Post and Beam Barn concrete slab help

[johns94cruiser]

I have a 150+ yr old post and beam barn. I want to put a concrete slab in the work shop side (about 19 x 30). Nothing is close to square......

Do I pour a square slab inside the stones the beams sit on and then do the perimeter or ...

do I include the stones in the pour right off, and just not worry about square?

Leveling with gravel, then vapor barrier, then 4 inch slab with wire mesh.

Thanks for your help!

 

[firestopper]

I would work with what you have to include the stones.
my .02

 

[Tennessee Jed]

Does the frame sit on a solid rock wall foundation? If so, then pour the floor solid, never mind what's square. If it sits on piers, then I would form it up between the piers so that it looked good, and pour.

Just a question - does it matter if the floor is square? Level, sure...but if one wall is 30' long and the other is 31' and the frame's already built, who cares, really?

Love to see photos - I've done a bit of timber framing and log building in my day.

 

[johns94cruiser]

I'll post some pics later today . I guess main concern is freezing and heave....keeping slab independent of barn . Barn sits on old field stone/boulders that haven't moved much in. 100 yrs or so. If I include them in the main slab, would that possibly affect them?

 

[Tennessee Jed]

Well, hadn't thought of that...I think what you would get would be that the stones would pull away from the pad but as for them busting up a good thick, well poured pad with fiber or steel in it, I'm skeptical that you'd get enough cracking to lose any sleep over. If it's a laid rock wall, I'd be more concerned about the pad busting up the foundation, and not the other way around, but it sounds like your frame sits basically on piers (in this case boulders in the ground.) If they weren't buried deep, below the frost line, I bet they move plenty, and it's a testament to the strength and flexibility of the frame that it's still intact.

FYI my standards lean toward the "good enough" end of the spectrum - I'm not a type A guy at all - and if you're concerned about a seriously good floor with real finish (to, let's say, put a lathe and mill on) then you should talk to a concrete guy. The need to save money, and thus skimping on materials like steel or concrete or gravel, and making a thinner pad with less reinforcement, are what lead to big cracks. Once it's down and drying, you'll hate yourself for skimping but love yourself for that extra 2" of concrete you went ahead and bought. Money won't matter to you when you see that smooth floor curing.

 

[sggoat]

I would not include the original stone foundation in the new pour. They have been there for the 100+ years, as you say, and have served well. Connect them in the new pour and you might interfere with their natural movement, compromising the stability of the whole structure. Give 'em some room when you pour the new floor

 

[johns94cruiser]

Set up to pour first section. Will not include current 'piers'. Leveled with stone, vapor barrier and then steel mesh. Will be doing a 5 inch thick slab

If course, may be two weeks before I can pour thanks to my work schedule.....

 

[sggoat]

The barn wood in your pic looks really authentic and cool. I would love to have a structure like this to work in---almost makes me say use brick--or even better-flagstone.

 

[Michael Hanson]

Hi, Personally I don't use wire mesh . Rebar all the way ,wire always ends up on bottom or top where it does no good. In a barn where weight will be a lot I would use rebar. Mike

 

[angerhater]

if you want the whole barn to rest on the new slab, I would move it over and then place it back onto the new slab.....I read a story of a man who basically installed a railing all the way around the outside of the barn....invited anyone to come help move it.....had a big picnic to feed all the 146 people from 8 states who came and lifted it up and moved it...kinda cool huh??

 

[batcon]

Hi, Personally I don't use wire mesh . Rebar all the way ,wire always ends up on bottom or top where it does no good. In a barn where weight will be a lot I would use rebar. Mike

This. Also have to consider the lack of proper compaction of the soil in the past. Rebar will help compensate for this.

 

[johns94cruiser]

I will add rebar, plus it will allow me to wire tie the mesh to it and get it suspended in center. Thanks for all the advice.

Not planning on doing entire barn, just two sections. Pretty big barn, this section alone is approx 30x18 or so. Fieldstone floor would be interesting , but I wouldn't finish it for years, I like concrete and will be poured in a half day!

Definitely not gonna pick up barn and move it! Haha