Insulating old 3x2 roof space

ThisIsWeird

That's good - there's a full, open void up there, from one side of t'house to t'other.

The 'white beam' is presumably just the top of that brick wall, and it stops at the existing rafters/old flat ceiling, and has gaps in between these, so a good air flow.

Ok. Consider your jazzy wall, your new flat ceiling, the sloping ceiling on the other side, and then the short ashlar wall to be the 'envelope' of that room. Insulate that. Do not go beyond it. Rigid insul sheet cut snugly in between, as you have done, ensuring a min 50mm gap behind it - obviously most gaps are much larger voids, so all good. Then overboard on the underside for max insulating effect - one or 2 inch, depending on how much room space you are happy to lose.

In this photo, your insulation appears to be continuing upwards, above your new room ceiling, to where it is simply not required, and could disturb air flow. Just not needed - cut at green line! 'Envelope'. Unless I'm not reading that pic correctly.

FreeBear

ThisIsWeird said: In this photo, your insulation appears to be continuing upwards, above your new room ceiling, to where it is simply not required, and could disturb air flow. Just not needed - cut at green line! 'Envelope'. Unless I'm not reading that pic correctly.

And those gaps are way too big to fill with expanding foam. A gap of less than 6mm is desirable, 12mm is the maximum in my opinion. That aside, it is looking good, and slowly taking shape.

CashStrappedTeen89

ThisIsWeird said:

That's good - there's a full, open void up there, from one side of t'house to t'other.

The 'white beam' is presumably just the top of that brick wall, and it stops at the existing rafters/old flat ceiling, and has gaps in between these, so a good air flow.

Ok. Consider your jazzy wall, your new flat ceiling, the sloping ceiling on the other side, and then the short ashlar wall to be the 'envelope' of that room. Insulate that. Do not go beyond it. Rigid insul sheet cut snugly in between, as you have done, ensuring a min 50mm gap behind it - obviously most gaps are much larger voids, so all good. Then overboard on the underside for max insulating effect - one or 2 inch, depending on how much room space you are happy to lose.

In this photo, your insulation appears to be continuing upwards, above your new room ceiling, to where it is simply not required, and could disturb air flow. Just not needed - cut at green line! 'Envelope'. Unless I'm not reading that pic correctly.

Perfect, answered it thank you again!

CashStrappedTeen89

FreeBear said:

ThisIsWeird said: In this photo, your insulation appears to be continuing upwards, above your new room ceiling, to where it is simply not required, and could disturb air flow. Just not needed - cut at green line! 'Envelope'. Unless I'm not reading that pic correctly.

And those gaps are way too big to fill with expanding foam. A gap of less than 6mm is desirable, 12mm is the maximum in my opinion. That aside, it is looking good, and slowly taking shape.

Noted. With cutting the excess off I should be able to work with it a bit more. Worse case I have some left over so can cut as needed, I’ve already replaced 2 as I was tired and did a sloppy job with massive gaps.

ThisIsWeird

I fear I would be filling these gaps with foam :-)

The stuff expands nicely and, once set, you just slice off the excess flush. You are planning to overboard the whole caboodle anyway, in full sheets?

CashStrappedTeen89

ThisIsWeird said:

I fear I would be filling these gaps with foam :-)

The stuff expands nicely and, once set, you just slice off the excess flush. You are planning to overboard the whole caboodle anyway, in full sheets?

I’ve already replaced the 3 I left big gaps. I’ll be cutting them level and insulating the flat ceiling and what I can of the wall (pending a plumber visit for pipe adjustment for a bigger radiator). I’ll be filling the bits were the bolts have been cut around and what is left as well as any open edges now there is free air flow throughout.

yea over-boarding the whole lot with as long as we can (it’s a third floor room with not the best angles to fit 8 foot boards around so plasterers will need to do their best).

does anyone have suggestion on insulated plasterboard and supplier? I’ve been looking at local and branded firms, a few cheaper alternative like build base and inslation4less which seems quite well priced but i don’t want to sacrifice quality over price.

FreeBear

To be honest, I'd go to someone like Buildbase, MKM, or Travis Perkins - Haggle over price and make sure you get free delivery. That should work out a lot cheaper than going to an online supplier.

As for plasterboard, I prefer using 1800x900 (6x3 foot) sheets - Much easier to get up the stairs and put up on your own. Having a couple of dead man props to hand also makes boarding the ceiling much easier.

CashStrappedTeen89

Back at work so little progress as not much more I can do until the plumber comes to move piping for a bigger radiator and then the plasterer.

managed to insulated everything I can now wall will be done once plumber does his thing but everything taped, edges cleaned up for the most part, carpet etc.

might Tackle the floor as it’s squeaky while I wait a few weeks.

FreeBear

You going to put a layer of insulation on the brick wall ?

CashStrappedTeen89

FreeBear said:

You going to put a layer of insulation on the brick wall ?

Brick wall is having insulated plasterboard on it. The only walls that aren’t are what lead to the stairs (to the right of the photo) and the wall on the left of the photo which is a party wall (as the door frame has literally no ability to take any additional boarding).