Crawl space cement slab project?
Question:I have a crawl space with gravel and plastic covering. No humidity problem. Now I want to pour cement slab. I want o know what quickcrete should I use? Minimun slab thickness? Should I pour cement over existing plastic covering?
Answers:
There is no standard for something like that. Basically all your doing is covering your gravel with a solid surface. I wouldnt put it over the plastic though. Maek it at least two inches so you can avoid too much cracking. Three would bebetter. You can have it pumped in from a truck if there is acess or just mix byhand or with a portable mixer. You can even make a slurry and pour that in so it almost self levels.
Any of the quick mixes will do but I'd go for one with nno gravel. It will make it easier to level it out if it's a tight space to work in.
I think that most of Pappy's answer makes sense except that I would be tempted to leave the plastic as a moisture barrier. Don't forget that cement is very porous, almost sponge like, and will let moisture through very easily.
this is what know in the concrete industry as "rat proofing"- covering your existing crawl space with a concrete mixture. If it is actually a "crawl" space with little room for movement we would pump a "slurry" of a pea gravel mixture right over what you are already have. If the plastic is covered with gravel you are OK. You can pour right over plastic but the concrete sets up very, very fast and if it is a hot day it will crack.
As far as thickness 2" is fine if its is not an area anyone is going to be walking on just Crawling on. In theses mixes it is a good Idea to have them add fiber to the mix and use a 6 sac mix, that's 6 sacks of concrete to a yard. its a stronger mix as you will be adding water to create the slurry. Contact a concrete pumper in your area and he may do it on his own with out the need to hiring a concrete contractor that in turn will hire him anyway for something like this.
You can pour it over the existing plastic, but how big is the area ur trying to cover. Mixing bag after bag may take to long and some will set before you finish which will give you a bad finish with joins. You may be better having a concrete truck come to your basement window and catch it in a wheel barrel.
Good luck
More Related Questions & Answers...