Steps to Dry Laying a Flagstone Patio

asantagaSeptember 12, 2004

We are in the process of laying a flagstone patio and I was hoping for some help. Everywhere I read, there is different advice on how/what to do. We plan to lay Arizona flagstone (without mortar). Can someone post step by step instructions?

What I have so far is to mark the area with spraypaint, dig out to 8", level grade & compact the soil, put down landscape fabric, place 3" of gravel (some say 4"), place 3" sand (what kind? also what kind of gravel?), level and compact, then lay flagstones, then fill in cracks w/some type of sand (not sure what type).

Also, since the patio will be meeting with the edge of the lawn, and a planting bed, should we sink some plastic edging between the two to prevent the sand from moving/mixing w/ the soil? Or use 2" x 6" to make a form?

Thanks for any tips. Let me know if I should post any more info. We are planning to purchase 3/4 x 2" flagstone

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well_drained(z6a MA)

I'm making similar plans, but I haven't actually done it, so take my advice with a grain of salt (or sand?). First, the depths of the base and base materials depends on the drainage situation -- the more variation in temperature and/or wetness, the deeper you need to go. I've read everything from 1/4 inch to 18 inches deep; from 0 gravel to 8 inches of gravel; from 1/4 inch sand to 2 inches sand. Second, I think the landscape fabric goes on top of the gravel, to prevent sediment from clogging up the gravel and ruining its drainage qualities. Third, I do think you need some type of edging to keep the sand from spilling onto your lawn, and to keep the stones on the outer edges from moving. (I don't know anything about forms -- most of the edging advice revolves around whether to use plastic, stone, brick or wood.)

I've heard different advice about the size/type of gravel, but the type of sand I've heard is 'construction sand' -- although I think there are other names for it. There is also discussion of crushed stone, and crusher fines, whatever they are. Certain materials get praised because they act like cement when you wet them down; in other plans, the same materials are rejected because they don't allow water to pass through.

Which reminds me, make sure to wet the patio down after laying the stones, and again after sweeping the extra sand between the stones.

As for step by step instructions, every book or website I read has slightly (or greatly) different steps, so I am making my own step-by-step that mixes and matches elements of several different plans. I'll report back when I actually finish it to let folks know if it worked.

Best of luck,


    Bookmark   September 13, 2004 at 12:40PM
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windy_meadow(5 SW_PA)

Try the link below for advice, it is a great site!


Here is a link that might be useful: Paving Expert

    Bookmark   September 15, 2004 at 12:35PM
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windy_meadow(5 SW_PA)

The link above is not working, type this one in:

Here is a link that might be useful: Paving Expert

    Bookmark   September 15, 2004 at 1:00PM
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GreggSev(z4 MN)

Hi, I just wanted to let those interested know what tips I have learned in designing/building stone block edging around my entire house with an integral flagstone patio.
I didn't want colored concrete blocks or rubber edging.

I decided on Minnesota Kasota (limestone) natural stone (sized) blocks & 2" flagstone sheets. I contacted a quarry and showed him my design I made on graph paper. He walked around and measured the square footage required to make an entire 8" (two 4" blocks high) curved garden wall above ground, 4-5 feet from my house (except in back of house for the wrap around above grade flagstone patio) that I will backfill with blackdirt, weed barrier, and 3 " of decorative stone or mulch on top.
Getting back to the purchase of my stone, I went direct through the quarry and avoided the middle man. I was able to get wholesale price with discount and reduced shipping charge. The order was for 19 tons of tumbled stone retaining blocks (sized 4" thick x 8" wide X radom lengths)and 2" flagstone. I needed about 6000 linear feet of block.
I started out by buying 1.5" pvc pipe with couplers to make nice uniform curves/semicircles around my house held by stakes, then spray painted lines around for the block following the natural grade of my yard. (This method worked much better than garden hose). I rented a trencher with a 4" block blade and followed the line around three times so I had a nice trench 12" wide X 4" deep. I shoveled out the dirt and cut landscape fabric in the base. I then put in compactable gravel that I hand tamped 1" below the sod. I then started setting blocks in the trench and found just the right lengths/ slightly angled pieces I needed in the pallets of stone blocks. I then started on the second layer overlapping the joints by 5" inches or so.
After the second layer was on, I removed the top layer and placed them on the ground facing up. I then brushed /swept the surfaces then applied block glue to each one and put them back. One area by my garage needed to go up 5 feet of block, so I just kept stacking/gluing blocks except I moved in each row 3/4" above previous row.
Now for the raised flagstone patio. Now that I had a nice curved block wall 8" high, I filled/raked 4" high compactable gravel inside, rented a compacter and went over it 4 times. I strung lines across the top of the 8" high block and measured down the thickness of the flagstone (2"-3/8" for sand compaction) and layed long lengths of old 1.5" waterpipes on top the gravel surface and shimmed the pipe up with wood up to where the bottom surface of the flagstone should be. I then shoveled in course washed sand on top of the gravel/pipes and using a long 2x4 resting on top of the pipes to screed the sand flat. Now I started laying flagstone. The flagstone was in big square sheets, so I tipped them onto the ground, and if they didn't break, I took a splitting axe and hit in the middle several times until it broke into smaller pieces that were still at least 2-3 feet in size. Take on piece at a time and lay it onto the sand, then take each matching piece and lay adjacent leaving a 1.5" gap for motar or sand. Continue this process like a jigsaw puzzle. When you have to cut or trim, I used my kid's sidewalk chalk to mark lines/cuts. Then use a stone chisel / hand sledge hammer to chisel along line two times to score a line. I then rap one end of the stone with the butt of the sledge and it breaks clean along the line. If needed, chisel away any ragged edges. Work from one edge outwords using large pieces, then going back and filling in any smaller pieces. As you go along, try to keep edges of flagstone nearly flush. If you disturb the sand as you going along, use a cement trowel to smooth out.

When your all done fitting, you can fill joints in one of two ways; buy SANDLOC and mix with sand and water, then put into joints, or what I am doing is mix 1/3 cement with sand and put in joints, smooth and wash away rest from flagstone using sponge. These are the only two things I would do for patios to make sure ants don't start drilling or plants/weeds don't start.
Good Luck, Hope this helps.

    Bookmark   September 21, 2004 at 1:07PM
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I was about to start a new thread with this same question, so I'll just tag onto this one. I used construction sand from the stone supplier and it's washing out from the stones and I'm not happy at all! I don't want to use an edging. The stone place has medium size river rock edging theirs, but I want mine left as natural looking as possible.
Here's my question: Can I mix the concrete with the sand and sweep between the joints, then water it down? Wiping all that premixed mess from the stones with a sponge sounds like a lot of work! Thanks for the info!

    Bookmark   September 23, 2004 at 12:55PM
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You cant add too much concrete mix or it won't bond (learned the hard way). I think you need to use a small amount.

    Bookmark   September 23, 2004 at 3:27PM
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windy, thanks for the link. It was very helpful.

welldrained, I too was confused by so many different recommendations, but in reading the above link, I now understand it is because different materials and methods are based on the type of paving (stones)you are using, the amt. and type traffic, the size of the joints and even the location and type of soil and drainage.

I realize I made an error in laying my patio. Since I'm using a natural stone that varies in thickness, I shouldn't have layed down a weed barrier on top of my top layer because now it's very difficult to level each peice of stone. The weed barrier doesn't allow me to dig out for extra depth. I'm too far along to take it up and remove the weed barrier, so now I'm cutting out peices of the barrier before laying the stone. I SHOULD HAVE DONE BETTER RESEARCH!!!! I hope my mistake helps someone else. :)

    Bookmark   September 24, 2004 at 11:56AM
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Digging in AZ is almost impossible. It's one of the reasons you see so few basements there.
I would level the area..... add a few inches of sand. Level your flagstones and call it done. The only reason to go thru the other steps is to limit the damage done by heavy frost. AZ has very little heavy frost.

    Bookmark   October 4, 2004 at 8:53PM
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Hi Fellow stone layers, I just started my research. I was worried about the mortar cracking and falling out eventually, I have seen that on other peoples patios and don't want it on mine. I want a maintenance free patio after my many months of work. The stone supplier in my area suggested a polymeric sand (may not be spelled right) well anyway this stuff looks just like sand, you spread it into the grout lines and spray lightly with water. It hardens up like concrete but stays plyable. Concrete just sounds bad to me such a narrow grout line will crack guaranteed. They also suggested 4" of class 2 gravel for a base. By the way great advice Greg, Thanks for your help

    Bookmark   June 11, 2006 at 11:30AM
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the best sand for the base is sharp sand (small stones in soft sand). the best gravel would be mixture of 10mm gravel on the bottom and 20mm gravel on the top layer or forget both and use scalpings (mixture of clay and hardcore) and compact will go like concrete.

the best thing to do for a maintenance free patio is to make up a wet/damp mix of fine washed sand (sand used for rendering) and cement 3 or 4 to 1 mix dependent on desired colour (either will be strong enough). This technique is the best and cheapest. (but i'm affraid very time consuming) make sure you have a bucket of water and sponge and wash off all the time as you go much better in the long run.

    Bookmark   May 25, 2008 at 5:59PM
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What about planting some kind of very low, dense ground cover or moss that will fill in between the stones and also block out weed growth? I've seen it done at a friend's place and the effect is really nice, smells good (they used herbs) and it's also low maintenance.

    Bookmark   May 29, 2008 at 12:08AM
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