Should I Insulate Under My Concrete Slab?

What’s the best way to insulate a concrete floor?

There are two ways to handle insulating concrete floors.

You can attach wood sleepers to the floor, fill the gaps with rigid-foam insulation, and then apply your finish flooring.

Or, as demonstrated here, you can cover the slab with rigid-foam insulation, add two layers of plywood, and then add the finish flooring..

Why do they put foam under concrete?

Concrete contractors learned that a layer of poly helps to keep a slab dry, because it stops upward vapor diffusion from the soil. … The foam layer isolates the room-temperature slab from the cold soil under the slab.

Do you put plastic under concrete?

Recently, though, research has shown that the old traditional layer of 6-mil Visqueen (polyethylene plastic) under the slab is seldom effective for two main reasons: Although it may seem water-tight, this grade of material allows a lot of water vapor to pass through.

Is concrete waterproof?

Concrete is a pretty remarkable manmade material that’s extremely durable over time. … That means concrete is not waterproof. Brand new cured concrete might be relatively waterproof for a little while, but it doesn’t take long at all for water to penetrate the surface and begin to cause deterioration.

What eats away concrete?

Concrete is a durable building material that takes special materials to dissolve once it’s hardened into place. Phosphoric acid and trisodium phosphate are the main compounds used to dissolve concrete leftover from masonry work.

What is the best flooring to put over concrete?

Best Flooring for Concrete Slab FoundationEngineered Wood. Natural hardwood flooring offers undeniable beauty and durability. … Vinyl. As a longstanding choice for kitchens and bathrooms, vinyl has a reputation for extreme water resistance. … Laminate. … Carpet. … Tile.

How do you insulate under a concrete slab?

For under-slab applications, the rigid foam insulation typically should be installed over a gravel base, with a poly vapor diffusion retarder between the gravel and insulation. Additional insulation is applied along the edges of the slab, because that is a primary surface for heat loss.

Can you use Polyiso insulation under concrete?

Most polyiso wall insulation products are very moisture resistant. However, “because the polyiso facer can absorb water, polyiso is not recommended for use under slabs or on the exterior of foundation walls,” notes Green Building Advisor, a website dedicated to the residential construction industry.

How thick should a garage slab be?

four-inchesThe concrete slab should be four-inches thick at least; it needs to be thicker if heavy equipment will rest on it. Building codes offer requirements for the concrete mix, which vary by region. The standards are expressed in terms of “compressive strength,” which boils down to the amount of water used in the mix.

How do I keep my concrete floor warm?

A layer of dense foam padding under the laminate can help warm up the floor somewhat. In slab situations, raising up the subfloor off the concrete with a layer of plywood over sleeper strips before installing the surface flooring can also make it warmer to the feet.

How do I keep my concrete floor from sweating?

How to stop concrete sweatingDry out the room by air movement: a high volume low speed fan works well.Turn down the air conditioning/turn up the heat to keep the concrete floor temperature and the air temperature at similiar levels.Use a dehumidifier to remove moisture from the air and reduce the condensation.More items…•

How much heat is lost through the floor?

Is your home leaking heat? In an uninsulated home, around 35 percent of heat loss is through the walls and 25 percent is lost through the roof. The remaining 40 percent is lost through doors, windows and the floor.

Do I need to insulate my concrete slab?

Builders with a bigger budget, especially those in cold climates, should consider installing continuous horizontal insulation under the entire slab. A continuous layer of horizontal insulation reduces heat loss in the winter, and it reduces condensation of humid air on the slab during the summer.

How much insulation do I need under a concrete slab?

A 50mm thick layer of proprietary floor slab insulation is usually enough to reach and maintain the target U value but this should be checked with an architect first. Insulation sheets should be laid tightly together with the joints staggered to avoid movement.

What is the lifespan of concrete?

Early 20th-century engineers thought reinforced concrete structures would last a very long time – perhaps 1,000 years. In reality, their life span is more like 50-100 years, and sometimes less.

What kind of foam goes under slab?

Two of the rigid foam insulations most commonly used below grade and under slabs are expanded polystyrene (EPS) and extruded polystyrene (XPS). Although both are closed cell insulations, they perform very differently over the long term.

Will rain ruin fresh concrete?

Heavy rain can cause problems to freshly poured concrete as it can wash out some of the cement from the mix. This can weaken the surface of the concrete, making it a softer consistency and decreasing the strength of the concrete.

Is it worth insulating a concrete floor?

Concrete floors have a reputation for being cold, and it’s true that concrete has a lower insulating value than most other building materials. Your concrete floor is probably not the biggest source of heat loss in your home, however, and if your floor is cold, there are ways to improve its heat retention.