How To Stop Sub-Floor Moisture From Damaging Your New Wood Floor

This is one of the biggest questions for people spending a small fortune on a new wood floor and rightly so! Who wants to throw their money down the drain?! Believe me, many have and many will. By finding this article, you may have just saved yourself future heart ache and misery. Read on to get the answer you want..

I want to start by letting you know exactly what the solution you are going to be given is referring to. That is to stop moisture from concrete or solid sub-floors damaging your new wood floor.

It’s said that death and taxes are the only things guaranteed in life. Well, I’d like to add ‘wood floors will fail if left in close contact with excessive moisture’ to that guarantee. My little add on isn’t quite as catchy but true all the same.

So you want to install a wood floor on top of your concrete or solid floor and have either found out it’s wet, believe it’s wet or are unsure.

Well in this game, taking a chance won’t double your money. You’ll either get away with fitting your floor without failure or you won’t!

How to test for sub-floor moisture in a solid sub-floor

The most accurate and only method currently excepted by British Standards under British Codes of Practice BS 8203, BS 5325 and BS 8201 to test for moisture in concrete sub-floors, is with the use of a hygrometer humidity box or RH probe. These instruments, used in conjunction with a relative humidity reader, measures the rate of evaporation of moisture from the concrete slab. If a reading of 75.01% relative humidity or over is recorded, a wood floor of any kind should not be installed without further preparation!! Regardless, of the fact you may be using an underlay with a moisture barrier. These types of underlays are only good up to a relative humidity of 75%..

But I came here for a solution?

Well, I will not disappoint! Concrete slabs can take months and even years to dry in certain circumstances. To say a concrete slab is dry just by looking at it or even going from the time it was installed and using rule of thumb guidelines, is just not good enough. A concrete slab can look perfectly dry, however, moisture evaporation from the core is very rarely visible! Take heed..

Concrete slabs often have a moisture barrier or insulation installed underneath. This helps prevent the concrete slab from taking on moisture when water levels increase. In houses built before 1960, ground floor concrete slabs were not required to have this additional moisture barrier. So, whether you wish to hurry up the installation process after a new concrete slab has been installed, have an older property without a foundation moisture barrier or are simply just not sure and require a cast iron guarantee, you’ll need the right products to do it!

Ardex 1 Coat Damp Proof MembraneThe solution is to use Adrex 1 C (coat) Damp Proof Membrane (DPM) in conjunction with Ardex NA latex based self levelling compound.

Ardex 1 C can be used on concrete slabs with a relative moisture content of up to 98%!! It can even be used on concrete slabs that don’t have a moisture barrier installed under the slab.

This type of liquid DPM doesn’t trap the moisture within the concrete slab (In the case of post 1960’s slabs with a sheet dpm installed) . In effect, it actually lowers the rate of evaporation so the slab can still dry but not effect your new wood floor. Ardex 1 Coat and Ardex NA are both fast drying solutions, that will enable you to install your wood floor within a week of installing the DPM and Ardex NA (Confirmed by Ardex).

Ardex logoSometimes in life, things can sound to good to be true. However, Ardex as a company have been around for over 50 years and stand by all their promises using the wealth of experience they’ve gained in the industry.

You wanted a solution and here it is. It’s now up to you to take on board all the guidance given by Ardex when installing their products and have complete peace of mind that your new wood floor will be down problem free for years to come.

Caution : Ardex DPM 1C is not recommended on slabs subject to hydrostatic pressure. In most cases, properties are built in a way that prevents the build up of pressure i.e. with adequate drainage, property situation etc. However, hydrostatic pressure may well be a concern for consideration i.e. basement excavations/renovations or local geographical changes etc. If in any doubt, contact ‘Ardex technical’.

Of course, there are other solutions available than Ardex. Take a look at other liquid Dpm options here..

© Copyright 2013 Wes, All rights Reserved. Written For: Fitmywoodfloor

I am a Pergo trained professional installer of 20 years. I've been up close and personal with lots of floors and have the knobbly knees to show for it...Should you have any questions or comments please feel free to add them below. Thanks for taking the time to call by and I hope the information you've found has given you some insight!........................................................................................................................................................................“When you click on links to various merchants on this site and make a purchase, this can result in the site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network,,,,,,, affiliate window network.” This statement is to comply with current internet regulations regarding transparency to consumers.

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