Fixing timber firring pieces to steel joists

[Modernista]

I'm using some existing steel rsj beams (already in position) to support a new roof deck to an existing garage comprising sawn parallel pieces / firrings of varying thickness to give a fall for a ply deck and I'm wondering how to fix the sawn timber to the steel? Perhaps some kind of metal strapping or cable ties wrapped tightly right round the steels? The whole roof deck will also have a good number of  L shaped metal holding down straps at the perimeter fixed to the brick walls (so less worried about the deck staying down). The ply will also be screwed to the firrings but I'll need some way of them staying in place before the ply deck is laid.  What about adhesive instead? The appearance underside isn't too important. Any suggestions welcome. Thanks.

Doc 03 Jun 2022, 3.41.pdf

 

 

[nod]

A self tapping tech screw 

 

[markc]

Or drill holes in steel and screw upwards with ordinary wood screws

[Gus Potter]

1 hour ago, markc said:

Or drill holes in steel and screw upwards with ordinary wood screws

Good solution Mark. +one

[Modernista]

Thanks both, will look into both those options. I guess I was trying to avoid all that drilling....

[saveasteading]

6 hours ago, nod said:

A self tapping tech screw

Designed for the job, and will cut and self-tap screw itself in one.

A wood screw might work fine but is a compromise.

 

Just be sure to get 'heavy' self tap screws that will go through an rsj, and get a few extra just in case any don't quite get through.

 

Hex head for maximum torque and certainty, or torx head if it has to countersink into the wood.

 

I look at these screws and all the complexity and wonder how we can buy them for 10p each.

 

[nod]

8 hours ago, Modernista said:

Thanks both, will look into both those options. I guess I was trying to avoid all that drilling....

Be sure to buy The bit at the same time I use these by the box 

They go through steel like butter No pilot hole needed 

[Modernista]

Thanks, they sounds ideal. Will give that a go. I seem to be behind the curve with fastener technology - I only discovered the brick screws you can get nowadays last year and given that our house renovation is entirely brick walls they've been brilliant too! These look like the equivalent for metal. Thanks all, much appreciated.

 

I think I will fix a consistent depth 47mm packing piece with these screws so I only need one length and then fix the variable depth firrings timber to timber on top.

[saveasteading]

13 hours ago, nod said:

They go through steel like butter

The good ones do. As for many such things, it is worth the extra for a known brand, other than an own-brand.

[nod]

12 hours ago, saveasteading said:

The good ones do. As for many such things, it is worth the extra for a known brand, other than an own-brand.

I always buy Techfast 

They never bend or snap

 

Its worth spending a five on a Techfast magnetic bit 

The  cheaper ones soon round

 

Edited June 5, 2022 by nod

[Modernista]

Thanks both, I'll do that