Q: Please tell me about installing Cork flooring over a concrete slab (on grade).
I live in the Las Vegas NV area and want to know if any special preparation is
is required. I plan to use the cork flooring in bedrooms.
Does the concrete slab floor need to be sealed?
Do I need to use a plastic vapor barrier?
Are there downloadable directions and recommended adhesives listed on your website?
Thanks you,
Randy
A: The first thing to keep in mind with any installation over concrete is whether you will be gluing your floor down or installing it as a floating floor. Let’s go over some universal subfloor prep before we get into installation specific preparations.
Regardless of how you are going to install your floor there are 3 basic things your subfloor must be: clean, dry and flat. First on our list would be to clean your subfloor, standard vacuuming and sweeping should do fine, but if you have any over spray from painting your walls or drywall mud etc make sure that this is scrapped off of the concrete. Make sure your subfloor is dry before installation, any moisture on the subfloor can cause all sorts of trouble during the installation process, especially with a glue down installation. Finally, make sure the floor is level and flat. Keep in mind all concrete floors will have slight variation in height, but get a good level and make sure there are no excessive differences in the height of your subfloor. Usually a difference of 1/32″ over 10ft is acceptable and should have no impact on your installation. If you have more variation than 1/32″ look into a self leveling compound to level out the dips in your subfloor. Give this plenty of time to cure and dry.
Let’s get into a bit more detail based on the type of installation you perform and answer a few of your other questions. Do you need to seal a concrete slab before installation? I would not say you need to, but I like to play it safe when it comes to a new floor. Should you seal the concrete? Yes! Think of this as a bit of extra insurance on your floor.
For a floating installation you will need to use a plastic vapor barrier, then install your underlayment and flooring. With a floating installation you won’t need to do any additional sub floor preparation, but you will want to ensure you tape the seams of your moisture barrier well to form a solid seal. Keep in mind the cork you will be using here is an engineered plank – so get one with a really good locking mechanism. Both Westhollow and APC are my preference here as they use the Uniclic locking system, which is the best mechanism on the market.
For a glue down installation, you will want to ensure your subfloor is as level as possible and make sure no moisture is on the floor before you begin to spread your adhesive. With a glue down installation, the adhesive will act as a vapor barrier, so there is no need to use a plastic one. As far as the adhesive itself is concerned, I would suggest using a contact cement with Cork, rather than a troweled on adhesive. Fastbond 30 which is made by 3M is a pretty good choice here. The key to making sure a glue down installation of cork succeeds is to roll the floor with a 100lbs. roller every hour after the entire floor is laid. This will prevent the floor from peeling up, which occurs naturally with pre-finished cork tiles and with enforce the bond the adhesive forms.
For directions, I would visit the DIY section of our Floor Buyer’s Guide. This has several great tips about installing flooring. Beyond the DIY section, nearly all manufacturers include installation directions within boxes of their flooring or via their websites. Although at times these instructions can be poorly translated, they usually will give you the basics of what you need.
