Hi guys when filling the chases in dot and dab walls what filler do you use? I’ve been told it needs to have the same fire rating as the plaster board but don’t know how easy this would be to find?
You don't chase in dot and dab, you install the wiring and box/boxes before the plasterboard, cut out pb to fit round box/boxes and then fix it.
Also, is there’s a sheet of plasterboard dot & dabbed on a brick wall then the fire resistance is the brick wall! The plasterboard is not a fire barrier so and repair does not require any fire-resistant properties. PS use Easyfill to repair holes
Fire rated plasterboard? The pink one? Doubt that Standard 12.5mm I'd cut chase tidy with vertical cuts. Pva edges. Cut new strips of 12.5mm plasterboard and stick with board adhesive. Seal the the new strips along cut edges and mix the powdered board adhesive and dot and dab in. Won't need tapes or anything if you have adhesive along edges as you go. Fill and sand off smooth. Wet sponge as you go to clean surfaces. Don't let it set proud
Sometimes you do have to chase dot and dab if they have gone overboard with the dots!! I do as Wayners suggests, and use Gyproc Easifil 60 (B&Q have it) to fill in, its a fast setting plaster very similar to the plaster that the board itself is made from, and is made for the job.
Thanks guys just was on the 18th edition course Thursday and the guy taking it was telling me that even in back boxes where the plaster board has been penetrated the cable entering the box needs a fire seal round it. Something that I’ve never seen hence why I thought I’d ask you guys. Thanks for Your kind replies
As above it is only needed if the plasterboard is a fire barrier. Which it hardly ever is in a wall. standard single thickness gypsum plasterboard is not fire rated and this means it will not meet the stringent fire performance requirements of current UK building regulations in any case. For it to be a fire barrier it would have to be two sheets of 12.5mm plasterboard or a single sheet of the pink jobby. Also, I assume that you are talking about metal back boxes? Drywall boxes tend to be plastic, so no fire resistance there either. Ask him(her) for clarification.
You can get fire rated & acoustic Metal back boxes, fire putty pads & intumescent sealer. I have always thought that one layer of plasterboard had a 30-minute rating unless I am wrong.
I think this is where I was getting it from, if this is the case surly the metal back box needs fire putty. Just not something I’ve not seen done .
So, steel back boxes on a block wall surrounded by plasterboard needs fire putty ? Can anyone show any building regs for this specification in domestic premises ?
Back boxes are covered on the outside with intumescent material. Mainly for timber stud / dry lined walls. In Part B of the Building Regulations, section 11.12 states: ‘All openings for pipes, ducts, conduits, or cables to pass through any part of a fire separating element should be fire stopped. It goes on to say: ‘Proprietary fire stopping and sealing systems (including those designed for service penetrations) which have been shown by test to maintain the fire resistance of the wall or other element, are available and should be used’. The IET Guidance note 4. Protection against fire 6.2.4. says: ‘Where knockouts have been removed to allow the access of cables. These should be fire stopped to prevent the spread of hot gases into the structure in the event of the accessory sealing the box failing. This is also applicable if there are gaps between the electrical accessory box and plasterboard wall.
Yes, BUT the essential words in Part B: through any part of a fire separating element In most domestic premises there are NO fire separating elements. None of the ceilings in the usual house are designed and built to be a fire barrier. The exceptions are usually the ceilings of integrated garages. there are differences where a building has a number of separate dwellings. Here each dwelling is a separate fire-compartment. That’s why your standard gypsum plasterboard doesn’t have a rated fire resistance. It doesn’t need to have one! so, unless the wall or ceiling is actually a fire barrier, then there is no need for intumescent boxes, fire stop putty or anything of the like.
So ALL ceiling roses and switches need to be fire stopped ? (including around the cables as they pass thr into a void ?) lol
If they penetrate a fire barrier, yes. When did you last come across a plasterboard wall that was a fire barrier? Brick is the usual way.
Why not? We seal the cable back entries in new consumer units, I know to contain the spread of fire, but ceiling roses yes especially. My view is if you penetrate a wall of whatever construction you are reducing the fire rating capability & the rating should be equal to that before you carried out the work. In general domestic dwellings must have some fire rating & compartmental design to reduce the spread of fire to aid evacuation, even just plasterboard must have some form of resistance to fire.
We don’t seal back entries to consumer units. It’s spaces on top that matter, and thats not for fire, it's to stop your child from putting their pinkies in the gap. And they do not anything of the sort. If you look at your house, there is a big thing that makes any sort of other fire resistance pointless.... ....it is that great big fire corridor that connects the various floors. The STAIRCASE. Houses are not built with fire doors on each floor. A substantial fire on the ground floor can take only a few minutes to roar upstairs. Certainly it will get to your bedroom faster than through a (non fire-rated) Gypsum plasterboard ceiling, even with a few pendants installed. So there is little point in plugging a ceiling rose, a back box, or anything else.
What about the plastic loft hatch cover?. How you gonna seal that? May be better to install a water sprinkler system throughout your house.
It is my own particular way of working & I do seal, back entries in consumer units/ceiling roses & cableways penetrating walls. Just because materials have not been officially Fire rated, does not mean they do not have some form of resistance.