Larch and fixings.

[Ollie78]

I have to build a large car port. I will be using 140mm square dried larch beams for the posts and main beams.
The supplier says on their website to use stainless fixings due to the high tanins in larch.
The legs will be on steel blade style bases chemical anchored into the slab.

I will be using large timber construction screws to join the posts to the beams (through the birds mouth's) . And for the trim boards etc.
The price for stainless Timco index in stainless is crazy, but they do green coated ones in the same size for much cheaper.
Would these be OK or should I bite the bullet and go stainless. Or does anyone know a different ideal fixing for this ?

Also will be using joist hangers and sheradised twist nails for the joists, will these be fine as well or will they stain.?

Ollie

 

[Jake]

I wouldn't use painted ones in high tannin wood. I put a deck/path down about 15 year ago in some cheap oak I came by and due to some changes to the garden it came back up this year. Some of the fixings were concrete screws which I could only find in the coated finish steel. The paint was long gone and the screws were very rusty, probably had another 10 years in them holding planks in place but not good enough for structural use in a construction built to last for me at least. I'd bite the bullet and go for A4 stainless for the screws. The best place I've found for these sorts of specialist fixings is Swiftfix - big selection and pretty reasonable pricing.

 

[Ollie78]

I wouldn't use painted ones in high tannin wood. I put a deck/path down about 15 year ago in some cheap oak I came by and due to some changes to the garden it came back up this year. Some of the fixings were concrete screws which I could only find in the coated finish steel. The paint was long gone and the screws were very rusty, probably had another 10 years in them holding planks in place but not good enough for structural use in a construction built to last for me at least. I'd bite the bullet and go for A4 stainless for the screws. The best place I've found for these sorts of specialist fixings is Swiftfix - big selection and pretty reasonable pricing.

I was afraid this would be the case !
I think the timco ones have some kind of ceramic coating which they claim has been salt spray tested etc.
I have been fairly impressed with the deck tite coated screws I used on my fencing, no rust yet. But as it is a more structural situation looks like I will spend the money.

There was some 150mm stainless quite cheap on ebay but not sure long enough even if I counter bore by 50mm.

I will look at your supplier recommendation.

Thanks

Ollie