Gaf Posted January 13 Share Posted January 13 Posted a couple of times and now at the stage of talking to builders/contractors with our construction drawings in hand. Original plan for external walls is below (aware that the IWI is generally seen as not a great way to go): Render Finish 100mm outer leaf block 150mm Ecobead pumped cavity wall 100mm inner leaf block 37.5mm insulated plasterboard Skim finish One builder mentioned going with the below on his own house and suggested it might be better to do this for ours: Render Finish 100mm outer leaf block 200mm Ecobead pumped cavity wall 100mm inner leaf block 12.5mm plasterboard (not insulated) Skim finish The insulated plasterboard adds approx €8k to the build. Was advised if we changed to 200mm, the additional wall ties would only add €1k. So there's €7k to claw back, but we're not sure if there's any saving in the additional 50mm thickness across the whole house for the cavity fill. Will be exploring a quote this coming week. I do remember our architect saying it was more than just the wall ties, that you'd need a structural engineer to review the whole house and ensure 200mm cavity was structurally sound - is that right? Main query I have is trying to get the U-value of the alternative approach. Kingspan did a U-value for the original plan (IWI) and came back with a U value of 0.16w/m2K. I've tried using that German (?) insulation website to work out the u-value of the alternative but I can't get it to work for me. At the risk of being a PITA, would anyone be able to use that tool to see what it comes out with for the U-value? I do plan to get in touch with Kingspan on it but was curious in the interim. Link to comment Share on other sites More sharing options...
nod Posted January 14 Share Posted January 14 I used a similar Accept for the beads to our previous build and have done the same on our current build The top build up will feel far warmer than the one he’s suggesting Personally I wouldn’t use blown in beads Quicker cheaper but have a tendency to settle Your looking at about £28 per per board extra and £3 per board labor Im not sure where he’s getting his figures My reckoning would be he’s allowing over 200 boards for the perimeter walls Very big house Link to comment Share on other sites More sharing options...
nod Posted January 14 Share Posted January 14 Just looking at our previous build spread sheet 295m2 I used 76 insulated pb on the exterior walls Less than 3k on today’s prices -about 600 saving on the origenal wallboard and of course £1000 on the ties Which would cover the extra labour and extra profit for him Link to comment Share on other sites More sharing options...
SteamyTea Posted January 14 Share Posted January 14 Would need to know the R-Value of all the components used. My limited experience of insulated plasterboard is that after a while, the screw heads popped though the skim of plaster. No idea if this is a real problem or just shoddy workmanship. Link to comment Share on other sites More sharing options...
Gaf Posted January 14 Author Share Posted January 14 4 hours ago, nod said: I used a similar Accept for the beads to our previous build and have done the same on our current build The top build up will feel far warmer than the one he’s suggesting Personally I wouldn’t use blown in beads Quicker cheaper but have a tendency to settle Your looking at about £28 per per board extra and £3 per board labor Im not sure where he’s getting his figures My reckoning would be he’s allowing over 200 boards for the perimeter walls Very big house Spent a good while deciding on the cavity insulation and settled (no pun intended) on the cavity bead for reason's I won't bore with. House is 218m2 (2,347 sqft). Based in Rep of Ireland. Calculated external wall area is 275m2. Quote for the IWI plaster boards, skim finish, and labour is €70 per m2 inclusive of VAT. Full quote for just this work is €19,250 (~£16,560). Each board is 2.4x1.2m, 2.88m2, so it equates to 96 boards but imagine some extra are needed to do the job. Link to comment Share on other sites More sharing options...
nod Posted January 14 Share Posted January 14 = 2 men 4-5 days work Link to comment Share on other sites More sharing options...
Gaf Posted January 14 Author Share Posted January 14 2 minutes ago, nod said: = 2 men 4-5 days work As in, this price is suggesting that the work should get done in 4-5 days? Link to comment Share on other sites More sharing options...
nod Posted January 14 Share Posted January 14 Yes 90 insulated boards and skim Link to comment Share on other sites More sharing options...
Avendit Posted January 15 Share Posted January 15 I wouldn't want to use it for doing real calcs, but for quick and dirty relative calculations, I use https://www.vesma.com/tutorial/uvalue01/uvalue01.htm Modern blown beads with glue shouldn't settle should they? Link to comment Share on other sites More sharing options...
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