Moisture barrier for floorboards on slab

I've got a slab in my extension, and floorboards in the old part of my house. It was planned so I could place 35mm battens on the slab, then floorboards nailed directly to these, so the floor blends straight from old to new.

My question is do I need to put some sort of moisture barrier like a plastic sheet on the slab first? Once they are sanded and polished is there really any worry that water (eg in laundry/kitchen) will stagnate under and sit on the slab?

Also are 70 x 35mm pine battens suitable, or someone recommend something else?

Cheers

G'day.
Yes. Always cover the slab. No matter how old it is. Good quality plastic sheet with good quality tape for the joins. Run the plastic 75mm up the wall as well.

Hardwood T&G should have hardwood battens.

But a lot of installers use pine.

Remember to Glue and nail.

Thanks heaps. I'll be using baltic pine to match the old part of the house... any general sort of construction glue do?

Forget Construction adhesive.

You are installing a floor. Use flooring adhesive.
Use Bostik Ultraset or Sika T55J.

Ok thanks. Makes me a bit worried not that the carpenters just used construction adhesive and nails for the yellow tongue upstairs, but I guess that's a whole different story.


Thanks a lot for the help!

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Originally Posted by glock40sw

Forget Construction adhesive.

You are installing a floor. Use flooring adhesive.
Use Bostik Ultraset or Sika T55J.

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I had some tongue and groove flooring laid in my house by a carpenter relative... Suffice to say that since it was laid it sounds like you are walking on chip packets unless you walk directly on the joists! :((:((It was laid using liquid nails and nailed.

It is 9 metresX 3 metres, with the floor boards running along the 3 metres. He didn't put in a gap at each end for expansion. I ripped up the 2 end boards, but it made no difference.

I will probably rip it up and re-do it myself, but am interested in reasons which caused it...

Quote:

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Originally Posted by AV Elec

I had some tongue and groove flooring laid in my house by a carpenter relative... Suffice to say that since it was laid it sounds like you are walking on chip packets unless you walk directly on the joists! :((:((It was laid using liquid nails and nailed.

It is 9 metresX 3 metres, with the floor boards running along the 3 metres. He didn't put in a gap at each end for expansion. I ripped up the 2 end boards, but it made no difference.

I will probably rip it up and re-do it myself, but am interested in reasons which caused it...

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G'day.
Were the joists at 450mm centres?
Was it secret nailed?

Did he use nails or staples if secret nailed?

Can you get under the floor?

If you can get under the floor, you can pump adhesive between the boards and the joists if the boards have warping grooves on the bottom face. You can also glue and nail up from the bottom, as false joists between the existing joists.
go to www.timber.net.au and download the flooring data sheets. they explain all the above.

Quote:

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Originally Posted by glock40sw

G'day.
Were the joists at 450mm centres?
Was it secret nailed?

Did he use nails or staples if secret nailed?

Can you get under the floor?

If you can get under the floor, you can pump adhesive between the boards and the joists if the boards have warping grooves on the bottom face. You can also glue and nail up from the bottom, as false joists between the existing joists.
go to www.timber.net.au and download the flooring data sheets. they explain all the above.

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• He ripped up the existing yellow tongue and replaced it with floor boards.
• The joists are at 450 centres
• I can get under 90% of the floor with perfect access. The last 10% is acheivable, although a bit tricky
• It was polyurethane coated approx 6 months after laying

It has made this sound since the day it was laid. That is 2 years ago:(

I have thought of screwing in false joists. Might try a section to see if it fixes it.

I have a feeling some of the joists were not level, and he tried to fill gaps with liquid nails :((. I will look into it further tomorrow. I had just resigned myself to ripping it up to start again...

Would appreciate more info on "warping grooves on the bottom face"

G'day Warping grooves are grooves machined into the bottom face of T&G boards. We use 1/2 moon grooves. Boral use a rectangular groove. Other manufacturers use a variety.

Download the data sheets and all will be become clearer.

Just make sure the slab has some grade to let any moisture run off.

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Originally Posted by DvdHntr

Just make sure the slab has some grade to let any moisture run off.

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Ummm...No. The slab should be as level as possible.
When we say Moisture, we are not meaning water. We are meaning moisture that is associated with climate variation and air bourne moisture.
If actual water gets under the floor, there is a huge problem outside the dwelling.

Quote:

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Originally Posted by glock40sw

Ummm...No. The slab should be as level as possible.
When we say Moisture, we are not meaning water. We are meaning moisture that is associated with climate variation and air bourne moisture.
If actual water gets under the floor, there is a huge problem outside the dwelling.

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Sorry, I didn't read the topic properly, just saw moisture and concrete. I assumed that the moisture would pool and rot away the timber.

Hey Glock, do you guys have Moistop barrier here in Aus?

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Originally Posted by Eli

Hey Glock, do you guys have Moistop barrier here in Aus?

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G'day.
No Idea.

Ask one of the floories. I only make the Hardwood T&G flooring :2tsup::2tsup::D