Cutting thickness of woodfibre board

[Kearn]

I'm not aware that they have two different sides. Could it be that the second hand ones that you are working with have simply been bleached or darkened by the sun?

Some brands do…. In practice it doesn’t seem to make much difference

 

[Glenn586]

Some brands do…. In practice it doesn’t seem to make much difference

Agreed, the last one I did I got half way up the wall before realising I had the slightly softer side facing me. I think the key is making sure you use the mesh to provide the tensile strength.

 

[larry]

No problem with not having an air gap surrounding the backbox. But even if you cut the woodfibre snug to the box, I think you may still have the issue that the box moves around too much and becomes loosened, or cracks the lime plaster surrounding the socket when plugs are inserted and removed. The backbox really ought to be quite secure. It may be better to cut a hole all the way through the woodfibre and attach some sort of mounting block of timber or similar solidly to the wall. But I'm sure you'll figure it out as you go along.
No, lime plaster does not count as insulation. Also, I'd recommend using deeper back boxes than the standard 25mm ones, given that you have the depth. Many decorative faceplates or sockets with USB etc require a deeper back box so you might as well.

If you use a 35mm backbox then you've only got 35mm extra of insulation to get through to reach the wall, so long screws and plugs should do it. At least then you're not making a massive thermal bridge with no insulation behind at all.
I ran new cables in through conduit which I chased into the wood fibre and then connected direct to the back box using the plastic adaptor things. Plastered straight over the conduit with mesh.

I think you ask a good question about fire risks with sockets in wood fibre insulation - my sparky was happy enough to connect it up, but I wonder if something like this https://www.electrical2go.co.uk/aur...ArJNLTaMycGpYg69Uzf33SzvYKVtHO2IaApUtEALw_wcB woud be a good belt and braces

PS I added extra expanding glue (d4 polyeurethane expanding glue) around the plugs when inserting for belt and braces to attach fixings to the wall.

Re: the drill I can't see why that drill bit wouldn't work. Are you sure you're not unexpectedly drilling into something other than limestone? I discovered some concrete quoins in the corners of my property after pulling back render.

Finally really do recommend mesh for plastering if you haven't thought of that.

 

[a twig]

It says it has on here. Stuck some on with lighter side to plaster so done now.

The real issue im having is drilling into the bloody wall. Ive got a hammer drill and these View attachment 15765


I would have throught this would have been fine, but been a nightmare. What did everybody use?

I used those bits but their ease of going in will depend on the stone - our walls at our old place were white lias with quite a high iron ore content in places, took a reasonable amount of effort even with a hefty blue Bosch SDS behind it, going through concrete was a breeze in comparison.

My cordless makita drill had a very happy life as it was only used for running in screws for those 6 years - even putting up a picture hook required the SDS!

The first sparky we had in was trying to chase into it to run cabling despite my telling him not to - I laughed fairly hard as he completely killed two cold chisels before politely asking him to leave and hiring someone else who would actually listen

The plumbers who installed our central heating weren’t happy either, due to the various levels in the property (every single room was at least 1 step up or down from the previous one) they had to diagonally drill through a 2ft wall to run the 22mm pipe upstairs from the boiler, writing off 2 brand new 900mm SDS bits in the process