Extension Cavity Insulation

[lookseehear]

On 15/01/2025 at 16:30, lookseehear said:

I came up with a solution for this today. I bought a couple of packs of these driveway grids https://www.wickes.co.uk/Wickes-Ground-Grid-Base---100-x-100cm/p/236266? which are 250x250 and come in a pack of 4. They cut really easily with a track saw, so I've cut them into roughly 120mm wide strips. Should do the job nicely.

 

'Fluffy stuff' as my builder calls it is going in. Seems pretty easy to work with.

 

 

And here's the jig for cutting the cavity tray profile. Straight cuts are super straightforward, but on an angle it's a lot trickier to hold the line.

 

[Pocster]

I remember when I insulated my slab . I put pir down , filled all the bits so nice and tight . Polythene over the lot , taped and up the walls all ready for screed .

I thought I’d get the screed guy to look first - make sure it was ok . He started swearing . I asked what I had done wrong !?

He said nothing . But no one fills in all the pir gaps . We just pour the screed and watch it push the pir apart as it flows into the void . Then the owner complains of cold spots in the ufh .

This tells me a specific person on a specific trade can be sloppy / don’t care / naive - clearly not everyone though .

[Roger440]

59 minutes ago, Pocster said:

I remember when I insulated my slab . I put pir down , filled all the bits so nice and tight . Polythene over the lot , taped and up the walls all ready for screed .

I thought I’d get the screed guy to look first - make sure it was ok . He started swearing . I asked what I had done wrong !?

He said nothing . But no one fills in all the pir gaps . We just pour the screed and watch it push the pir apart as it flows into the void . Then the owner complains of cold spots in the ufh .

This tells me a specific person on a specific trade can be sloppy / don’t care / naive - clearly not everyone though .

 

Same when i did my garage base. Spent forever getting the thing bob on. Then insulation over, again, no voids taped etc.

 

Concrete guys arrived and asked who did it. Reckon it was the best prep they had ever seen. Certainly doesnt say much for what they usually see.

 

 

[lookseehear]

You could eat your dinner off that!

[Pocster]

Right !

Photos of mine now !

 

Edited January 17 by Pocster

[Canski]

On 17/01/2025 at 12:31, lookseehear said:

Fluffy stuff' as my builder calls it is going in. Seems pretty easy to work with.

 

Why is the insulation lower than the courses ? And where are the wall ties?

[lookseehear]

23 hours ago, Canski said:

Why is the insulation lower than the courses ? And where are the wall ties?

 

There's a cut layer of insulation above the layer you can see the top of to account for cavity tray. The wall ties start in the next course up.