Is nogging really necessary for studs? 2

[Escher]

Timber studs in Australia (& many countries ofthe world) are required to have nogging (dwangs) between studs at about 4'6" (1.35m) centres vertically. Their function is often debated. Is it needed to stiffen the wall against a concentrated load, to fix the wall lining, to prevent the studs from twisting or to provide restraint against buckling in the stud's weak direction when it is in compression?

If a loadbearing stud wall is lined both sides does it need to be nogged? Does it depend on the lining material?

If it is lined on one side (as in brick veneer construction) does it need to be nogged?

If the noggings could be eliminated or reduced then that would facilitate services installation and speed up construction but lining would have to be added before heavy weight roofs are installed.

 

[UcfSE]

Is "nogging" what we in the US would call blocking?

 

[boo1]

Typical blocking in residential wood stud walls provides:
Shear transfer for sheathing, stability for wood studs, and nailing surfaces. The external sheathing, and internal wall covering typically provide adequate stud support. For walls 10 ft and greater we block at 4' OC min. tto prevent twisting of the studs.

Cheers

 

[UcfSE]

The blocking will also provide a fire stop to keep flames from running up the stud cavity very quickly.

In the US, the code we use, the National Design Specification, gives some guidelines on the use of blocking or sheathing material for stud stability. Basically there are some assumptions and requirements that have to be met to ensure stability is provided and so on. As boo1 mentions, blocking may also be used for the shearwall sheathing to increase shear capacity.

Typically we use blocking as standard and then it doesn't matter what the sheathing details are (for stud design) plus there are often code requirements for blocking to provide a fire stop. If it has to be there anyway you may as well use it.

 

[Escher]

Nogging is the English word for small pieces of timber (wood)inserted horizontally between studs. In Scotland they are called Dwangs and from your replies I believe you call them blocking in the USA. In Australia we also have short timbers called blocking used in other parts of timber framing but the term nogging is normally used with studwork.

In North America are your external walls always sheathed with a structural sheeting? In Australia many houses are clad with a single skin of bricks and attached with metal ties at 2' centres (centers)to the stud frame - called brick veneer. There is usually only an aluminium paper on the outside of the studs and sometimes with a non-rigid insulating batt (blanket). So there is no structural restraint to the outside of the studs as you would get from plywood, OSB or the like.

Fire control has not been an issue in detached (houses spaced some 10' apart) house construction.

Do you have a similar construction method to brick veneer in the USA?

 

[UcfSE]

In the US it is common to have some sort of sheathing material on the exterior face of the studs. It is normally either plywood, OSB or exterior gypsum board. Even with a brick veneer there is some sheathing on the outside, at least in all the cases I've come across. Most of the major brands of exterior gypsum board that I've encountered have been load tested for out-of-plane loads and some for in-plane loads and it used to transfer the wind pressures to the studs.

In Florida where I'm from, we have fairly high wind loading and therefore the wall studs we design have to be braced well for moment capacity, so we're used to seeing nogging (I learned something ) in our details. There is a rationale available for using the sheathing to brace studs. You just have to follow the proper referenced code if it is available or another code if permissible. In the US this is the NDS for wood or our AISI specification for metal studs. The concept is making sure that the sheathing and connections of the sheathing to the stud are adequate. Even with the codified methods we have, some of the assumptions required are based on rules of thumb and not solid rigorous engineering or testing.