New and old ways of fixing flat roof insulation.
As the warm roof market has progressed standard ways of construction are starting to develop. Fixing down the insulation with long metal screws and or screw nails is becoming a thing of the past.
You can see on this photos that the tops of the warm roof insulation fixings have melted the frost. This is thermal bridging through the fixing.
So now the new way of fixing the roof insulation is to use a broken thermal fixing, development of the fixings has been ongoing for some time and because of the amount of rigid insulation now being fixed to walls “External wall insulation” the manufacturers have had to develop all sorts of thermally broken fixings.
Flat roof insulation fixings thermally broken.
This blue fixing you can see is what we are using on flat roofs today. The metal screw is hidden deep down inside the tube of the fixings this keeps it away from the cold outside, together with the fact that it is surrounded by plastic that is not a good thermal conductor the fixing now stops the transfer of heat.
The use of glue to hold down the flat roof insulation is another method that also has no thermal bridging involved. Sometimes we cannot use thermally broken insulation fixings because we are laying the roof insulation down over a concrete base and then we have to use glue.
One other point that shoud be taken into consideration is that if you are screwing through your vapour control layer (VCL) you are making holes into it, and this downgrades its water vapour resistance so a good quality vapour control layer with self-fealing property should be used.