Questions about casting some footers..

[rerod]

Hey folks..

I'm relocating a mobile home and want to set it on 3x3 concrete bases, but I can only find blocks less then half that size locally.. I don't want to pour a full size slab because the site is uneven. So my guess is, the best approach is to cast sixteen individual 3x3 concrete bases, and place them after the MH has been moved.
The mold could be tapered to make them lighter and I would add reinforcement, but is this a project someone with no masonry experience could pull off with some help from this group?

Thanks!

 

[mike93lx]

3x3xwhat? If 2' thick, they'll weigh about 2700 lbs. Can you safely move those? That's a substantial amount of weight to form up, as well

 

[oldcarpenter]

I have typically seen roughly 16” square pads used. Normal soil bearing is around 2500 pounds per square foot.

 

[rerod]

3x3xwhat? If 2' thick, they'll weigh about 2700 lbs. Can you safely move those? That's a substantial amount of weight to form up, as well

2" on the edges tapering up to 4" maybe.. But your right, its going to be heavy as hell, but 2700? Your right, about 4000 lbs per. Cant do that

I have typically seen roughly 16” square pads used. Normal soil bearing is around 2500 pounds per square foot.

That's what I have now on top of 2' x 2' green plywood lol. It keeps sinking

 

[mike93lx]

2" on the edges tapering up to 4" maybe.. But your right, its going to be heavy as hell, but 2700? Your right, about 4000 lbs per. Cant do that

That's what I have now on top of 2' x 2' green plywood lol. It keeps sinking

Oh, only 2-4"? That's only 300ish lbs.

That said, that feels thin to support real weight

 

[bb29510]

sonic tubes

 

[PCustoms]

18"18"x6" ought to be plenty.

Make form from 2x6 screwed together. Just take 2 corners apart and the form will come off. No reason to be fancy

 

[LXCam]

You said this was on uneven ground. How you plan on dealing with that?

 

[mike93lx]

sonic tubes

FYI, it's sonotube

 

[PugetDude]

Any reason you can't cast these in place? Small shallow forms can be really simple- I have even seen 5/8 sheetrock used; backfill before pouring and leave them in place, no stripping required.

Put the MH on temporary cribbing, pour your pads and then jack/anchor as required.

Good luck.

P. S .Rent a mixer.

 

[bb29510]

we do alot of footers form with dirt, dig a hole, fill with concrete

 

[rerod]

I was talking to the fb group mobile home mafia and a pro suggested basicly a rubble trench foundation.. Except dig 3'x3' holes every 8' and fill them level with surface with 2" stone. Move the trailer over them and build your piers off the stone. Ideally the holes should be 48" here..

 

[billconner]

In NY, code requires a slab under trailers and a shallow frost protected foundation is typical.

As to your rubble trench - it is or should be a trench, nor a hole, with a perforated drain pipe to daylight - which sounds possible on you site. If you just dig a hole and don't drain it, it can fill with water, freeze, and move your trailer.

If you want piers - and that may make sense on a slope - dig below frost line, and set a sonotube on a plastic footer form.


Or dig smaller hole and bell it out at bottom to do same thing. Some more work but the BigFoot forms are $20-30 each.

 

[cvairwerks]

Parents sat their lake place on a pair of formed beams. Trimmed the hillside to roughly level, then formed level beams. 18” wide at the top and wider at the bottom.

 

[rerod]

In NY, code requires a slab under trailers and a shallow frost protected foundation is typical.

As to your rubble trench - it is or should be a trench, nor a hole, with a perforated drain pipe to daylight - which sounds possible on you site. If you just dig a hole and don't drain it, it can fill with water, freeze, and move your trailer.

If you want piers - and that may make sense on a slope - dig below frost line, and set a sonotube on a plastic footer form.


Or dig smaller hole and bell it out at bottom to do same thing. Some more work but the BigFoot forms are $20-30 each.

No code enforcement here..

Wouldn't any water that doesn't run down my hill and away, drain to the bottom of the rock column which is below the frost line where it never freezes? Can you give me a idea on the cost difference between stone and the sonotubes?

The trailer goes back where the barn was.

 

[rerod]

Any reason you can't cast these in place? Small shallow forms can be really simple- I have even seen 5/8 sheetrock used; backfill before pouring and leave them in place, no stripping required.

Put the MH on temporary cribbing, pour your pads and then jack/anchor as required.

Good luck.

P. S .Rent a mixer.

I could cast in place, but I would have to cast level of course, and there's one section thats a bit steep where a flat 2x2 footer would create a bump or step for the truck and trailer to roll over.

 

[PugetDude]

I could cast in place, but I would have to cast level of course, and there's one section thats a bit steep where a flat 2x2 footer would create a bump or step for the truck and trailer to roll over.

Cover it so the truck can roll over it, then dig it out afterward. Still easier than wrestling 300# slabs into a hole and trying to level them.

 

[mike93lx]

No code enforcement here..

Wouldn't any water that doesn't run down my hill and away, drain to the bottom of the rock column which is below the frost line where it never freezes? Can you give me a idea on the cost difference between stone and the sonotubes?

The trailer goes back where the barn was.

Codes exist for a reason, enforcement or not.

Soil conditions will dictate how much water stays in the hole, here, it will fill, no question.

 

[billconner]

No code enforcement here..

Wouldn't any water that doesn't run down my hill and away, drain to the bottom of the rock column which is below the frost line where it never freezes? Can you give me a idea on the cost difference between stone and the sonotubes?

The trailer goes back where the barn was.

How deep will water get? If it won't reach frost depth, fine. That's reason for drain line.

I think rubble trench (trench, not hole) is great. Built my 28 x 32 garage last year on rubble trench. But you have to be sure water drains.

 

[rerod]

I think rubble trench (trench, not hole) is great. Built my 28 x 32 garage last year on rubble trench. But you have to be sure water drains.

Ive decided to remove 6" of soil at the high spot and then pour 3 x 3 concrete pads every 8', and then fill in between and over with stone mainly to drive over, and just let the MH heave in the winter..

But can I ask how you provided drainage for your rubble trench foundation? Im guessing it was on a hill where you could slope a drain to daylight? The thing I wonder about rubble trench foundations, is when the ground heaves in the winter, Ive heard it can grab and heave a rough earth formed concrete structure, so I'm guessing a rock foundation would do the same?

 

[billconner]

Ive decided to remove 6" of soil at the high spot and then pour 3 x 3 concrete pads every 8', and then fill in between and over with stone mainly to drive over, and just let the MH heave in the winter..

But can I ask how you provided drainage for your rubble trench foundation? Im guessing it was on a hill where you could slope a drain to daylight? The thing I wonder about rubble trench foundations, is when the ground heaves in the winter, Ive heard it can grab and heave a rough earth formed concrete structure, so I'm guessing a rock foundation would do the same?

Yes, on a slope, easy to get pitch to daylight at the road.

The building is bearing on the stones to below frost, and with drainage. I don't see how it can lift. The rubble - 2" clear - is not one solid mass like concrete - and there little chance of an ice lens forming because of drainage.

I'm a little unconcerned in this particular case - I was only a couple percent in soils test from being able to just do thickened slab because soil drained so well.