How to raise slab-on-grade floor height
I have a dry, slab-on-grade utility and bathroom (400 sq. ft) that I am converting to living space; however, I need to raise the concrete floor level approximately 3″ to match the existing joisted living area. There is also a 3′ by 20′ area that is dirt. (It used to be a stairway.) There is a second story above the entire first floor, including the slab-on-grade portion and dirt portion.
One thought is to pour concrete to the desired level. The other thought, which seems better to me, is to rip down 2x4s for sleepers and attach the subfloor to those. If I go that route, should I place poly between the existing concrete floor and sleepers? What type of insulation would be best? How feasible would it be to install rigid foam board first and place sleepers on top of that? What would be the best method for covering the dirt area where the stairs were?
A couple concerns come to mind. First, I will need to shim the new floor system as the concrete is not level. How would I do that if I put foam down first? Second, I do not want squeaks.
Any thoughts would be appreciated.
Replies
crete or sleepers
place heavy plastic first
no sqeaks better use FG batts or spary faom tight around foam panels
If using foam, less worry about plastic under but use polystyrene, not polyisoanurate or other open celled faom.
Insulation may not be necessary or desireable. What part of the country?
Is rest of house on crawl space?
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Pacific Northwest--mild climate. The rest of the building is on foundation with a 3' to 4' crawlspace.
I wonder about ventilation if I go with sleepers. Why would insulation not be desireable?
Thanks for your response. I have come to respect your opinions, even though I don't know what a Piffin screw is.
For a mild climate, it really comes down to which choice is easier for you to accomplish.Primary reason why it could be undesireable to insulate would be that if the house was designed with a slab that needed the heat of the slab to keep it from heaving around, you would want to keep that slab warm instead of isolating it from the heat of the house interiopr. Crazy thing happen and I don't know alll the ins and outs of you4r house, but It often helps to play cards when you follow suit and play the hand dealt.Dinner time for me so later on the piffin screw definition....short version is don't hanfg cabinets with sheet rock screws - or build staging - or....
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Concrete is the best job. 3" is not enough room to create a good sleeper/floor system on dirt.
The dirt area is small (3' x 20') and I could either dig it out some or pour concrete and use a sleeper system over that.
I know, you are probably thinking if I use concrete for a portion, I might as well do the whole thing at once. That does have merit and may end up being the most cost efficient solution, but I'm thinking that a wood floor would feel more like the existing joisted floor even though there will be carpet and pad over both. What do you think?
Levelone,If you use a good carpet pad, most people won't even notice the transition from wood to concrete. So long as it is dry and level/flush at the joint. If the existing wood floor squeaks, they may notice the quiet at the transition.I vote for the concrete as easier, more trouble-free.If you need thermal insulation, lay down one or more thin layers of extruded polystyrene board before pouring. The weight of the wet concrete will make it conform to small dips in the old slab. If the dips are large, cut the foam into smaller pieces so it tiles the contours of the old slab. Still use a plastic moisture barrier under the foam.On the dirt, set screeded sand over the plastic and under the foamboard.Bill