Pole barn on a slope...maybe save you some grief
Had a 40x60 pole barn built with the long side (60') running the slope.
Just eye-balling it, the builder guessed the drop at the back was going to be around 4'. Well, when he shot the thing it turned out to be 8'! [img]/forums/images/icons/confused.gif[/img]
I didn't have any experience dealing with building on a slope like that nor did anyone else I knew so I had nothing to go by but to trust his judgement on how to handle it (this guy was an experienced builder).
Here's how he did the fill: He had a guy haul in 20+ loads of fill dirt and used that to build a slightly compressed dirt berm all the way around the perimeter. Then he filled the inside with blast rock fines. The result was an extremely steep dirt slope in the back, 10' at one corner and 7' at the other. The land in the back continues to fall away at a steady rate so there was no way to continue to add fill to bring the slope up to anything that would hold.
At that point, we had a couple of rains before I could do anything to address the problem and the dirt in the back began to shear down and away from the building, opening up a deep chasm. The wife and I had to take a day off from work to wrap the whole thing in plastic sheeting to minimize any further damage until we could get it fixed.
THEN BEGAN THE MARCH OF THE RETAINING WALL CONTRACTORS! I talked to so many people it'd make your head swim. A number of them suggested, as the cheapest option, to use blast rock to shore up the berm. I live in the woods and like it that way. Therefore, I wasn't interested in taking out any more trees or staring at a huge pile of fill rocks every time I look out my back window, so large blast rock would have had to be used to provide any reasonable slope and minimize its footprint. I asked each person who suggested blast rock a simple question which none could suitably answer: How do you keep the dirt from, over a period of time, washing down into the voids between the blast rock? They himmed, hawed, and zig-zagged but none could say for sure, or guarantee their work against that happening.
The next cheapest option was a guy offered to, essentially, pour a basement wall around it, maybe with a sleeper or two, and fill the gap with blast rock. Several things bothered me about this idea. The first thing was that he was proposing to make the wall no thicker than a regular basement wall, 8". An 8" wall to hold back tons of rock and dirt just didn't sound right. Another thing was, the way he was talking, I got the impression he had never done a job like that before. Would you like to be this guy's guinnia pig with a $22k building at stake? Not me.
So we arrive at the last option, a block retaining wall. If you've never priced a real retaining wall, not the 3' landscaping variety, better be prepaired for sticker shock. Anyway, we ended up with a Versa-Lock wall about 8' high in the back and wrapped half way up the sides of the building. Clean rock fill was used on the inside with geo-gridding and compaction.
We've had a lot of rain lately and the dirt has continued to settle, but at least the shearing has stopped and the settling is more or less staight down. There's about an 8" drop away from the poured concrete floor in the back now so I'll still need to figure out some way to pack underneath there to slow the cracking of the floor.
Total Costs:
$22,000 40x60 Pole Barn w/Poured Concrete Floor, Gutters, & Roof Insulation
$5,000 Fill For Site Prep
$15,000 Retaining Wall
Now, IMHO, knowing what I know now, how it should have been done. The whole thing should have been put up on blast rock from the git-go...big stuff at the bottom and smaller on top. This is the way they fill entire valleys when they put in a new highway. This is the way some floodplain was raised here locally to build the new Wal-Mart. A depression in the middle could have been filled with blast fines where the floor was going to be poured. The fines set up like concrete when compacted but have enough give to float a concrete slab. My guess is this would have saved me $10-12k overall and no further settling would have occured or further shoreing up would have been needed. The overall footprint wouldn't have been any bigger than the one I have now and no further tree clearing would have been needed.
Hope this helps someone.
Re: Pole barn on a slope...maybe save you some grief
Welcome to the forum.
Sorry to hear of your woes, and too, wish the contractor had given you some 'heads up' before you found out the hard way. Maybe thought your job with him would have changed some, and he'd lose some of your money.
Pictures of before and after would be great.
Thanks for posting.
Re: Pole barn on a slope...maybe save you some grief
Something you didn't mention in your list of options which has become popular around here, and might bear investigation - retaining walls built using wire cages which are placed in position and then filled with appropriatley sized stone. The cages appear to be stainless steel for long life, the process is fairly simple, and less expensive by far than block walls. Appearance wise you end up with a rough stone wall, but over time soil can wash or be intentionally introduced into the stone, allowing cover to take root. Theres one such installation I know of thats about 3 years old and is now covered with ivy. Very nice. I have seen retaining walls as high as 50 to 60 feet built this way, also the facing wall of several railroad bridge abutments - the rails pass right over the stone cages.
Another alternative that we see around here is precast concrete blocks - about 3 feet high, 2 to 3 feet thick, and 5 or 6 feet long. They're made with ridges to lock together, and cast in loops for lifting. They can be set with a crane or backhoe. Relatively cheap, but not pretty, I see them used for short walls, bunkers, and bridge abutments in industrial settings.
Just some info...
Gregg
Re: Pole barn on a slope...maybe save you some gri
Thanks for the input.
I hadn't seen or heard of that first suggestion being used around here. Interesting.
That second one concerning the large blocks had occurred to me and I did ask about that with one guy but I can't recall right now what he told me.
In any case, I try to use herd phychology in areas that I don't have enough personal knowledge in. Firstly, 95% of the retaining walls around here are using Versa-Lock style blocks for both individuals and businesses. Secondly, by my observations there were basically 2 situations in which the large blocks were used and both of them had to do with large developements, with lots of heavy equipment already around to be used for the rest of the developement, in addition to the construction of the wall. I'm sure it's happened somewhere, but I have never observed an instance in which someone was hired after the fact to install the large blocks for either an individual or a business. I'm thinking there must be a reason. I don't know what the cost of the large blocks is but I do have an idea what the cost of the heavy equipment and manpower to deliver and move those blocks around might be. My wall, although large to me, is positively puny compared to some of the walls they build with the large blocks. It seems to me to be an economy of scale. There must be some break-even point in which it becomes cost effective to use the large blocks, with the extra associated equipment costs.
On the other hand, my Versa-Lock wall was constructed by 2 guys, using only a pick-up and a Bobcat. I have a pretty good idea on the cost of the blocks and, between the blocks, rock, fuel, & geo-grid that the builder had to pay for, I feel he only cleared at the most $3000-$5000 on a $15,000 job. That's not that bad when most home construction is figured on double the cost of materials.
Anyway, that was just my reasoning.
Re: Pole barn on a slope...maybe save you some gri
Around here, the 2X2X6ft versa lock blocks cast $30 each, delivered (from the cement batch plant). I'm sure it would be more for just a couple.
There are smaller sizes that cost less and often they are a better choice since the former are to heavy for most back hoes to lift into place.
The old (non versa lock) blocks with just a rebar in the top for lifting (no locking humps, rough finish) 2X2X4ft weight 2300# and cost about $15 to 25 each, depending on your negotiating skills.
If your only going to lay one or two courses of these blocks you could use the cheaper ones.
In most cities or counties any wall over, say 3 ft tall, requires a permit and higher walls, say 8ft, require engineer design studies (soil compaction, etc.).
My opinion, FWIW.
Steve
Re: Pole barn on a slope...maybe save you some gri
AsleepAtTheWeel,
Welcome to CBN.
A picture is worth a thousand words. If you have the capability, please post some pics.
Something to have considered. The drop (hopefully) was found before anything related to the construction of the building was started. When it came out 4' different, I'd have stopped to consider all options at that point.
I live in W. PA. Flat ground???? Pretty much non-existent.
Instead of bringing any kind of fill, multi-story buildings are more the norm. Heck, the garage attached to the house is 2 stories (garage door out the front of the house, regular man door out the back).
Dig out underneath where the building will go and put a lower level in. In the lower level, have the doors out the back (or whatever the low side is). Depending on particular needs in terms of space, adjust the size of the building itself. (e.g. instead of 40x60, go with 40x32 @ 2 stories. You then put a french drain around the perimeter and use the fill taken out for landscaping around the new structure.
Not sure if this would work in your particular case but the $20K you have invested in fill and retaining wall would have built a pretty good sized basement around here.
Re: Pole barn on a slope...maybe save you some grief
I built a 45x65 barn into a very steep sloped hill. I graded off my building pad and then built up the pad. I graded the hill back 8' from the barn and put tile and rock in. Then I built a 4' retaining wall out of railroad ties, filled the back with rock and tiled it. I never had one problem with water. Total cost was less than a thousand dollars.
Re: Pole barn on a slope...maybe save you some gri
I don't know if I'm picturing this right, but you built a pole barn on a slope that dropped 8 feet over the length of the building? Why not just pour a foundation with a garage door on the low side? Worse comes to worse, you could cap the foundation and use that as your building.
RonL
