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Chuck Atkinson 09-27-2010 05:43 PM

how to brace wood walls for fill dirt
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I just had built a 30 x40 pole buildimg on a slope. One 40' wall is on the high side With the bottom of the building 2 inches off the ground and the other 40' wall is on the lowwr side which puts the bottom of the building 30 inches off the ground. I need to fill level. So far, I used 2x12x8 treated lumber on the inside of the building attaching them to the 6x6 poles that are 8 feet apart to close in the bottom making a complete wall. Will this hold the fill dirt or do I need more bracing to keep the 8 foot sectioms of walls built from the 2x12x 8 treater lumber from bowing out. If so. How should I do this.

jogr 09-27-2010 06:10 PM

Can you just fill on the inside and outside so no retaining wall is needed?

Daniel Holzman 09-27-2010 06:58 PM

Sorry, I couldn't follow your post at all. Can you post some photographs, or better yet a scaled diagram with a cross section showing the most critical wall section?

stadry 09-27-2010 08:31 PM

dan, i forget but aren't we generally supposed to grade bldg sites level 1st ? ? ? :yes: or not ? ? ? :no: i seem to remember engineers like to balance cuts & fills whenever possible w/onsite mtls,,, i don't want to see the sketch,,, oy vey ! ! !

Chuck Atkinson 09-28-2010 12:23 PM

Thanks, I'll take photos tonight and post them on here so everyone can see what I'm talking about. I dont want to backfill the outside of the wall since it basically is the end of the slope and continues out to level ground. Just want to fill the inside. I'll post tonight. Thanks again.,

Chuck Atkinson 09-28-2010 12:34 PM


Originally Posted by Daniel Holzman (Post 508043)
Sorry, I couldn't follow your post at all. Can you post some photographs, or better yet a scaled diagram with a cross section showing the most critical wall section?

Picture this.

The building is 40 feet long. The poles that hold up the building are 6x6's. They are 8 feet apart. The poles are set in holes that are 42" deep and 30" Wide. There is approximately 30" deep of concrete and the other 12" are filled with dirt. So the poles are very stable.

On the inside of the building, I started at 36" off the ground installing 2x12x8 feet pressure treated boards to close in the bottom. Therrefore there are 3 2x12x8's to make the wall between each 8' pole. I realize that the total with of the three boards are 34-1/2" but that left 1-1/2" open on the bottom where I am going to put gravel for drainage before the fill dirt goes in.

My concern is, that when I have the building filled, will the wall of 2x12's be stable enough to hold the pressure of the fill dirt or do you think they will bow out. I'll ad photos tonight to show you. Thanks so much

Oh Yeah, and to the guy that make the comment about the grading of the site, you would have to see property and what would be required to stop the gush of water coming off the hill above in from flooding the building after cutting 30 inches into the hillside to level it. Even with drains installed on the high side it would have been a bigger problem than building the lower side off the ground and filling. Plus the grading for the drive for entrance into the building would have been cut into the hill also and would have washed out I'm sure. So, help with this problem, its already there. Thanks so much.

jogr 09-29-2010 07:50 PM

The wood will never last. 30" of soil is quite a bit of pressure. A concrete foundation would work.

Aggie67 09-30-2010 07:41 AM

Chuck, my advice is to find a local engineer and ask him to provide a correct solution. There are issues at play here that will come back to haunt you if you leave this as is and fill it in. You spent a bunch of money on the pole barn, but it sounds like you didn't spend the teensy little bit more that would have avoided this.

But, to answer your question, in my opinion this scheme is going to be a problem as it stands now. There's an easy enough solution that doesn't involve changes to the structure, but you should get that from a local engineer, and have him seal the plan. You'll sleep easier at night knowing it was designed properly.

Chuck Atkinson 09-30-2010 08:05 AM

Thanks so much for the advise. My other thought was to take 4x4's, and on the outside of the building, put 2 4x4's for each 8' section and attach them between the post up against the 2x12 along the seams, then go to the inside and put exterior screws through the 2x12's into the 4x4. I thought that would give it a really ridged strength and keep the 2x12's from bowing out. What do you think? I realize now that it should have been built differently, and I actually talked with the building company prior to starting about grading, and they said that the fill would not be a problem. The building I'm very happy with, but guess they just wanted to get it done without proper advise on grading out the area. We didn't realize at the time that the slope would have been so steep, and I'm surprised that the county inspection office who approved the plans didn't make a suggestion or bring up the point. Oh well, sucks but we are where we are and have to solve it now. I actually like the way the wood wall I built looks from the outside, sorta rustic, but visual is the least of the worries at this point.

Daniel Holzman 09-30-2010 10:40 AM

You can brace the wood wall adequately to support fill, however as noted by others pressure treated wood is generally not rated or designed for direct contact with soil, hence it will ultimately rot, leading to big trouble. There are specific types of PT wood that are rated for ground contact, however they are expensive and unusual, so if you have standard PT wood forget about backfilling either side.

jomama45 10-01-2010 08:51 AM

I guess I'll have to go against the grain on this one. If the boards (2x12's) have the same pressuretreating as the posts that extend 4-6' in the ground, what's the difference? They'll both rot out through time. It's a pole barn, not a 100+ year structure here.

Chuck, I'd personally bring the grade up slightly outside to help support the walls, as you're going to need to anyways to get decent access into the door if you're pouring a level floor. As for the rigidity of the 2x12's while backfilling, I would certainly stiffen them up first. I'd suggest screwing a "stiff-back" to each plank from the inside. Use a 2x6 (or w/e the width of the posts are) flat, cut to fit snug between each post. ou can even toe screw the stiff-backs into the posts. Fill and compact in about 4" lifts inside, and you shouldn't see any problems. Good luck.

Chuck Atkinson 10-01-2010 09:43 AM

Thanks so mich for your thoughts. I talked to the county inspector yesterday. He said if I put the 4x4's between the post on the outside up against each of the seams of the 2x12,s that it should be good. He also suggested that I get the snow and ice rater tar paper material and put it on the inside wood and wrap thw.bottom of it under the bottom 2x12 just to keep thw fill of dirt and gravel off direct contact. We are going to put 2" of gravel down first for draining, then the fill, then 2 or 3 inches of gra el on top. Wish me luck. Thanks again. I may go ahead with 2x6's also on the inside per your recomendation.

joed 10-01-2010 02:42 PM

Consider putting gravel up against the wood for drainage. Fill the rest with dirt if you like.

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