# What is the best base for flagstone patio?



## KUIPORNG (Jan 11, 2006)

*my neighbour did theirs*

by putting concrete underneath and cement over... that is not the problem... the problem is the joints... they also use cements... now after just one year... cement broken off from joints and they need to sweep from time to time and strange plants grow up on various joints and they have to fill in various strange materials on the joints....

so my only comments is never use cement to do the jonts... may be in certain climate is ok... but not in climate like Toronto...

the job was done by their hired contractor who almost becomes ours too...


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## stardell (Aug 27, 2008)

*Good tip*

My plan is to fill the joints with the 3/8 inch crushed rock and dust along with a little cement powder to keep the rock in place.


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## yesitsconcrete (May 11, 2008)

which is it, base or jnt filler ???,,, w/o a decent base, nothing else matters,,, i wouldn't use any cement & i don't have to ask questions about flag patios,,, worry about the base & just sweep in sand or cinders.


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## stardell (Aug 27, 2008)

*Please read initial question about the base*

My question is about the choice of base material. Crushed rock with sand above it or 3/8 inch minus (crushed rock and fines).


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## yesitsconcrete (May 11, 2008)

depending on the frost depth you usually experience, 3/8"- graded aggregate base, crusher run, # 87, or # 89 crushed stone'll work.

last flat patio i installed was 12" of #89 w/2" of gab under ashlar treads,,, more important, tho, were the drains to carry away wtr.,,, 40 yrs & still in good shape.


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## retro (Apr 1, 2008)

stardell said:


> My question is about the choice of base material. Crushed rock with sand above it or 3/8 inch minus (crushed rock and fines).



I used crushed rock. Graded it then rented a compacter to, then I used sand above it. Looks ok ten years later. The ants absolutely love it though. I throw poison down twice a year to keep the ant population kinda sorta in check. Sucks for the dog, sucks even worse that the patio is right outside the kitchen wall. In retrospect I should have had a mason come and pour a slab and laid the flagstone on top of it.


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## KUIPORNG (Jan 11, 2006)

*I would use HPB*

as it does not require sand.... and very good at defeating weed....


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