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Question DetailsAsked on 5/4/2017

Is it good to use a concrete base for pavers?

We are putting in a 200 Sq ft patio in our Brooklyn, NY, backyard. The first two estimates are in the $7500 range (demo of existing damaged concrete included) and both have concrete slab bases. That seems like overkill to me. Is there a good reason to do this? I talked to one guy today who said I'd maybe save $1500 but lose durability and it might get uneven over time. He also said he'd drain it properly if there were a concrete base, that it would be underground and less subject to cracking, and that the pavers would not be set directly.intonte concrete.

Most opinions online seem to be no concrete. Perhaps a few reasons masons might want to do it here: it's faster and all access to our yard is through the house, so it would be impossible to get a big compactor in here.

I'd love some perspective.

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Voted Best Answer

In theory yes - most large patio or foyer areas on public buildings and parks with pavers use a concrete pad underneath to provide a firm base and prevent future settlement - but in my book that is ludicrous overkill for a 200SF patio.

My recommendation - unless you are adverse to a bit of manual labor or are all thumbs on DIY jobs - for that size job, DIY. Do a good research on base preparation on how to do it, and make it a self-expansion project. Sloping and grade to prevent water accumulation (including in the excavated area under the base material so it does not pool there), compacting properly (which for that size job is a lot easier with a rental plate compactor, which also does a LOT better job of compacting the joint sand in place), and making sure it is installed as a flat surface (though not necessarily level - commonly best to slope 1% or so away from the house) - and making sure the finish level lies well below the door sill level. Oh - and use perimeter control to prevent the blocks from moving outward - normally a plastic framework edging held in place with driven metal rods (get utility locates first). And rubber sesal between foundation and patio blocks.

While with fancy paver work and raised patios, and especially with driveways, it definitely helps to have a professional touch, for a simple personal patio it is not rocket science if at grade level (not built up above grade or at leat not more than 3-4 inches) and does not involve significant walls. And may give you the confidence to tackle slightly more complex DIY jobs in the future. And remember, if not perfect, you can fairly easily adjust the occasional block which sticks up a touch (rubber mallet and water) or sinks in a bit (pry up with putty knives or slip hooks and resand with water), so not getting it perfect is not catastrophic. For that size job, even totally redoing it 10-20 years down the line is likely to only take a weekend day or so, if needed.

On the compactor - two men can carry it (I can load one into a pickup myself with only a good bit of grunting) - about the size of largish shop vac though heavier - commonly 150-200# for the size usuallyi used for your job. Actually, if all access is through the house, I would require tarps on the floors because carrying the base materials and sand and block will drop a fair amount of grit which will wreck havoc with hard surface floors. This going through the housemay well be a major contributor to your high cost estimates.

I would be curious how they intend to get the concrete there - unless there is room around the side for pumping, or they intend to snorkle it over the roof with a pumping truck (which adds about $300-500 to the job usually for your size job). I just have visions of a concrete pumping hose snaking through the house bursting and spraying concrete all over - not something I would risk, though I did once pump concrete (hundreds of cubic yards) through the lobby of the World Trade Center (original tower 1) and down an elevator shaft for a repair - we encased the hose in 4" PVC drain pipe to protect against joint leakage/hose bursting.

Other than say 3-4 inches of base material (if your native soil is poor) the over-slab option still requires all the same materials - base sand, joint sand, blocks, plate compactor. And putting in a slab probably deepens the excavation, os more waste soilto move out through the house.

You know - the more I think about going through the housefor all the material, the more I think maybe you should consider jusat digging the lawn and topsoil out, putting down an inch or so of masons sand, and putting in interlocking I paver blocks like following - they interlock quite well and stay in palce quite well even with fairly poor underlying material, as long as it is not soggy. Would be an easy Saturday afternoon job.

Interlocking blocks come in different shapes, but the I blocks seem to interlock best.

Another option - Daisy Blocks filled with sand - I have placed them directly on lawns with dirt or pea gravel in the voids (for grass or gravel infill) with pretty good success - a much cheaper way to do a patio, though you commonly do have to realign every 5-10 years. Just compacted crushed driveway base also works well for many people - compacts down almost concrete firm and does not track into the house significantly.

Answered 3 years ago by LCD

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