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Sid’s Tip

IN my role as an independent flooring expert I get consumers telling me that the installer fitted the floor, but never said a word and on completion gave no advice at all.

I have compiled a short list of how to avoid complaints: One of the biggest problems for a wood flooring professional (that’s not including Bob the builder) is dealing with customer complaints. Many complaints I see are about moisture-related problems, like gaps between boards, cupping or crowning. Most floorlayers can prevent the complaints, if they take proper precautions in installation and educate the customer about what

to expect.

To begin, it’s important to understand the basics of how wood interacts with moisture. Wood is hygroscopic, meaning that it gains and loses moisture as the relative humidity and temperature of the air around it changes. Depending on humidity, wood will reach equilibrium moisture content (EMC). As the EMC of the timber flooring decreases, the wood shrinks. But as the EMC increases, wood expands.

The effort to minimise moisture problems starts at the manufacturer, where most solid wood flooring for the UK is dried to a moisture content of 8-12% in most cases before being milled, engineered flooring a bit less. Until it is installed, the flooring should be stored in an enclosed, well-ventilated building that is clean and dry. Wood flooring should never be unloaded in wet weather.

On-site, avoiding moisture problems begins with installing the proper flooring. Solid products should never be installed in rooms exposed to excessive moisture, including any basement or under ground level. (Engineered wood floors are appropriate for these areas.) If drastic humidity changes are expected, choose species with above-average dimensional stability.

Before the flooring is delivered to site, the proper ty should be fully enclosed, with and windows in place; interior have been on for at least 48 hours. Wet trades such as painting and plastering should be completed and dried.
Once the interior is at normal living conditions, solid wood flooring should be set indoors and spread over the subfloor, allowing at least four days before starting installation.

Some manufacturers say more, some say less, so unless you have the required moisture meters follow the acclimatisation instructions.

(Engineered flooring manufacturers say no such acclimation time is necessar y.) Before beginning work, check the moisture content of the concrete slab and/or wood subfloor. For wood subfloors, check several different areas with a moisture meter and average out the results.

A moisture content of 12% or less is considered acceptable in most cases. The level must be within 4% of the moisture content of the flooring to be installed. For solid plank flooring, the level should be within 2%.
There is only one recognised standard in the UK for testing concrete: The hygrometer test. In good conditions you want 1mm per day up to 50mm when dr ying can take much longer.

Always check the wood flooring manufacturers’ recommendations for ‘acceptable relative humidity’.

Even if subfloors are within an acceptable range, that doesn’t mean moisture won’t seep from the ground into concrete and subfloors in future. That’s why it is imperative for the installer to use a moisture-vapour retarder, especially for solid wood flooring.

If it’s a concrete slab, apply an epoxy sur face dpm. In joist and floorboard construction with crawl space, always install a bitumen impregnated paper with joints overlapped, taped with water proof tape and lapped up walls. It should be laid between the wood subfloor and the wood flooring.

Whatever the method used, installers should verify acceptability with the flooring manufacturer. If gluing down over a moisture retarder, also check with the adhesive manufacturer for compatibility. I always recommend that you use one system. Don’t mix different manufacturers’ floor preparation materials.

After beginning the installation, you are strongly advised to follow nailing recommendations (available from the British Wood Flooring Association). (Installation manual). With wider flooring, fixing should be closer together.
Once the installation is complete and all the necessary precautions taken, your best chance of avoiding future problems is customer education. All your painstaking work to prevent moisture problems will go down the drain if the customer starts damp- mopping the floor once a week. And you’ll save yourself a headache in the winter if you tell them that small gaps may appear at that time of year and don’t worry; they will close up later in

the season.

Just as with the actual installation, it pays to be prepared. Other wise expect problems like those shown in the photo above, which was an installation by ‘Bob the builder’. But I hold out no hope for Bob, because he will never learn, but if you want to learn and even become a qualified apprentice check out the panel below on how to find courses offered by Flooring Assessments in association with the British Wood Flooring Association

T: 07841 500940

Interested in wood apprenticeships?
Speak to the British Wood Flooring Association?

Contact Dave Brown:


T: 01709 749062

M: 07515 885 912

Office T: 0114 360 1105

Flooring Assessments is an official CSkillsCAA apprenticeship provider in floorcovering level 2 & 3. Full funding is normally available in carpet, impervious and wood apprenticeships.

This article has been reproduced from the Contract Flooring Journal website. You can find them at