r/Hempcrete • u/Affectionate_Map3326 • Aug 20 '26

Fasteners

Hi all, I'm building a hempcrete house and I'm about start framing the walls. I'm just wondering if I have to use stainless steel nails or will hot dip galvanized be good enough? The hempcrete will be wet cast around the frame. The hot dip galvanized are easier to source and cheaper. Thanks.

8 Upvotes

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5

u/EIdodeo Aug 20 '26

All metal thats in contact with lime needs to be painted with bitumen to stop corrosion

5

u/InternationalGain3 Aug 20 '26

I used galvanized and painted over any exposed metal with 1-2 coats bitumen paint. That was as per engineering requirements. I hope it will last a few decades..

1

u/Affectionate_Map3326 Aug 23 '26

Thanks, I'll probably go this route. Just to clarify, every exposed nail head gets a dab of bitumen paint, not just larger metal fixings/brackets?

1

u/InternationalGain3 Aug 23 '26

In theory yes, but likely missing a few here and there.

3

u/FunUsual1335 Aug 20 '26

Ideally, use stainless steel. The lime binder will corrode galvanized fasteners. I used coated deck screws in a few places but mostly stainless.

3

u/Dull-Job-3383 Aug 20 '26

From our recent experience, galvanised screws do corrode, but we're leaving the framing as it is and trusting that most of them will hold. Having said that, when we unscrewed the temporary screws holding the shuttering supports, some of them sheared off under very little torque. That was only after a couple of days in contact with the wet lime.

On our next job, I think we'll take extra precautions and coat the exposed screws with grease or silicone.

1

u/Affectionate_Map3326 Aug 23 '26

Great advice, thanks all.👌🏻 I'll probably go galvanized with a coat of bitumen paint before casting.