As concrete is a cold hard surface and a carpet creates a warm layer on top, there is a danger of condensation and damp forming on the underside of the carpet. For the best results, invest in a good-quality synthetic underlay to provide extra cushioning and a barrier between your carpet and the floor.
It can be difficult to put carpet directly over concrete due to the possibility of moisture underneath. You'll need the correct kind of carpet, as well as a level and dry concrete surface, and the carpet must stick securely to the concrete.
Over time, this can extend the life of your carpet. Though the price may be slightly higher, there are several reasons to consider a moisture barrier with your carpet or carpet tile. Even with a concrete subfloor under your carpet, it is important to have a moisture barrier.
Keep your finished basement floor dry, even if the concrete gets wet. Prevent damp basement floors from ruining carpet and other finished flooring. Install dimpled polyethylene to create an air space between the concrete and the finished floor, sealing off dampness and giving moisture a chance to dissipate.
Carpet pad
Any carpet that can be used in other areas of the house can be used in the basement. But as a precaution against moisture, use an open cell pad to allow the concrete to “breathe.” Nearly all pads are open cell pads, which provide better insulation and are less expensive than closed cell pads.
Most residential carpets are installed over padding. On a cold, hard basement floor, a soft pad is essential for comfort and warmth. Underpad is generally fine to use in a basement, provided it is also synthetic. Opt for a polyurethane foam pad, and stay away from a rubber pad.
The American Concrete Institute (ACI) also recommends a minimum of 10 mil polyethylene or thicker for vapor retarders under concrete. According to its Guide to Concrete Floor and Slab Construction ACI 302.1R-15, thicker poly provides a better barrier and is also more puncture resistant.
Sealers should be applied after pouring to help prevent water from coming into contact with the slab and provide protection against staining. The sheeting or membranes should be placed between the soil and the slab before the concrete is poured so that water does not come into contact with the surface of the slab.
“Without a vapor barrier, concrete will deteriorate much faster through water vapor intrusion which degrades the quality of the concrete over time and can lead to foundation and building failures, like Surfside Condominium Collapse in Miami, Florida,” says vapor barrier plastic sheeting expert and Americover account ...
Moisture barriers are usually installed on the warm side of the wall. In warm climates the vapor barrier is placed on the exterior, while in colder climates the vapor barrier is placed on the interior, to prevent water and vapor from entering the wall cavity.
Underneath most carpeted, finished basements a concrete slab exisits and if not properly sealed it is susceptible to mold, mildew and water seepage. By using a moisture mitigating concrete coating, water will be stopped, carpet will be kept dry and humidity levels will be kept at bay.
Applying a liquid membrane is usually the best option whenever the final surface of the concrete is going to be covered, such as a carpet or wood flooring. Liquid membrane products tend to have good adhesive qualities and impressive drying times.
PU foam is the most recommended underlay for carpet given it's luxurious cushioning and comfort underfoot. It's great for keeping in the heat, reducing sound levels and available in different types of thickness, density and quality which suits all budgets.
Vinegar Solution
Spraying a vinegar solution (1 cup of vinegar per gallon of water) onto the surface, saturating it fully, should kill most strains of mold.
By using a penetrating concrete sealer like the Siloxa-Tek 8500 mold, mildew and organic growth will be reduced and made easier to clean. The Siloxa-Tek 8500 is our favorite product to treat nearly any application.
WET CARPET = BLACK MOLD IS COMING!
Water under carpets, behind baseboards and cabinets and other hard to reach areas are a ticking mold time bomb. Even with fans going and mopping up the water, it may not be enough to prevent mold growth.
As moisture wicks up from the foundation, it evaporates, hence the reason why basements maintain higher humidity than elsewhere in the home. Once a carpet, area rug or a pad is placed on top of the cement foundation, it will begin absorbing this excess moisture.
There is nothing to prevent you laying a carpet on top of a floor made of concrete, but as you can see, it is a bit more challenging than other types of floor surface. It is advised to hire a professional flooring firm instead of attempting it yourself, as this will make the process a lot easier.
If you're remodeling a room with a concrete floor, laying carpet on top can completely transform the space with softness, warmth, and color. It's possible to do this project as a DIY, but you'll need specialized skills and tools, plus some extensive prep to pull it off.
Moisture barrier pads are essentially what they sound like — a barrier that goes underneath your carpet that keeps liquid from soaking through to the floor or subfloor underneath. They add an extra step for carpet installation, as well as an extra cost, so some homeowners decide not to use them.
Average Traffic: Most carpeted residential areas require a carpet pad with a six to eight pound density rating. Heavy Traffic: Areas that experience a high amount of foot traffic, like hallways or stairs, require additional support. A carpet pad with an eight to ten pound density rating or higher is recommended.