Hi Team, Im replacing a subfloor in my bathroom and getting conflicting info in what i should be using. Ill list my project below * 1950s house with floorboards and on stumps. * Have removed the floorboards and repaired the joists etc * Need to add new sub floor to get it ready for new floor covering, thinking vinyl, probs not going to be tiles. Questions I have * What subfloor am i using to begin with? Plywood, cement sheeting, yellow tongue? Have had lots of conflicting information. * Do i need to lay another layer over the intial subfloor? Been told to use ply or cement sheeting for this, and also not needed. Been told this is for strength. * After this theres water proofing and final covering, probs vinyl in my case. Is this correct? Im getting trades to do some of this, but will do evrything I can myself. I would love some help with this please! Any other information and tips would be great. Thanks

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What material to use for new bathroom subfloor?

Hi Team,

Im replacing a subfloor in my bathroom and getting conflicting info in what i should be using. Ill list my project below

1950s house with floorboards and on stumps.
Have removed the floorboards and repaired the joists etc
Need to add new sub floor to get it ready for new floor covering, thinking vinyl, probs not going to be tiles.

Questions I have

What subfloor am i using to begin with? Plywood, cement sheeting, yellow tongue? Have had lots of conflicting information.
Do i need to lay another layer over the intial subfloor? Been told to use ply or cement sheeting for this, and also not needed. Been told this is for strength.
After this theres water proofing and final covering, probs vinyl in my case. Is this correct?

Im getting trades to do some of this, but will do evrything I can myself.

I would love some help with this please! Any other information and tips would be great.

Thanks

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chriscam82

fiber cement sheeting is your best bet for any wet area its just very very heavy so prepare to have someone help

then you will need to

waterproof

lay screed

waterproof again

then tile

MitchellMc

Welcome to the Bunnings Workshop community @Garen. It's brilliant to have you join us, and many thanks for your question about bathroom subfloors.

As @chriscam82 mentioned, the standard modern approach would be to use Hardie's Secura compressed cement flooring. It will be laid directly onto the existing joists, though some changes/additions might be needed to accommodate them. Here's the installation guide.

You could use Hybrid Vinyl in non-wet areas, though vinyl sheeting is not an approved flooring for a bathroom.

Here's another useful guide: How to plan a bathroom renovation.

Please let us know if you have any questions.

Mitchell

MartinM

Hi @MitchellMc, I'm in a similar project, but I already removed all wall and subfloor.

From your answer I understand cement flooring (Hardie's Secura) will be the recommended way to go. A few more questions:

1) is it recommended to tile directly over Secura sheet or is better to add in a tile underlay or mortar/cement mix?

2) for wall, is it better to go with Aquacheck (or similar) or Hardie's Villaboard?

Thanks!

Martin

JacobZ

Hi @MartinM,

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

As per the Hardie Secura Flooring Installation Guide, it is possible to tile directly over Secura Sheet without a mortar bed or underlay, but you'd need to ensure that the recommendations for control joints are followed. Essentially, what this means is that your tiles cannot sit directly across the control joints; the gaps between the tiles need to follow along this control joint and be sealed with a suitable flexible sealant to ensure that the tiles move with the movement of the flooring. With a floating mortar bed, the tiles do not need to be laid out according to your control joints in the same way.

There's a little bit to it, but the installation guide has everything you'll need to understand. Have a read and let me know if there is anything you require clarification on, and if there is anything specific about your scenario that you are not sure about, please let me know so I can assist further or reach out to James Hardie for their assistance.

For your walls, either Aquachek or Villaboard can be used in a wet area, so it really comes down to personal preference and your budget. In saying this, Villaboard is the option that most bathroom renovators and builders that I have met tend to use.

Let me know if you have any further questions.

Jacob

Garen

Thanks Mitchell,

I did a bit of reading on the installating and sounds easy enough. Just to clarify, the boards are layed directly on the joists, and it says there is no need for water proofing other than the shower. Is this correct? If so that saves some time and work!

Thanks

MitchellMc

I believe the full excerpt @Garen, would be: In addition to these benefits, when using Hardie™ Secura™ Flooring or Hardie™ Panel Compressed Sheet, full floor waterproofing is not required outside the enclosed shower area (unless a floor waste is specified by the NCC.

If you have an enclosed wet-area shower recess and no floor drain outside it, no waterproofing is required. Always best to check with your waterproofer, though, to ensure that complies with regulations in your application and area.

Mitchell

MartinM

Thanks @JacobZ.

Another question... my bathroom floor dims are 1900mm x 1800mm. (beans run over the 1800 side). I was plannig to cut 3x 2400mm board to the 1900 lenght and lay them side by side. However, the installation guide recommend to use a staggered pattern. It sound to me this is applicable for larger areas where more than 1 sheed is neede per row. In my case to make a staggered pattern, it will mean I use 2x1900mm board on the sides and then 2x950mm pieces in the middle...which doesn't make a lot of sense to me.

What do you think I should do?

Thanks,

Martin

MitchellMc

Hi @MartinM,

Yes, that's only for larger bathrooms, so you don't end up with a continuous non-tongue join across the floor. If the sheets can span the entire length, they can sit side by side. I've double-checked this with the Hardie's Technical team, just to be sure.

Mitchell

MartinM

Thanks @MitchellMc !

Another question... I just realised that the floor waste (and the future puddle flange), sit right in the union of two of the FC sheets. Is that a no-go? Should I need to look into relocating the waste? or is that ok?

Thanks,

Martin

MitchellMc

So, initially, if you can, it would be best to relocate it at least 100mm in from the edge of a sheet @MartinM. If that's not possible, then you can get away with having the penetration on the joint, but by having the holes there, the concern is that the tongue is no longer supporting the joint. To get around this, you can box up around the penetrations so the joint is supported on both sides. These timbers obviously need to be tied back into the floor joist with a structural connection. I've created the below rendering for you to illustrate.

Mitchell

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