Attic Framing

[Ph505]

Hoping I can get a definitive answer from someone. My home was built in the 60’s and I am in the process of clearing out and reinsulating the attic. I will also be installed some decking for storage. The roof is stick framed with collar ties. It appears that at some point, there was a 2x4 at each gable end that was screwed to the ridge. It ran down to the joists and screwed to a 2x4 that was screwed to the joists. Someone cut the joists open to install pull-down access steps. They shortened the one 2x4 and screwed it down. I've attached a picture of what it currently looks like. Are these considered structural or were they only intended as a construction brace? They don’t really seem to be all that strong at this point. Also, can the rafter ties be raised? Would like a little more space when moving around up there.

 

[Snoonyb]

They are just a brace and if the roof is solid sheathing or sheated with plywood, you have a diaphragm shear.

 

[Ph505]

Not familiar with the term diaphragm shear. It does have plywood sheathing. Does that mean that it is structurally sound without the 2x4 brace? Hoping to remove it for floor space.

 

[Snoonyb]

In a wood framed, residential, dwelling, with plywood subfloor, the plywood and the method of installation create a diaphragm or platform shear, and the same exists for roof sheating. The shear is developed in the method of installation, IE, sheet layout and nailing.
And in that case the brace can be removed.

 

[Ph505]

Great. Thank you for the explanation.

 

[nealtw]

Not familiar with the term diaphragm shear. It does have plywood sheathing. Does that mean that it is structurally sound without the 2x4 brace? Hoping to remove it for floor space.

That is true with a few details to the rule.
It is true if the gable stud go all the way down to the next solid floor, balloon frame.
it is true if you have a solid floor or mostly a solid floor in the attic.
If the gable walls are joist nailed to the lower end walls or there is no floor, the angle brace is preventing the hinge point, bottom of gabble, by using the structure of the roof that was mentioned.