Hey, guys I just installed a flagstone patio on concrete in my yard. So now I am telling you how to lay flagstone on concrete.
To lay flagstone on top of concrete first you need to cut the flagstone and lay directly on the concrete base like a puzzle. Now your structure is ready after that you need to pull out flagstone one by one for laying the cement underneath the flagstone. After that use tuck pointer for tucking the joins with cement and after use brush to clean the excess of cement and clean again with the wet sponge. This is how you can lay flagstone on concrete.
Here is the list of supplies and tools you will need to lay flagstone on top of concrete:
Supplies and Tools
First, lay all the stone on grass or ground because of that you can get approximate guess how these irregular stones match with each other, and while laying flagstones on concrete you can easily pick right flagstones.
The main advantage of this technique is more you can find the right type of stone, less cutting you have to do.
1. Flagstone
Thickness - 1" to 1 1/2" Thick
1 Ton flagstone covers about 80 Sq. Feet
2. Cement Mixture
If you have a smaller job then there is no need for mixture and If you have a big job then you definitely need a mixture.
You can rent a mixture from rental services it cost you about $50 to $75 for a day.
And if you have a job of 100 square feet of patio or more than that then it's worth buying small mixture instead of giving $75 a day.
3. Type portland 1/2 Cement
You need about 5 bags of 1/2 portland type cement/100 Sq. Feet.
4. Masonry Sand
You need roughly 1 yard of masonry sand for every 100 Sq. Feet.
5. Broom
You need to have a clean surface before you lay down your material so because of that you need a broom.
6. Chisel
You need two types of chisels one is chipping chisel and the other is the straight chisel. Chipping chisel is used to cut out small bites from flagstone and straight chisel is for cutting the flagstones straight. If you don't have a budget to rent or buy demo saw then you can use a straight chisel to cut the flagstones.
7. Trowel
A trowel is used for spreading the cement underneath the flagstone at the time of laying the flagstone in the concrete.
8. Hammer
A metal hammer is used along with the chisel to hit the chisel for cutting the flagstone.
9. Plastic Mallet
A plastic wallet is basically used for tapping the flagstone to make sure the level of the stone for getting a great fall.
10. Shovel
A shovel is used for taking the cement out from the wheelbarrow and for handling the sand.
11. Demo Saw
The demo saw is used for most of the cutting besides chisel and you can use a diamond blade for this saw which is very good for cutting flagstones.
If you have a small job then you can rent this saw from rental services.
12. Ear Muffs
Ear Muffs to protect your ear from sound generated by demo saw and this sound is above normal so you must need ear muffs.
13. Mask
It's going to be quite dusty while cutting the stones so the mask is also necessary to protect your lungs from the dust.
14. A Pencil
A pencil is necessary for doing markings on the stone.
15. Tuck Pointer
Once the stone is laid down then it is used to pull out stones to fill the cement.
16. Masonry Cleaner
You need about 1 Gallon of Masonry Cleaner/100 Sq. Feet.
17. Siloxane Sealer
It lets moisture breathe out doesn't let water in and if you use another sealer then you might trap moisture between sealer and flagstone and it turns into a gray film so use siloxane sealer to prevent this problem and you need about 1 Gallon of siloxane sealer/200 Sq. Feet.
A step by step guide to lay flagstone on top of the concrete:
Foundation
If you already have a concrete base and there are some little cracks are in the concrete then you can directly lay flagstone on concrete.
But if cracks are big then you need to first lay metal lath and use a nail with washer and using hammer you can fix the lath to the concrete and that way it ties whole concrete on each side of the crack and stone hold longer.
Cutting Stone
You need straight cut flagstones at all edges and after laying the flagstones at the edges then you can go for inner portion.
To fill inner portion you need to first lay one flagstone and then you can lay second flagstone, third flagstone, and so on.
For cutting the flagstones you can use a demo saw with a diamond blade for perfect cutting and after laying the flagstones if you need to cut flagstones then you can use chisel and hammer to cut out small bites.
If you don't want to spend money on demo saw then you can cut the stone straight with the help of straight chisel.
For cutting using straight chisel you need to first draw a line using pencil and then using chisel and hammer you can cut the stone and while cutting the stone don't hit hard instead hit gently.
And the cut done by demo saw doesn't look natural cut then you can use chipping chisel to cut this demo saw cut edges and trust me the cuts after using chipping chisel looks natural.
Laying Triangle cut flagstone with curve cut flagstone look very beautiful. If you only have triangle cuts all over the place then it looks very bad.
So keep that in your mind that cut the flagstones in triangle and curve cuts and lay them like odd-even(odd is a triangle cut and even is curved cut) format.
If you lay two triangle shape cut flagstone then you must need to join these two with curve cut flagstone.
Determining the Fall
If you are laying flagstone on concrete for making the patio then you must need to determine the fall.
First, establish four points on your patio two points for starting the fall and two points for ending the fall.
And put the cement underneath the flagstones of these four points so that you can easily determine the level.
Generally, you need 2 inches of fall for every 12 feet so according to these measurements establish your four points.
Mix the Cement
For making the mix of cement you need 1 full bag of 1/2 portland type cement and put 20 shovels of sand and add 5 gallons of water in the cement mixture and it takes 5 to 10 minutes to make the perfect mix.
After that add water according to your requirement and if you have a small job then you can avoid renting the mixture and you can do it manually by using a shovel.
If you are using cement mixture then make sure that first, you need to add water in the mixture and then add 1/2 portland type cement and sand. So your mixture doesn't jam or lock up and it goes pretty well like that.
Make your mix soft enough so the flagstone lays on it but not so soft that the flagstone squeezes down after you tap it.
Lay Flagstone On Concrete
For laying the flagstone you need to pull out flagstones that are laid down on concrete at the time of cutting.
Now pull out one stone and before putting cement on the concrete first pour water down on the concrete and then after you can lay cement.
If you don't pour water then existing concrete especially in summer suck all the moisture from the cement so it's better to pour some water before using cement.
While laying flagstones on concrete the most important thing is to make sure that your fall right or not. You can make sure the fall by taking level using string. As you are coming down with line you wanna make sure the line touches even on the stone then you know you have the proper fall to the lower part of the patio.
Use a sponge to clear cement if little particles are available on the flagstone if you don't clear this little grey at the time of laying then it will so hard to you after a couple of days even if you use still brush because it becomes dry.
Cement for Tucking
For tucking the joins the cement consistency is different from the cement we use underneath the flagstones. If you have the cement too wet then it's hard to sponge it out properly.
If you are confused then just take cement which is used underneath of the flagstone and add some cement to this to make a little stronger or you can take 1 shovel of 1/2 portland type cement and 2 shovels of masonry sand.
You can't make the cement too rich because then the cement rise up too fast and you will get crack in it.
Tucking the Joints
For tucking the joints you need tuck pointer to tuck the joints perfectly. If you leave the cement too loose then joints will break out.
Some people prefer to use grout bags to for filling the joins but as compared to tuck pointer you can make joint very strong by applying pressure using tuck pointer on the cement and on the other side you don't apply extra pressure on cement So it's better to use tuck pointer for tucking the joints.
After tucking the first join you need to smoothen this joining using a trowel and do the same process for the rest of all joins simultaneously.
And after tucking you need to clean the cement on the flagstones. It's a little time-consuming process and painful for one person to do all this work alone. So it's better to have one person for cleaning the flagstone using a sponge.
To clean cement on the flagstone you need a broom to sweep it up lightly and don't sweep aggressively otherwise you will destroy the joins and then after this you can use a sponge to clean it off with water.
When you are sponging go across the joints, don't go a lot with the joins. You do a lot better job by going across the joints because it does polish a join by going across the joints.
Washing the Flagstone
After sponging, you can see a little bit of white stuff on the flagstone. Basically, it is a grey cement residue leftover from sponging.
For washing, you can use 600 Detergent (masonry cleaner) by PROSOCO. Take that cleaner with water in a bucket and wash it with a brush.
And don't let cleaner stand on the flagstone too long otherwise it will burn your joins. After doing cleaning with masonry cleaner get a hose and simply rinse it off.
Sealing
Basically sealing is done to protect flagstone and joints from the weather. So implementing sealing on the flagstone just take siloxane sealer in the pan and take a paint roller and spread this siloxane sealer directly on the stone using this roller.
Siloxane sealer is like milk so don't worry about just spread using a roller and dry it for 72 hours. If there are any chances of raining then don't do sealing otherwise it will ruin your sealer.
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