Gooman

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  1. I don't think that's going to fly with my BCO. He's insisting on a 10mm gap for acoustic reasons, and the thermal rating. I think I'm back to plan A : 10mm gap 50mm timber studs infilled with 50mm PIR 12mm PIR on top 25mm battens and mineral wool (plus cables in conduit) 15mm Soundbloc 5mm plaster skim I think that's the best I'm going to get. Unless nextdoor turn their garage into a major workshop working evenings and weekends, I don't see that I'm going to have a big noise problem. Thanks everyone for all your suggestions and help!
  2. That sounds a lot simpler. Can you give more specifics on the cross section and the type of product? Do you mean 110mm of dense mineral wool? For example, 100mm Isover Acoustic Slab and two layers of Soundbloc only gives me a u-value of 0.319 (and that's not taking account of the 70mm metal stud, as I'm not sure how to add that in Changeplan). The BCO has said that although the other side is not exposed to the outside, as it's an unheated non-integral garage it's regarded as an external wall and needs to achieve 0.3.
  3. Ah, I hadn't realised that Changeplan handled the studwork and thermal bridging implications. Neat! Celotex PB4012 is 12mm. Not priced it up yet ... that may change my plans again. I'm in England, so unless someone else can comment positively on that route it's not going to be an option.
  4. Good point well made. I've skimmed BR443 and unfortunately I'm none the wiser. I assume I need to account for a timber bridging factor of 15%, but it doesn't seem to explain what that means. Is the R value for the elements that are bridged reduced by 15%, or to 15%? OK, read other stuff on this. Man, this gets complex. My head hurts. A different approach is needed I think. So now I'm thinking: 10mm gap 50mm studwork filled with 50mm PIR 12mm PIR surface mounted, joints taped 25mm batten filled with rockwool 12.5mm PB Plaster skim That seems to give a u-value of .261 on a combined thickness of around 115mm.
  5. Just occurred to me. If my stud wall is independent from the garage party wall (offset by 10mm) do I need to worry about thermal bridging at all? The footer will be fixed into the concrete floor, but I doubt that's a big deal. If bridging isn't an issue I can have a party wall build-up of: 10mm gap 75mm studwork filled with 50mm PIR and 25mm rockwool 2 x 12.5mm PB Plaster skim According to http://www.changeplan.co.uk/u_value_calculator.php that gives me a u-value of 0.297 and a depth of only 115mm - see image
  6. The floor level needs to be raised and that will then require that the roof height is increased. My builder will be doing that work. I'll then be insulating it with PIR between and over the roof joists, extending over where the stud wall will be fixed through to the ceiling joists. My current thinking on the order of work is: Builder raises roof and levels floor (but doesn't raise it) Builder builds pillars and installs steels (leaving house side wall for the moment) Builder removes far, garden wall and builds footing for bi-fold door track (with temporary shuttering) I insulate ceiling (but not yet plasterboarded) I construct partition stud wall between front end of garage and new room area and insulate I construct frame for party wall, insulate and dry line I install floor insulation (but not yet chipboard) 1st fix - pipework for radiators cut into top of floor insulation, socket wiring within party wall rockwool gap (cable suitably derated), lighting wiring on ceiling I install chipboard floor I install battens on ceiling (for cable void) and plasterboard over Builder installs bi-fold doors Builder removes house side wall Sundry insulation and PB (window reveals, pillars, steels) and plaster skim 2nd fix Rough plan attached ...
  7. The Changeplan calculator is exactly what I was after, thanks! That suggests that 50mm PIR (as part of the cross section I proposed above) would give a u-value of 0.286. The enclosed unheated space on the other side is a non-integral garage (as is the space I'm converting) which seems to be specifically excluded by BR443. So now the tricky part is specifying the timber frame. Ideally I want PIR between the studs and a separate layer over to avoid thermal bridging. But with only 50mm PIR that seems tricky, as the timber frame will need to be rigid enough. Any thoughts?
  8. Thanks all for your good advice. The BCO has confirmed that he doesn't need any specific acoustic insulation. I'll definitely plan to add double-thickness plasterboard. If I can avoid putting electrics or plumbing in that wall I'll also include 35mm of mineral wool between the PIR and PB. Does anyone know of a u-value calculator that would help me work out the minimum PIR thickness I need, given that the mineral wool will have some thermal properties, and given the double PB? Seems to be beyond the capabilities of the Celotex and Kingspan ones. For clarity, proposed cross section of wall is now: Existing brick party wall (presumed single-skin, unheated garage on other side) 10mm gap Timber frame fixed to ceiling, floor and end walls with PIR board between studs 35mm timber frame with mineral wool between studs 2 x 12.5mm plasterboard Plaster skim
  9. As this is a conversion within a self-contained dwelling, and not a "room for residential purposes" in the meaning of Part E, doesn't that mean that Part E requirements don't come into it and that Building Regs for sound won't apply? If so then obvs I still need adequate measures for my own satisfaction, but I don't need to satisfy Part E and it's not a BC issue.
  10. I think he was meaning that the 10mm gap with the stud frame not attached to the wall would be sufficient insulation. The PIR insulation (see first post) is the thermal insulation.
  11. Nope, that's still a double length garage. BCO didn't mention anything about fire spread ... what would be expected there?
  12. Ah, I think I misunderstood BC's comments ... it's a 10mm gap from the party wall, not a 10mm frame. The new stud frame needs a 10mm gap and it's attached to the floor, ceiling and walls either side rather than the wall.
  13. As we're not in the property yet I'm not 100% certain ... I believe it's just a single 100mm skin as it's just a single storey shared between the two garages. I guess my other alternative is to see if I can avoid having any electricals or rads on that wall and so avoid the need for a service gap.
  14. I'm planning to convert the far end of a double-length garage that's attached to the house on the left-hand side and has a party-wall with next-door's garage on the right-hand side. Most of the far end wall will be gone and replaced with bi-fold doors. At the front end there'll be a blockwork partition wall between the new space and the remaining garage/workshop/storeroom. The left-hand wall will go (in the converted space, not the remaining garage) and it will be open-plan to the kitchen. The party wall is the problem bit. Building Control have told me that as it's a party wall I need to achieve appropriate sound insulation levels, which they recommend doing by erecting a 10mm stud frame. I'll then need 100mm PIR insulation which will be taped to provide a vapour barrier. Then (presumably) I need a 25mm service void, so more battening. Then plasterboard. I hate the idea of battening twice - sounds like a real faff. Any bright ideas?