andos-
(And for @Rich_G)
I did a fair bit of research online and unfortunately I don’t have the links but the new government guidelines are a good place to start
https://assets.publishing.service.gov.uk/media/614b30aad3bf7f718a54c0be/iwi-guidance.pdfI found out that there were guidelines suggesting that you had to insulate to a certain level and just adding a few mm while not technically illegal was frowned upon but there was also a reasonable approach of realising that doing every surface was not always possible or practical.
So I went for 65mm as that was giving a significant gain and at a point that any further increase was into the law of diminishing returns.Can only really offer advice if you doing something similar with insulated plasterboard but my tips would be:
Do not use dot/dab plasterboard adhesive as the number of fixings per board is 3x as many as using foam adhesive ( Cersasit CT84) you only need 3 per board and the foam is easy to use and far easier to get a seal round the edge and in a grid to stop interstitial moisture.
Use intumescent sealant on the board edges towards the face and the foam for the back.
It’s a 2 man job even with cutting the boards in half for ease of use, we did them in halves and started at the top half and used a dead man/brute force to hold in place while somebody drives the fixings in but the adhesive works quickly so the dead man was free to use on the next board by the time it was cut and scribed to fit.
I Used Ancon Insofast fixings, they work well but be really careful to not overdrive them through the plasterboard. they are only there to stop the boards falling off in a fire and blocking your exit but take pictures of the installation and keep receipts as they are needed for your new EPC and as proof of following guidelines.
buy a sureform as it’s the most useful tool for shaping the edges to get a good fit.
Ask somebody how! we took half a day to cut some boards in half do lots of measuring, work out the wrong method (fixing a batten to wall and resting a board on it) and get half a board on the wall. Things got a lot quicker after that once we had a system going.Our walls were mostly cavity so damp was not an issue and the one solid wall was tile faced on the outside so no issue there either, no rising damp as we are on the 6th floor.
I did leave the concrete corner pillars uninsulated and they are a cold bridge but not to the extent they are dripping with condensation, the windowsills are also very cold to touch, the window reveals were not insulated either as the narrowness of the steel windows meant an expensive and above my pay grade job of cutting into concrete and masonry.
The secondary glazing meant the colder uninsulated side of the reveal is between the 2 windows and the insulation is on the warm side which helps a bit.Not sure what i would do with a solid wall though, probably a totally different method/product/approach.
some pics:
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Mr_Smyth
Now the cold weather is here I’m glad of all the hours/pounds put into the internal insulation I fitted but having only ever had wooden windowsills I’m shocked at how cold the quartz ones are.
A massive cold bridge though handy for quickly cooling cups of coffee.