the store. It is simply .60 retention with no heartwood, find the pile and see if you can pull out enough saps.What height are you trying to get between the pier saddle and the underside of the floor?

MountainDon · December 01, 2012, 12:46:52 AM

I'm happier with my piers now that I built a shear wall between some of them. That would be much easier to do now than later like I did. A half sheet of 3/4 PT plywood, above ground like Don_P said, would probably be the minimum height you'd want to use. One 4x8 = 2- 2x8. Frame it like a short stud wall. If you make the floor joists line up with one side or the other of the pier then a sheet can cover the joist, extend down over the wall framing and lap over the pier. Nail in every three inches. LINK... I did not take many pictures, but would be happy to see what drawings I might still have someplace.

It's not as good as a real PWF because the shear wall is shorter, but I'd wager it would be better than any other pier foundation in this forum.

December 01, 2012, 10:05:47 AM

I don't have a specific height I am trying to get to, but want enough room the be able to get under there and insulate. I also need to be mindful of how the 16 x 24 will sit and tie in to the 12 x 12, even though it may be a couple of years before breaking ground on the larger. I figure the crawl space would be about 12" to 24" depending on the grade.

If I were to sit a pony wall in the pier saddles, then I would need to level about 40 studs before adding the top plates. Would it make more sense to just level the posts, then wall between the posts, and use top plates and sheathing over all?

Don_P · December 01, 2012, 10:53:57 PM

That would work, the pier is still there and not a great thing but if you're going to do it this at least puts something better braced and connected between the floor and the pier than a post and kneebraces alone. In other words I would rather see you on a prescriptive foundation but if you are not going that route it is not necessary to revert all the way back to an unbraced or poorly braced post design, that seems to be the default position of many when rejecting a conventional foundation. There are aspects of the pwf and postframe that can probably help improve on that. So that's sort of where my thoughts are headed.
If you look at post frame construction there is a skirtboard, usually a treated 2x12 running around the perimeter across and attached to the posts at grade. The sheathing, in that case ribbed metal, is connected from the bottoms of the posts to the eaves, that is very good lateral bracing. The framing posts run continuously too. Anything you can do to sheath the entire wall and make it act as a unit is going to make it stronger. The stud framing is keeping the sheathing from buckling out of plane when the wall is trying to rack. Running the bottom 4' row of sheathing up onto the walls, blocking the edges and going up from there with untreated sheathing would help tie it together. Stepping way out there, you could balloon frame walls from the pier saddles to the eaves.

DmnYnkee01 · December 04, 2012, 10:39:47 AM

Wasn't able to get out there this weekend. The hot water shower valve in our master bath failed Sunday morning, so I had to spend the morning fixing it, which killed our trip out to the site. Keeping our fingers crossed for good weather this coming Sunday, so we can try again.

As far as foundation.... Since I am planning on 10' sidewalls with the cabins, by sheathing the foundation and up 2' on the stucture walls, it will work out well when it comes time to sheath the rest. Would that be sufficient for tying things together and having a well braced foundation?

December 04, 2012, 11:13:01 PM

Well, it's a step along the path. The sheathed walls accept and distribute the load better than individual highly loaded kneebraces. So for that portion of the foundation I'm confident that you have it adequately built and braced. To make it prescriptive refer to section R602.9 on cripple walls
http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_6_par026.htm?bu2=undefined
It should still be on a continuous foundation. The drawing in the text shows a stemwall from the footing to just above grade and the sheathed cripple wall between stemwall and floor. What they are trying to develop in those minimums is adequate resistance to sliding or overturning. The spot piers are still a problem in that regard. I was talking with an engineer about this, his thought was a gravel filled trench with a couple of courses of ICF foam forms that run 4' out of each corner. If you read the footing part of the precast foundation section with a little squint you can get there, I like the bracing aspect over piers. I'd bet an ICF dealer would have that in leftovers.

archimedes · December 05, 2012, 10:10:21 AM

I think it's worth pointing out at this point that a piece of 3/4" PT plywood runs about $37 (and that's for conventional PT not PWF PT). You'll need 1.5 sheets per side, or about $56 per side. And that's before you buy all the 2x4's, posts, piers, and Simpson brackets ( if you haven't already priced them, Mr. Simpson doesn't give his stuff away cheap)

Doing the foundation in block you would need 9 blocks per row, probably 3 rows high per side (maybe 4) so 27 - 36 blocks. That's about $30 - $40 per side for the blocks. Plus about a bag of mortar per side at $3- $4 a bag.

You will have a substantially better, stronger, safer, and cheaper, foundation when you're done.

I know when the fever to start building bites, it's hard to resist. But sometimes it's better to slow down and consider your options.

You have gotten some very good advice in this thread.

And now I'll shut up.

MountainDon · December 05, 2012, 10:19:10 AM

If the appearance of the concrete block wall is a factor in not choosing that, it can be covered... furring strips and metal roof/wall panels for example.

DmnYnkee01 · December 05, 2012, 12:05:26 PM

How difficult is it to make forms for a poured foundation? Can you just fill a continuous trench, and just have forrms at grade for prepping to accept walls? Or do you need to pour the footing, then come back later with the foundation wall? I just verified that the concrete truck will be able to get to my site. There is a fairly steep hill getting there, which had me concerned. Right now, conrete is at $87/yard, with a $45 delivery charge for less than 4 yards.

Regardless of which direction I go, I will not be mixing the concrete myself.

December 05, 2012, 02:33:56 PM

$87 a yard is a good price, that's good news.

The reason why I suggested CMU's is because it's a pretty simple DIY project. You could build forms and pour the whole thing, but I think you're starting to get beyond a simple DIY, IMHO. Doesn't mean it can't be done, just takes a little more skill.

The money you spend renting or building forms could be spent on the block. Then there's no tear down or return of the forms necessary. Dry stack the block, surface bonding cement to cover the blocks, if you don't like the look. You could even fill the blocks if you want a sold concrete foundation, but not necessary.

http://www.bing.com/videos/search?q=surface+bonding+cement&view=detail&mid=56C4DE5A4504A0D0A40F56C4DE5A4504A0D0A40F&first=0

I hate the color they used in the above video, but you can use any color you like, or no color at all.