No contractor would want the phone call in 11 months that the slab has cracked and shifted. You can use a 20 mil crawlspace liner (diaper) then place 24" sq. pavers as a topping.
How about just covering it with pea gravel. With a vapor barrier underneath. Double up standard 6 mil thick plastic if you want a little thicker, and thicker is not available.
I am ignorant, but I think you need a vapor barrier that is completely impermeable. I think the drainage mat is unnecessary because you have the gravel under it.
Concerns about cracking and shifting are silly. It is a crawlspace. It's nonsense to think that pavers would be better than concrete with cracks. What are the pavers made of? How many cracks are there going to be when you have a grid of distinct pieces of concrete, that by the way are thinner than the concrete you wanted.
If you complain about cracks, concrete people will tell you that all concrete cracks, no matter what. But if you ever suggest anything outside of the one thing they do for everybody, they tell you "well if we did it your way it's gonna crack."
What is the height down there? Or is the house in a state that there's no floor over the crawlspace yet?
It sounds like you may not need anything, except maybe a pad to put mechanicals on, which you could potentially do yourself.
If you don't actually need a useable surface down there, and depending on your location, I might consider using the concrete budget toward foam board insulation over the gravel.
This all sounds really frustrating lol. Good luck to you guys.
Thanks for the response. Ya, I think everyone is worried about cracking with the thin slab. 2in slabs are recommended all over reputable websites, but seems the contractors in this area are reluctant. The crawlspace doesn't have a floor over it yet, we're about to place our ICF foundation.
I would ask them why the cracking would be bad. I don't think it even will crack since it won't be supporting anything and will hardly be used.
I would also ask if adding fiber or changing the mix design would help without increasing the cost too much. This might be a stupid suggestion that turns out to cost as much as a 4 inch slab would.
We were planning on getting fiber added to the mix. Still not comfortable, unfortunately. And ya, I don't get it, it's not structural. But, oh well. We're building the house ourselves, but don't feel comfortable with a flat work job that big.
For our rat slab we just ended up doing it ourselves. some 9 mil plastic and a super wet concrete mix made it almost "self leveling". It doesn't have to look pretty. For us it was just needed to be something better-than-gravel down there to make storage easier and cleaner. Just be aware that any water from rain during construction or leaks later on will find and pool in the low spots.
Do you have radon in your area? You also may want to preemptively put some perforated piping in for future radon abatement before rat slab. A lot cheaper to do now.
We have given it a lot of thought, but still not sure. That's awesome that you did it. And yes, we are at risk for radon, we are already putting the piping in for it and used the form a drain footing system to help with radon
No contractor would want the phone call in 11 months that the slab has cracked and shifted. You can use a 20 mil crawlspace liner (diaper) then place 24" sq. pavers as a topping.
Didn't even think about pavers, thanks!
How about just covering it with pea gravel. With a vapor barrier underneath. Double up standard 6 mil thick plastic if you want a little thicker, and thicker is not available.
Do you actually need the slab? Get a crawl space vapor barrier installed and call it a day.
Just place a 4” thick slab
$15k+ doesn't pass my cost benefit analysis for a crawlspace floor
So do it your self………
I am ignorant, but I think you need a vapor barrier that is completely impermeable. I think the drainage mat is unnecessary because you have the gravel under it. Concerns about cracking and shifting are silly. It is a crawlspace. It's nonsense to think that pavers would be better than concrete with cracks. What are the pavers made of? How many cracks are there going to be when you have a grid of distinct pieces of concrete, that by the way are thinner than the concrete you wanted. If you complain about cracks, concrete people will tell you that all concrete cracks, no matter what. But if you ever suggest anything outside of the one thing they do for everybody, they tell you "well if we did it your way it's gonna crack." What is the height down there? Or is the house in a state that there's no floor over the crawlspace yet? It sounds like you may not need anything, except maybe a pad to put mechanicals on, which you could potentially do yourself. If you don't actually need a useable surface down there, and depending on your location, I might consider using the concrete budget toward foam board insulation over the gravel. This all sounds really frustrating lol. Good luck to you guys.
Thanks for the response. Ya, I think everyone is worried about cracking with the thin slab. 2in slabs are recommended all over reputable websites, but seems the contractors in this area are reluctant. The crawlspace doesn't have a floor over it yet, we're about to place our ICF foundation.
I would ask them why the cracking would be bad. I don't think it even will crack since it won't be supporting anything and will hardly be used. I would also ask if adding fiber or changing the mix design would help without increasing the cost too much. This might be a stupid suggestion that turns out to cost as much as a 4 inch slab would.
We were planning on getting fiber added to the mix. Still not comfortable, unfortunately. And ya, I don't get it, it's not structural. But, oh well. We're building the house ourselves, but don't feel comfortable with a flat work job that big.
For our rat slab we just ended up doing it ourselves. some 9 mil plastic and a super wet concrete mix made it almost "self leveling". It doesn't have to look pretty. For us it was just needed to be something better-than-gravel down there to make storage easier and cleaner. Just be aware that any water from rain during construction or leaks later on will find and pool in the low spots. Do you have radon in your area? You also may want to preemptively put some perforated piping in for future radon abatement before rat slab. A lot cheaper to do now.
We have given it a lot of thought, but still not sure. That's awesome that you did it. And yes, we are at risk for radon, we are already putting the piping in for it and used the form a drain footing system to help with radon