Iceverge

This is completely bonkers. It's not as if it's ye olde wall Henry VIII boinked an fluttering milkmaid against. Someone needs to challenge this legally.

I'm not a massive fan of internally insulating with PIR. (I guess this is what you meant rather than polyurethane). It keeps the timber too cold IMO and the end of your first floor joists will be cold. You could put the PIR outside the frame like they do in the state's. Have you considered just using a 220mm stud full of cellulose and a battened insulated service cavity? Putting PIR inside studs is a PITA, ask @Thorfun

What is the spec of your TF wall? It can be relatively easy with TF to make pretty much thermal bridge free foundations. Depending on the layout of the building it may be possible to eliminate all load bearing internal walls. This means that all internal walls won't bridge to the ground. 2020 prices but our 114m2 base cost €16226+VAT vs an insulated slab at €20300.

Strip foundations can be made to work too. About 5k cheaper for us but we're lucky with our ground conditions and blocklayers were cheaper 4 years ago. Although UFH has been proven to be robust there's nothing wrong with radiators in a well insulated house if you're suspicious of pipes burried in concrete. Otherwise I wouldn't go reinventing the wheel.

Maybe my terminology is wrong. I meant the ones outlined here. It rules out the idea of making a good job of external insulation as there'll be too many thermal bridges. With internal insulation you'll end up with a much smaller room or with external insulation you'll end up with a minimal improvement due to the aforementioned thermal bridges. A knock and rebuild, even of 3 walls and the roof might be worth considering. A small timber frame wouldn't break the bank. Otherwise some PIR inboard and foam tape all joints and 22mm battens for a service cavity. And then plasterboard. Some PIR on the floor and float 2 layers of OSB crossed glued and screwed over it. Get some dedicated ventilation in there too. Otherwise it'll be musty. Germany has more or less everything for sale s far as I can remember.

Play with that website @HughF linked. I'll really give you a good idea of what's possible and importantly the cost differences for all the options. For example a full height fixed window is cheaper than a door with a sidelight, is cheaper than a french door, is cheaper than a slider, is cheaper than bi-folds. Amusingly the cheapest is best thermally too in this scenario. Don't rule out good quality uPVC. My parents have 10 German made white UPVC 2g windows since 1985 and they're going strong apart from one broken hinge that needs fixing, a bust door lock, and two failed 2g units. Zero maintainence in that time otherwise. Also pay attention to the lentils and thresholds. These details can add up.

I get how it's important to have the same look of building as essentially the countryside will remain unchanged aesthetically but from a building science its raving lunicy. Agri buildings are always very budget constrained and mostly planned with a lifespan of only a few decades. They don't have the structural margins required of domestic houses and are often made from carcinogenic materials like asbestos and creosote. Add to this the possibility of zoological diseases from old mould spores and animal waste I would favour taking some accurate measurements, before bulldozing the entire thing. "National Heritage" is not something that will suffer if someone takes a 1980's cow shed and replaces it with an exact replica.

Welcome @vagrantly3893. I've been studying the pics and not coming up much the wiser as to the layout. Can you provide a quick sketch as to what are internal and external walls etc? Also any abutting walls. The structure looks a little like my standard of blockwork...... Might it be worth just starting from scratch? You're on continental Europe also I'm guessing? ( Plug sockets + bricks) Are you familiar with the range of products available in your local builders merchants? No point in specifing materials that are not available.

Not to worry you can still make it work. We have a cold loft and it works fine. 1. Lay a wide strip of VCL on top of all the internal wall plates (if you have any) pre roof commencing. You don't want to end up trying to seal around roof timbers where they rest on internal walls. 2. Make sure that any of the internal walls without wall plates have enough space to pull a VCL through. say 25mm, also it'll make the sparkys life easy. ( easy job = non damaged VCL) 3. Apply VCL to the bottom of the ceiling joists. and return to the external walls. 4. Put 22*70mm battens below it to create a service void. Run them at 90deg to the ceiling joists so you can run wires easily. 5. Put 2 layers of standard plasterboard for noise, staggered and sealed to external walls. 6. Install MVHR plenums after the VCL and tape as appropriate. 7. Forget the airtight box in the loft. Make something like a base of timber suspended on wires or a platform on isolating rubber feet for the MVHR to sit on. put the upstairs MVHR manifolds on the floor of the loft and run your ducts from there. Cover the whole lot of the ducting in insulation. Wrap the MVHR unit if it isn't insulated already (many are) and insulate all exposed ducting with flexible foil backed mineral wool and tape. 8. Run 2 large ducts through your airtight layer to the downstairs and host your manifolds somewhere along the line. Sealing around ten to twenty ducts would be a total pain and they will need to be spaced out lots to do it properly. 2 large ones would be easy. 9. Substitute a sheet of OSB for the VCL above a suitable cupboard for all the wires that have to go in the attic We had 5. In hindsight just the TV aerial would have been needed. Get the electrician to drill ONE small hole for ONE wire and you can seal afterwards with sealant/tape. 10. If you can afford a blown cellulose insulation or mineral wool it'll cover the ducting much easier. Cellulose is my fave, helps airtightness, good for heat protection, noise, non itchy etc etc etc. 11. Otherwise consider something denser like Rockwool which will help with sound proofing too. Any questions just ask.

Is it permitted to level it and start from scratch with a new TF that would match exactly the old building?

I'd have thought a steel portal frame and insulated panels would have been the cheapest as well as being very fast. It depends on the preferred design aesthetic I suppose. I do like glulam however but I seem to remember it being dearer than steel.

You could just use a polythene sheet. Lightly to tear if not treated well. I would spring for something with some reinforcement involved. Not terrible dear either. Have you abandoned the warm loft idea?

Minimum risk however as it is on the warm side of the insulation and everything is breathable outboard. Most damage occurs anyway I thought when vapour is carried through air leaks rather than diffusion.

Yup, just standard blocks on their side.

We have 215mm blockwork with 20mm wet plaster on both sides between our living rooms and some of the bedrooms. You can't hear anything through them.

I'm guessing at the joist spacing here and sizes. If you run 50mm battens at 90deg under the main joists (can't show it here) and then some 50mm insulation in-between it'll eliminate most of the repeating bridging. Make sure the membrane is well taped as this will be a windy corner and you don't want wind blowing into your floor. 22mm airgap and then cement boards. It'll be a good spec. If you use denser batts like Rockwool it'll make a difference with noise for the room above too.

That looks like external insulation?

I've come to the conclusion that bagless vacuums are rubbish, especially Dysons. The filters get clogged very fast and a 99 year old asthmatic smoker would have more suck. There's always a terrible mess when you go to remove the dust inside. Then we got a Meile C3. THE THING IS AWESOME. Off brand bags are less than £1.

@richo106 It can be any width you want. Have a look at the video I sent, it might be clearer than explaining it.

For air tightness use a 600 mm strip of DPC under the wall plate on the inner leaf. Mesh it and plaster into your inner airtightness layer on the blockwork. Then wrap it around the end of your rafters and tape it to the top of the ply. Tape all the ply deck together and you'll have a really robust airtight layer and simple to execute.

If you can draw it you can build it! Here a quick sketch I did. Just attach some rafter tails on top of the rafters and fit the PIR around them. Your builder is a sadist if they think it's a good idea to put PIR between rafters!! Matt shows how to do it here.

Slightly different as you will need battens to hold the tiles and can do without the top layer or ply/osb. You would need to ventilate behind the tiles also. Do you have a cut roof or a trussed roof? Have you many overhanging eaves/gables etc? In fact do you have any drawings of the roof as planned?

There's mis match of terminology here unfortunately that regularly gets confused. A "warm roof" has the insulation above the rafters. This will naturally result in a "warm loft" where the attic space is inside the conditioned space of the house. This can also be done with a "hybird roof" (insulation above and between rafters ) or insulation between and below the rafters. (sometimes called a "cold roof") A "cold loft" is naturally where the entire cold loft is cold and all the insulation is placed above the ceiling. In your situation I suspect you are better off with a "Warm Loft" You just need to decide on a 1. Warm Roof 2. Hybrid Roof 3. Cold Roof

If you use something like caberdeck flooring over the joists and are careful to glue all the joints with foaming glue this will do fine as a VCL. Use a flexible mastic at the perimeter. If you want to be belt and braces make an insulated service under the caberdeck and then a taped VCL.

It's a top idea, every room in a house with pipes should have one I think. Consider an airless trap as a wet one will dry out quickly with no regular filling.