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  • Big impact on comfort levels
  • Save on fuel bills
  • Lasts as long as the roof

If you have a flat roof above any heated room, then you will want it to be insulated to help keep the heat in.

If any of your house has a flat roof, and the room beneath that roof is heated, then you will want the roof to be adequately insulated otherwise the room beneath will be difficult to keep warm and you will be spending a lot of money trying to heat it. It is very difficult to tell how much insulation there is in a flat roof just by looking at it, but if it was built before about 2000 then it probably doesn’t have enough.

If you have a flat roof over an unheated space like a garage, then there is no need to insulate this.

How flat roofs are insulated

A flat roof should have a layer of insulation built into the structure at some level.

When an insulated roof is built from new, the insulation layer can be included at different levels within the structure. The roof may be described as “warm deck” or “cold deck” depending on whether the insulation is above or below the main solid roof layer.

Adding insulation to an existing flat roof generally requires the removal and replacement of some of the existing structure. It is not normally possible to spray or blow insulation into an existing void or attach insulation to the underside. It is also important to carry out any insulation work in a way that minimises any risk of condensation building up within the roof structure over time.

Flat roof insulation is most often carried out when some part of the roof needs to be replaced for other reasons – for example, when the weatherproof layer has started to leak. However, it is possible to insulate a flat roof at any time, in which case it may be possible to replace the weatherproof layer at the same time to avoid problems in the future.