joists

[mmzz]

does glueing and screwing a length of 2x2 on top of a 6x2 joist make the equivelant of a 6x2? What if the 2x2 was at right angles to the 4x2?

[dom]

Gluing and screwing to build up the height of a joist does not give you the same strength as if the full height was one piece of timber. Beams can be built up as glulams, but only with very carefuly controlled design and construction. If you're working to an engineers specification for joist dimensions, it's very important that the joist used is the one specified. If however you're looking at building up a single joist where all the others are correct, and it doesn't have a key role to play for some other reason, it may be ok.

[Vass]

you mean 2x2 on top of a 4x2 ?

[Phil L]

No, except in size.

I've no idea what you are talking about? - do you mean to cross batten it with 2X2's?

[mmzz]

[meow2222]

Assuming you mean 2x2 + 4x2 then if it were perfectly fixed, yes. In practice glue and screw every 6" gets you closeish to this.

no, not even close.

NT

[Darryl Bailie]

Unless the connection is designed to adequately transfer the shear through the joint then no.

As a guide, if you were to put 2 3x2s on top of each other this would be half as strong as a 6x2 and 4 times bendier.

[meow2222]

in normal household use, glue and screw does do this. If you pushed the wood right to its limit it might not, but that does not occur under any normal household circumstances.

if they werent connected, yes. But I think the idea is that they are.

NT