Another Insulation question

[petej42]

Hi, I'm looking for a bit more advice on insulating a store room over my attached garage. Building control are happy that building regs are not needed but the room couldnt be classed as a living room/ bedroom etc. However I want to do the work to a decent standard.

I understand that i need to leave a 50 mm gap above any insulation for ventilation purposes, however, I have noggins(?) in a couple of places that prevent me from having a continuous gap. How much if an issue is this?

Is anyone able to provide any advice on this?

 

[noseall]

Hi, I'm looking for a bit more advice on insulating a store room over my attached garage. Building control are happy that building regs are not needed but the room couldnt be classed as a living room/ bedroom etc. However I want to do the work to a decent standard.

I understand that i need to leave a 50 mm gap above any insulation for ventilation purposes, however, I have noggins(?) in a couple of places that prevent me from having a continuous gap. How much if an issue is this?

Is anyone able to provide any advice on this?

Have you got soffit or OFV's and vented ridge? Is that breathable membrane?

We fit narrow nogg's for that very reason, i.e. airflow. Drill some holes in the nogg' away from the fixing zone.

 

[petej42]

Hi thanks for the reply,
We have soffit but I can't see any obvious vents and I am not sure if the ridge is vented.(Going to find some binoculars and try and see) I think the membrane is breathable, it's like thick canvas. The house was built about 25 years ago by the previous owner. I've just contacted the local council to see if they can provide copies of the plans.

Regarding the noggins, what size holes would be appropriate, and how many, would I need to add an extra piece to the noggin to maintain it's strength?

 

[noseall]

Regarding the noggins, what size holes would be appropriate, and how many, would I need to add an extra piece to the noggin to maintain it's strength?

You could halve the depth of those nogg's and they'd be ok.
Drill a few 25mm holes in them, away from any fixings.

 

[noseall]

it's like thick canvas.

Breathable membrane is like paper and became widely used about 20-25 years ago. I first started using it 2003 ish.
It may not be breathable so you need to be prepared to add through ventilation.

 

[petej42]

Great, thanks. I'll wait to see what the local council have and look into through ventilation if necessary

 

[aveatry]

Are those noggins purely there to give the strap something more than just the rafters to fix to and why do the 3 rafters with the strap and noggins have joining plates - seen lower down.

 

[petej42]

The straps are just nailed to the rafters, not the noggins.
The sloped roof is huge. The rafters are joined to stretch the full extent of the roof. There are other rafters in the roof that don't have noggins that are also joined.

 

[noseall]

Are those noggins purely there to give the strap something more than just the rafters to fix to

They link the three rafters together for additional oomph (stability). They are gable restraint straps, so the masonry is reliant on the lateral stability of the roof, to prevent failure - hence using the lateral stability of three rigidly linked rafters.

and why do the 3 rafters with the strap and noggins have joining plates - seen lower down.

Standard gang nail plates on that type of (manufactured) roof truss.