Soil pipe fire collar

[brianivor]

My bathroom is above my garage and the soil pipe runs down through the garage.
I had a building inspector in for a separate matter and he recommended an intumescent fire collar round the soil pipe to prevent fire getting into the bathroom should a fire in the garage melt the soil pipe.

Could someone advise whether this should be located just below the garage ceiling or just above in the void between the joists?

Many thanks

 

[DAZB]

They are generally fitted on the side of the greater risk from a fire which , in this case, is the garage. So the ceiling of the garage would be the place for it and a bead of intumescent mastic may help to bed it up against any imperfections.

 

[ajrobb]

My BI told says I have to fix the intumescent collar to something structural. I guess that would be easier with noggins between joists above plasterboard.

 

[digdilem]

I've had cause to look into this a bit too, as it's a question I was puzzling over a few years ago.

Fitting it between a sheet of plasterboard in a ceiling is not going to be that useful as the plasterboard may fail, and the extra pressure exerted by the intumescent strip expanding may be enough to force a section of ceiling away around the pipe. Given that all the collars I've seen are soft shelled and rely on the solidity of the material around the pipe to exert pressure inwards to close it, if there's no ceiling to push against it's just going to expand away from the pipe instead.

So yes - noggins would give a better protection - if they're placed flush against the top of the plasterboard, but it's only going to buy you minutes as the fire can otherwise get into a normal under-flood void by melting the pipe and will burn out around it. 3/4" chipboard won't take long to go with a decent flame under it.

Light fittings also act as a way for fire to get into the void, but unlike pipes don't chimney straight up into the room above.

The collars are pretty cheap, they don't seem to come with any instruction, and it can buy you a few minutes which might save somebody's life so it should be done. It can be quite a performance to get them in place though.

 

[ajrobb]

Should we put the collar below the plasterboard with noggins above to support the plasterboard and collar while the collar expands?

I'm tempted to put a ring of 18mm WBP ply between the noggins and the plasterboard both to take the fixing screws and for full support of the plasterboard.

I've seen both soft and steel backed rings advertised. The soft ones are for building into block walls so are not appropriate for plasterboard. The steel backed rings are fixed with screws through the plasterboard into something substantial.

 

[Nige F]

slightly different way - possibly - box in the pipe with 2 layers fireproofed plasterboard - intumescent mastic seal all round joins to wall/ floors / ceiling - maybe cheaper/ easier . I`d run it past Build Control

 

[Agile]

When I built an extension with garage the architect showed the WC plastic soil pipe boxed in like that.

Isn't the reason the intumescent bands are often below the ceiling so they get heated and activated quickly by the surrounding fire?

Tony

Product Features

The intumescent material in our steel pipe collar will expand during a fire and collapse the plastic (or UPVC, ABS, MDPE, HDPE) pipe that it's protecting. Stocked in 55mm, 110mm and 125mm (many other sizes on request) for both 2 and 4 hour fire resistance, these are ideal for soil and waste pipes that pass through walls and floors in all kinds of buildings.

Our pipe collars are normally surfaced mounted but can be fitted into masonry floors or walls. They come with brackets as an extra fixing option.



Technical Specification
•Tested to BS476 Part 20 and EN1366-3
•Choice of 2 or 4 hour fire resistance
•55mm, 110mm or 125mm - other sizes on request
•NHBC Type Approval
•LANTAC Building Control Approval

 

[digdilem]

Isn't the reason the intumescent bands are often below the ceiling so they get heated and activated quickly by the surrounding fire?

I would guess the plastic pipe melting, and the fire chimneying up through inside it - is going to raise the temperature around the pipe pretty quickly and activate a collar fairly rapidly wherever it is along the pipe.

 

[brianivor]

Thanks to all for your replies:

There still seems to be a variety of answers to this one!

The fact is that, due to a soil pipe joint just below the ceiling, I will have to put the collar just above te ceiling plaster anyway - I had hoped that that would be the correct location but there is now doubt.

I guess that provided the collar sat just on the top of the ceiling panel then if activated it would still block the hole.

 

[digdilem]

I guess that provided the collar sat just on the top of the ceiling panel then if activated it would still block the hole.

Yes, but as I said, only if there is something solid around the collar for it to push against. Otherwise it'll just expand away from the pipe and not seal the void.

 

[brianivor]

Maybe I was mistaken, but the collars I saw on the internet appeared to be a metal collar clipped round the pipe with the active marerial on the inside thus the metal would restrain the reaction from expanding outward - have I got this wrong?

 

[ajrobb]

The collar must be supported by something other than the pipe as the pipe will melt in a fire.

 

[DAZB]

I agree with brianivor in that I always thought that the intumescent collar material expands and crushes the pipe inwards thus sealing it in the process. The retaining ring that secured it to the pipe gives it the resistance needed to crush the melting pipe. This explains the process :

http://www.pipestock.com/fire-protection/intumescent-fire-collars/