Which screws for hardwood beams?

[NeilScotland]

Hi All,

 

im fitting a deck in my garden. I’m using hardwood beams (Azobe, 4.5 x 7cm). 
 

I have some stainless steel torx head fasteners. They just snap. Even with pre drilling. So I tried just a general purpose cross head screw - also snapped (and with pre-drilling)….. it seems to be when it gets towards the center of the beam (approx 1cm in). 
 

I also tried using my drill to drive the screws vs impact driver. Same result. 
 

so - I think I just have the wrong screws. Can anyone recommend some stainless steel screws that would work well here?

 

thanks.
Neil 

Edited June 4, 2021 by NeilScotland

[Mr Punter]

Spax seem pretty good. https://www.spax.com/uk/projects/outdoor/decking/

 

If this is to screw the boards down, drill a full diameter hole through the board and a slightly smaller one into the joist the depth of screw embedment.

[Conor]

Look for structural timber screws. Almost like coach bolts but partially threaded. Usually 8mm hex head.