deuce22

ProDave I understand that the electric coming from solar will be used for anything electric in the house, not just on the HP, but I wouldn't bother installing PV if I wasn't installing a HP, so I'm combining them together. ReedRichards So how many KW over the year do you think you save through solar?

ReedRichards So in your experience there's no benefit to installing solar to reduce bills from the HP? Have you got storage batteries as well? PeterW I didn't think it went on what my requirements are, I thought it was on the size of the house and how many bathrooms there are. It has 5 bathrooms, a utility room with sink and shower and kitchen. There is only myself, wife and child living there, but I have family that will stay multiple times per year. Our DHW requirements are not that much, but if a larger family moved here in the future, their requirements may be different. I started this build 3 years ago and have about another year before it's all complete, the plan was to have it complete in 2 years. This won't be my final property as I have an opportunity to live on a small holding in 5 years time, so i will eventually be selling this.

nod Saving money must be one of the top reasons for people installing these. Why would you pay more for something at the start to then pay the same or possibly more to run? When I started this build 3 years ago, the plan was to install a heat only boiler with 300l cylinder, run off gas. ProDave It is a new build constructed from Nudura ICF, 150mm PIR in floor, warm/hybrid roof with 150mm PIR, 200mm mineral wool between rafters. The boiler and cylinder I was going to install, was £3000 and this HE I mentioned, said he could do a HP for around £8/9000 and then get the £5000 grant. However I should then install PV to counter act the high running costs. This would add another £4/5000, so between £7/9000 for heat pump and PV and £3000 for gas + plus connection.

PeterW That's what I was thinking, surely a small cylinder in one of those combo boilers isn't sufficient for 5 bathrooms. JohnMo I was thinking of installing solar if I go down the ASHP route. billt I've joined an ASHP group and there is a lot of unhappy people, one person is paying £20 per day to run as it wasn't set up properly. ReedRichards I was planning on installing a heating loop, but watched a video on youtube where the calculations were done and it cost a lot to have these running all year.

I'm wondering whether to install an ASHP and would like to get some feedback from others on whether these are actually worth it. I have a 350m2 property over 3 floors and was planning to use underfloor heating on each floor. I've read quite a lot and have noticed that although they are a greener choice, they are not as efficient as gas and in some cases ridiculously expensive. A heating engineer that fits these have told me to install a heat only boiler and cylinder or a combo storage boiler. What are your opinions about this? Thanks.

I am coming to the end of fitting the insulation on top and I'm not too confident in this setup. I was thinking of adding the mineral wool in between and then more PIR underneath the rafters. Would this have any benefit to stopping condensation? Who would do a condensation risk analysis?

Definitely worth checking. I lived in a property years ago and on very cold days, ice would form in the the roof space and you'd here it cracking as the day warmed. That is the last thing I would want on a new build. Thanks for pointing it out.

I've just spoken with, both Kingspan and Celotex and they've both stated that it won't be an issue with condensation as its only 150mm.

I haven't got a cross section. I'm not trying to hit a specific U value. I asked the SAP company to get it as low as possible with the materials I was using and the depth of the rafters. I increased to 8x2s rather than 7x2s that were specified, due to their advice. These calculations were completed about 12 months ago and not one person has made any comments on this. I've never used this method before, I normally fill, in between and below rafters. I'll speak with a manufacturer today and see what they say. Thanks.

Thanks for pointing that out Andy. I've had 3 BCOs come to the site and not one of them has commented on it. This build up was advised by the company who provided my SAP calculations. I'm now thinking that I should just fit vented soffits and ridge as well as the vapour barrier below the rafters.

Ok, no ventilation needed. What about a vapour barrier underneath the rafters? I'm using 150mm PIR and completely filling in between 8x2 rafters with mineral wool.

Thanks Temp. Ive got a roofer helping me, but he hasn't fitted a warm roof before either. I was planning to fit eve's and ridge ventilation, but was told not to by the BCO, this is just a standard thing that I've always done. I also asked if I need to fit a vapour barrier under the rafters or any where within the roof build up and he said no. I was planning to get the membrane for fitting to sheet material, but I think I'll do what you suggested as I do prefer it draping between each timber. The roofer thinks I'm fitting OSB unnecessarily and should just counter batten directly onto the insulation.

Hi. Can somebody with experience please let me know, the most efficient way of completing a warm roof. It is the first time that I will actually be doing a roof this way. The roof is temporarily covered and so I will be adding on top of this. My understanding is: insulation is fitted first, then OSB, breather membrane and counter battened. I've found these for fixing insulation https://ukflatroofing.com/insulation-fixings/warm-deck-insulation-fixing-for-plywood-deck-box-100-ejot-150mm-timber-deck-td-150-95-100 and I'm not sure on whether to use screws or twist fixings. Any advice would be appreciated. Thanks.

I agree. I don't think its my job to have to question things, but the carpenter thinks I'm over reacting. The SE is a family friend and the carpenter is also a friend of his. He's obviously just assumed that the carpenter knows what he's doing and hasn't given me any calculations. The angled hanger that is advised for this has a SWL of 520kg, but a normal hanger is stronger. He has said he will do it with normal hangers as he prefers these to the angled type. He will birds mouth the rafters at the top, just like George has mentioned, similar to the image. He will then attach the horizontal tie and bolt into the rafters.

The reason we're not sitting them on top is because the person I had dig the foundations, didn't do them to the correct level (they were almost 500mm to high). I was told that this would be within the tolerance that planning would be ok with. If I sat the rafters on top, it would add, close to another 500mm. As the chippie told me not to worry as he can flush fix them, I wasn't concerned. However, I am now wondering if this will be strong enough, once its loaded with weight. I mentioned about using the rafter hangers and he said he prefers the way that he does it (he believes 2x 20mm rod, bolted each side, with the horizontal tie supported on joist hangers is stronger). The area of the roof is around 140m2, the weight of the tiles is around 6 tonne and I've allowed another 2 tonne for the other materials. This works out at 57kilos of weight per m2, so with a rafter length of 4m @ 400mm centres, one rafter is supporting just over 90kilos. If these calculations are correct, it doesn't seem like a large amount of weight per rafter. I'm just trying to find the best solution to this issue before we get too far ahead. Thanks.

Hi. I've just started framing my roof with a carpenter friend. The way that he frames roofs with steel ridges is to bolt timbers into the web, flush cut the rafters, tie the rafters together with bolts into a cross section and then nails long legged joist hangers under the cross section below the steel. He believes this is stronger and it is more cost effective than angled rafter hangers. His preferred method is to cut the rafters to sit on top of the steels, but as I'm doing a warm roof and I don't want to add any extra height above the ridge, this is the other method. Is this something people have seen before?

I am in the process of framing my roof on an ICF construction. I used UB steels for the ridges and 10mm flitch beams for the valleys and hip. The rafters will be 8x2s filled with mineral wool and 150mm PIR on top to create a warm roof. It will be slightly cheaper than raised tie trusses because I'll be doing it with a chippie friend. Loft trusses lost me 2m on the width of the rooms and raised tie trusses lost head height. If the cost is roughly the same, I'd go with steels and a cut roof, you can then maximise the area of the loft.

I didn't have any detailed drawings or any other details. I have had SAP calculations completed, so would the info I need be in there?

I've got somebody coming on the weekend to do a heat loss calculation and let me know exactly what I need. Thanks for all the advice.

I've had the SAP calculations done, but not heat loss, I'll look into it. The property is an ICF build. I'm just about to start framing the roof and will have doors and windows fitted soon as well. I'll bo doing a warm roof with 150mm PIR on top and mineral wool in between 8x2 rafters.

Hi. I am trying to get some info on installing a ASHP on a new build. I have just spoken with a company and they have suggested a twin 16kw-8kw with a 400l water tank. The floor area is roughly 350m2 over 3 floors. A friend who is a heating engineer (but doesn't have much experience with ASHP) advised installing UF heating as it runs off a much lower temperature to radiators and also combine it with solar (so in theory heating and hot water would very cheap). I don't really have a clue about heat pumps and solar at the moment, but will educate myself on both. I just wanted to check if these are actually worth installing as another person said it will take him a very long time to recoup the cost of it. Thanks.

Ok, thanks. So it's probably not going to give enough energy for year round living. I was also planning on installing an ASHP and underfloor heating. Would solar be good enough to run the ASHP for heating and hot water? I would then have mains electric for everything else.

Hi. I am just about to start framing the roof and up until now, the plan was to install a gas boiler for heating the property and also the hot water cylinder. I am now thinking of installing solar and I'm wondering if it's actually possible to use solar without mains electric to run everything in the property. Can somebody tell me if this can be achieved? Thanks.

Thanks.

Thanks. I have two areas of my property that needs cladding with timber. How much was it and where did you buy it from?