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That's sounds the same as my external Egger DHF layer. I do have a "breather" membrane on this, trapped under the cladding batons, which protects the sheathing from weather in the short-term, until the cladding and roof finishes are on, and continues to protect in the long term in case any water breeches the rain-screen.

I don't have a distinct VCL membrane in my build-up. I have foil-backed plasterboard that restricts moisture entering the wall/roof. Unlike your air-tightness layer, the VCL can have small gaps and breaks, as long as each layer towards the exterior has a higher vapour permeability than the one before. Just for good measure, I also don't have a distinct air tightness membrane. My frame is externally sheathed with T&G Egger DHF board that has a non-curing butyl adhesive in all joints, which is the air-tight layer.

I believe the advice is not to plant a vegetable patch or fruit trees over, but as long as you are not consuming anything grown over the area you can plant what you like, incl. lawn. Assuming you haven't got a very high water table, where a drainage field would not be appropriate, it won't be boggy. I don't believe you could install in such a way that it would be OK to drive over.

For me, the visible fixings are a compromise, on a residential building, but would be less noticeable within a strong industrial/agricultural aesthetic. Acoustically, they are poor, for both blocking external noise coming into the building as well as rain noise. Difficult to incorporate roof lights. While they have OK airtightness across the continuous roof and there are solutions for continuity to walls that are clad with the same product, some careful detailing is required to the walls if you plan different wall construction. You may wish to mitigate some of those compromises with internal ceiling/wall studwork, plasterboard and perhaps acoustic insulation, but this needs to be balanced with what additional weight the SE can accommodate through the portal frame. If the SE starts wanting any new structure to take the loads down to ground floor level via load bearing walls then you may as well build that structure to carry the thermal insulation that doesn't carry the compromises. The SE would also need to satisfy themselves that the existing slab was capable of taking the loads. Is there a ring beam, for instance, already incorporated into the existing slab and are the reinforcing steels of known size? If there are existing heavy (masonry) external walls to the barn/shed, that aren't showing any movement, then that should give the SE some confidence.

You need to go though all the "Application for approval of details reserved by condition" and check all the conditions of the outline planning are resolved. There's lots of planning history including a couple of Appeals (one lost, one won) It does look like it could be all in order, but some reading is required. https://publicaccess.westberks.gov.uk/online-applications/propertyDetails.do?activeTab=relatedCases&keyVal=000QKS00LI000

I'm not suggesting the pads will need under-pinning, just that the condition of the uprights is checked where they join their pads. As long as there are no signs of movement, the pads should be capable of continuing to hold the frame up, as long as you don't plan to increase the loads through the uprights with a new mezzanine or substantially heavier roof. Your conundrum is how to support the insulation for the roof without overloading the existing structure. There are insulated profile sheeting panels from Kingspan that are light weight and maybe able to go straight on to the existing (or replacement) purlins, but they do come with compromises. When I did mine I tried to avoid the compromises and built a new timber structure inside the existing portal frame that was filled with blown cellulose fibre insulation. The timber frame structure took the new loads straight down to the new insulated raft foundation and not through the portal frame. The portal frame remains in place holding up a light weight rain screen (standing seam aluminium roof in my case). It would have been cheaper to have removed the portal frame, but 8 years ago the LPA would not entertain a knock down and rebuild, so I had to retain the superfluous steel portal frame. Surprisingly cheap, although I wouldn't be sure how much a today's prices. Two people with a 5T excavator, pecker and a dumper will have it out and levelled in under two weeks. If you've got some hardstanding to do then crush the concrete on site to use later. There will still be perhaps 100T to muck-away (or loose in a corner of a field if you have land) as you won't be able to reuse the hardcore that the existing slab is sitting on. Taking the existing slab out then allows you to put in an engineered insulated raft that can be spec'd to take whatever loads you want to put through it, drop the finished floor level if need be (accepting that you may need to detail the raft around the existing pad foundations) and putting the new drainage in will be an easier task.

Assuming the permission is for a Change of Use Conversion, then no. But some LPA's will allow a CoU to be used as a fall-back for a New Build application, and that has to be the better option for all concerned if the primary frame of the existing building has no architectural or historic merit.

Welcome @seano Ideally you'll want 200mm of PIR insulation so that the UFH is efficient. Regs will allow you to drop lower, but I'll let others say by how much as I've not looked at this since the U Values were recently changed. But, a few questions first. Do you own the barn? have you had a good look at the levels of the floor and the condition of the bottoms of the portal frame? Agricultural barns/sheds will typically have a fall on their slabs. If it was built for animals then it could be quite significant for draining slurry. My own had a 200mm fall from one end to the other. Often the base of the portal uprights, which are likely bolted to a foundation pad, are then concreted over when the slab gets poured. It can trap water, or worse, slurry, that can corrode steel columns, or the reinforcement of concrete columns. It may be worth considering taking the existing slab out, and digging a bit lower to install an new insulated raft foundation.

I don't personally believe Kingspan or any PIR/PUR insulation is a particularly good option with a TF either, especially with with a light-weight rain screen. For a timber-frame construction I'd only consider either as a larsen truss (twin-stud) or an I-Joist structure filled up with an insulation that gives a better decrement delay than PIR/PUR/EPS, such as a blown cellulose fibre. They offer better performance at similar costs, and less potential downsides. What are you perceiving as "simplicity" with regards to a SIPs structure? Is it being able to package up the build as a kit for a 3rd party to have responsibility to erect? The same is available for a twin-stud build, or for an I-Joist structure it can be built on site with traditional carpentry skills and no need for any cranes etc.

Congratulations. Now the fun begins. Why SIPs, have you considered other build methods? I can see the advantage of SIPs to volume builders, combining them with a masonry skin, but I feel there are better options for the self-builder. I can understand that, but it's worth making sure you've considered all options for the big decisions.

There's not one solution that works for all houses, you need to give some thought to how your house will react to dynamic factors, especially solar gain. While you can set up an UFH system to work off a single thermostat and manually set flow rates to stabilise temps room-to-room at roughly what you want them to be, if your house benefits from, say, solar gain, that's going to mess up all your manual settings and some rooms will then overheat and depending on where the thermostat is it may switch the heating off where other rooms are not at their target temperature. A multi-zone setup with electronically controlled actuators really works for me. For heating days where there's only enough solar gain to heat the rooms directly receiving it, then the UFH is shut down to those rooms and just heat the rooms on the North-East and North-West side of the house. A PassivHaus that can maximise its solar gain easily compensates for the loss of a couple of tenths of COP that a buffer/volumiser may incur.

That will put holes in your socks... Ours was power-floated to get it level and smooth, but it's only smooth compared to tamped concrete. Cracks were less visible in the power-float finish, but got more visible as we lightly ground the surface in the prep for the poured resin.

Yes, we went with tiled, but could have done poured resin. You've got a tricky interface between a tray and the slab if you're not putting any finish on the slab. We initially wanted polished concrete in other areas, but the slab engineer wouldn't accept any curring product in the mix to help with cracking, so we decided on poured resin in the living areas. We would have had quite a few visible surface cracks if we'd gone polished concrete.

There's no screed on mine either. It's a Insulated raft. We were between tiles and a poured resin (which we have elsewhere) in the bathrooms. For poured resin we would have needed to skim coat (with an epoxy mortar) the slope that had been cut into the slab, to get it back to smooth, and to overlap the linear drain.

If the building has come into Agricultural Use after 20th March 2013, then unfortunately you'll have to wait 10 years after the date on which it came into Agricultural Use, before it is eligible for Class Q conversion. The other issue you may have is that just keeping farm animals doesn't cross the threshold for "Agricultural". The building must be part of (or was previously part of) an "established Agricultural Unit". As such, it needs to have been a working farm. That tends to be interpreted as able to sustain a farm worker that is earning the majority of their income from the farm.

You can avoid a tray and cut the slope into the slab, and then tank and tile. The 110mm waste will give you a +/- 50mm tolerance as you can fit a 110/50 offset adapter that you can then rotate into any position to move the drain coupling left or right. I used a linear drain like this, with an integral trap and a 50mm outlet. It's not rodable, but has a strainer at the top that doesn't let anything significant through. I've got 4 showers set up like this, and after 5 years is a really robust solution.

When was the building last used, and what was it used for? Has it ever been part of a commercial farm? If it's last used was equestrian, then as that's not Agricultural, it's unlikely to qualify for a Class Q conversion.

Your heat pump should have a minimum distance from a wall. Orientated "back to the wall" so blowing away from the house, mine had to be a minimum 150mm from the wall, which seems really tight. I went with a position where the ASHP is 500 from the wall, and brought the pipes up in between it and the wall, towards one end. I also went with the Ø32 twin pipe in a Ø150 duct (Rauvitherm from Rehau). From memory it was an R750 bend radii, so the trench does need to be quite deep. Penetrations through the raft should come through perpendicular, so my trench was at least 750mm under the bottom layer of EPS. My ASHP states Ø22 Min for the flow and return pipes. The installers wanted the Ø32, and as I have a longer route than ideal to the UVC and Buffer, I was happy to go with it. I placed the pad for the ASHP after the pipes were installed, so no issue with pipe positioning on the outside. Within the house, it depends on your construction method and how flexible it is to accommodate out of position services, but that does for all penetrations, not just the ASHP. Foul drains to toilets and showers gave me the biggest head aches as the tend to be close to a wall so more of an issue if they are 50mm out of position.

Looks very nice. But that South facing glazing is going to be an issue. I'm assuming there are good views, so you're going to want to keep the glass and mitigate it as best you can.

Mine came as a frame package with Touchwood Homes, so Touchwood "introduced" CTD to me and I worked with them and Touchwood to develop the Frame. Touchwood then took delivery of the frame at my site and erected it on the insulated raft I'd contracted separately with AFT. CTD, Touchwood and AFT were all first class. There's a few image of my frame in the following thread. I believe there was an option to pay a bit more for delivery on smaller vehicles, but my frame was delivered on a couple of artics. I knew they wouldn't be able to get up my track, so they parked in a layby opposite and we unloaded with a loadall.

Ah, OK, I got a quote from TSD also, but profiles were a bit different to yours, but it was 7 or 8 years ago now.

Yeah, who designed/Engineered it. There's more and more people offering them and I don't recognise the former profiles, so am "just interested".

Looks to me that with the narrow 50mm of EPS under the threshold, yours would benefit from the higher U Value that I assume Phonotherm has, over GRP, to minimise the thermal bridge. Your EPS former also angles down at 45° on its inner wall, from the threshold, so an L profile would leave a small void. I'd stay as specified. Assuming it needs to be in place before the pour, I guess it needs sticking to the EPS to stop it floating away? Can I ask whose raft that is?

I do remember reading the PH principles of Thermal Comfort, and avoiding drafts through differential temps, but iirc that was with regards to convection currents caused by any of the inner surface of the thermal envelope being more than a few degrees lower than ambient (3.5°C is the delta I remember). As I remember the cooling air drops to the floor and moves away from the exterior wall, causing a draft. For a delta under 3.5°C the drafts should be imperceptible. I believe it's a key part of the PH Certification of windows, ie. not just their U values, but also the thermal bridge Psi values for the frame. I don't believe rooms at different temps would cause the same issue, at least, not once temps are stable.

I take it your threshold is over the EPS upstand? and the suggestion is to recess the EPS and lay the Phonotherm over to spread the load? I used a GRP "L" profile, and yes, added screws to the "L" Pofile that were then captured in the slab when poured. Like this: