Installing a hardwood floor over a concrete slab american. This video describes the process of installing a moisture barrier over a concrete subfloor. Can i install underlayment under laminate with attached. We have a partial concrete slab that we are planning to subfloor over to make a level floor throughout the house. Attached vapor barrier underlayment surface prep the. If there is too much moisture in the concrete, and an impermeable layer is placed over it the moisture migration can delaminate the coating sealer or overlay. Permeation of water vapor through concrete slabs can. Some underlayments such as cali complete when used with the metallic tape are also moisture barriers. Bostik vapor barrier membranes provide essential moisture mitigation and suppression for subfloors. It should serve as an additional element of protection. Some contractors like to place a layer of sand over the vapor barrier, but most have adapted to placing the concrete directly on top of a heavyduty.
Premium foam underlayment for laminate and floating wood floors. Concrete may seem very dense, but it is actually full of small pores that will absorb water from the ground. The misconception around slab curl and vapor barriers has been much. Looselay the first layer over the slab or over the moisture barrier above the slab, with 14inch expansion gaps between the sheets. The barrier comes in rolls about twentyfour inches wide. Im putting ceramic tile flooring in my kitchen and live on a 10yearold, groundlevel concrete slab. Dec 19, 2018 before you install any flooring material over a concrete slab, it is important to inspect the slab for defects.
Concrete floor problems building science corporation. If your concrete passes the moisture test, then plastic sheeting at least 6 mils thick will prevent moisture from getting into your laminate flooring. Signs a concrete floor has moisture issues buildings. I have been researching a lot and would like to install a plywood floor over concrete in two bedrooms in our basement. Jan 03, 2020 applying a sheet material that serves as a moisture barrier, such as a 6mil thick polyethylene pe plastic sheet overlapped with taped seams, can be one way to mitigate concrete moisture. Why underlayment matters to a tile installation project. This product is a 90 mil sound control, waterproof, and. When rolling out the moisture barrier you want to go from wall to wall and cover the entire floor. Construct a subfloor with sheets of 34inch pressuretreated plywood over the moisture barrier. Note any cracks in the substrate for future reference. How to install laminate flooring over concrete 2020 home. For moisture to accumulate between the concrete slab and the flooring, it needs to find its way to that middle layer. Diffusion is a direct function of surface areaif i get 95 percent of the surface covered i am pretty much 95 percent effectiveand the parts that are left i have filled with concrete which is.
Tile cannot be attached directly to painted concrete, as the thinset will not adhere well to the paint. Need some advice to install a plywood floor over concrete please. This installation contains the moisture in the slab, increases the subfloors stability, and helps to keep the finished floor from swelling, buckling, or cracking. Installing underlayment for laminate flooring hunker. Whenever pouring concrete over a wood subfloor, a moisture barrier must be installed first to protect the wood from the water in the concrete and to allow the concrete to properly cure. I have read in some places that you need a vapour barrier to put over the concrete before installing the plywood and in other places to just glue the plywood to the concrete floor.
For optimal moisture control you will want to overlap the poly barrier by at least six inches. For what its worth, what i wound up doing is using the floor muffler underlayment, which is its own moisture barrier. Pair with metallized seaming tape to ensure a full moisture barrier, even over concrete. Curling and warping of concrete slabs 5 facts you should know. Americover has a high performance 15 mil vapor barrier for installation under concrete floors and slabs that will retard moisture migration and radon from escaping through the surface of the concrete floor. It helps reduce mold and condensation in buildings and is resistant to decay so it will protect against. But for ceramic tile, the best subfloor is the cement slab itselfprovided the slab is stable and in good condition.
A liquid coating is then applied to the bare concrete subfloor, such as customs cmvc 100% solids moisture vapor and alkalinity barrier. Home subfloor coatings and toppings concrete moisture barriers applying. Without the proper moisture barrier, vinyl flooring acts as a moisture barrier, causing it to buckle, bubble and lift. Whether it is an overwatered pour, a lack of a quality vapor barrier. The concrete mix itself, in the event the slab is insufficiently cured or. Also, with some types of membrane, the contractor can offset the sealantfilled soft joints in the tile, so they do not have to fall directly over the crack or control joint in a concrete slab in this case, create soft joints on both sides of the crack or joint figure 638, using a flexible sealant instead of grout. The house was built in the 70s so im not sure if there was any kind of moisture barrier under the slab. When youre installing a wood floor over a concrete slab, the vapor retarder should be placed under the plywood subfloor. Moisture is the numberone enemy of laminate flooring, and few manufacturers will honor the product warranty if you dont install a vapor barrier thermal insulation. A readytouse elastomeric waterproofing membrane for both commercial and residential tile and stone application. Where plastic sheets must be joined, overlap the sheets by several inches, and use strong vinyl tape to. Moisture can come up through your subfloor, especially if you are installing over concrete or belowgrade. Adhesive glue with moisture barrier and sound barrier.
Dips, bulges and cracks occur frequently as concrete cures and ages. For more information about this video or fausfloor products visit. In order to achieve the proper vapor barrier, you must use a 14 x 14 vnotch trowel it has an ultra low voc content and is low odor, so you can relax knowing that you are. Drytek moisture vapor barrier is a single coat, 100% solids, liquid applied 2 part epoxy coating specifically designed for controlling the moisture vapor emission rate to new or existing concrete slabs prior to installing underlayment, decorative toppings and most resinous coatings. How to put a wood floor on concrete home guides sf gate. Its dimpled, rugged gray plastic membrane provides a seamless mold and moisture barrier for any concrete, slabongrade floor in your home. How can i install porcelain tile over a concrete slab with. In the mortar bed installation, the mortar bed is not bonded to the concrete rather it is isolated from cracks in the concrete by the cleavage membrane. I have seen many blogs and read a lot, and know it can be done, but, need a bit of help. Sounds like its going to crack, but im doubting this to happen. How to install the moisture barrier over concrete subfloor.
This sheet material does not negate the importance of installing a vapor barrier underneath the slab. Betty, i have never put a vapor barrier under carpet in a basement. For a warm and comfortable basement, choose the dorken deltafl subfloor. Laminate is a floating floor, and it needs to be unrestricted to properly expand and contract with temperature changes. Before you install any flooring material over a concrete slab, it is important to inspect the slab for defects. Bone dry original penetrating concrete sealer is a permanent, low voc, cost effective solution to protecting finished flooring from concrete moisture related issues. I think he is just handing me bs and hiding behind the moisture level issue. Redgard crack prevention and waterproofing membrane. In this section, we breakdown the main ways water can get into your concrete, which causes a buildup of excess moisture, and list effective methods to prevent moisture problems from occurring. Vapour barriers are a good idea to prevent radon gas from coming up through any cracks in the floor. The concrete subfloor has no direct access with the ground. Vapor barriers have been associated with certain concrete slabongrade problems including curling and cracking.
Applying a sheet material that serves as a moisture barrier, such as a 6mil thick polyethylene pe plastic sheet overlapped with taped seams, can be one way to mitigate concrete moisture. Oct 14, 2019 snap the chalk line over the top of the concrete or moisture barrier between the marks on opposite walls making a cross in the center of the room. Along with the moisture barrier, you may want to install an underlayment. The subfloor will consist of 2 x 6 joists about 1 inch off the slab. This is a moisture barricade that protects finished floors from moisture over concrete slabs and subfloors. Cracking or bubbling of a floor covering or resinous floor coating. Dorken deltafl plastic subfloor system for basements.
Bone dry original is easy to apply using a pump sprayer. In the thinset installation, a crack isolation membrane is bonded to the concrete. Our original sealer can be applied to new and existing concrete surface and can be applied underneath or over the surface. Do i need to put any type of underlayment or vapor barrier underneath it. Most other flooring materialsincluding hardwood, laminate, or carpetwill perform best in a basement environment if they are installed over a subfloor of dricore, or plywood or osb elevated slightly on sleeper boards. Confusion and debate over the use of vapor retarders will likely continue into the future. A moisture barrier is need to protect the flooring against moisture or moisture vapor. Concrete vapor barrier what is a vapor barrier and do i. The soil under a slabongrade, in the event of an improperly functioning vapor barrier. Im up in the oakland hills, so the temperature extremes arent. Best concrete floor vapor barrier the truth from a real. Check with the manufacturer of the epoxy moisture barrier to make sure it will be suitable for your situation. This product is a 90 mil sound control, waterproof, and crack isolation membrane.
Adding a subfloor over the concrete slab is one installation method. If the rh is over 80% then you have to use an epoxy coated system with a cementitious selfleveling underlayment to seal the concrete. Painted concrete can be made porous with sandblasting or other hard. For concrete subfloors we recommend using a moisture barrier, not to be confused with a vapor barrier, the latter being less effective. Figure 1 typical detail of slab on grade with vapor retarder. Dec 29, 2019 installing a vapor barrier over a plywood subfloor will cause moisture to be trapped within the material which causes mold and mildew growth and can lead to warping of the laminate. Sealers that allow some vapor passage can be used, but most topical membrane sealers require a moisture vapor emission rate mver of 3 or 5 pounds square feet24 hours. I am putting down the plastic barrier on top of the subfloor, and then the new pergo laminate on top of that. Need some advice to install a plywood floor over concrete. By itself, laminate flooring is a poor insulator, and if you dont add an underlayment, the floor can feel uncomfortably cold sound insulation. Drytek moisture vapor barrier is a singlecoat, 100% solids, liquid applied 2part epoxy coating specifically designed for controlling the moisture vapor emission rate from new or existing concrete slabs prior to installing drytek underlayment, decorative toppings and most resinous coatings. The safest way to approach questionable concrete is not to cover it over with cbus but to fix the concrete. This video demonstrates how to install a moisture barrier over a concrete subfloor.
Drytek epoxy moisture vapor barrier ideal for concrete. Many moisture problems associated with interior concrete floors and slabs on grade can be minimized or. With the right moisture protection, you can turn a damp, moldy basement into a safe and livable family room or workshop. A concrete vapor barrier is simply a sheet of polyethylene plastic visqueen placed directly on top of the subgrade before the concrete floor or slab is poured to help keep moisture from the soil from passing up through the concrete. However, the fact that the cost of floor coverings over concrete floor slabs in the u. Snap the chalk line over the top of the concrete or moisture barrier between the marks on opposite walls making a cross in the center of the room. We understand that flooring installers need to supress moisture as quickly as possible before applying primer, smoothing compound and floor coverings. Concrete flooring installation 2020 home flooring pros. Moisture problems between the flooring and the slab. Cracks and gaps can be filled with portland cementbased fillers. The only exception is when you want to install laminate over high moisture areas like basements and bathrooms where a moisture barrier is needed.
This flooring adhesive with moisture and sound barrier provides a moisture barrier to protect your floor from any moisture transmitted from a sub floor, as well as filling in any cracks or ridges in the concrete. The condo has had laminate flooring in it for years. Testing with either method will tell you how precisely how much moisture is present, making it possible to choose a surface flooring that is appropriate. Should i use a 6 mil poly moisture barrier for engineered. Oct 23, 2015 laminate is a floating floor, and it needs to be unrestricted to properly expand and contract with temperature changes. I have read in some places that you need a vapour barrier to put over the concrete before installing the plywood and in other places to just glue the plywood to the. Installing a vapor barrier over a plywood subfloor will cause moisture to be trapped within the material which causes mold and mildew growth and can lead to warping of the laminate. Its hard to see, but i have indeed left an appropriate half inch expansion gap between the wood and the drywall. Jun 05, 2009 this video demonstrates how to install a moisture barrier over a concrete subfloor. Prepping a concrete subfloor for hardwood or laminate flooring. Cmvc can be applied to concrete with moisture vapor transmission rates as high as 25 lbs.
Subfloor coatings and toppings, concrete moisture barriers. New concrete is heavy with moisture, and it must be a minimum of 30 days old before moisture testing begins. It is vitally important to test your concrete slabs moisture before installing flooring over it. By restricting the planks ability to move, you can end up with damaged planks. Determining moisture content of both the wood flooring and the subfloor is an important part of quality control in the flooring installation process. It insulates and cushions the flooring, making it more comfortable to walk on. When installing certain types of flooring such as sheet vinyl the moisture content of the concrete can be a problem. Where plastic sheets must be joined, overlap the sheets by several inches, and use strong vinyl tape to secure them.
How to put down flooring on a cracked concrete slab home. Wood subfloor moisture posted on july 17, 20 by flooring professionals administrator in many of my weekly emails over the past few years, i have talked about concrete moisture, but rarely about moisture in wood subfloors and what can happen. Why underlayment matters to a tile installation project the. The concrete slab is the air barrier, and the ripped and torn and punctured polyethylene sheet is the vapor barrier. Crack isolation membrane the tile council of north america. Jul 17, 20 wood subfloor moisture posted on july 17, 20 by flooring professionals administrator in many of my weekly emails over the past few years, i have talked about concrete moisture, but rarely about moisture in wood subfloors and what can happen. Suited for interior and exterior substrates, redgard creates a continuous waterproof membrane barrier with outstanding adhesion and reduces crack transmission in tile and stone floors. Aug 27, 2010 moisture can come up through your subfloor, especially if you are installing over concrete or belowgrade. Theres a wide range of moisture barrier products on the market and various installation techniques. Does a floor above a first floor, basement or crawlspace have to be reinforced for concrete. Can i install underlayment under laminate with attached padding. Mver floor preparation s452 seal strong a two part moisture mitigation system designed to create a moisture barrier between concrete and resilient flooring suitable for use up to 100% rh or 25 lbs cacl. As per the directions, i applied it over the subfloor and about 2 up the walls. Tile is bonded with thinset to the surface of the membrane.
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