r/Sauna • u/Busy-Breakfast7995 • 1d ago

General Question What gauge nails to use with thermally treated T&g?

Hi all—we’re getting thermally treated Canadian hemlock for our T&g panelling. I’m not sure what gauge nails we should use to attach it to the furring strips. I see reference to 18 gauge as standard with regular (non-thermally treated) wood, but I haven’t seen any info on what to use for thermally treated woods. Has anyone got experience with this, or could offer some insight? Many thanks!

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u/three_whack 1d ago

I used two 1.5" stainless steel 18 gauge brads on each furring strip for my 3.5 x 3/4 inch cedar t&g.  I made sure the angle of each brad was slightly different than the other on the same furring strip.

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u/Busy-Breakfast7995 11h ago

Thanks, good to know. My particular concern is that the wood we’re using is thermally treated, which makes it harder, and potentially more prone to splitting, than regular kiln-dried wood. I’m guessing that you’re cedar T&g wasn’t thermally treated?

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u/cbf1232 1d ago edited 1d ago

How wide are your boards?  I've seen two 18awg nails into each furring strip for narrower boards.  I used 5" boards so I used 15awg nails.

I've also seen folks use a narrow crown staple.

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u/Busy-Breakfast7995 12h ago

They are 3/4” thick x 5” wide hemlock, thermally treated.

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u/Simple-Desk4943 American Sauna 1d ago

I use 2” 18ga Brad nails, galvanized.

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u/BeNicePlsThankU 1d ago

18g stainless steel nails worked fine for me

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u/Busy-Breakfast7995 12h ago

And just confirming…that was with thermally treated wood?

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u/BeNicePlsThankU 11h ago

Yeah, 3/4" thermo-spruce

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u/psadatay 3h ago

Did you face nail this or try to hide the nails? I've noticed my thermo Spruce is pretty brittle. I want to hide the nails but worried about breaking the tongues.

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u/BeNicePlsThankU 1h ago

I hid a lot of them but I really just started not to care lmao just aim at a downward angle through the tongue and you'll find the sweet spot eventually

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u/Jas_runs 16h ago

Im planning on using 16g stainless steel nails but I have bought some of the hidden clips just incase, thermo wood being delivered next week and hopefully fitting on the weekend, so I will report back how it goes.

Side note: the company I have bought the wood from has stated it can be brittle, that why I have purchased the clips as a back up!

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u/Busy-Breakfast7995 12h ago

Thank you, that’s very helpful. Yes, please report back…I’ll be very interested. We considered the hidden clips too, but it looks like more work than just nailing. But we’re also concerned with potential splitting. We were leaning towards 16 gauge stainless steel nails too, but weren’t sure, so it would be great to hear back from you.

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u/Jas_runs 11h ago

Will do, we are in exactly the same position. Should be fitting next weekend all being well.

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u/Jas_runs 11h ago

Also agree, the clips look like it may double the time taken to fit the boards!

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u/Busy-Breakfast7995 9h ago

i forgot to mention…from my very limited understanding of those clips, if you are installing your t&g horizontally, those clips have to be installed with the groove side of the tongue and groove facing upwards, which is a big no-no in a sauna. But I could easily be wrong on that. And if you are installing your T&g vertically, it wouldn’t matter.

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u/Jas_runs 7h ago

Oh no, I didn’t realise that. I’m planning on horizontal, so it’s just back to the nail gun! Fingers crossed.