Frost, and heaving of post frame buildings

[TCJatko]

It's frost lifting the poles. Get down below frost level with the donuts, add uplift anchors, and the problem goes away. Here in central NH it's 4 feet required down to footings, I suspect you might need to go down 6 feet or so.

 

[SPIKER]

One other thing to wonder about since the poles are above the concrete cookie then frost could also be pushing up the skirt boards which are firmly attached to the pole lifting the poles.
Next time you dig up the poles use sand CRUSHED gravel mix rather than all clay to back fill tamp the gravel tight to the post which will grip the post to help hold it down. when opened up try & get a better uplift preventive on posts, wide 2x6 that is 12" on both sides sticking out beyond the posts 3+ inches on each side. Wont hurt to soak the treated 2x6 in something since it will be there for ever and use S.S. lags or if room use drill & put in stove bolts.

Like others mentioned also keeping water away from the barn side & skirt boards as far as possible. On mine I have about 18" of gravel on my north sidewall, prior to putting that in I ran 2" white EPS (Styrofoam) below grade attached to the skirt boards to above grade to height my concrete was to be poured (and was poured this past September.)

When barn was NEW I had the skirt boards all exposed needed 24" of fill on north east side & 10~12" on south west side. Prior to any back filling I dug a 20" or so wide trench 24+/-" out all way around the barn and put in 2 separate dry wells and 4" tile following these steps. I put the EPS in on the skirt boards nailed with roofing nails, then back filled and compacted sand/gravel against the EPS at an angle the ground was sloped to the trench I dug for the tile to go in. I stapled 6 mill black poly to the skirt boards just above the EPS and ran it out & down into the tile trench. The role of Poly was 6' wide, the poly was stapled almost in the middle to the skirt boards, the lower section of poly went down into the tile trench (prior to putting in the tile) and formed a trough in the trench bottom. The tile was put in and sand laid in on top of it. The 2nd half of the poly was un-folded (I had folded it up and stapled it to the barn sidewall to hold it up out of the way while the tile and sand was put in.) That half of the poly was put down and stopped right on top of the tile. sand and rounded wash gravel was then back filled in the trench and the drywells got large gravel out of the creek. I had bought a 4 pack box of 100'x6' of the plastic & had plenty left to lay on top of the drywells to keep dirt out of them.

The back fill for about 4 feet out is mostly sand/gravel/creek wash with some clay on top to help seal & run the water away from the barn. extensive landscaping was done to help the water move away as well. after 10 years the only issue I have had was the dang staples that they used to install the siding with & the T1-11 paint wont stick to it for nothing... Been no frost heave and no creaking popping or groaning without a good wind blowing. Preparation is key to having a long lasting stable building and I kept my eye on the boys building mine and made them change a few items along the way...

BARN photos pictures by WPSPIKER - Photobucket

Mark

 

[BeezFun]

What you're experiencing is called an ice lens. The soil freezes and attaches itself to the foundation surface, so when it heaves it takes the foundation up with it. It can occur with all foundation types in areas that have frost in the soil, even poured foundations can be lifted off their footings. In the old days architects specified visqueen plastic be draped along the outside of the foundation wall before backfilling, it acted as a sliding lubricant to keep the frozen soil from attaching to the foundation and lifting it up. These days it's so common to have sub grade insulation on foundation walls that the insulation plays that role. In your case you could do a couple of things, the simplest being to wrap the posts with visqueen and then backfilling again.

The devices designed to prevent uplift (cleats nailed to the bottom of the posts, rebar through the post, etc) are intended to prevent uplift caused by high winds. They can't resist uplift due to frost because the forces involved are too large (see below).

The skirt boards may be exerting an uplift on the posts due to frozen ground under the boards, but the fasteners would fail before they actually lifted the building. In your area the snow load is probably 40psf, so for your building just the weight of the snow is 40x60x135= 324,000 pounds. If you have a hay loft you can probably double that number. The weight of building is probably another 10-20psf depending on construction style. So you're looking at a minimum 500,000 pounds spread over however many posts you have. In a building that size I'm guessing you have three dozen or so load bearing posts, so each one is carrying 500,000/36 = ~14,000 pounds. No fastener is going to withstand lifting that amount of weight, and no uplift device is going to keep it on the pad. If you did anchor the post firmly to the pad, all you'd succeed in doing is lifting the pad up. You need to make sure the soil can heave independently of the foundation elements.

 

[BMod]

I know the bottom board is not being pushed up. I took and stapled plastic to the bottom board on both sides, and left it hang down two inches below. I then put 4" of foam insulation butted to that in the ground. I then backfilled again. The plastic would have to cut into the foam 2" before the foam even touched the bottom board, and even then it would squish the foam some after that before it pushed up the board.
That was my first thought about what was pushing up the building, but this did not work. It is frost grabbing the posts. This building keeps very little snow on it, so snow load is very limited. The posts are 9' on center.
Very interesting the plastic idea, I thought of foam, maybe I will do both? Not many people have fixed this issue. I plan on staying here for many years so I don't want a heaved up bent up building.......

 

[Rustyiron]

winds.[/COLOR] They can't resist uplift due to frost because the forces involved are too large (see below).

+1 and if they are they nailed on at a depth where they will be in the frost, they'll AID un frost up lift. I've read, been told (?) that an inch of good foam insulation (not the white, coffee cup stuff) equals a foot of earth backfill. It might be worth a try at one of your worst moving posts this summer.
I agree 100% with you, that your builder is responsible to alert you to any conditions that might be discovered during the const. process, that would have any efect on your bldg.'s performance!

 

[BeezFun]

...It is frost grabbing the posts. This building keeps very little snow on it, so snow load is very limited. The posts are 9' on center.
Very interesting the plastic idea, I thought of foam, maybe I will do both? Not many people have fixed this issue. I plan on staying here for many years so I don't want a heaved up bent up building.......

I think foam would be an unnecessary expense, but it would work. You could also wrap post with tar paper or anything that will create a boundary that slides. Tar paper might be even cheaper than visqueen. Foam is only of value if one side is heated and the other side isn't, otherwise it doesn't provide any thermal advantage other than delaying how long it takes for the post to reach freezing temps, but that's not what you're trying to prevent.

 

[BMod]

I was just thinking it would lessen the frosts grip on the pole, not a thermal use.

 

[Jimmy Joe]

BeezFun has it right, the clay is freezing to the sides of the post and lifting them out of the ground, in most situations unless the ground is driven on a lot near the posts the frost will not get under the posts. Some people wrap with plastic or box the posts in with styrofoam before back filling. If you have to dig the post up st get the building back down it wouldn't hurt to box the bottom of the post where it sits on the pad with some treated 2x6 sleeves so if it does heave nothing can get under the post. Then all you will have to do if the post doesn't settle is push down on the post.

 

[BMod]

BeezFun has it right, the clay is freezing to the sides of the post and lifting them out of the ground, in most situations unless the ground is driven on a lot near the posts the frost will not get under the posts. Some people wrap with plastic or box the posts in with styrofoam before back filling. If you have to dig the post up st get the building back down it wouldn't hurt to box the bottom of the post where it sits on the pad with some treated 2x6 sleeves so if it does heave nothing can get under the post. Then all you will have to do if the post doesn't settle is push down on the post.

I wonder how I would to do the 2x6 sleaves so they would be dirt tight? Maybe I should just make treated wooden boxes all the way up, that would go up, and not the post, or make something out of PVC pipe.
I see you are from Medford, I am from the Stevens Point area, but I have a buddy Paul Socwell that lives in Stetsonville, I was just there yesterday.

 

[Jimmy Joe]

I wonder how I would to do the 2x6 sleaves so they would be dirt tight? Maybe I should just make treated wooden boxes all the way up, that would go up, and not the post, or make something out of PVC pipe.
I see you are from Medford, I am from the Stevens Point area, but I have a buddy Paul Socwell that lives in Stetsonville, I was just there yesterday.

Good thing you were in Stetsonville yesterday. We got about 4 inches of snow and wind today. I've heard the Sockwell name, but don't know any personally. If you make the sleeves fairly close fitting I don't think dirt will get in, most of the dirt will pack and stay in place. Treated boxes all the way up sounds like it might work also.