What direction to lay cement underlay and vinyl self adhesive flooring?

[Ambrosia]

I am working out my shopping list to install new bathroom flooring. Currently it has yellow tongue subfloor (previously covered by looselay vinyl sheet). I want to install cement sheet underlay over the subfloor, then prime, then use self-adhesive vinyl planks.

What direction should the cement sheet and planks be layed? What transition strip do I install at the doorway? What type of floor waste/grate do I need as before the vinyl covered the pipe?

 

 

 

[JacobZ]

Hi @Ambrosia,

Welcome to the Bunnings Workshop community, it is wonderful to have you with us.

I'll start by mentioning that you are working in a bathroom, which, under the National Construction Code (NCC), specifically Part 10.2 Wet area waterproofing, is classified as a wet area, which will require a waterproofing system. As you have a timber floor, Part 10.2.3 stipulates that you will be required to fully waterproof the floor.

With the inclusion of a floor waste and the requirement for the floor to be waterproof, this will have to be tied into this waterproofing system using a puddle flange. This will require the assistance of a plumber and licensed waterproofer to ensure the installation is compliant with the NCC and relevant standards. Puddle flanges will often come with a grate, which should be used in conjunction with them.

With this being said, you would typically run your Tile Underlay so that the joins do not line up with the Yellowtongue beneath. In your situation, you'd need 3 sheets and this is the layout I would use.

You would then lay your vinyl plank flooring perpendicular to this. As a general rule, floorboards should run perpendicular to the main doorway - that is, they should point in the direction you enter the room rather than lying side to side. This layout gives the best visual flow and makes the room appear longer and more cohesive when you walk in.

The transition strip would be relevant to the height change from the outside floor to the bathroom. Where there are differences in floor height, transition ramp trims are common.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[Ambrosia]

Thanks JacobZ,

Will the Gerflor self adhesive vinyl planks stick to waterproof membrane? It is Gripset Betta Under Tile Membrane.

[JacobZ]

Hi @Ambrosia,

You'll have to let me double-check with Gerflor's technical team when they reopen tomorrow.

If they are marketed as being usable in wet areas, then I imagine it should be fine, but I would like to double-check if there is a specific method that they would recommend.

Please bear with me, I will get back to you as soon as possible.
 

Jacob

[JacobZ]

Hi @Ambrosia,

I've gotten in touch with Gerflor's customer support, who are passing the questions through to their technical team.

Hopefully, they will get back to me shortly with an answer.

Jacob

[JacobZ · Accepted solution]

Hi @Ambrosia,

I've received the following response from Gerflor's team.

"We do not recommend installing over yellow tongue subfloor (chipboard). For wet areas, our recommendation is to install a cement sheet on top of the yellow tongue subfloor before proceeding with the flooring installation.

We also don't recommend installing the planks directly over the waterproof membrane. A feather finish should be applied on top of the membrane to achieve a smooth surface, followed by a primer before installing the planks.

While the installation method you've described could potentially work, please be aware that it would fall outside of our warranty coverage due to the yellow tongue subfloor base."

Unfortunately, due to the chipboard flooring, any installation in this area would not be covered by Gerflor's warranty. If you were to do it, attaching your fibre cement sheeting, waterproofing, applying a levelling compound, then priming and attaching your flooring should work, but it would not be covered by their warranty.

If this is not an option for you, you might have to look at a different flooring type, like tiles.

Let me know if you have further questions.

Jacob