Question
Hello,

I just purchased a house at which the previous owner installed slate around the trees and plant beds.  This is not really mine or my husbands taste.  We were thinking of dismantling the beds and reusing them to make a patio.  The pieces are jagged and uneven not tiled like most patio slate.  Would you suggest doing this? Is there anything we should do differently before starting?  I just think it's better to reuse the materials we have already.

Thanks

Answer
Hello,

Using the slate you already have sounds like an excellent idea.   slate is best layed on a mortar bed.    Use these guidelines:

Slate tile of 30mm or less;lay on 35mm to 50mm of a very stiff class 4 mortar over a prepared base.

Slate flags of 30mm to 65mm; lay on a 35mm to 50mm of a 10:1 semi dry bedding mix of grit,sand and cement.

Slate blocks of 65mm or more; lay on a 35mm to 50mm of semi dry bedding mix.

A semi dry mortar mix contains little or no water.  Its water content comes from water in the sand, in the air and in the soil below it.   This increases the time it can be worked,typically about 8 hours.   It will not cure to the hardness of ordinary mortar or concrete,but this is not necessary for a slate patio.

If your slate is not gauged (the pieces were not shaped to the same thickness),back butter the uneven pieces (apply mortar to the underside of the piece to make it match the other pieces in thickness).

Place the mortar bed and slate over a sand base of about 6 inches thick.   Use concrete sand. Do not use masonry sand.   Masonry sand is too fine and will not drain properly.  Good luck. Write back if you have further questions.

Mark   Harshman
http://www.mahdrafting.com
Email: [email protected]

http://www.scribd.com/markscrib47