Paver patio strong enough?

[bwilliby]

Hello, we have a paver patio where the pavers are laid on top of 4 inches of "crush and run". Is that strong enough to build a brick oven on top of, or do we need to pull up the pavers and pour a concrete slab where the oven will go? Thanks in advance for any advice!

[UtahBeehiver]

These ovens are really heavy. Spending all the time and money on a WFO, do it right and lay a solid concrete pad with the appropriate base material.

[Chach]

Yes I agree you will be sorry if you don't....it all starts with a strong base for sure

[bwilliby]

Thanks for the input! There is so much conflicting information out there. For example, I read last night that a properly installed paver actually supports more weight than poured concrete, 8000 pounds per square inch compared to 3000 pounds with standard poured concrete. Granted they could be talking about a paver driveway instead of a patio. But anyway, you both are saying that a 4 inch thick poured concrete pad is a stronger base than 2 3/8 inch thick paver on top of 4-5 inches of compacted crush and run?

[rwiegand]

Either will hold your oven up assuming (big if!) the prep work was done correctly, eg excavation down to undisturbed earth with appropriate compressibility, gravel sub-base installed in lifts with mechanical compaction, etc. If you live where it freezes that's a whole other story, or out in Texas/Oklahoma with expansive clay soils. Your safest bet is almost always a footer that extends below the frost line tied into a concrete slab (expansive soils would be different). What is the standard for house foundations where you live? You probably want to follow that model to be safest.

Compressive strength of any of the materials involved isn't an issue; your oven will weigh at most a couple of tons, a typical block foundation has close to 2000 sq in of block in contact with the slab, so the loading is only 1-3 lb psi,

Since it doesn't matter too much if an oven remains completely level you can probably put up with a bit of frost heave as long as the oven moves as a unit rather than breaking. That's what would make me nervous about pavers, they could lift one corner or edge, stressing your oven-supporting slab.

Rather than digging 4-1/2' footers for my oven I did a 6" reinforced slab on 12" of compacted gravel-- our soil is very sandy and virtually non-compressible but very rapidly draining, so near perfect for support. I let it sit for several years to see that it didn't move unevenly before building the oven. So far so good-- if it lifts at all with the frost it does so uniformly, which I don't think is problematic.

An alternative strategy with less digging and concrete would be a variant on a pier and beam foundation, with holes (~12") dug at the corners to below frostline tied into an on-grade slab with rebar.

[fox]

You could build a slab on top of your pavers.

[Chach]

I agree with rwiegand I did pretty much the same. I did like 8" grade 7 stone compacted in 2" lifts then poured 8" slab with rebar reinforcement. Do not build a concrete base on top of your pavers please.. you need to mark out the location and remove the pavers from the area and make sure your base is solid underneath. The paver is not holding the patio the base underneath is so if you build on top of the patio your base is holding the paver and the concrete base or CMU base. I know a guy that has a landscape business and he also builds fireplaces outdoor and outdoor kitchens. He builds those patio paver retaining wall outdoor fireplaces in Chicago here and he just puts down 6" crushed compacted stone and he said he's never had a problem and those weigh 10,000 - 14,000 lbs some even more. I went over what he does and so far so good and we even had tons of rain and a -30 day -55 with the wind chill.