G and J Posted July 25 Share Posted July 25 11 minutes ago, joe90 said: And the council will never measure We are advised that our planners will, rightly methinks, come out and measure if there is a complaint. Link to comment Share on other sites More sharing options...
SBMS Posted July 25 Author Share Posted July 25 On 07/07/2024 at 23:36, ETC said: Post a section. Posted a section. Link to comment Share on other sites More sharing options...
joe90 Posted July 25 Share Posted July 25 45 minutes ago, G and J said: if there is a complaint. What oversize are we talking about? Mine was going to be 150mm above planned height, that would be difficult to see on a two story build. Mine was a hipped roof so difficult to measure ridge height anyway. As stated I reduced the slope by a couple of degrees which was not noticeable but reduced the ridge by that required. Link to comment Share on other sites More sharing options...
G and J Posted July 25 Share Posted July 25 Architect just had a case where a 100mm over height was complained about and they had to re work..........one of our neighbours to be would notice.....they did a lot of measurement and comparisons in their objection and are peeved their objections were all ignored.......we may have this issue as alternative to a slight kick in the upstairs or lower ceilings in which case we'd do what @joe90 did and lower pitch very slightly .......for running of mvhr and cost we want to use 304mm posi joist, architect had assumed 200mm and we didn't check...... ho hum Link to comment Share on other sites More sharing options...
SBMS Posted July 25 Author Share Posted July 25 I wonder whether the valleys and complexity of our roof are making blown cellulose a difficult or suboptimal option? I keep trying to work out whether there are going to be a lot of ‘nooks and crannies’ to fill with cellulose? Link to comment Share on other sites More sharing options...
Iceverge Posted July 25 Share Posted July 25 1 hour ago, SBMS said: cant really go much more than 300mm rafter depth Rather than rafter thickness do you have an overall thickness of the roof please? When considering 0.12 Vs 0.13 might be worth sitting down and doing some calcs to really get a handle on the little difference it will make. 0.01w/m²K will really pale into insignificance Vs a little better airtighess or improved COP on a heat pump. Say 100m² of roof, a pessimistic average delta T of 15deg for the heating season of 4 months. About 2900hrs x 0.01w/m²K x 15⁰ = 435Wh or 0.435kWh. Run it through a heat pump at a COP of 4 and it'll cost you about 3p per year. Link to comment Share on other sites More sharing options...
SBMS Posted July 25 Author Share Posted July 25 1 minute ago, Iceverge said: Rather than rafter thickness do you have an overall thickness of the roof please? When considering 0.12 Vs 0.13 might be worth sitting down and doing some calcs to really get a handle on the little difference it will make. 0.01w/m²K will really pale into insignificance Vs a little better airtighess or improved COP on a heat pump. Say 100m² of roof, a pessimistic average delta T of 15deg for the heating season of 4 months. About 2900hrs x 0.01w/m²K x 15⁰ = 435Wh or 0.435kWh. Run it through a heat pump at a COP of 4 and it'll cost you about 3p per year. Hi @Iceverge I have attached full roof makeup showing depth below. I suppose I felt that 0.1 would be a great target and so every point I move away from that is psychologically difficult! But your logic makes sense. Link to comment Share on other sites More sharing options...
Iceverge Posted July 25 Share Posted July 25 390mm is the depth I'm adding up here from the plasterboard to the membrane on top. How about this. Or a hybrid warm roof as shown below with 150mm above the rafters and 100mm between. You'd need to tape the bottom layer of OSB as airtightness here. Link to comment Share on other sites More sharing options...
SBMS Posted July 25 Author Share Posted July 25 36 minutes ago, Iceverge said: 390mm is the depth I'm adding up here from the plasterboard to the membrane on top. How about this. Or a hybrid warm roof as shown below with 150mm above the rafters and 100mm between. You'd need to tape the bottom layer of OSB as airtightness here. The first option is interesting - the staggered timbers looks good for thermal bridging. How would you go about connecting the 97x45mm To the 220s above? Link to comment Share on other sites More sharing options...
saveasteading Posted July 25 Share Posted July 25 I once had a tentative complaint that a building was too high. I asked what their datum was and they had no idea. Sorted. Link to comment Share on other sites More sharing options...
Iceverge Posted July 25 Share Posted July 25 (edited) 3 hours ago, SBMS said: The first option is interesting - the staggered timbers looks good for thermal bridging. How would you go about connecting the 97x45mm To the 220s above? Toe nail them to get them in place, then 150mm screws would be my idea but I'm not a carpenter. I would run them at 90 Deg to the rafters. Alternatively you could just nail gun 45mm service cavity battens. And extend the 220mm rafter by the same on the other side of the membrane and use more cellulose and less mineral wool. Edited July 25 by Iceverge Link to comment Share on other sites More sharing options...
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