Warm roof or Cold roof Insulation
I get asked this question all the time not only roofers calling me but customers who want to know just that little bit more about their roof.
Well this video shows warm and cold roof construction and links to a real reroof we did in Chiswick, we changed the insulation in the flat roof from between the joists ( Cold roof construction) to on top of the joist (warm roof construction) at the same time we stop the roof ventilation from flowing into the now “Warm roof ” and placed more ventilation into the existing cold roof areas. We find that not all roofers are doing this as its an additional cost to the customer but if you are going to upgrade to a warm roof you realistically have to do this or you are wasting your time and money. Look at it this way at night you sleep under your quilt if you leave a gap around the outside you get cold. Obviously you can upgrade the edges at another date however until then the warm flat roof is not performing correctly.
Another thing to think about when deciding if its a warm roof for a cold roof that you will build is just how you will build it the disadvantage of the warm roof are its high however its performance and ease of build makes it the much better choice if you have the height.
Cold flat roofs have to have ventilation and forming that ventilation can be difficult, time consuming and costly, detailing of the roof become complicated and costs can spirale.
If you look at the detailing at the ridges of this cold roof you can see that vents have been built into the front of each tiles, using vented tiles like these makes venting the cold roof easy however they don’t come cheap.