irieemon

I am in the planning stages of building an outdoor patio with some slate that I already have. I was planning on Dry setting the slate in, but others have told me to go ahead and use concrete.

Does anyone have experience with this and preferences? It will get getting foot traffic and a few furniture pieces.

homerhop

If its going to get alot of trafic cement it in.As long as you keep everything level it should be ok

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twan5

Actually, what you can do, is after making sure that you have a 2-3 inch base bed of sand (to keep the terrace level), place the slate (varied shapes I'm assuming) on the sand - making sure to tap with rubber mallet to get a good grip. Then mix sand with dried cement powder (not sure of ratio - probably half and half, just look on the bag) and broom into joints. Then hose down with a moderate amount of water, making sure not to wash the grout out. The powder cement mix will set in the joints.

Another thing you can do is, if your in a well shaded area and moderate traffic, is instead of jointing with concrete, just let soil fill in, and plant moss or some type of aromatic herb, and everytime you step, it will let out an aroma - like lavender, etc...

jbrooks544

There are several things to consider and multiple variables. It is not so simple as mortar vs. not. If it ever gets below freezing where you are then the chances are that a concrete installation will fail or crack badly - depending on exactly how it is done. To use concrete, the only correct way of doing it is gravel bed, well compacted and then a 3" slab poured, leveled, screed and floated and then you would have to figure out how to install slates - probably using portland thinset mortar and then grouting and sealing the whole lot. Lots of work, lots of expense and even with proper base, drainage and allowance for controlled slab cracks you will probably get cracking.

If you were thinking of just using mortar mix for filling between the pieces then don't bother b/c it won't work or last and will be a mess.

If you have high clay or poor draining soil I would dig down 1 foot, level, compact, add 6 inches sharp gravel, compact, then a couple inches of mixed stone dust, compacted, then an inch of sand or stone dust - loose for setting slates. Put down slates, tap to set and then fill over everything with stone dust and compact and refill and compact. done. If well draining soil then skip the bottom gravel. If tough drainage area then fix and drain the area first with drains or drainage - or groundwater will freeze under it and heave it up. Keep the whole thing flat or slightly tipped one way for drainage - no low hollows for puddles, etc and no surrounding landscape shedding water to it. This will work great for you - cost the least and last the best with the least work. The hardest part is removing the sod, if you have it and moving the slate. Get a back support belt or you might never walk right again.

irieemon

Thanks for all your insight and suggestions - I have a very high clay soil which dosent drain really well (part of the reason for the patio) I've got plans to dig a french drain under where the deck is going to be, so I'll work the draining of the patio somehow into that.

I dont think I will do a full concrete installation, but I do like the idea of a gravel underbed with sand to level and Install.

Now the fun begins... actual work!