IGP

Yeah I’d fully fill the depth of joists where you can, otherwise do what you can. In terms of breathing, using a breather membrane and breathable insulation like mineral wool should be fine. Any moisture can flow over time through the mineral wool and out through the breather membrane. I have around 0.8m from the bottom of the joists to the ground below. In terms of cost, it was around £700 excluding insulation (entire ground floor of my house). I bought the materials from Latzel in Germany (there’s a thread about it somewhere) and it’s massively cheaper for the Pro-Clima stuff. Knowing what I know now, I’d probably skip the Pro-Clima membranes for this job, and get the equivalent but cheaper elsewhere however the tapes and primers etc I would still absolutely recommend. I hope that helps

I’ve completed the ecological building systems method on my ground floor. Results are amazing, can walk on it bare foot when it’s -5 outside and be very comfortable.

Fixed the boost issue - stuck it into comfort mode. Edit - didn’t last long!

I’ve installed a Vent Axia sentinel FH in my 1930’s semi detached. Generally all good apart from when firing it up for the first time today, it always goes into boost mode and gives an ‘ls’ symbol when I press boost. Allegedly, the manual says this is because the live switched is making the unit boost, problem is there is nothing connected to the live switched terminal in the unit which is bamboozling me. Am I missing something obvious here? Also, the supply terminals are gushing air (as it’s in boost) but the extracts are a damp squib in comparison. I experimented just venting to the loft for a few minutes but no joy. And I accidentally connected the supply and extracts to the house the wrong way round and the extract terminals were gushing air (supplying) and the supply terminals was a damp squib for extract. So to me, that suggests that the all the ductwork is fine, possibly with the exception of the extract distribution box to the unit as I had to use some flexi ducts as a temporary solution. But given I literally moved them 10cm to swap them around on the spigots, it’s seems unlikely. Does this suggest the extract fan is a bit dodgy - assuming the ductwork is fine?

I would go option 1. It’s simple, effective and with EPS beads, unlikely to cause damp issues as the beads themselves cannot get soaked. You could always add IWI (or EWI???) later.

I’ve no doubt about the BBA certification for their wool installation. The problem I see with all blown wool insulation is that the wool will snag on the rough surface inside the cavity and wall ties with mortar snots and create voids on the lea side from where it is blown. This could create cold spots leading to all sorts of problems. Blown EPS beads on the other hand don’t do this and also don’t have capillary action to retain water, unlike wool and therefore can never get soaked themselves. Cavity batts for full-fill during construction however I can see could be superior to EPS for u-values, but that’s a different question.

EPS beads every time over blown in wool.

Local Heat Geek rated tradesman? https://www.heatgeek.com/find-a-heat-geek/

In fact, the pro-clima stuff while bomb-proof, I’d say you don’t need to bother membrane wise for the expense. Just use appropriate vapour checks and breathers in the right place. However the tapes and primers etc are top drawer and I’d highly recommend still using them.

Absolutely, I actually ran out of Solitex plus for the breather layer for the last room, so bought some standard roofing breather layer from screw fix and has done the job.

I hear compriband is considered top notch above any mastic sealants. Worth an investigate.

I’ve just done the ecological building system approach above, the floors are amazingly warm compared to before. I just had to be mindful of the attention to detail, some of the labourers did better jobs than others when it came to taping to the wall. If I found any loose tape or gaps, I’d foam (FM330) or Orcon F to get as good a result as I could.

Yes I buy it from Latzel in Germany, massively cheaper, and delivery is only €25 flat rate.

I’ve been using Pro Clima Contega Solido SL. It’s insanely sticky, especially when I’ve used the Tescon Sprimer sprayed on masonry. Not cheap mind.

I would remove the plaster on laths you have as you’re already in for a penny it seems. Once then you really will know what you have to deal with, but whatever you have now isn’t insulated. Post back with some pictures if you do take the plaster on laths off.

For me it’s relatively straightforward, focusing on what I can realistically can control. Getting the big calls right, meaning replacing my next car with an EV, replacing my boiler to an ASHP when I can. Avoid eating beef & lamb. Vote for those who take climate change seriously. Try to take fewer flights. Smaller things, ensuring all my taps excluding the bath have aerators on. Grow some of my own food, some potatoes, beetroot, strawberries etc, nothing world changing. I’ve thought a lot about the ‘having less kids’ argument and have come to the conclusion that they bring hope that they can do better than those who have come before.

On the presumption that its free cavity, save the EPS presumably affixed to the internal leaf, I’d fill the rest with blown EPS beads. Airtightness, check brickwork and penetrations like pipes, wires, windows , doors and seal up with FM330 and AT tape. Otherwise looks sensible so far to me.

The walls are already cavity insulated with EPS beads. I’m fairly sure our joists are just above the DPC so the VCL was automatically above it. Yeah I’m really happy I managed to spend a few hours to get the details as good as can be expected in a retrofit in such a space.

Yeah so it’s been ‘fun’, not easy in a relatively cramped space and definitely not perfect. Builder was initially unimpressed working membranes but when I did the detail work (taping and AT foaming) was ok. Hopefully will be easier in the larger rooms!

Day 2 of starting work and turns out I’ve got timber lintels on all openings on the inner leaf. How to deal with airtightness, just tape the hell out of them with Contega Solido SL? I’d rather not have to replace replace literally every lintel internally unless it’s absolutely necessary, ££!

https://www.ecologicalbuildingsystems.com/post/suspended-timber-floor-insulation-installation-underneath ?

I’m not sure that’s true, my walls have a 65mm cavity (1930s semi) and EPS beads went in without a problem?

@larry turns out my floor joists aren’t an even spacing, anything from 12” to 16” centres. Probably to do with how the joists fit in the spaces created by the chimney breast in the room.

So when the window is removed, cut a rebate out on the internal side of the cill and place something like compacfoam to fill the rebate before installing the new window?