Cold Flat Roof Ventilation

[BrianBedford]

I’m planning a small extension to the rear of my property and wish to go with a cold flat roof in order to minimise the overall height

The extension will run the entire length of the house (circa 12m) and project 3m,

As the roof timbers will obviously run the short length, is there any trick methods of providing the required ventilation?

I’ve seen “abutment ventilation” kits like the below pic but not that keen as it looks like a potential weak spot with the flashing screwed to the brickwork?

Any althernatives?

 

[noseall]

I’m planning a small extension to the rear of my property and wish to go with a cold flat roof in order to minimise the overall height

The extension will run the entire length of the house (circa 12m) and project 3m,

As the roof timbers will obviously run the short length, is there any trick methods of providing the required ventilation?

I’ve seen “abutment ventilation” kits like the below pic but not that keen as it looks like a potential weak spot with the flashing screwed to the brickwork?

Any althernatives?

View attachment 324723

Your venting issues are the very reason architects and builders choose the warm deck (zero vent) method. It’s not just the edges that need attention, but the whole area can have issues such as noggings preventing air movement etc.
You may want to look at Posi-joists etc, as they are hollow web design.

 

[robinbanks]

cold flat roof in order to minimise the overall height

I don't understand; a warm flat roof is more height minimising than a cold one

 

[noseall]

I don't understand; a warm flat roof is more height minimising than a cold one

It is?

 

[BrianBedford]

Your venting issues are the very reason architects and builders choose the warm deck (zero vent) method. It’s not just the edges that need attention, but the whole area can have issues such as noggings preventing air movement etc.
You may want to look at Posi-joists etc, as they are hollow web design.

Posijoists are a great shout!

I’ll run them by the BC officer

 

[matlob]

I used deep firring strips to vent across the top of all the joists with vents at each end of the roof.
Had to use a cold roof to bring the height down as was joining a house and garage

 

[^woody^]

Flash the abutment vent in lead.

Buy a different proprietary product.