Does this roof insulation look correct.

Stupify

New build house and the insulation has been done in the roof.

I have attached two photos I took of the finished work. I had assumed the builder would use kingspan k3 for the entire roof but when it reaches the apex it switches to some kind of rockwool. Does this seem like the correct process to people here?

Bonzo Delaney

I'd be more concerened as to why the block wall wasn't rendered in sand and cement for Airtightness before the battens went on

BryanF

What does the details and spec state
What was priced
What was agreed by arch

Metric Tensor

It's possible that the insulation is ok but without knowing the exact materials, depths and how it is installed no-one can tell you for sure.

Ask your architect/engineer/technician to have a chat with the builder about the spec for it.

Stupify

Thanks guys, will ask my engineer about it tomorrow. We agreed on K3 for the entire roof so was a bit worried when I saw this, when I asked my builder he said he went with the wool on top to prevent mold.

Stupify

Bonzo Delaney wrote: »

I'd be more concerened as to why the block wall wasn't rendered in sand and cement for Airtightness before the battens went on

I didn't know about this, will also ask why it wasn't done.

Calahonda52

well if that is alu faced foil the siga is basically redundant except where the rockwool is so my guess is the builder knows this and used the RW to allow the condemnation to escape, assuming that its countered battened inside.

open rant> this is what pi$$es me off about this a la carte approach to building up roofs and walls using modern materials: no full understanding of the way they work ,<close rant

A more worrying observation is that the staples are pretty scarce, will not withstand a negative pressure cycle when airtightness tested.

Stupify

Calahonda52 wrote: »

well if that is alu faced foil the siga is basically redundant except where the rockwool is so my guess is the builder knows this and used the RW to allow the condemnation to escape, assuming that its countered battened inside.

open rant> this is what pi$$es me off about this a la carte approach to building up roofs and walls using modern materials: no full understanding of the way they work ,<close rant

A more worrying observation is that the staples are pretty scarce, will not withstand a negative pressure cycle when airtightness tested.

Plasterboard will be going directly over the membrane, will this still be a problem with the staples?

Lumen

I'm no expert, but stopping the K3 before the slope junction seems like a recipe for cold spots.

Stupify

Lumen wrote: »

I'm no expert, but stopping the K3 before the slope junction seems like a recipe for cold spots.

Yeah, that was my thought when I saw it.

Bonzo Delaney

Stupify wrote: »

Plasterboard will be going directly over the membrane, will this still be a problem with the staples?

Sure what's the point of putting in an air tight layer if he's boarding directly on to it I was going to ask if that cable in the photo was penetrating the air tight layer obviously is now
Calahonda is right al a carte building methods indeed what was the architect design of the roof build up.

Stupify

Bonzo Delaney wrote: »

Sure what's the point of putting in an air tight layer if he's boarding directly on to it I was going to ask if that cable in the photo was penetrating the air tight layer obviously is now
Calahonda is right al a carte building methods indeed what was the architect design of the roof build up.

I'll have a look when I'm at home today, it has changed slightly from when we started though. Originally the attic space wasn't going to be plasterboarded but now there's a stairs going up to it so plasterboard it is.

Calahonda52

Stupify wrote: »

Plasterboard will be going directly over the membrane, will this still be a problem with the staples?

The AT test is done before slabbing and if they go negative, the siga will pop off

Stupify

Calahonda52 wrote: »

The AT test is done before slabbing and if they go negative, the siga will pop off

I know the builder plans on doing the AT test after plastering is done, again thought this was strange as would need to tear down the boards to fix any problems at that stage.

An_Toirpin

It is unimportant but is this an estate house or one off?

Stupify

An_Toirpin wrote: »

It is unimportant but is this an estate house or one off?

One off house.

Wartburg

Stupify wrote: »

New build house and the insulation has been done in the roof.

I have attached two photos I took of the finished work. I had assumed the builder would use kingspan k3 for the entire roof but when it reaches the apex it switches to some kind of rockwool. Does this seem like the correct process to people here?

What´s the idea about the battens at the gable? The window tape with perforations and the open holes for pumping the cavity do frightening me regarding air tightness, in case you do not apply a full plaster coat there.

Stupify

Wartburg wrote: »

What´s the idea about the battens at the gable? The window tape with perforations and the open holes for pumping the cavity do frightening me regarding air tightness, in case you do not apply a full plaster coat there.

There is a full plaster coat going up in the attic as it'll be a bedroom. I didn't ask about the battens but it might be too late now, the plasterer has started up there since Friday and was working through the weekend.

Metric Tensor

The battens make it look like the plasterer was going to slab that wall and skim it. You do not want this from an air tightness point of view.

Go up to that gable wall this evening and tap on it with your knuckles:
1. If it sounds hollow then it is slabbed and skimmed and unless all the slabs are taped to the AT membrane it's a waste of time from an air-tightness point of view.
2. It would be impossible for it to be solid unless the battens were removed!

Tefral

Metric Tensor wrote: »

The battens make it look like the plasterer was going to slab that wall and skim it. You do not want this from an air tightness point of view.


2. It would be impossible for it to be solid unless the battens were removed!

Plasterers don't seem to get this. I had to convince by plasterer to sand and cement my walls first before lining with boards. He still thinks i'm mad.