Concrete Floor Insulation Requirements Construction Essay

Concrete Floor Insulation Requirements Construction Essay

Is your basement or garage exceptionally chilly? An uninsulated concrete floor may be a large part of the problem. Insulating a concrete floor can save you money on your heating bill, making your garage or basement warmer and, by extension, the rest of your house.

In addition to offering insulation and energy savings, the plywood subfloor described here can provide the perfect foundation for finish flooring such as carpeting, adding warmth in look as well as in feel.

To prepare for insulating the floor, first evaluate the condition of the concrete. If you know you have issues with moisture, tend to those problems before installing the insulation. Also, check the floor for smoothness and level; you may need to grind down significantly high spots to ensure an even surface.

Measure the distance between the slab and the ceiling; you must leave approximately 7 feet, 6 inches of clearance between theceiling and the surface of the finished floor to comply with building codes. The subfloor will take up about 2 inches, and any floor covering will also reduce your clearance, so plan accordingly. Finally, clean the surface of the slab thoroughly.

Next, unfurl 6-mil polyethylene sheeting over the floor to provide moisture protection. When laying the next row of sheeting, be sure to overlap the existing row by 6 inches, and then tape the seams. Adhere the edges of the polyethylene to the slab with caulking to prevent slippage.

Lay out pressure-treated 2-by-4 sleepers at the edges of the room. Abut their ends and fasten them to the slab with 2 1/4-inch masonry nails. Mark these perimeter sleepers for additional sleepers, which will be centered every 16 inches and laid out in one direction across the room.

Affix these additional sleepers to the slab, nailing at the end of each board and approximately every 4 feet thereafter. Check for level frequently as you go. Shims can be added where needed to ensure a level surface.

Fit 1 1/2-inch-thick rigid foam insulation between the sleepers; strips should be about 12 1/2 inches wide. Always measure for an exact fit so as not to compress the insulation, which can compromise its performance.

Place 3/4-inch plywood sheets across (not parallel to) the sleepers. Start alternate rows with half sheets to stagger the joints. Drive in 6d nails every 6 inches where the ends of the panels meet the sleeper supports and every 12 inches into sleepers under the panel centers.

Once the plywood surface is laid out, finish with the flooring material of your choice. (For more on insulating foundations, see the article on how to seal (caulk) around your home’s foundation.)

hello all, this really doesnt pertain to my basement since we dont have one. but what we DO have is a house with concrete slab for our floor. the home used to be crawl space on one side and just slab on the other, we’ve been going through an extensive remodel and part of that was filling in the crawl space (60 tons of gravel with wheel barrows  ) and just pouring an entire new slab that covered the newly filled crawl space and the old slab. now, while plumbing, walls, electrical and so forth have taken priority its coming time soon to work on the flooring.

we intend to cover the slab with that laminate hardwood looking stuff but the winter here in PA has made me wonder if theres something i can do to help with the cold floors.

i was at home depot earlier this week and saw that pink styrofoam insulation comes in folded-up 3/8 thick 200 square foot bundles, while it has an r-value of only 1.5 i figured it would be better than nothing. from what i can tell the 3/8 plus the thickness of the laminate and the foam underlay stuff that goes under the laminate will just fall short of being a problem for floor clearance of the interior doors.

so i guess what i am askng is weather or not this is a good idea, or if anyone has a better solution.

thanks in advance for your time


Think of the surprise and delight a new homeowner would have to find that their basement is not only usable space, but warm and comfortable as well! By taking a few extra steps, builders can toss out the notion that basements are cursed to be dank, cold, musty storage rooms.

Most basements are built in direct contact with the cold moist ground. Concrete will absorb moisture, like a sponge, and the result is an uncomfortable, musty living space. The additional water introduced into the home can also lead to mold issues. Finding a way to keep water out of the basement will greatly improve the smell and health of the home.

Heat is also lost through the basement floor. The notion that heat always rises isn’t entirely true. Heat will flow towards relatively cooler places. If ground under the home is cooler than the basement temperature, which is the case in almost every climate year round, heat will naturally try to escape through the concrete slab.

Creating an insulation layer and a vapor barrier between the concrete slab and the ground beneath it is the best practice in insulating basement floors. The insulation barrier will help keep warm air in, and the vapor barrier will keep unwanted moisture out.

Here’s how to do it:

Evenly spread the base gravel under the basement slab, keeping it one inch lower than the conventional method.

Place a one-inch layer of 4’x8′ extruded polystyrene foam board over the gravel, covering the entire floor area.

Tape the joints between the boards with builder’s tape; you want to create a tight insulation layer.

Place 5 mil. polyethylene sheets over the foam board, overlapping at least 6 inches at the seam. Make sure there are no gaps, tears, or holes in the sheets and repair any you find with builder’s tape. This covering will act as the vapor barrier.

Tape the joints with builder’s tape and pour concrete as normal.

To go the extra mile, learn about insulating basement walls at

BuildIQ also offers a comprehensive online course on water management for foundations. More information can be found on their website. Website, which has fact sheets and information on insulation.

How to Insulate an Existing Concrete Floor

By Cameron Easey, eHow Contributor

updated: November 27, 2009

Existing concrete floors, like those found in most basements, can be cold if the floor has not been covered with carpet or insulated. If you plan to finish your basement or just want to provide a warmer floor, you can add a new sub-floor on top of the existing concrete. A new sub-floor can be constructed using rigid insulation and wood. Insulate existing concrete floors by first determining how much building material will be needed.

Difficulty: Moderate


Things You’ll Need:

2-by-4 inch pressure-treated boards

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