Sticking timber to steel

[george765]

I need to pack a 20mm gap where loft conversion floorboards pass over a 6" wide steel. The steel takes the position of the next joist so I need to support the floorboards at this point.
I had planned to simply glue a 20 x 150 piece of timber to the top of the steel. I could then screw the floorboards to this.
I am now wondering if a glue will be good enough to cope with all the expansion/retraction in a loft area that, at the moment, has no ventilation so get very hot/ very cold.
I don't have much experience of modern building adhesives so my question is.....will a glue, such as Gripfill be good enough or do I need to mechanically fix to the steel ?

 

[^woody^]

Glue and fit some straps to the joists or noggins in the web of the steel. The 25mm flexible banding that comes on a roll.

 

[Notch7]

A 150 board may cup which glue wouldnt hold.

If you do use timber, have it so the end grain is a smiley face not a frown -that way if it cups it will try and come up in the middle, rather than edges.

Or strap it as above.

Or just get some tek screws and screw it down -they have a drill end on them so you just drill through the timber and keep going until they wind themselves in.

 

[george765]

great advice thanks.
is there a better material I could use, i.e. one that doesn't 'cup' ?
total size to go on to top of steel is 2690 x 150 x 18

 

[noseall]

Foam. Plywood.

 

[Notch7]

great advice thanks.
is there a better material I could use, i.e. one that doesn't 'cup' ?
total size to go on to top of steel is 2690 x 150 x 18

Thinking about it, I would say stick on 2 separate strips of 50 x 25 (or to suit -some prepared stuff comes about 18) leaving a gap between

CT1 would give you a strong bond

 

[george765]

great, thanks again for advice