Flisby, from whom we are considering buying paving stones, recommends using natural stone that is about 6cm thick for surfaces where cars will drive, instead of the usual 3cm thickness.
Unfortunately, we are set on a type of sandstone that is only available in 3cm, so the question is how well would it hold up, and what happens if it doesn't?
Flisby's solution is to pour concrete underneath, which is an additional project and extra cost.
This is in southwestern Skåne, which is Sweden's mildest climate, and the ground is sandy and drains well (if that is relevant).
Thank you in advance for your response and help.
Unfortunately, we are set on a type of sandstone that is only available in 3cm, so the question is how well would it hold up, and what happens if it doesn't?
Flisby's solution is to pour concrete underneath, which is an additional project and extra cost.
This is in southwestern Skåne, which is Sweden's mildest climate, and the ground is sandy and drains well (if that is relevant).
Thank you in advance for your response and help.
You can place the stone in concrete instead of compacted stone dust. It will obviously be more expensive but not a huge cost. That is, put out a reinforcement mesh and then a blob of concrete under the stone before setting it.
You can take a chance if you buy a dozen extra stones and do a good preliminary work.
You can take a chance if you buy a dozen extra stones and do a good preliminary work.
3 cm stone laid in the "usual" way is not drivable for cars. And then the stones crack when you drive on them, which doesn't look nice and then you will probably still want/need to redo the driveway in some way, which costs more money.....
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3 cm sandstone will not hold. Also consider that a garage floor should be able to withstand point loads from the jack, for example.
Isn't there a risk of frost damage over time if you cast and lay tiles in the concrete? Old concrete stairs with stone tiles can have such problems.
One should probably stick to recommendations for driveable tiles if one wants a parking space or driveway that lasts.
One should probably stick to recommendations for driveable tiles if one wants a parking space or driveway that lasts.
I have laid 30mm granite slabs on a concrete slab. It is not for cars, but a walkway to the entrance stairs from the street. The ground underneath has some clay, and I want to ensure that there are no settlements.
I cast a 100mm concrete slab on a bed of 0-16mm crushed stone, 100mm draining macadam, 100mm frigolit, to avoid frost heave.
I regret the frigolit a little, it insulates so that the slab gets cold faster when it's cold. Sometimes there is black ice right where you walk, even though the adjacent slabs, which are regular paving stones laid in the usual way, have "summer road conditions."
I set the granite with Ardex adhesive for outdoor natural stone. And Ardex grout for outdoor use.
Everything still looks like new after 6 years.
If I were to use it as a drivable driveway, I would probably have laid a thicker base layer underneath, and maybe to be safe, also cast it a bit thicker. If it were a long driveway, I would probably also consult someone about whether it should be sectioned with expansion joints.
I cast a 100mm concrete slab on a bed of 0-16mm crushed stone, 100mm draining macadam, 100mm frigolit, to avoid frost heave.
I regret the frigolit a little, it insulates so that the slab gets cold faster when it's cold. Sometimes there is black ice right where you walk, even though the adjacent slabs, which are regular paving stones laid in the usual way, have "summer road conditions."
I set the granite with Ardex adhesive for outdoor natural stone. And Ardex grout for outdoor use.
Everything still looks like new after 6 years.
If I were to use it as a drivable driveway, I would probably have laid a thicker base layer underneath, and maybe to be safe, also cast it a bit thicker. If it were a long driveway, I would probably also consult someone about whether it should be sectioned with expansion joints.
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When casting narrow and long concrete slabs outdoors for walkways, etc., one should expect them to crack sooner or later.
To prevent the concrete slab from cracking uncontrollably, grooves are usually sawed across the concrete slab so that the cracking can be controlled. The grooves do not need to go all the way through the concrete slab; it's sufficient to saw the grooves about 0.5-1 cm deep (depending on how thick the slab is. A thinner slab requires shallower grooves).
If you then plan to tile on top of the poured slab, you saw the grooves so that they match the seams between the tiles. When it cracks, hopefully, the tiles themselves won't crack but the crack will end up in the seam between the tiles so that it is barely visible.
But if you are casting a large rectangular concrete slab for, e.g., a driveway, you can make it thick and with the right material underneath so it does not need to crack. So either you cast a cheaper and thinner slab and prepare for it to crack, or you make a thick and expensive slab that hopefully does not crack.
Professionals who cast walkways and driveways usually opt for the thinner variant and saw grooves to achieve controlled crack formation.
To prevent the concrete slab from cracking uncontrollably, grooves are usually sawed across the concrete slab so that the cracking can be controlled. The grooves do not need to go all the way through the concrete slab; it's sufficient to saw the grooves about 0.5-1 cm deep (depending on how thick the slab is. A thinner slab requires shallower grooves).
If you then plan to tile on top of the poured slab, you saw the grooves so that they match the seams between the tiles. When it cracks, hopefully, the tiles themselves won't crack but the crack will end up in the seam between the tiles so that it is barely visible.
But if you are casting a large rectangular concrete slab for, e.g., a driveway, you can make it thick and with the right material underneath so it does not need to crack. So either you cast a cheaper and thinner slab and prepare for it to crack, or you make a thick and expensive slab that hopefully does not crack.
Professionals who cast walkways and driveways usually opt for the thinner variant and saw grooves to achieve controlled crack formation.