Hannah82w

We are about to start lining and filling our stud walls and would like some advice on acoustic and normal cavity insulation please. Studs are either 150mm (6x2) or 100mm (4x2) wide, mostly 400mm centres (so the gap to fill is only approx. 350mm wide). Architect specified 50mm Isover APR 1200 insulation, but we're happy to look at similar products such as Rockwool and Knauf. How much of the stud wall depth should you fill? 50mm doesn't seem enough in either 100mm or 150mm stud depth. Do you need to leave an air gap or fill completely? All the products seem to come in 600mm width, with the exception of the Rockwool Flexi at 400mm, but more expensive. Am I missing something on the market that is made for 400mm centre studs or do you just have to cut down and expect wastage? Walls will then by lined with plywood and plasterboard. Thanks very much.

Thanks all for your thoughts and advice, very helpful. I haven't actually seen class I, II or III on any descriptions of ply products!

Thanks, so class I is softwood?

Thanks, I'll check (and find out what that is!)

Ah ok, thank you. I will take a look at the regs. I'm told WBP is an old term, but essentially is the current hardwood that is suitable for exterior use, so some water resistance.

Hello, we've built a timber frame single storey house, watertight and screed poured, so now looking to start lining the walls - internal studwork, internal load bearing walls and the inside of the external walls. The technical spec just lists '9mm ply' or '18mm WBP in the bathrooms about pan, cistern and wash basins' (with vapour barrier under the ply on the external walls, and 12.5mm plasterboard over the ply on all walls). We want to use 12mm ply throughout for extra depth to aid hanging things on the walls, and don't plan to have wall fixed basins etc (will opt for free-standing). I've just rung round the various builders merchants and timber yards and got differing advice on what to use! Is 12mm softwood ply acceptable in all cases except the bathrooms where we could use hardwood instead (for its more waterproof properties)? Thanks

Hi Tony, interested to hear how you got on with installing a mist system and which company you used? Thanks.

Thanks all for your thoughts and suggestions. Having got a clearer idea of the full set up and requirements from the sprinkler companies, I sent an email to our BCO to update and ask for confirmation of likely approval of it all...and to ask one more time if there was any other way to mitigate for the fire access issue. And he has now suggested we could look at mist systems that comply with BS8458, which could be an acceptable alternative, despite me asking about them 2 years ago! So, back to the research drawing board with fingers crossed for a positive outcome!

We'd really like the original company to supply us with all the right info, but after several emails and trying to call them again today, still no further forward. Also tried to arrange a site meeting with them, and not yet got a positive response. Time to ditch and move on, despite deposit paid for initial sprinkler system.

Thank you. My previous research on this suggests that water mist systems don't meet BS9251 and BS9991 which is what we have to comply with. Will check again though.

We asked about a dedicated sprinkler supply when we applied for our water connections and they said they wouldn't agree to it, and that was 32mm! We are fairly rural and the pipes come up a hill from the mains pipe, so I suspect a bigger pipe will still not give us the flow and pressure we need, but will explore again.

Thank you, I've seen this table as part of my research, will look at it again. 3 phase hasn't been mentioned by the various companies were talking to, and not sure we can achieve. We've been told 3000l by one company and 5000l by another!

I just wish it was all a bit more joined up - why give permission for something when building regs then impose restrictions or make life difficult to achieve the permitted scheme.

Unfortunately we have to comply with cat 2 as it's to mitigate for fire access, so need enough for 30mins of water. Didn't know there was a difference on categories until this week, and assumed cat 1 but BCO says cat 2. We also don't have a loft as they are all single storey buildings - they are like barn conversions but now new build replicas, if that makes sense!

So far I've been told that 3000 litres is ok for cat 2 i.e. 100l x 30mins.