How can I seal and damp-proof 19mm particle board flooring?

[Dimitri1]

Hi. What is the best way to treat and seal particle board flooring? I’ve removed old carpet that was damaged by mould and damp and I want to make sure that no moisture rises through the particle board flooring. I believe it’s yellow tongue 19mm board, nailed to joists on a concrete slab.

I plan on putting a vinyl or cork flooring directly onto the particle board for the final flooring material. But I want to treat the particle boards and seal them first.

Thanks in advance.

[MitchellMc]

Welcome to the Bunnings Workshop community @Dimitri1. It's sensational to have you join us, and many thanks for your question about sealing particle board flooring.

The best way to prevent moisture from rising through the particle board flooring is to resolve the moisture issue under it. By sealing it, you would only trap the moisture in the boards, causing them to deteriorate. If there is a moisture issue, it needs to be addressed at the cause to prevent damage to your subfloor and joists.

It would be difficult to find a product that would seal the particle board whilst allowing you adhesive for the vinyl or cork flooring to adhere to it, and I'm not aware of a product that's suitable for such purposes.

Do you know where the moisture is coming from? If you can tell us a little bit more about the issue, our member would be better placed to offer helpful advice.

Please let me know if you have any questions.

Mitchell
 

[Dimitri1]

Hi Mitchell. I haven't been able to locate the source of the moisture. There are stains on the particle board so I'll need to lift them to investigate the joists and concrete slab. The boards do feel stable at the stain areas, which look more like someone dropped tea or coffee directly onto the boards. But the stains a re too many for my liking.

Is there a way to determine if the stains are from rising damp without lifting the boards?

[EricL]

Hello @Dimitri1 

I'm afraid I know of no other way to detect the rising damp other than by removing the particle board. Once you've removed the board, you'll see the damage from the timber frame, they will often have a dark colour due to being damp. The presence of mould and mildew is also an indicator of heavy moisture being trapped under the floor. Timber deterioration will be the biggest sign of moisture damage.

If you need further assistance, please let us know.

Eric

[Dimitri1]

Thanks Eric. If I do have rising damp in the beams and concrete, what can I use to seal the concrete and beams once they've dried out? This is assuming that the beams haven't rotted through.

[EricL · Accepted solution]

Hi @Dimitri1 

I suggest using Dunlop 4L Damp-Proof Waterproofing. It's an acrylic brush-on membrane, and will prevent rising damp, efflorescence. It will also resist negative hydrostatic pressure. It has excellent adhesion to most substrates including brick, masonry, concrete block, concrete, stone and timber and is simple to apply with a brush or roller.

My number one tip is to make sure that the surface you are sealing over is totally free of mould and mildew.

If you have any other questions we can help with, please let me know.

Eric

[karen101]

Hi I too need to do this with my floor. Due to the damp smell of the underlay it has left a slight smell in the room or on the wood flooring and becomes noticeable when we have a damp cool day.  I can’t see any mildew or mold. Do I need to clean the floor down with anything before applying the sealant 

[EricL]

Hello @karen101 

Welcome to the Bunnings Workshop community. It's sensational to have you join us.

Putting the Dunlop 4L Damp-Proof Waterproofing over your flooring now will technically be a short-term solution. Your wood flooring is becoming damp due to condensation and moisture trapped under the floor. This is the first part of the problem you'll need to address first. Is water settling under the house? Is there any ventilation under the house? Any water under the house must be removed or diverted away when rain occurs. There must be enough ventilation under the house to allow evaporation to occur. 

Installing insulation and a moisture barrier will help divert the moisture away from your flooring.

Once these issues are addressed you can then replace your timber flooring with a new set.

If you need further assistance, please let us know.

Eric