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We have seen huge changes on site in the last couple of days. The SIPS team have worked very hard to keep things on track. I can't fault anything they have done. All the walls are in place now and we're waiting for the scaffolding to have the last lift built so the roof lift can happen, planned for early afternoon on Monday. Craning the roof panels into the assembly area. The small part of the L shape roof that goes over the master bedroom sitting waiting to be lifted. The front gable end is nearly completed. The rear elevation as seen from the lower part of the tiered garden. This is the veiw we'll get when driving in to the driveway. It gives a good view of the lounge and front door. Steico joists, a few steels and glulam beams for the ceiling of the first floor. The racking walls are waiting for covering. This leaves me with one or two sections of stud wall to install myself to complete the first floor layout. The master bedroom. We now have a view on what the vaulted ceiling is going to be like in here. The other side of the bedroom half round window, looking at the racking wall to support the far end of the purlin. Here's hoping the scaffolders will show up promptly on Monday morning having been allowed to go to the pub for the first time in an age!

I had a look in the manual and it might be more sophisticated..

I was speaking to a plumber about the oil-ashp hybrids the other day. Apparently the grant ones figure out what the most financially optimal source is to use based on heat pump CoP and delivered oil/electric price. They only use one or the other source at any one time. Other hybrids might work differently though.

My issue is HOW does that work? It would have to rely on the return temperature being very low, so the ASHP could heat it first then the oil boiler top it up. That would imply a very low flow velocity, which is exactly what an ASHP does not like. My concern is the ASHP would only end up working in the initial stages of heating and once up to temperature the oil burner would be doing it all. I would love to hear how these work in practice. Regarding which heat pumps to avoid. Just make sure it is INVERTER driven, so it can modulate it's power to the actual load.

What has put you off an air source heat pump? The price of oil, while cheap just now is too volatile for my liking. And they are noisy smelly things. I don't think anyone has ever explained how the hybrid combines ASHP / Oil boilers work. how do they handle the transition to ensure you are not just burning oil? It's hard enough finding someone that understands an ASHP, it must be harder finding someone that understands a particular make of hybrid.

Yep I know one ..! Newark Copper Cylinder will make whatever you want with whatever thickness insulation you ask for. Only reason I didn’t use them was because we got such a good deal via Cylinders2Go

So that gives even more possibilities, like he could re draw the boundaries between the 2 properties enabling you to square off the extension.

My main bedroom is downstairs and it works for us. I have another bedroom next door plus 2 larger rooms upstairs. Your going to be building a hopefully forever home so think long term. When mine where young you wanted them close now they are teenagers they are smelly, huffy, messy, noisy and generally a pain in the hole they can't be far enough away.

Not sure how editing works, so had to quote my post. Viessmann in their ASHP brochure indicate that their UVC is appropriate for heat pumps, but on the direct website they offer the OSO Delta Geocoil. The rating for their 300L tank is similar to the OSO, only the 200L & 160L have the A+. I believe that what makes an UVC more suited to heat pumps is the length of the internal coil. In the 200L OSO Delta Geocoil the primary heat exchanger surface area is 1.4m2, this is from UK manual. I could not yet find these details in the Viessmann UVC documentation.

I like ashp's, I like oil boilers but I fail to like the idea of combining the two systems together. Sounds like the control system could be a pain in the ass to mantain/repair further down the line. I would keep the system as simple as possible (although I have failed on that with our hybrid system). Have you seen the price of the vortex air unit?

Yep they do straight through pipes for Geberit frames.

I would agree with this. We have just installed an oso cylinder and the only bit of it that feels warm (with water at 65) is the hot water pipe coming out the back. The cylinder itself doesn't feel much above room temp.

Polar Energi don’t make heat pumps - they make cylinders. They use Panasonic ASHP external units. Both Mitsubishi and Panasonic are decent brands so either is fine.

Yes Boris isn’t known for being subtle But I thought by saying that it’s a good way to tell people they need to try and look after themselves

I’ve lost around 8lb during lockdown down. Might be down to weeks of working on my own, starting by carrying 140 sheets of plasterboard into the house, then moving them around the various rooms. Also we’ve cooked from scratch using fresh Ingredients. Mind you, we’ve drunk more!

@Meabh Kelly Mine was a “Kingspan “ unit (of the insulation industry) and the reason it was sold off was Kingspan decided not to go into the ASHP market after they launched it, however it is a re badged Carrier unit, and Carrier make millions of air con units and ASHP,s based in the USA. They have a good reputation in the industry. Mine had no warranty but it was still shrink wrapped on a pallet out of the factory so I thought it worth a punt. The only ones to avoid (I have heard) are the non induction ones coming out of China.

Interesting that on Marr this morning the head of the NHS said obese people were twice as likely to die from Covid if in intensive care.

I may be wrong but I think the hybrids are to boost the water delivered by the heat pump (fairly low) to “norm” DHW temps. However both @ProDave and myself heat with a heat pump to a temp of 48’ which is enough fir DHW (if you have a slightly larger tank) and way hot enough to blend down fir UFH or straight use with larger radiators. I paid £850 fir my ASHP on Ebay and fitted it myself, it’s only 4kW and we have a 3 bed detached house with “good” insulation levels copied from passive principles but not certified. I would never consider oil after having an ASHP.

They distribute via a long of different plumbing merchants so recommend going there, and likely get discount off list price: " There are many in your area HBS Heating & Bathroom Supplies, Tucker French, Beggs & Partners, James Hargreaves are all independent plumbing & heating merchants, alternatively PlumbCity, Plumbase, City Plumbing Supplies, Wolseley or Graham Plumbers Merchants who are all national plumbing & heating merchant chains to name just a few." In the end it makes much more sense for me to purchase it via the guy installing the ASHP too, as that way I'll pay 5% VAT rather than 20%. Happily I'd already gone through all the details with OSO sales office, so when my ASHP guy contacted them directly they already knew the project and what I wanted so put him straight onto a preferred merchant who they knew would do a good prices and arrange delivery direct to site. All done via sales.uk@oso-hotwater.co.uk, super helpful folks. I'll of course withhold final judgement until its installed and working, but so far I'm quietly optimistic this will be spot on for us.

I am willing to bet if you shop around, you will get an ASHP for no more than cost of an oil boiler plus oil tank plus fire valve plus oil pipe etc. Oil boiler needs (or at least should have) annual service. Just choose over sized low temp radiators upstairs or UFH upstairs, Or like many of us you might find with a well insulated house, no heating is needed upstairs.

Welcome! Before you plough into heating systems (which, as a NI native I know is close to everyone's heart) have you thought about modelling the performance of the house as a whole (including how it performs in summer), hot water requirements etc to understand what you actually need? If you're going for a good level of insulation you should think on airtightness and also ventilation strategies plus think about how much glazing you have, what the orientation is on the plot, natural and designed in shading etc. Risk is you could get uncomfortably warm when the sun is shining (even in spring / autumn) even it it's not that hot outside. Even in winter, you may not need as much heating as you think.

Hmmm -- it comes with 12 bales of warmcell as well, bit pricey, might try a cheeky offer once I have done the PHPP change to warmcell from current product to check all is well.

Welcome to THE forum for selfbuilders and like minded types. Our experience, still building in Kent, was to create a mood board, in our case a word document, into which we pasted dozens of images, furniture, interiors / exteriors / details from the web and photos we took out and about. We thinned this down and gave it to the architect as 'our sort of thing'. They then worked with that as their starting place. We have put a bedroom, with ensuite, downstairs as we are basically retired and we were wondering how long we would be able to climb stairs - however we put another upstairs and that will be our bedroom at the outset, the room downstairs will be our snug / guest room, albeit with a rather odd ensuite attached, complete with sofa bed. Our kids are grown up - well mostly, and live away so the extension we built at millstone manor is now largely empty - we have three bedrooms and a sitting room we don't use - how daft is that we now think. If I were going for a forever home I think I might just think about the tightest spot, when the kids were about 16/18 and create for that but working out how each of the spaces would be used once they are flown away. Eventually, one hopes, they will be back with partners & kids of their own so maybe those rooms will get used sometimes.

Lol that’s my problem I’m thinking probably too far ahead, I’ve us 1 foot in the grave already. My sister has her master bedroom downstairs too and always thought it was a good idea as I’ve had a few knee injuries and had to move into my parents house a few years back for the downstairs bedroom. As you said this is our forever home so don’t want to have to do renovations down the line. I’m itching to see other plans with a similar floor plan with good use of space so we can go with a clear plan and not be swayed.

They don't really communicate like normal people. All you get is grunts or doing tic toks.

No the calculation is for all perimeter walls for the void so you 12 vents overall.

The point is, if he wants the extension as wide as possible this should have been agreed with the neighbour first and the fence taken down to facilitate that. If the neighbour chooses not to put the fence back he could gain a few inches of garden for his good will.

How do you intend tying the new bit of concrete into the original bit, I wouldn’t be happy just pouring a funny shape bit of concrete on the side. I would want it all tied into the original pour.

60 minute fire protection assuming its two layers .? If not then it is 30 minute with a single layer.

That is tiny - in the Telford HP UVC Range it is 3.3sqm as standard.

And not by coincidence, these are exactly two makes of car that are constantly in the local crime reports for getting stolen off of driveways. Seems pretty common around here for the big houses to have (at least) one of each so the organised crime units seem to treat them as "nick one, nick another free" opportunities. The BMW and range rover security is so bad you have to figure it's by design as this way they sell more from all the insurance claims.

I’ve found an ‘A+’ rated UVC. Vitocell 300-V 200, seems a bit pricey compared to the OSO and Panasonic, also not appropriate for ASHP. As far as I can see as it does not have the longer internal coil. The 200L model has a standing heat loss of 0.75, which is better the the Sunamp UniQ9, which is their 200L equivalent. https://viessmanndirect.co.uk/Catalogue/Commercial-Cylinders/Vitocell-300-V-Type-EVIA-A-Single-Coil/Vitocell-300-V-200-litre-EVIA-A-White-Z016794

If it’s nothing complicated find a local architectural technician, I paid £20 per hour.

Just remember that most breakers are not double pole - you really should be isolating both live and neutral.

As a roofer I completed a GRP course, one day and about £90. Was brilliant and you can then attain a warranty on the installed roof, its not hard, but there are a few tricks of the trade. The course I did was through Sentinel, you can even view their manual online which is very useful https://www.sentinelgrp.co.uk/assets/sentinela5installationguide2018.pdf As said before, keep your boards dry and make sure you get your resin mix right, if you are struggling with the weather then roll out a thin coat of resin over the boards as soon as they are down as this will stop them from getting properly wet. Even if it rains they are easily dried. One thing to mention...don't use ply the resin doesn't properly bond to it and will eventually delaminate. Only OSB should be used under GRP roofs. If you have any questions I will try and help out.

My advice (slightly off topic) would be to look away from scotframe. Its a circa 25% markup using them compared with others. Fleming homes (located in the borders) seemed to offer a very competitive price when compared to scotframe. As a background to the above... I'm located in Scotland and at the final stages just about to select a supplier for my kit currently between SIPS ECO (sips kit obviously) and fleming homes for their factory insulated TF kit. Either kit will be finished with render board and render mounted in batons to provide my external cover. I did weigh up block and render as that seemed more 'sturdy' but...it added cost to the insulated foundation for an extra ring beam..and I can't be doing with relying on brickies turning up and at ridiculous rates and having a messy wet trade. I'm aiming towards high levels of airtightness and insulation but not to passivhaus levels (budget driven). I'm also going for an insulated raft foundation semi DIY. Save yourself time and just look at Kores foundation system. Half the cost of others out there for me such as isoquick and izodom. From under your render board down to cover your insulated foundation edge you would use cem-rock I believe. That's what kore says and shows on their wall buildup. See attached. Hope this helps Kore IFS Standard Details Rev 4-TF_46.pdf

So for a small building, your 100mm concrete is fine if it’s timber framed. The issue is the insulation and as what @Russell griffiths says, it is not fully insulating the floor. I would keep the insulation for now, cast the slab 50mm lower (ie without the insulation) and then double up the sole plate with a second 50mm tanalised beam and drop the insulation inside this. It won’t be “warm” floor but it will at least insulate the whole internal floor.

I would remove the insulation, without it forming a fully insulated slab it will do nothing to help heat loss i would get a concrete slab down and then build your building and then insulation on top of your concrete and put a floating timber floor on top of that. Pictures would help, don’t worry we won’t bite, much.

This question has been asked a lot regarding services and slabs. I wonder if we could get a list of all the things to go in before the concrete is poured, and keep it somewhere on the site as a reference guide. @AnonymousBosch because I know your not that busy really.

To get a draw string through I favour a square of plastic bag with a small hole in the centre. I thread a string through and knot / tape it back to the bag. I then form it into a sort of cone and insert in one end of the pipe. Then attach the vac the other end with some duct tape to make a seal. Job done.

You been on the pop again!

You'll need to get a design SAP done for Building Control so that'll be a useful bit of modelling.