LiamJones

Dense cellulose is coming in about 3x as expensive as PIR to get similar u vals for the material alone, let alone paying a firm to blow it in!

+1 on the JS Harris spreadsheet! Very similar results to PHPP and far less complexity!

Really good idea, I was going to run PIR under the beam and put in a collar tie to fix the plasterboard onto. But yeah that cold bridge isn't ideal. Getting away from hangers would be nice too! What does the detail look like, a piece of timber on top of the steel, with the rafters birdmouthing into it? I've also fired the question off to the SE. Thanks for the detailed respone, given me lots to think about whilst eating lunch! You've just introduced me to decrement delay and i'm curious, the phase shift of the PIR build up i proposed is longer (7.6hr) than that of the rockwool version (7.4hr) you proposed. That prompted me to do a bit of reading, and articles like this one, show rockwool (i've assumed rockwool == stonewool) as having a shorter decrement delay than PIR. What am i missing @Iceverge?

I'm doing a bungalow conversion, raising the eaves and replacing the roof to form 3 bedrooms upstairs. I initially looked into trusses, but decided against them after reading of troubles fitting insulation and achieving airtightness around the webs. Since, i've instructed a structural engineer to design a ridge beam and specify the rafter spec. I now need to make a decision on how i incorpate my insulation and airtightness into this. I've gone back and forward on cold vs hybrid vs warm roof, and i think i've settled with a cold roof for simplicity. I've also deviated from the original structural spec (with SE's permission), and gone to 44 x 175 rafters @ 450c to reduce PIR wastage (after watching Robin Clevett on youtube) Would anyone like to change my mind again?

I also ended up getting g99 approval for 8kw on a single phase, so I’ve got all the options available. Nice chunky 25mm 5 core to the house and 2 x 10mm 5 core for 2 x 22kw car chargers.

Ended up going with 3 phase to just mine. They ended up wanting a load more for the neighbours. Heres the kiosk, roof slab is cast just waiting a few more days to cure then will attempt to lift it into position on a bed of mortar.

Interestingly, for me, A flow temp of 45 would increase annual heating demand from 8875kWh to 10356kWh, or 16% 🤯 A flow temp of 35 would increase annual heating demand to 9764kWh, or 10%

How do i factor in additional losses from UFH using this spreadsheet? Should i adjust row 51 - Floor fixed heat loss to use the flow temperature, rather than the room temperature? Floor area * (Room temperature UFH flow temp - ground temp) * U value

On a heat loss calculator (from this forum), for a ground floor area of about 100m2, the difference is about £50 a year between 100mm and 200mm of PIR. How does one factor in the additional losses from having UFH?

I got a quote of them yesterday, keen to take advantage of the above. They based it on the existing EPC of F. I told them I’m doing a deep refurb, and had calculated a heat loss of 5kw. They couldn’t adjust the quote based on what I needed, so needless to say the quote was crazy money. Advised me to requote once I had a new EPC 🫠

Here’s what the structural engineer has come back with. 9692 structural markups.pdf

Tangentially, could you simplify the joints, mostly to get rid of that flexi? Hard to tell from the pic if possible. that’d make me far more confident it’ll be fine.

Hi @will_k can you remember how thick the ply was for these? Any tips on how to do the plywood boxes? How'd you fix them? what about the cavity and lintels? I'm about to do something similar, inspired by this, so thank you! Cheers, Liam

In this months Home Building and Renovating magazine. ’Radiators won’t do it, UFH in screed won’t do it’

In this months Home Building and Renovating magazine. ’Radiators won’t do it, UFH in screed won’t do it’

That was me, I hoped I’d caveated it enough with but clearly not

I’m looking forward to seeing what octopus quote me, I’d hoped I wouldn’t be left with much to pay on the boiler upgrade scheme!

Good shout, although be careful of separation distances between power and data to avoid interference. 200mm (I think) for unshielded cables.

All depends on how many amps over how many meters. Let’s make a guess at 13amp for now plug this into the calculator, for single phase 230v over 200m with a 3% drop (acceptable for lights) we end up with 25mm 3 core https://armouredcable.net/armoured-cable-calculator/#

I’ve had exactly this just happen, was expecting 450mm dpc to be used on inner leaf, it’s sitting there on site. Arrived tonight to find 100mm dpc has been used on both leaves 😫when is that ever the right thing to do?

I landed on the medium density blocks as a happy middle ground lightweight/aerated Low thermal conductivity Low sound attenuation lightweight for the bricklayers, less labour more expensive material more fragile, less ability to fix things to. less airtight heavy density High thermal conductivity high sound attenuation heavier for bricklayers, more labour less expensive material High ‘thermal mass’ Better airtightness medium density’s sat in the middle for all of these properties and are a good balance in my opinion.

Oh, and BC advised happy with full full cavity to the foundations with no tray or weep vents, given I was EWI and render to prevent driving rain.

Hi, thanks for all your opinions and advice! I’ve decided to go with medium density blocks to both skins. Combined with the EPS bead cavity and EWI gives me a very small condensate point way out in the render and a u value of 0.16. Here it is going up

I’ll certainly report back. yes, 1.5 story with 3 bedrooms upstairs.

I’ve gone local authority, have used them in the past but their website states next day inspections if booked before 4pm and they’re true to their word. Very prompt and reliable. This is CNC in the Broadland district. Once you’ve paid your fee, you’re also able to speak with their surveyors for advice E.g if a wall build up would be acceptable and if I needed weep vents.