Another foundation question

[thebadger]

Re: Another foundation question

Mfiore

Very carefully... kidding.

I dug everything by hand - probably about 16 inches wide - just enough to get in with my shovel. I just got the bottom as level as I could to the depth I wanted. I then built a "grid" on top with 2x4 that was my "true" level. I then uses a long "screed" to ensure that my concrete was level throughout the trench 6+" thick. All in all I was only off by a 1/4 an inch or so.

Hope this helps.
Dick
Again, you can do it all with concrete but I liked this method as I was able to to it all myself.

[mfiore]

Re: Another foundation question

Clever leveling system! You still had to get into the trench to lay the block, though, correct? Working in a skinny 4 foot deep trench seems uncomfortable, as well as claustrophobic.

[dbhansen]

Re: Another foundation question

Looks like a good way to do it, Dick. I'm still trying to figure out what to do with all the leftover dirt from mine; you probably didn't have as much.

I also dug by hand, over several weeks. It wasn't too bad, and there were no rocks to speak of. Mostly solid red clay. But we do have lots of frost heave around here, so I think it was worth it.

Daren

[thebadger]

Re: Another foundation question

My boys found out what to do with the dirt - drag it inside the house!

Actually I'm going to install a small "retaining" wall to the left of the oven (hill) on that side. I should be able to get rid of the dirt I had left.

Yes, there wasn't a lot of room to stack the blocks. The tricky part was back filling with dirt as I worked my way up...

I think it worked out pretty well myself. I'm planning on pouring the concete hearth this weekend.

Thanks
Dick

FYI - I just lined the inside with pavers.

[Ken524]

Re: Another foundation question

OK, you two guys are nominated for next month's "Deepest Footer" contest!
Nice work guys.

Ken

[gjbingham]

Re: Another foundation question

You're definitely a builder! Everything looks great, even overdone a bit. That's good. Removes the chances for errors. Nice pics too. Keep up the good work!

[biondoli]

Re: Another foundation question

Mfiore,
I had the same dilemma you are going through...I am in Minnesota and our frost line is 48" I think. My oven is built on a brick patio, I should say that I built the patio in order to build the oven, but anyway...I had 2 choices: build 4 concrete pillars below frost line and on top build the base slab for the oven, just like a first floor of any building. All of this seemed too complicated and cumbersome to me, and after speaking with a friend who build the oven on a floating foundation in the middle of woods 10 years ago and it is still there without any crack...I decided to take the risk; the foundation of the brick patio goes down 2-3 feet with packed sand and gravel which keeps the water away. So I decided to take the risk. You need to consider the place you are building the foundation, if it is stable, if it is a place where water stands or it is a place where water runs during big rain...all of these factors will play against the stability of the terrain. On the other end, garages are built on floating concrete with no re-bars. So if you want to be 100% sure go with the pillars or something similar, if you think you can take the risk, my only suggestion would be to build a solid slab (more re-bars) and ticker (6-8") and even if it moves, will not brake, so all the structure will move a little bit and it should not be a problem. Hope this help, Carlo

[sharp21]

Re: Another Foundation question

Here's a quote from the last link, the Canadian Building Digest:
Where a detached building is located on a concrete slab on grade, protection will be provided by placing the slab on a mat of coarse granular material, which will act as a buffer against any movement of the soil under the mat. A mat 12 to 18 in. in thickness is usually adequate

Would you compact sand on top of this layer for levelling purposes, before putting your slab down?
S.

[biondoli]

Re: Another foundation question

If the gravel is well compacted then I would not, as you can level with the concrete pour (for the slab)

[sharp21]

Re: Another foundation question

I actually have a 6'x8' slab that I am going to put down, instead of pouring one.
Should have clarified
S.

[biondoli]

Re: Another foundation question

then I would add the sand otherwise I don't see how you can level it, on top the sand will help to distribute evenly the weight

[sharp21]

Re: Another foundation question

Thats what I thought, just wanted to double check
Thanks!
S.

[SpringJim]

Re: Another foundation question

Okay guys, if I have a natural sand base on higher ground, do I need anything under my slab?

I think when the garage nearby was poured it was just done on the sand.