Reinforce roof truss

[nimhed]

If I am going to reinforce the last rafters on the gable by gluing and tightly screwing a board, is there any significant difference in reinforcement if I use construction plywood or OSB?

 

[anaitis]

Yes
Plywood is better

 

[nimhed]

Thanks for the answer!
I probably knew that plywood is better. But is it much better or marginally better?

 

[anaitis]

Much better

 

[Mikael_L]

And OSB has some kind of wax on it that makes the glue bond rather poorly, at least the OSB boards I have encountered.

If it's for cost reasons that OSB is being considered instead of K-plywood, I would personally choose non-K-plywood, but not OSB.
But honestly, K-plywood isn't that much more expensive either:
http://www.byggmax.com/se-sv/byggva...lan/plywood-osb/1005/konstruktionsplywood-p30

But not non-K-plywood for too important things then. On roof trusses, it seems a bit sketchy to use materials with unknown properties. :eek:

 

[Johan Gunverth]

And OSB has some kind of wax on it ...

They are made from wood, wax, and glue. The wax is therefore throughout the material.

 

[nimhed]

True! You shouldn't be penny wise and pound foolish.

 

[Mikael_L]

True! You shouldn't be penny-wise pound-foolish.

Yes, I personally prefer slightly less luxurious wallpaper over having uncertainties in the house's technical construction ...

But that's just me ...

 

[nimhed]

It ended up being plywood in the end. I thought I would be smart and bought these
http://www.biltema.se/sv/Bygg/Faste...t-galvaniserat/Universalskruv-traregel-87843/
Instead of using drywall screws (which rust in no time).

But am I missing something, or are they just bad screws? The tip is so dull that it's a pain to attach it and then it doesn't pull the board together with the beam.

 

[haavard]

Rule no. 1: Biltema's screws are cheaper than "regular" screws.
Rule no. 2: You get what you pay for.

 

[nimhed]

Well, maybe so. Or perhaps a reduced drill bit is not for me. Or I should have chosen a length of 51 instead of 32.

 

[Gabbe1]

Drywall screws work poorly if you want to create clamping force between plywood and rafters, the drywall screw will pull equally on the plywood as on the rafter. Chipboard screws, decking screws, or some other screws with a shank (without threads a bit under the head) work much better.
Regarding Biltema's screws, I have no experience with the ones you linked to, but generally, I am very satisfied with Biltema's screws, I have used them in two house constructions.

 

[nimhed]

The problem I had with these is that they never bit into the rule, I could just screw and screw and the screw just went round and round. I will try again to see if it was just me being tired on a Monday evening in the rain, or if the screws are faulty.

 

[MUSS]

Shouldn't the anchor screw work? Or will it also be too short?

 

[nimhed]

Shouldn't anchor screw work? Or does it also become too short?

It would definitely have worked. The head would have protruded a bit more. My comment about the length was more about it not clamping tightly and that a longer screw has a larger contact area. It should definitely be enough with 32 mm to screw in a 12 mm board.