How to lay engineered floorboards over particleboard?

[joe19]

I have around a 10sqm area that I am looking to lay engineered floorboards in. The boards did not come with manufacturer instructions for laying, as I acquired them from another DIYer with surplus stock (and the manufacturer has not responded to me).

Below are two photos: 1) The particleboard and a cross section of it (this is from a section to access services but will be covered). You can see the underside of the engineered timber on the left of this photo. 2) The engineered boards.

I am looking for advice on a few areas:

1. The area is relatively level but for any areas that need further levelling I plan to either sand back or use self levelling compound. I understand the latter may be better but would appreciate any advice on this.

2. What is the recommended method for laying engineered timber on particle board? I have heard that nails are not recommended because they don't stay in particleboard. I would prefer to use a floor adhesive if possible.

3. Is an underlay required if a floor adhesive such as Sika or Bostik is used? It's on the ground level so noise absorption is not a big concern.

4. Is there a recommended glue for the grooves?

Have I missed anything else?

Thanks very much in advance.

[JacobZ]

Hi @joe19,

A warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.

1. For any minor high spots, sanding is a perfectly acceptable approach. For any dips or low areas, you will have to use Dunlop Timber Floor Level Flex Kit as it is the only self-levelling compound that I'm aware of that can be used over timber floors.
    
2. You're right that nails are not recommended for particleboard, as they can easily loosen over time. A high-quality flexible adhesive, like SikaBond T55 or Bostik Ultraset, will give you a solid and durable bond. These adhesives are designed specifically for timber flooring and will accommodate any minor movement in the substrate. Just make sure to follow the adhesive manufacturer's guidelines on notched trowel size and working time for the best results.
    
3. Underlay is not required and should not be used. Underlay is designed for floating floors and placing it under glued boards would interfere with the adhesive's bond. 
    
4. For the tongue and groove joints, using a PVA-based wood glue can help create a tight fit and reduce the chances of creaking down the track. This Gorilla Wood Glue would be suitable. Apply the glue sparingly to the groove and clean up any excess immediately to avoid staining the board surface.

Make sure to acclimatise the floorboards in the room for a couple of days prior to installation, as this helps prevent movement after they're laid. 

Also, leave a 10–12mm expansion gap around all walls and fixed structures, which can later be covered with skirting or scotia.

Allow me to tag @Dave-1 and @Nailbag to see if they have any other insights they can offer.

Let me know what you think.

Jacob

[Dave-1]

Good Afternoon @joe19 

I really cant add more to @JacobZ 's instructions. I did learn something new and that was about underlay should not be used in this type of situation  

I would measure out where the access point is for the service hole is and file it away if ever needed (take a photo of the measurements) as its always handy to have some reference point to start from if needed.

Dave

[Nailbag]

Hi @joe19 

All the stepped out advice by @JacobZ is spot on. But just to confirm the boards you have as it "engineered" floor boards vs "floating" are often referred to incorrectly. If you have boards a min 10mm or more then yes they are engineered and follow @JacobZ directions. If they are more like 6-8mm then they will most likely be floating and a foam underlay will be required.

When using self-levelling compound, first mark out the low lying areas with chalk. A long trusted straight edge will help you work this out. Pour the compound centrally and allow it to spread. Less is better than more in the pour. Use a Bricky's float to feather out the edges. Follow the mixing instructions exactly and bear in mind it goes off quickly!!!

Nailbag

[joe19]

Thanks very much @JacobZ, @Dave-1 and @Nailbag! Appreciate the quick advice. Confirming they are engineered timber. I will be having a go at the project soon and will reach out if I have any follow up questions.

Thanks again.

[Nailbag]

Hi @joe19 

Throw in the Google machine "how to lay engineered floorboards over old yellow tongue Australia". These videos will give you some great learns to make the job a little easier.

Regards Nailbag