Iceverge

And Worked the best for me on threaded fittings. Scrape the thread with hacksaw roughen it. Wind on appropriate amount of hemp. Butter on jointing compound and tighten. You tube told me PTFE was just a lubricant for tapered threads. 🤷‍♂️ Then again youtube regularly gives me advice that would see me dead and bankrupt in days.

About 15m was the longest one via some sweeping bends. From memory about 30m³/HR was the rate I planned for it.

I've just installed a vented thermal store for my parents. It's working well so far. Balanced pressurised hot and cold is vastly superior to gravity fed. For your situation it might be simpler and cheaper to install an exhaust source heat pump like @Thedreamer if you have much pipework to revisit. Use the immersion via solar in the summer and the heat pump to harvest excess heat from the stove in the winter at a COP in excess of 3.

Yikes, we used 75/63mm ducts everywhere on a suck it and see basis apart from the kitchen which is doubled. Seems to work fine.

@Space Race Is there any way you can get a look inside the walls? At meter boxes, broken plasterboard etc? If not perhaps just measure the overall thickness of the wall as accuratly as you can at a window or door opening. I hadn't thought of it as @Gus Potter suggested. A solid walled house with a TF inside just to provide insulation. These days the TF takes the loads of the house and the blockwork is largely there as a rainscreen. For my own interest I put the original spec into Ubakus for a gander. It's unlightly to perform anywhere near this as the aeroboard is unlightly to be a tight fit. If you were to go room by room refurbing, pull out the EPS, and replace with PIR cut and foam in place. Then add a taped vapour membrane. Then a 45x45mm counter battened service cavity with 0.035W/mK mineral wool infill and 15mm plasterboard You could have something like this. Much more respectable in comfort and energy terms. Tons of work however.

Ok how about something like this. For the walls from the outside in. 70mm log construction. Chicken mesh stapled to the inner surface to prevent moisture being sandwiched between PIR and timber and to stop any water moving via capillary action. 50mm pir screwed through to the logs. Vapour barrier taped to all edges or PIR boards diligently taped together. 45x47mm battens with 50mm mineral wool 0.032W/mK infill. Good as a service cavity also and no drilling of logs. Plasterboard. Total thickness about 180mm including logs. U value about 0.25W/mK Roof construction sounds fine so long as you are diligent to ensure the vapour barrier is continuous from the walls to the roof. Assuming it is well orientated (south facing) it should need almost zero heating if it is small and you install MVHR.

Ok I think I know where you're at. You've bought something like the below off the shelf. It needs a base and a roof and you're planning on a thermal upgrade to boot?

Do you have many electrics? Do you want them hidden or are you happy with conduits on the surface? Have you considered insulated roofing panels instead of a flat roof? It may be less labour?

How on earth are they justifying a 3m stack?

@MattMiller It sounds like a whole chunk of heartache. What will your budget allow? Can you provide any pics of the outside structure etc? In the short term I would get a dehumidifiers and let it in there 24/7 and stop bathing/showering too if possible. You need to stop putting any more moisture into the structure ASAP. What kind of ceiling height do you have to play with internally? Maybe there's a cheaper solution than stripping the roof and starting from scratch.

Unless you have an enormous volume of air or the alley is severely enclosed it should be fine. Hard to say without seeing it. Any chance you have a section through the build showing the alley and dimentions?

Can we dig into this? Various trades onsite and designers can be all too happy to solve their problems by doing the easy thing and shoving the problem to the next guy. Do you have any plans + pics to post and maybe the collective here could come up with some clever ideas for routing the MVHR? Rectangular ducting, combined external terminals etc all offer flexibility that your MVHR designers may not be aware of. Avoid holes in the roof if possible!!

It's there to ensure the airflow to allow the framing to dry to the outside. I think 50mm is normally specced as a minimum with external clockwork just to give a greater allowance for any mortar droppings. 25mm is fine from a ventilator perspective and it is lightly any big problems would already have made themselves know. 215 block externally may have been the originals plan. As the timber frame has no sheathing it's possible the engineer was counting on the external wall for racking strength. Maybe @Gus Potter would be more knowledgeable. As for insulation like @ProDavesays insulated plasterboard is probably the easiest win. Worth costing this I would say.

Have you an unvented DHW system or an open vented one?

Is it for hanging shelves etc from? 9mm is a bit thin IMO. You might save yourself a lot of money and Hassle using batt insulation between the studs than cutting PIR too

Holy Moly!!! Congratulations and welcome! This is not a project for the faint of heart but a very interesting one. Step 1. Deal with the water. Fix the roof. Did all around the walls right down to the foundations (carefully with a small digger) and install a french drain. Step 2. Obviously make it liveable you will need to do some serious insulating. As the external has such lovely stonework and proximate buildings I would suggest internal insulation. Two choices here. Breathable insulation stuck to the inside of the walls or a box within a box. Given you have no shortage of floor space I'd go for the latter. Here's a nice project for inspiration. https://www.greenbuildingstore.co.uk/technical-resource/cre8-barn-stirley-farm-enerphit/

Do you have a laser level? I did my garage with a cheap one from Lidl. Just attach it at one side of the site onto something solid that won't move. Use a story pole ( like a 3x2" stick) to take a measurement of a known height (eg the floor) and hey presto you can transfer all heights around the site.

With that budget I'd consider EWI. Then all the interstitial problems go away. Also it is important that you have a proper ventilation strategy. Suckling out or blowing in continuously at a small volume. It'll really help control moisture in the house.

What kind of joists are you using?

One should always include a set amount of typos, spelling and grammatical errors. It lays a ready trap for the deviants to expose themselves.....😁

Maybe start a new topic with a request for a trusted roofer in the area you are hoping to move to. There's a big network of folk here. They can reply by PM too if preferred. There's a chunk of me that thinks you could probably just build a proper apex if you were on good terms with the neighbours and planning would never bother you. Either way a fiberglass cap would work fine too.

Do the sums on an A2A split unit for the lions share of the heating. Maybe topped up locally by a few electric rads. You sound like you have a similar heat load to us and I think it's the way forward. Have you considered switchable ducting on the ESHP ? It could be useful to cool the house during heatwaves if you extract and flow to inside the thermal envelope. Noise may need to be considered however. At 10mm and 3bar we see 5-6 l/min at the hot tap. A 15mm cold pipe to the same tap is 10 l/min. It's a 13m run and time to hot is about 9 seconds to hot. It works for us as the reduction in wasted hot water balances out the lower flow. I did attach the hot manifold vertically to the top of the tank which preheats the water before it gets in the pipe. I recently used 10mm for replumbing my parents house for everything except the bath and showers and cold taps in the kitchen. Its very easy to cable through tight spaces, almost like a wire, and does the toilets fine in my experience. Similar trick with the manifold from the thermal store. It isn't as fast as a hot return for the one distant basin but for the sake of a 5-10 second wait it isn't worth the hassle I think.

Deary me, It's an inherently compromised design, but not beyond salvage. Nothing is really it's just a matter of cost. I would advise getting a your own roofer to have a good poke at the timbers in the roof and existing construction. It may be a couple of hours labour out of your pocket for their time but it will be well worth it to have an independent quote. It may be a simple fix of initially unblocking the gully and then later fiber glassing a new ridge or taking the roof to an apex and putting a proper ridge on it. Worst case the roof timbers are rotten, the whole thing needs to come off. Then you're in a position to negotiate something on the price or walk away.

I wonder is this a factor also. I don't think they would perform well where wind-tightness isn't done well.

Managed to get this done just before Christmas. Used a 250l Maxipod from copper industries . Not cheap at about €2k but it seems to be well made and has a 25 year guarantee. I installed a new galvanised tank in the attic as a header tank, this leaked at a corner but I plugged it with a small bit of silicone. I was keen to avoid any joints in the pipes, especially in inaccessible areas so it looks a bit messy where I've curved them into the ceiling space etc. As I was limited on time and skills I didn't want to pull down any ceilings or dig up floors. All pipes were routed behind cabinets etc except across one ceiling where I put them in conduit. I used Hep20 manifolds and a radial layout for the hot water with 10mm to the kitchen tap and all basins. It results in a very quick time to hot. About 6l/min at the kitchen tap which is fine. 15mm everywhere else and the flow rate is about 10l/min at the bath taps. Picked up a Triton mixer from Screwfix which works very well. In fact the DHW performance is as good as the UVC in our own house. I don't know how long the DHW lasts but it seemed to satisfy 5 adults over Christmas so it can't be too bad. The hot tap is fresh water also which is nice and there's no servicing as per UVC's etc. I think I may consider one when the SS cylinder in our own house gives in. The store is mainly heated by a Rayburn 355SFW burning a mix of soft and hardwoods on a thermosyphon/gravity circuit. It burns for about 12hrs a day so no shortage of input. I just used one pump for the CH which turns on when the bottom of the tank gets hot to circulate the water through the radiators. Thermosyphon is proportional to the temp difference between flow and return and height of the tank. I really had nowhere else to put the tank so it's base is only about 150mm above the top of the cooker and 2m horizontally away. This limits the amount of heat transfer we can get from the cooker so the rads typically never get much above lukewarm. This is fine as the long duration of burn has made the house very comfortable for the first time ever! The oil boiler is just on a timer and heats the tank directly. When the bottom of the tank is hot the CH pump kicks in on a thermostat. As the oil boiler is probably about 3 times more powerful than the cooker it has no problem with the rads but there is a lag between it coming on and heating the house, it has the benefit of heating the DHW proportion first however. Any other questions fire away.