insulated upstand

[Glanmor]

Hi All

Rear extention, EPDM Roof - concentrating on the side that abuts the original house.
Question is, should the EPDM upstand against the house walll be insulated?

I see it in recomendations and Roofing books but if the house wall (1938) iteself is 75mm cavity wall and cavity is not insulated, what good is insulated EPDM upstand going to do.

House wall cavity is very droughty as it has 2 x air brick at the base feeding it, which I had to extend out of the extention build.

I now have one wall that was external skin of the house as internal skin of the extention room.
Andy advice on how to keep this wall warm, whilst it remains cavity wall?

Thanks.

 

[vinn]

I know very little about EPDM roofing but there are insulated upstands available - whoever is supplying the trim should be able to say whats needed.
We use rippings of Celotex as upstands in various situations.

Is the (flat?) roof a warm roof or a cold roof?
Were cavity trays used at the extn roof line?

 

[seasickstevie]

The (what was) external leaf is now an internal surface, no I'm guessing that's why the upstand needs a thermal break.



And who's Andy?

 

[Glanmor]

Vinn, I was thinking of 25mm Celotex behind the 150mm upstand too, but kind of scratching my head over what exactly would be the benefit of this given the situation. External leaf of the house wall will always be cold so this 50mm thermal break over and above the extention roof insulation is is thermally isolating what?

Roof is warm deck - OSB,VCL,150mm Celotex,OSB all machanically fastend down then EPDM.
I'm having 2nd thoughts about cavity tray at the roofline just above the upstand/flashing; becuse after removing chipping layer plaster the base coat is extremely tough and all sound. This wall is south-facing and gets plenty of sun to dry up (when the sun decides to show up). As said before given the house cavity wall is un-filled and proper ventilated should I must install cavity tray?

Im more stressed about what was the outside wall now become the cold inside wall, inside the extention. Best described as the 4th wall of my extention. Im thinking of lining it up with 50mm Celotex, VCL and then board it up with plaster boards. VCL should prevent condensation hitting the the cold wall and celotex should provide some thermal barrier. Any alternative methods here welcomed.

Seasickstevie, I agree with thermal break idea (built one into the concerete floor parimeter of the extention) but at the roofline in this case I couldnt figure out the advantage.

I appreciate both of you commenting back on this. Thanks.

 

[chappers]

As said before given the house cavity wall is un-filled and proper ventilated should I must install cavity tray?

If you have cut an opening below then yes