JohnW

This door threshold detail provided by our Architect appears to have a major cold bridge in the form of the pre-cast concrete threshold. Can anyone suggest an amendment to the detail to remove/reduce the cold bridge? Thanks John

@dpmiller this sounds very similar to what we're thinking of designing into our new house... We're thinking of having a kitchen cabinet dedicated as a pantry/larder. If we can't purchase a suitable cabinet we'll line the inside of the door and two sides with 60mm of insulation. There will be an inlet vent in the floor and extract vent at high level. The door from the kitchen will be air-tight and when the door is closed an extract fan will automatically run for a minute or two, drawing external air in through the floor level vent and expelling warm/moist out the high level vent. Do any of you see any flaws in this plan or know of kitchen cabinets that can be purchased with air-tight doors and insulation? Thanks John

Thanks @Stones fair point about the lack of cooling.

Thanks @Stones, we're going through a phase of doubting our decision to go for a very similar setup to yours and this timely blog entry is not only very clear and informative but has gone a long way to settling any doubts we had. My only question would be, if mains gas had been available would your chosen solution have looked any different?

Hi, I'm interested in a resolution for this problem too...mind if I PM you?

Thanks for all the replies - seems that the general consensus is that if we do not turn heat on upstairs (not brave enough to have no heating upstairs) the ambient heat from downstairs (via MVHR or rising heat) will be good enough to heat upstairs to 2-3 degrees lower than downstairs which is exactly what we want.

Hi I've been reading a lot of very informative posts in the forum relating to UFH & MVHR and think it is the way I will go with our new build. However...one thing I am struggling with is that we like our bedrooms to be a few degrees cooler than our living spaces, e.g. 21 in Kitchen/Living/Dining and 18 in upstairs bedrooms. Am I right in thinking that if we only have heat on downstairs, the MVHR will distribute some of that heat upstairs? If this is the case, in a well insulated, airtight house surely the temperature upstairs will eventually be the same as downstairs? Appreciate any advice, especially from anyone who has been living with MVHR. Thanks

Tile Tac Direct in Castlewellan seem very competitive - http://tiletacdirect.co.uk I know a couple of people who have used them and were happy with the price, service & quality.

that was my reaction too!!

Thanks @PeterW, I'm still very undecided about the whole airtightness thing, based on our windows being opened frequently.

Thanks @Bitpipe, totally agree that having no heating upstairs would take a leap of faith, one unfortunately that I'm not prepared to take. My compromise will be probably be small radiators upstairs and either electric or wet UFH in the bathrooms.

Thanks @Redoctober, because timber joists move, will a screed floor above not crack?

Thanks @PeterW what is the purpose of the aluminium spreader plate?

Thanks @AliG this is something I will definitely look into as the space savings alone are attractive.

Thanks @jack

Thanks @Mr Punter

Thanks @jack - having no heating upstairs would be too brave a move for me. P.S. "...nipply in winter..." conjured up images I didn't really want to see at this early hour of the morning

Thanks @Bitpipe, we like our bedrooms cool. I'm interested in know why you put electric UFH in the bathrooms and not wet UFH, especially considering you have the wet towel rads. I appreciate your point about shopping wisely etc... I'm hoping the main contractor I choose will be open to ideas.

Thanks @Declan52, with teenage kids, I'm not sure that anything other than slabs will do it. It is an area that we can trim back if needed but it would be good to have slabs. Using the Kingspan ecobead website it seems that the following fully filled cavities give the corresponding U-values; 150mm - 0.20W/m2K 175mm - 0.18W/m2K and 200mm - 0.15W/m2K for a 200mm cavity. Which, would you say, is the best cost/benefit point? Yes, it's a 2 storey house with a very small roof space, about 1.7m at it's highest under the ridge. I've a family member who does spray foam insulation, so I'm hoping to get a good deal. Yes, internal walls will be wet plaster. Thanks for the BPC pointer - I'll check it out. UFH downstairs & rads upstairs is probably the way we will go. I'm amazed you know the ground in Newcastle - that's class, thanks. Realistically, I've no time and no experience in building, so it's best left to the professionals. We hope to use a main contractor to do almost everything, hence the focus on cost.

Thanks @Ferdinand all good points but as we'll be using a main contractor these options will be his.

Thanks @AliG, I think you hit the nail on the head when you said "...doubt they focused much on cost benefit of various points...", that is exactly what I'm trying to determine. In general I completely understand the benefits of low u-values & good airtightness, but at what cost, and how long it will take to recoup that cost based on the ongoing savings, i.e. return on investment? I'm trying to find that elusive balancing point. I will be using a main contractor and know that I will be limited in my options, but when it comes time to trim the price, I want to discard the right items.

This sounds interesting - have you any more information or links so I could explore this option? Our architect tells us that we would save approximately £10k if we did away with the MVHR. We are a family that frequently open windows in our current 20 year old house and I can see this continuing in the new house and can see all benefits of MVHR "going out the window". Therefore, if we decide to have no MVHR, I'm wondering is there a minimum airtightness level we should aim for or should we just let the builder build within the regulations i.e. 10m³/hr/m² ?

Thanks @ragg987, interesting to hear that you have very low u-values but still need heat on the upper floor. We are considering liquid screed for the ground floor and also UFH in slab as per @PeterWs suggestion. It seems that achieving very good airtightness is expensive along with the expense of the required MVHR system. We frequently have windows open in our current house which has poor insulation & airtightness.

Thanks @Ferdinand, I've asked some specific questions regarding upstairs UFH in the relevant sections and I appreciate that if the spec is good enough we may not need heating upstairs, however I'm more concerned with how I can reduce the cost of achieving that high spec or alternatively how I can reduce the high spec to acceptable levels.

Thanks @PeterW, I'm not sure about the UFH upstairs either to be honest, but it's what our energy consultant recommended. Considering the good U-Values in the floor, walls & roof what heating would you suggest for upstairs? The property will be approx. 200m².