Airtightness and VCL help needed!

[James94]

Hi looking for some advice on a few points, 

 

We’ve reached this stage at the moment. (See photo) and trying to do as much of the build ourselves now that we have a watertight shell. (Naturally ventilated)

We’ve been doing a bit of reading but not really getting anywhere, more confused than anything. 

 

I see a lot of different methods and materials being used when it comes to air tightness and VCL's

 

We are in the middle of adding pir to the sloping ceiling with 150mm in between the rafters and planning on maybe 60mm underneath with all joints taped to form the VCL, and battens to create service cavity. 

 

1, Architect has specified 100mm loft roll in between rafters at ceiling level with 350mm over that, could we put pir inbetween rafters and tape over rafters to continue VCL?

 

2, does a parge coat act as a VCL for walls?


3,How would we go about making the expansion joint around first floor, floorboards air tight as we have missed the opportunity to use tony trays.

 

Thanks james


[nod]

A Parge coat can help with airtightness 

But you are better making sure that your tackers seal the perimeter when Dot and Dabbing 

and also round all sockets 

The and seal the perimeter of the ceiling with acoustic silicone 

You need to to leave the expansion joint clear If the boards are correctly sealed and air getting into the flood void will have nowhere to go 

Proving all down lights are are sealed 

[AdamSee]

I used a parge coat (sound coat) internally to act as a air tightness barrier when renovating my place. Blower proof paint is the best way to get in between the joists if there is a room below to get access from.

I believe it is important to ensure that there is a solid bed of drywall adhesive at the bottom of the boards to stop fire spreading in that worst case event. But If you have sealed the walls properly, I cant imagine its necessary to seal around all of the sockets as no air should be penetrating the walls to be able to escape via said socket......it is however good practice to do so.  

 

As for the ceiling. I don't see a problem with taping the PIR to for make a VCL, except that fitting down lights may be a problem (might not be a problem if your not having any though). In the past I've made plywood boxes to fit between the joists and painted/sealed them to a staple on VCL as this made space for the down lights while maintaining a air tight barrier. 

 

Good luck with it.

[nod]

5 hours ago, nod said:

A Parge coat can help with airtightness 

But you are better making sure that your tackers seal the perimeter when Dot and Dabbing 

and also round all sockets 

The and seal the perimeter of the ceiling with acoustic silicone 

You need to to leave the expansion joint clear If the boards are correctly sealed and air getting into the flood void will have nowhere to go 

Proving all down lights are are sealed 

 

[AdamSee]

Good looking job with the adhesive. Just out of curiosity, Is that an external wall?

[James94]

Thanks or all the great advice sorry I haven’t replied sooner, as been away to lakes with family. 
So it looks like I’m going to give all external walls a skim of sound coat plus, if I can get hold of any. I understand this will aid the air tightness to the building but will this also form the vcl or should we be adding a layer of something? what material and where would it be applied.
 

 

Thanks James 

[James94]

Just a quick bump,
I know your all probably busy cracking on with your own projects but can’t continue with this stage until we know what we are doing, don’t want to get this wrong.
As above some great advice but not sure how to tie all together. If we apply parge coat from floor to wall plate( does this become vcl too)
If not can you help with materials and how we would tie it all together to the taped PIR ceiling.

 

Thanks james