Backfilling pole barn, need advice

[Doughknob]

Don't you have to put forms anyway to hold the #57 and sandrock inside? I'd be afraid to pour concrete with the rock below able to squish out the sides (while pouring plus over time.) So, might as well continue the PT skirt down to ground and now it is formed for the inside stuff.

 

[s219]

Don't you have to put forms anyway to hold the #57 and sandrock inside? I'd be afraid to pour concrete with the rock below able to squish out the sides (while pouring plus over time.) So, might as well continue the PT skirt down to ground and now it is formed for the inside stuff.

Depends, it can be stable if the outside backfill is stable. There is a lot less side pressure under a slab than people think. I've seen garage slabs on top of gravel base several feet thick and the gravel didn't squirt out. I think the key was that the base was wide and sloped gracefully away from the slab. Any ground pressure under a slab would propagate out along an angle of influence very much like that.

If pouring concrete, you can rake the gravel away from the skirt on the inside of the barn, and let the concrete flow down against the skirt to form a thickened edge on the slab and cap off the gravel. That will really help take pressure off the skirt boards.

 

[scaredychicken]

I'm learning here - thanks All. I like the new barn Drew.

My pole barn plans (30 x 40) are for next year - site prep and a slab will be the key starting points. Power and water. might even add a washroom while I'm at it, with composting toilet

but I'm trying to be practical without going over the top on budget ... big ideas

 

[Egon]

Skirt inside and outside with metal. Use gravel for fill against the skirting.

 

[DrewStyduhar]

Thanks for all the advice. Randy mentioned crushed concrete. I talked to the county and they would not approve that under the concrete slab..not that I really care for their approval (ha) but their reasoning wasn't very good.,......they just cited the fact that there can be junk in the concrete. When asked if I could simply pick through it to remove any junk, they didnt really know. Sounded well thought out! haha.

When talking to some other folks about a second skirt, they said the only way they would do this is if there was stone up to the skirt....inside and out. If dirt outside, they wouldnt waste the time since I guess even the ground rated stuff isnt very good anymore? Our dirt here has a ton of clay, doesnt really drain well and holds moisture so I guess that makes sense. The rock (including crushed concrete) wouldnt keep the second skirt wet?

scaredychicken - thanks for the compliment! Damn wood prices and all....it was do or die time. The metal carport style around here are very popular but I dont really like them. This barn has three ply lam posts and plastic sleeves. We ended up pouring the footers so they are HUGE. 24" diameter x 8" thick 4kpsi. They sent those precast cookies but I wasnt feeling it.

thanks!!!

Drew

 

[deezler]

Yeah the extra skirt board would eventually rot, but by that point you dont really need it anymore. It's not structural. That said, giving it a thin layer of gravel up against it wouldn't be a bad idea.

Yeah I don't think the county gets to forbid you putting crushed concrete under the slab. It would work great for that kind of compactible fill.

 

[DrewStyduhar]

According to the county, pouring a slab requires a permit. I can obviously fill it up with whatever I want but IF I get a permit to pour, they said they wouldnt approve the crushed concrete. told them I wouldnt be pouring until early next year so the pole barn can be finaled and not be tied to any concrete prep or fill work. Maybe the inspector was full of crap though? The slab would be floating so its not like its structural or anything. I called the soil/compaction guy that tested our fill and he confirmed the no crushed concrete thing. Said folks get around that by adding a few inches of #57 or crusher on top so the county doesnt know, haha.

I guess my point earlier about the skirt board is folks thinking it would last much longer with rock up to it compared to clay dirt. We have bad termites around here so I dont want anything in the ground rotting.

thanks,

Drew

 

[nyone]

Site prep is so much easier to do with no building in the way.

I would fill the outside first, grade away from the building and go from there on the inside. Do you plan on useing concrete underlayment?

 

[DrewStyduhar]

Hi guys,

Life got in the way but I'm back on this now.

I went to place my order today for the pressure treated wood (2x8's) for extra skirting and after the sales guy understood what I was doing he said he thought it was a bad idea. Curious to get some feedback on his thoughts:

- The second skirt will eventually rot and then you have a void where your 57 or fill under the concrete can wash into and you lose support under the perimeter of your slab

- You cant cover the PT stuff with tin.....even that nice painted metal, it will eat it up.

- He thought maybe you could roll/brush on roofing tar on the outside but couldnt vouch for that.

I wish there were some more composite lumbers being sold for a price that's not insane. I found a place online out of Maine that sells dimensional material made out of recycled plastic (MARKSTAAR). I would pay the price but their shipping is a deal breaker.

I put together a crude drawing in MS paint to show the fill I need. There is 15" between the sandrock pad and the spec'd finished TOP of the concrete. I plan to go with a 5" slab so figure 15"-5" leaves 10" of fill needed. The concrete guys want a few inches of 57 under the concrete but didnt recommend putting 10" of 57 as it would be too unstable. So figure 10" of fill - 3-4" of 57. That leaves about 6-7"inches of crushed concrete/crusher/etc. needed.

thanks,

Drew

 

[Midniteoyl]

Hi guys,

Life got in the way but I'm back on this now.

I went to place my order today for the pressure treated wood (2x8's) for extra skirting and after the sales guy understood what I was doing he said he thought it was a bad idea. Curious to get some feedback on his thoughts:

- The second skirt will eventually rot and then you have a void where your 57 or fill under the concrete can wash into and you lose support under the perimeter of your slab

- You cant cover the PT stuff with tin.....even that nice painted metal, it will eat it up.

- He thought maybe you could roll/brush on roofing tar on the outside but couldnt vouch for that.

I wish there were some more composite lumbers being sold for a price that's not insane. I found a place online out of Maine that sells dimensional material made out of recycled plastic (MARKSTAAR). I would pay the price but their shipping is a deal breaker.

I put together a crude drawing in MS paint to show the fill I need. There is 15" between the sandrock pad and the spec'd finished TOP of the concrete. I plan to go with a 5" slab so figure 15"-5" leaves 10" of fill needed. The concrete guys want a few inches of 57 under the concrete but didnt recommend putting 10" of 57 as it would be too unstable. So figure 10" of fill - 3-4" of 57. That leaves about 6-7"inches of crushed concrete/crusher/etc. needed.

View attachment 708490


thanks,

Drew

I added a 2nd skirt board to close the gap like 16yrs ago. Painted PT wood a few inches deep into the dirt No problems yet.