James T

I’ll look into tapered insulation cheers. Yeah cavity tray full length of the wall.

My current thought is it needs to be 320mm high. My sketch below shows how I come to that total.

That block is the outer leaf so insulation will be butted up to it. Planning to take it up to around 320mm. It’s the depth of the warm roof that I’d like to reduce so door can be as big as possible.

Looking for advice on how big this step needs to be to accommodate a warm roof from the top of the steel. The block built in is 150mm with the thought I’d go with a cold roof system but didn’t like the ventilation options and been told to avoid cold roof so going with a warm roof and going to build this step bigger. The opening is going to be a patio door opening outwards (Juliet balcony). My current plan is to go, 50mm firring 12mm ply 150mm insulation 25mm ply 75mm upstand sitting under door Totaling 312mm This makes the patio door pretty small but it’s a compromise we’ll have to make because the Juliet balcony is a late addition, was previously a window. Any tips to make opening bigger would be great.

About to start construction of a flat roof but changes I have made along the way are throwing up problems with ventilation. My initial plans included a window looking out onto a flat warm roof but we had a change of heart and decided we wanted a Juliet balcony and to maximise the door size we changed to a cold roof system. We have created an opening (6ft 6) with a 150mm step above the joists. But in creating the 150mm step we have limited the space for abutment vents to create air flow above the insulation. - The roof has a full surrounding parapet. - Size 3.4m by 3.5m My options I’m working through are: 1. I could run firrings perpendicular to the joists and then install mushroom vents in all 4 corners, this means air can flow through the full roof. My concern with this is building control might not approve this proposal as mushroom vents aren’t preferred method of ventilation. 2. I could do abutment vents and only have 50mm up stand. Nervous about this not being enough as 150mm normally used to give better clearance below flashing. 3. I can knock my 150mm step out and make a 300mm step and got back to a warm roof system Issue here is my door on my Juliet balcony is only 6ft tall and might look a bit odd. imagine below shows my first idea (ignore number of joists it’s actually 9) Any advice appreciated. Thanks