So, they didn't nog out..

[AronSearle]

Heat causes materials to expand/warp/ or otherwise react.

Why are they not specified in conjunction with metal web floor joists?

Lack of joined up thinking.

Where a single layer of plasterboard is to be used, most plasterboard manufacturers will say they need to be nogged where fire resistance is required.

 

[freddiemercurystwin]

Where does it state in the White Book or a British Standard that in order for a plasterboard faced partition or wall is a noggin required at a horizontal plasterboard joint in order to achieve the designated fire resistance? I'm on the fence with this one atm. Though I've not read 100% of this thread.

 

[cjard]

Nubs seems to say that 15mm plasterboards are the nog less solution to all problems. How does this compare to a 12.5 board with 3 mm of skim?

 

[RonnyRaygun]

BS 8000-8 1994 states the following:

3.1.7.1 Supports for plasterboards
Provide or ensure the provision of supports for plasterboards and planks as given in Table 2 and also for the perimeter of the ceiling.
COMMENTARY. It may also be accessary to provide support to all four sides to meet special performance requirements, e.g. in fire or vapour control.

As with the NHBC guidelines, the document says noggins may be required, but not are required.

This from Exeter Council for HMOs:

Where it is necessary to upgrade internal walls, the following materials will give the required 30-minute resistance:

• One layer of 12.5mm fire resistant plasterboard securely fixed to joists/studs with joints sealed with intumescent mastic, or joints taped and finished with plaster skim.

• One layer of 6mm rigid fire resisting board (e.g. Supalux or similar) securely fixed to joists/studs with joints sealed with intumescent mastic.

Upgrading must be carried out on the risk side, i.e. inside the room/compartment where the fire is to be contained.

The above document implies that no noggins are required as long as the joints are taped and finished with a skim coat.

Try as I might, I'm yet to find any document that says noggins must be provided.

 

[AronSearle]

Where does it state in the White Book or a British Standard that in order for a plasterboard faced partition or wall is a noggin required at a horizontal plasterboard joint in order to achieve the designated fire resistance? I'm on the fence with this one atm. Though I've not read 100% of this thread.

Suitable timber noggings, typically 38mm x 38mm or 50mm x 50mm, may be required between joists and at the ceiling perimeter to
support the edges / ends of the board. The provision of noggings depends on several factors; the thickness of board, spacing of timber
joists and any technical performance requirements, e.g. vapour resistance and fire resistance performance. Table 1 provides information on
the general requirement of noggings. However, reference must also be made to the relevant technical performance tables within the
WHITE BOOK to establish the need for noggings in fire-rated situations.

Bear in mind that there are 3 plasterboard manufacturers (the white book is for one of them) , the performance between plasterboard from different manufacturers can vary, stud/joist centres and board thickness determines the need for noggins.

Try as I might, I'm yet to find any document that says noggins must be provided.

You won't

Plasterboard manufacturers have their products fire tested, when they are fire tested they will be fixed in a particular way, and that is how you have to fix it, or you can't claim it will still work.

There is no requirement to nog, it is all down to the individual products fixings recommendations.

If no guidance is given, tests are likely to have been performed with all edges supported.

Nubs seems to say that 15mm plasterboards are the nog less solution to all problems. How does this compare to a 12.5 board with 3 mm of skim?

But if you look around at tables, 15mm can only be used without noggins at 450mm centres or less.

Most studs are installed at 600mm centres.....

 

[RonnyRaygun]

Some pages from the white book below. While it is clear that where ceiling joists are at 600mm crs, noggins must be provided at the ends of plasterboard, for walls it is less clear, stating that noggins should be provided "where necessary", while, as far as I can see, neglecting to state where exactly they are necessary...

The implication though, is that noggins should be provided in stud walls where joist centres are greater than 450mm, as said above.

The link below states to always support every edge, and I have to say that, for robustness, I would now be inclined to specify that on drawings.
http://www.carpentry-tips-and-tricks.com/cutting-plasterboard.html

 

[AronSearle]

This has been a fairly useful calm discussion, can someone please start throwing around some insults.

 

[cjard]

deleted

 

[jeds]

As with the NHBC guidelines, the document says noggins may be required, but not are required.

I'd say the reason it says 'may' as opposed to 'must' is because it depends what system you use. The bottom line here is that the correct method is that specified by the manufacturer of the system. The manufacturers are the ones that have these systems tested and produce certificates to say they will perform x and y in certain situations. If you take Lafarge, for example, they do in fact specify noggins at board edges for over height partitions. They also specify noggins at board edges on ceilings when using standard wallboard, but they don't for baseboard. So it is a bit of a pick and mix. Generally I wouldn't think it's critical for 400mm centres studs but might be for 600 centres.