Even if you have a concrete floor under your carpet, as in the case of a finished basement, you should still install a moisture barrier under the carpet. Liquid spills can do more damage to concrete than you might think, and can even erode concrete or cement board over time.
When moisture penetrates your flooring, it can cause mold, mildew, and the potential for water damage. A moisture barrier helps control the water vapor's movement to help protect your floors. Therefore, if you're installing floors in an area that sees moisture, even a little, a vapor barrier is needed.
Does carpet need underlay? Yes, All carpets apart from felt-backed carpets should have underlay. Obviously budget is sometimes an issue with underlays, but it is well worth the extra money.
Carpet padding is a type of foam cushion used underneath carpeting. Without the right padding, a new carpet may not lay as well or can be uncomfortable.
Moisture barrier padding is floor padding that has a layer that prevents liquids (spills, urine, etc) from passing from the floor to the floorboards, and it also prevents vapor from coming up from the base floor (concrete, etc) through the carpet. The hope of this type of padding is to make moisture less of a headache.
So to provide your hardwood floor or carpeted area with the best protection it's best to face your felt rug pad soft side down. Carpet rug pad - a carpet pad will have a rubber side and a softer side. To face a carpet pad the right way simply lay the pad so the rubber side is up and the softer side is down.
As a general rule, you can lay carpet over concrete. Concrete provides a stable subfloor for carpet, and carpet can be installed on it using the tried and true method that virtually all carpet installation contractors use. You can also install it yourself, however, you need many specialized tools.
Underlayment: Some types of flooring can be installed directly on top of the subfloor, such as vinyl flooring. Other types need a middle layer, called underlayment, such as laminate,carpet and tile.
The subfloor is the layer underneath the carpet and carpet padding. It's usually made of plywood, but can be wood, OSB board, or particle board as well. It's laid on top of the joists in the floor and attached with nails or screws.
A subfloor is the solid material beneath your floor covering. It is attached to your home's floor joists and acts as a base for your finished flooring, such as carpet, hardwood, laminate, tile, etc. Typically, a subfloor is made of plywood or oriented strand board (OSB) panels.
Underlay isn't just crucial for comfort underfoot, but it also drastically helps maintain your carpet as well as providing extra protection against moisture. It is also a great shock absorber, meaning it's ideal for reducing noise from things like footsteps, voices or moving furniture.
If you have a concrete floor you will need an underlay which is anti-bacterial and made from rubber. Not all types of underlay will cope well with constantly being rubbed up against concrete so you may want to seek advice from carpet fitting experts before purchasing.
Flooring Underlayment
The thin layer of material helps cushion, sound absorption, insulation and reduce wear with your flooring. For laminate or engineered wood flooring, it provides a “vapor barrier” to prevent moisture from coming through and damaging your floor.
If you live in a mixed climate – hot and humid with several heating months in the winter, you probably need a vapor retarder. Specifically, if you live in climate zones 4C (marine), 5, 6, 7 and 8.
Plastic, specifically 6-mil polyethylene plastic, is the most commonly used vapor barrier. Plastic has a very low permeability rating, which means water, in its gaseous or liquid state, does not travel through it.
Moisture barriers function to help in preventing water from entering inside of the wall cavity. On the other hand, vapor barriers basically prevent water vapor from the interior of the house to filter through the wall and condense on the warm side of the insulation.
If the existing floor is damaged enough or there is too much adhesive to clean it off, leaving a smooth surface, it might be necessary to add a layer of underlayment. While there are several different types of specialty underlayment materials on the market, the most common for use under carpeting is ¼” thick plywood.
If there is black stuff under a carpet pad, it is likely leftover rubber pieces from old carpet padding. In rare cases, it can be mold that is caused due to a leak under the carpet pad. To fix the issue, check for moisture underneath. If there's no moisture, scrape the black stuff away and remove it.
Look for any floor vent you can find, and carefully pull it up to remove it. They are rarely secured down in any way, so they're easy to take out. The carpet won't be tacked down around the edge of the vent opening, so you'll be able to easily pull the carpet and pad up just enough to see what is underneath.
Underlayment
The underlayment material is installed below the floor covering and placed on top of a subfloor. Under the visible covering, there is a layer made of soft or foam-like materials with a thickness of between 1/4 – 1/2-inch.
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.
You can glue carpet to concrete floors either directly or via a pad. Direct glue-down installation is the most popular installation option in residential and commercial spaces. Ensure your concrete floor is clean and smooth before installation is carried out.