AMK said:

The walls that border the neighbouring property have a 60-minute fire resistance rating

A typical requirement for compartment walls between buildings.

AMK said:

and the walls that partition the rooms have a 30-minute rating.

A typical requirement for walls that form protected stairs, lobbies and corridors in the same compartment.

AMK said:

the walls have a fire resistance rating of 30 and 60 minutes, but there is no mention of the ceilings.

It is the floor that is required to meet the required fire resistance and this will vary depending on the height of the building, its purpose group and whether it has a sprinkler system. If you look at British Gypsums White Book, for example, you will see some very fastidious detailing for protecting floors with the ceiling and the floor being treated as a composite in terms of overall fire resistance. 

So sticking downlights and other apertures in these ceilings, even with fire hoods, can compromise the fire rating detailed in the White Book. 

Clearly, in all cases, it would be prudent to minimise openings in any element, that has a fire resistance. It is particularly important that electricians carefully consider how they propose to install their wiring systems to avoid compromising the fire resistance integrity of the building. 

My photo above indicates a total lack of care in that regard! 

With respect to fire doors, they are normally required to be half the rating of the wall into which they are set with certain minimum values. If the wall is required to be 60min, the door is usually 30min on the basis that combustible material is usually set well clear of doors to allow passage through. 

The use of stud partitions, either wood or metal offers a chance to avoid chasing masonry walls to install sockets and switches but one needs to exercise care when the walls are required to be fire resistant and particularly where they form protected corridors and the like. 

On the last large job I was on, this problem came up. One of the Contractors had fitted plastic plasterboard boxes on an 'external' wall [1]. When inspected, this non-compliance was brought up, and all of the plastic boxes had to be changed to the metal plasterboard boxes with intumescent pads in them.

They were also very keen on intumescent sealing on any hole, however small between fire compartments.Which was quite surprising, as their design was truly bad, with safety services being powered by the same supply as for general use, and a 200 amp fuse being used for 75 flats with electric heating. Of course, during functional testing, the incoming fuses blew numerous times until the incoming supply was upgraded. They never did fix the safety services supply.

[1]'External' being a wall that adjoins another flat or communal area, internal walls could have plastic fitted, as the flat was considered as one fire compartment.

Hi Alan, if the sockets on the external wall were standard plastic dry lining boxes but the intumescent pad manufactures/ fire stopping specialist confirmed that the required fire resistant time had been tested in accordance with the relevant standard, is this really a non-compliance? From what I’ve seen fire stopping is all about following the tested detail

the white book alluded to is available here M.

No idea, I was only working there when the Inspector came round. He wanted metal in any backbox that adjoined another flat, pads were in the plastic boxes, but it wasnt enough for him.

Given this information, is it reasonable to assume that the ceiling should be constructed using fire-rated boards to ensure adequate fire protection ?

From my renovation I recall that you don't necessarily have to use special fire boards - ordinary 12.5mm boards plus a skim were adequate for some requirements (I don't recall off the top of my head whether it was 30, 60 or 90 mins) - but certainly kept my BC happy in our 3-storey home.

   - Andy.

'pink board' as our local merchant calls it has among other things glass fibres in it, and because of this is rather better at holding together once the paper facing has burnt off than the cheaper pure gyproc. Sometimes at holes etc it looks a bit 'hairy' and this allows it to be identified.

In some constructions this reinforcement may not be needed to achieve a 30 mins resistance as the board is mechanically well supported  some other way. I'd be very careful of anyone claiming that ordinary board was generally going to meet 30mins, and determining the rating of any non-standard arrangement is a specialist job and rather more than a desk study and comparing labels . - hence why the folk who make the fire rated fittings etc do so many tests, and BCOs and the like go on courses to learn this stuff.

Mike

As I recall the 12.5mm plus skim was a standard/well recognised arrangement (I'm sure there was something in the AD or some compliance guide at the time but I can't locate it now). As you say, strength is lost when the paper surface is burned away - presumably the plaster skim was thought to prevent that. As I recall that was only one of several "usual" options - two layers of plaster board with all joints staggered was another if I remember correctly.  Wet plastering seems to be going out of fashion though, with many builders preferring tapered edge and simple jointing - so fire rated board can simplify things a lot.

   - Andy.

Its interesting reading replies and of course photo of the problem.

The thread then goes into all the details then about fire ratings of compartments, walls ceilings etc which I have no issue with at all.

But surely this is all down to the "Competency" of persons/organisations??

In other words failure to ensure compliance with standards during the build, so the client didnt receive what they should have done and has been let down badly by installing contractors/inspectors and local authority or a combination of those parties and could possibly suffer because of those ommissions. Or subsequent alterations/additions since original install.

I have said this many many times in numerous arena's and meetings. One can have as many Standards/Regulations etc etc as you like, but without adequate enforcement of those Standards/Regulations by competent people and of course compliance to the details of the same Standards and Regulations we are all simply wasting our time. Yes, money has a lot to do with it and many clients dont help themselves but in 2023 in the UK surely we can do far better?

Regards GTB

You are correct AJ. We used to use, and continue to refer to, BRE's "Guidelines for the Construction of Fire Resisting Structural Elements" published 1988.

Table 14(B) of that document allowed one 12.5mm layer of standard plasterboard + 5mm of gypsum board finish plaster. The assessment assumed joists of 37mm breadth with depth and span suitable to support imposed load, floor at least 15mm softwood tongued and grooved. Plasterboard supported 40mm galvanized nails at 150mm centres.