I am working on a 3 bed semi and have had to call in building control due to the relocation of a bathroom and a couple of other items. The problem is that there are a couple of items raised by building control that I was not aware applied to a house - I thought they just applied to flats - I could of course be wrong!
They want sound insulation in the ceiling between the ground and first floor.
They are demanding 12.5mm plasterboard ceilings throughout with a
3mm skim as they consider anything less will not provide 30 mins fire resistance. This scuppers my plans of not having to have the ceilings skimmed and there is no way I can lift and fix 15mm plasterboard!
Can anyone advise if the above points are mandantory in a 3 bed semi or is it possible I/they have lost something in translation?
Unusual: that one may have just come in recently. Its not a bad idea. though.
There are plenty of ways you can..a mate, two step ladders and some plies of books, bits of wood wedged up - make up a T-bar - like an oversize broom that is slightly longer than your ceiling is high.
The fire stuff certainly is, and its a Very Good Idea too.
As to what sound insulatiion you CAN put in? who knows. Personally two layers of 12,5mm plasterboard is probably as good as it gets on both counts. Ask the BCO.
Thank you for the replies - trying not to get too tied up in red tape!
I agree with the sound insulation, especially since the new bathroom will be above the living room.
The fire stuff makes perfect sense - its just a pain because I have reasonable quantity of standard plasterboard spare but it looks like its going to be 12.5mm LaFarge FireCheck throughout.
If this was a conversion to flats you'd be very surprised at what it would take to comply. e.g. Special triple layer acoustic isolating flooring.
The get the thickness of P/board you can put up two thinner layers. There are also adjustable legs which are like very (very) light weight screw jacks (screwfix/14003) to help you. Then it won't need to be skinned. So
2x 9.5mm gives 19mm which should comfortably comply. You stagger the joins.
But I don't understand why building control are demanding all this uprating to meet modern regs - the usual principle is that you can't make matters *worse* than they are currently, but you don't need to upgrade everything.
Unless the building is undergoing a 'material change of use', maybe? What actually is the work which is ongoing, that's requiring BC intervention?
They gave me the option of 12.5mm + skim, or 2x9.5mm for 1/2 hour fire resistance. I also used 900mm wide boards rather than the heavier and harder to manoeuvre 1200mm ones. You then have more joints to fill as the downside.
The main reason BC are involved is because the bathroom used to be downstairs, I am moving it upstairs with completely new drainage and breaking into sewers etc. BC carried out an initial inspection (they turned up while I was working one day) and went round the house with me and identified the points I have raised RE ceiling because I was having them all replaced.
For building regs purposes, converting to flats is a change of use, and you would probably find that more than a few planning departments put conditions relating to soundproofing in planning consents.
There's a lot of Part L (thermal) that applies to flat conversions too.
You may be able to kill two birds with one stone. Adding a layer of chicken wire between the joists and laying rockwool over it will give extra sound and fire resistance.
Lifting at fitting plaster board is actually quite easy. Just make yourself dead man prop:
On Tue, 4 Dec 2007 05:41:37 -0800 (PST), a particular chimpanzee, slogical randomly hit the keyboard and produced:
Assuming it's a two-storey semi without a loft conversion, the requirement for fire resistance is a 'modified' 30 minutes. 9.5mm plasterboard & at least 5mm skim under, with floorboards at least 15mm t&g boards over will meet this requirement. You could do it in two layers of 9.5mm p/board if you're determined not to skim.
The bit about adding mineral fibre between the joists could possibly be justified on the basis that the work is a material alteration by having the potential to make the floor not comply with a relevant requirement (structure and fire safety) where previously it did, and therefore the 'new' work must comply. You could counter with the view that your work does not extend beyond the upper surface of the plasterboard, and therefore you are making the building no worse in terms of sound insulation than it was before the work was carried out. However, this is all dancing around on the head of a pin, and for the sake of a couple of rolls of Rockwool, is it worth it?
The fire resistance bit is not a 'new' requirement, in that floors have needed fire resistance for donkeys years. The sound resistance for internal floors bit has been in since 2003 IIRC.
12.5mm board on it, pumped handle and it raised it to the ceiling. I managed to re-plaster board my kitchen and dining room by myself no problem.
One hint get a decent cordless electric drill/driver that has two gear ratios as mine on slowest speed was too fast and kept driving screws through the board. Get spare batteries and quick charger as it will run out at most convenient moment. Borrowed a DeWalt £100 one from my brother 1/2 through the job when my Black and Decker drill went flat again....
Also buy millions of drywall screws over, nothing worse than going out to buy more again 1/2 way through the job (about £3 for 500 from Jewsons).
The most important bit with drywall screws it to use the right bit:
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these you can run the drill as fast as you like, and it will still stop driving the screw at the right depth. I typically find I can use the fastest speed on my cordless drill with these.
The problem that I have with those is that they only stop driving the screw because they start ratcheting when the required depth has been reached. This leads to damage to either the screw-head, the bit or both.
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