Bracing against horizontal (racking) forces - some basic questions

[walker]

I'm trying to read up on the fundamentals of bracing to resist horizontal forces (racking forces), before we get started with our build (the house is to be stick-built)

I've a few fundamental questions I can't find answers to, which I'm hoping someone can help me with:

1. The guidelines I've been reading always seem to talk about using sheet flooring (such as plywood or particle board) as the basis for bracing horizontal diaphragms (i.e. ceilings and floor surfaces). Do floorboards (laid directly on to the joists) provide a similar degree of horizontal bracing? Or are they significantly weaker than sheet flooring?

2. Due to sensitivity to formaldehyde found in plywood and particle board we're trying to avoid it's use in our home. The home will be in a cyclone area, however, so its looking like a lot of plywood bracing for the stud walls is the usual prescription. Are there other alternatives? Can anywhere near the same bracing be achieved with metal strap, for example?

[Don_P]

Go to the old way before we had plywood... diagonal sheathing. A triangle cannot change shape, use the boards to create triangles, which is all the plywood is doing.

The need for bracing does not stop at the floor, it stops at, or rather in, the ground. The foundation is, or should be part of the braced structure.

[rick91351]

Go to the old way before we had plywood... diagonal sheathing. A triangle cannot change shape, use the boards to create triangles, which is all the plywood is doing.

The need for bracing does not stop at the floor, it stops at, or rather in, the ground. The foundation is, or should be part of the braced structure.

Thanks for posting that Don_P there is a lot said there in concerning how and why....

[walker]

Go to the old way before we had plywood... diagonal sheathing. A triangle cannot change shape, use the boards to create triangles, which is all the plywood is doing.

The need for bracing does not stop at the floor, it stops at, or rather in, the ground. The foundation is, or should be part of the braced structure.

Yes, thank you Don! We'll certainly be making sure the foundations deliver appropriate support and bracing for the rest of the house.

Back to the floor diaphragm....What about T&G floorboards? Can they be laid perpendicular to the joists and provide anywhere near the same bracing as sheet flooring? Or do they really need to be laid diagonally too?

[Don_P]

They don't provide the same bracing but it is not required on a floor. I've laid 2x T&G without a subfloor, with 1x I've gone over diagonal subfloor boards as an alternative to ply before but code does still allow single ply T&G laid perpendicular to the joists as a single layer floor... this is where end matching, end T&G, on flooring originated. I can't say I care for it, it is significantly weaker in every way, old code that has stayed in as a minimum.