Glue Down Wood Floor Installation:
Site Preparation for Engineered Wood Flooring

This section, is designed to answer the most common questions on glue down wood floor installation, as well as outline the steps necessary to prepare your room for this renovation. If you wish to nail it down, follow the instructions for installing a classic 3/4" solid wood floor.

This is not meant to replace a professional installer, but rather to help our customers understand the process and guide, those that wish to install the flooring themselves. Please read carefully all the information included with your flooring purchase, and follow the manufacturers recommendations!

Step 1. Preparing The Job Site for an Engineered Wood Floor

What subfloor is considered adequate?

As with standard 3/4" nail down flooring, The National Hardwood Flooring Association recommends a minimum of 5/8" tongue and groove plywood as a base. Aspenite or any other particle board product is not considered to be suitable substitute.

Many of these products can and are designed to be glued down to a concrete base. Check with the individual manufacture for guidance, and follow specific instructions for moisture barriers etc. Mirage, will warranty an engineered wood floor, glued to a concrete slab, as long as there are NOT any related moisture problems in the concrete, and their recommended hardwood floor adhesive are used in the installation.

Should I do anything to the subfloor before I install my Engineered flooring?

Both wood and concrete subfloors should be tested to see how level they are. Manufacturers typically require that your floor must be flat to within 3/16" in 10 feet. High spots must be sanded or ground down and low spots filled within an appropriate floor leveler (make sure it is given time to properly dry).

All old flooring must be removed, if it does not provide a solid gluing surface (or a new subfloor installed over top).... and the prepared surface must be clean for good glue adheasion.

Wood Subfloors:
It is essential that a wood subfloor be screwed down every 6" to the underlying floor joists. Once that has been completed, although it may seem kind of stupid, it is a good idea to jump around on every corner of the floor, to locate any remaining squeaks.

Add additional screws and reblock the floor from underneath in any areas that persist in being noisy. Don't let anyone convince you that squeaking can be solved by nailing or glueing a new floor on top. At that point, it is usually too late to solve the problem!

Concrete Floors:
A conrete floor must be free of grease, oil or dust. If it has been coated or painted, and you wish to glue your flooring directly onto the concrete, you may have to wash it with an acid to etch the concrete, prior to installation. This will improve the quality of adhesion, between the concrete, glue and floor. Ask your installer for advice!

All cement floors must be properly dried (typically 60 to 90 days old for new concrete) before considering any floor installation.

Test for moisture! Tape a 15" square of clear polethylene plastic to the concrete slap with moisture resistance tape, sealing the plastic around all four sides. Leave it for 24-48 hours. If no condensation collects under the film, then the slab is probably dry enough to install your floor. Test a number of different locations around the room and test it in the damp part of the year.

Use heat and fans to speed drying if necessary, on a new slab.

If this is an older home and moisture problems are present, DO NOT install wood flooring. The glue will not hold in most cases and the moisture will get into the wood and cause all kinds of problems

Below Grade vs At Grade Concrete Slabs
When a cement slab is located at ground level (at grade), you don't usually run into problems with moisture, once the slab has cured properly, and can easily glue this type of wood flooring directly onto the concrete.

BUT, with the traditional basement floor, that is lower than the surrounding land (below grade), drainage around the house becomes a key issue in determining whether you will have problems. A "wet basement" can exist "one time of the year" and not another, or "one year" and not the next..... so be sure that you are comfortable in saying you DON'T have moisture problems year round before you invest any dollars in any kind of wood floor.

Plywood laid over concrete on below grade applications:
If you wish to install a subfloor, over a concrete base, for insulation or to address minor moisture issues, please see these web sites from The Hardwood Council and Oak Flooring Association, for specific advice:

Can I use a glue down wood floor installation over radiant heat?

Yes, usually, but check with the individual manufacturer. Most Engineered floors are constructed in layers to make the product more dimensionally stable (relative to a solid wood floor). It can withstand minor fluctuations in temperature, caused by an infloor heating system. Ask First!

Recommendation: stay with the 2 9/16" wide flooring, avoiding wider planks.

Make sure your radient heat system has been operating for a number of days prior to installing your floor, so any residual moisture is removed..... check the moisture as suggested above.

The fact that it can be glued down, gives one a degree of comfort in not worrying about putting a nail through one of your pipes during installation..... but yet still ending up with a floor that looks exactly like a traditional 3/4" solid wood floor.

There are many different methods of installing radiant heat systems, both for new homes and to retrofit an older home. This is beyond the scope of this article, but let me say this: Most important is to have a system that works on water volume and low temperature (most new systems).

These low operating temperatures, go a long ways not to shock your floor and cause any buckling or cupping. You want a system that maintains a steady even water temperature with limited radical movement, and then you can glue down this floor, as you would under any other applications.

For more information try: The Hardwood Council
Tips on Installing Hardwood Flooring over Radiant Heat

I'm installing this flooring in a new house, are there any special issues here?

Follow the advice for a traditional wood floor, get your house to a reasonable humidity (ie under 55%). All engineered floor is made from natural wood fibres and will react to excessively high or low moisture levels. If you follow all these basic guidelines you should have no problem with your glue down wood floor installation.

Further Information:
Hardwood Floor Installation
Acclimatizing a Hardwood Floor