Flat Roof Insulation Fixings

Thermal Fixings

Flat Roof Insulation Fixings

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.

Thermal Fixings
Flat Roof Insulation Fixings

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.

Thermally Broken Flat Roofing Fixings

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 should 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-healing properties should be used.

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Comments (2)

  • Liam Reply

    Interesting post Steve. If thermally broken fixings are to be used and the roof is to have an upper decking (in case it ever needs to be walked on), should these be used through the decking also? Or just use them to secure the insulation and secure the decking how? Glue?

    2nd September 2018 at 1:46 pm
  • Robert CHENDLIK Reply

    Hi Steven I have issues with a warm flat roof. My 97-year old mother lives in an extension next to the house which was once a garage. As she is very frail and needs to keep warm I am anxious to ensure the roof works properly and we also are not storing up problems for the future. May I email you some photos for your comments please of what you think is likely to be causing the problems and from the photos if other long term issues are possible, which will help me decide what to do next?

    I live in Hemel Hempstead.

    Thank you


    6th May 2020 at 12:09 pm

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