Laying a patio on a contrete base? Quick question.
Discussion
I have a conrete base which is 5m x 5m and have 600mm x 600mm slabs to lay on it.
The base is sound and level so what will be the best method of fixing them? Balls of mortar in each corner and the middle of each slab or a mix covering the whole base with the slabs laid on it? (if so what ratio will be best for the mix and dry or wet)?
Any help would be appeciated.
The base is sound and level so what will be the best method of fixing them? Balls of mortar in each corner and the middle of each slab or a mix covering the whole base with the slabs laid on it? (if so what ratio will be best for the mix and dry or wet)?
Any help would be appeciated.
Don't do the balls in the corners, especially with 600mm slabs. A couple of years down the line when you put something heavy down on one and it snaps, just why you shouldn't do this will be evident!!
Depending on how thick the distance between the top of you concerete base and the bottom of teh slabs is, I would probably say to lay them on sand (max 25-40mm in thickness), knock them down to level with a rubber mallet and/or hammer and a block of wood, and then fill in the gaps between the slabs with a cement mix. This way, the sand will provide a good solid base and there's next to no chance of them ever dropping.
There's a website called pavingexpert.co.uk (I think that's it?) that is absolutely brilliant for advice like this.
Depending on how thick the distance between the top of you concerete base and the bottom of teh slabs is, I would probably say to lay them on sand (max 25-40mm in thickness), knock them down to level with a rubber mallet and/or hammer and a block of wood, and then fill in the gaps between the slabs with a cement mix. This way, the sand will provide a good solid base and there's next to no chance of them ever dropping.
There's a website called pavingexpert.co.uk (I think that's it?) that is absolutely brilliant for advice like this.
+1 for proper muck, Ive got a whole patio to relay where it was laid with dabs in each corner. There are no broken tiles but they all rock nicely! Plus if you leave gaps underneath ants can nest in it!
I'd wait for the previous poster to answer properly but I was thinking about laying it about two inches deep with ripples so it levels itself down to around the inch thick but I await correction!
I'd wait for the previous poster to answer properly but I was thinking about laying it about two inches deep with ripples so it levels itself down to around the inch thick but I await correction!
All you really are wanting to do when you lay slabs is to create a solid bed which doesnt allow the slabs to move or allow moisture beneath.
A lot of paving gets damaged when we get frost, thats becuase moisture gets in the voids and then pops the slabs when we get freezing and thawing. So you want to make the bed as complete as possible. You will always get a slight void here and there because when you tap them down you need to leave the muck almost loose so it actually goes down when you tap them in.
Too much muck will mean the slabs break when you put them down as its human nature to hit something harder when it doesnt go down
I've been doing it for 13 years and still break the odd slab!
You ideally want the bed to be about 10-15mm higher than finish level so you literally just gently tap them down.
Depth of bed imo is not overly important. 2" is ideal really but thinner or thicker shouldn't cause any problems.
You need the mix to be wet but not runny, quite stiff but wet enough to be pushed about, pretty much the same consistency as a bricklayers mix, it will be stiffer though because its sharp sand (dont use building sand, too soft). Use a bit of febmix to make the mix more workable.
Dry mixes are never good imo as theres no adhesion.
Try and just have one fall, so one way the paving is level and the other you have a slight fall, working to a string line is only good for the first couple of slabs to get you started as its inevitable the line will be slightly pushed up when you lay meaning the whole thing goes out.
Just lay with a level, take your time and if your half competant you shouldnt go far wrong. The reason so many tradesman are bad is because they either dont care or they rush becuase they price the job too cheap. I have seen a lot of diy jobs which are better than so called professionals.
If its sandstone or riven slabs you need a very good eye as the level will lie to you as you need to place the level stragically over the slabs leveling across several at a time (the use of the level is not just to make sure its flat but to make sure the water runs off) as its all too easy for water to get stuck in the riven bits leaving potentially huge puddles or a nasty hump.
hth
A lot of paving gets damaged when we get frost, thats becuase moisture gets in the voids and then pops the slabs when we get freezing and thawing. So you want to make the bed as complete as possible. You will always get a slight void here and there because when you tap them down you need to leave the muck almost loose so it actually goes down when you tap them in.
Too much muck will mean the slabs break when you put them down as its human nature to hit something harder when it doesnt go down
I've been doing it for 13 years and still break the odd slab!You ideally want the bed to be about 10-15mm higher than finish level so you literally just gently tap them down.
Depth of bed imo is not overly important. 2" is ideal really but thinner or thicker shouldn't cause any problems.
You need the mix to be wet but not runny, quite stiff but wet enough to be pushed about, pretty much the same consistency as a bricklayers mix, it will be stiffer though because its sharp sand (dont use building sand, too soft). Use a bit of febmix to make the mix more workable.
Dry mixes are never good imo as theres no adhesion.
Try and just have one fall, so one way the paving is level and the other you have a slight fall, working to a string line is only good for the first couple of slabs to get you started as its inevitable the line will be slightly pushed up when you lay meaning the whole thing goes out.
Just lay with a level, take your time and if your half competant you shouldnt go far wrong. The reason so many tradesman are bad is because they either dont care or they rush becuase they price the job too cheap. I have seen a lot of diy jobs which are better than so called professionals.
If its sandstone or riven slabs you need a very good eye as the level will lie to you as you need to place the level stragically over the slabs leveling across several at a time (the use of the level is not just to make sure its flat but to make sure the water runs off) as its all too easy for water to get stuck in the riven bits leaving potentially huge puddles or a nasty hump.
hth
m3jappa said:
All you really are wanting to do when you lay slabs is to create a solid bed which doesnt allow the slabs to move or allow moisture beneath.
A lot of paving gets damaged when we get frost, thats becuase moisture gets in the voids and then pops the slabs when we get freezing and thawing. So you want to make the bed as complete as possible. You will always get a slight void here and there because when you tap them down you need to leave the muck almost loose so it actually goes down when you tap them in.
Too much muck will mean the slabs break when you put them down as its human nature to hit something harder when it doesnt go down I've been doing it for 13 years and still break the odd slab!
You ideally want the bed to be about 10-15mm higher than finish level so you literally just gently tap them down.
Depth of bed imo is not overly important. 2" is ideal really but thinner or thicker shouldn't cause any problems.
You need the mix to be wet but not runny, quite stiff but wet enough to be pushed about, pretty much the same consistency as a bricklayers mix, it will be stiffer though because its sharp sand (dont use building sand, too soft). Use a bit of febmix to make the mix more workable.
Dry mixes are never good imo as theres no adhesion.
Try and just have one fall, so one way the paving is level and the other you have a slight fall, working to a string line is only good for the first couple of slabs to get you started as its inevitable the line will be slightly pushed up when you lay meaning the whole thing goes out.
Just lay with a level, take your time and if your half competant you shouldnt go far wrong. The reason so many tradesman are bad is because they either dont care or they rush becuase they price the job too cheap. I have seen a lot of diy jobs which are better than so called professionals.
If its sandstone or riven slabs you need a very good eye as the level will lie to you as you need to place the level stragically over the slabs leveling across several at a time (the use of the level is not just to make sure its flat but to make sure the water runs off) as its all too easy for water to get stuck in the riven bits leaving potentially huge puddles or a nasty hump.
hth
Thats just what I needed to hear, thanks for the excellent advice. Truth be told I have already tried with the blob in each corner and it doesnt work LOL. A lot of paving gets damaged when we get frost, thats becuase moisture gets in the voids and then pops the slabs when we get freezing and thawing. So you want to make the bed as complete as possible. You will always get a slight void here and there because when you tap them down you need to leave the muck almost loose so it actually goes down when you tap them in.
Too much muck will mean the slabs break when you put them down as its human nature to hit something harder when it doesnt go down
I've been doing it for 13 years and still break the odd slab!You ideally want the bed to be about 10-15mm higher than finish level so you literally just gently tap them down.
Depth of bed imo is not overly important. 2" is ideal really but thinner or thicker shouldn't cause any problems.
You need the mix to be wet but not runny, quite stiff but wet enough to be pushed about, pretty much the same consistency as a bricklayers mix, it will be stiffer though because its sharp sand (dont use building sand, too soft). Use a bit of febmix to make the mix more workable.
Dry mixes are never good imo as theres no adhesion.
Try and just have one fall, so one way the paving is level and the other you have a slight fall, working to a string line is only good for the first couple of slabs to get you started as its inevitable the line will be slightly pushed up when you lay meaning the whole thing goes out.
Just lay with a level, take your time and if your half competant you shouldnt go far wrong. The reason so many tradesman are bad is because they either dont care or they rush becuase they price the job too cheap. I have seen a lot of diy jobs which are better than so called professionals.
If its sandstone or riven slabs you need a very good eye as the level will lie to you as you need to place the level stragically over the slabs leveling across several at a time (the use of the level is not just to make sure its flat but to make sure the water runs off) as its all too easy for water to get stuck in the riven bits leaving potentially huge puddles or a nasty hump.
hth
Im using Sandstones which are all different thickness and have ridges etc so I realise its going to be really hard to get them completley level. I think they end up holding some water
Going to hire a mixer and do it all on Tuesday.No problem.
Due to the nature of sandstone you will get some pcokets of surface water. The trick is to make invisble (to the eye) little gullys withing the paving to get it off (some will always sit on certain slabs)
Be selective over what you lay, anything to riven put to one side for cuts. Make sure you start with the best slabs as it will set the rest off.
Use a short and long level. long level over a few at a time to make sure the general fall is good and a short one on individual slabs to get rid of the water pockets.
Its not uncommen or strange to have to pick up a slab you just laid and lay it elsewhere as it may not be suitable next to the others. Sort of try and match up the corners iykwim.
Good luck mate
Due to the nature of sandstone you will get some pcokets of surface water. The trick is to make invisble (to the eye) little gullys withing the paving to get it off (some will always sit on certain slabs)
Be selective over what you lay, anything to riven put to one side for cuts. Make sure you start with the best slabs as it will set the rest off.
Use a short and long level. long level over a few at a time to make sure the general fall is good and a short one on individual slabs to get rid of the water pockets.
Its not uncommen or strange to have to pick up a slab you just laid and lay it elsewhere as it may not be suitable next to the others. Sort of try and match up the corners iykwim.
Good luck mate
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