Insulating Existing Concrete Flat Roof

Roofing insulation is one of the most important and misunderstood building components.

Insulating existing concrete flat roof.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. The existing ceiling is sound but provides no insulation. Cold roof a very bad idea. This is used for refurbishment e g.

Gable roofs hip roofs intersecting roofs butterfly roofs mansard. I ve built a timber frame to support a new plasterboard ceiling below the existing one. Refurbishing an existing timber joisted flat roof which has no insulation. I want to insulate below a flat roof without removing the existing ceiling.

Cold roof systems are highly inadvisable as insulation from the inside will inevitably lead to the formation of condensation. This method eliminates the need for ventilation and the risk of condensation whilst providing superior thermal performance to cold deck. How to insulate a flat roof. To produce a hot roof rigid insulation is fitted outside above the weatherproofing.

Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation. Both these variants require different approaches to insulation which will be covered in this guide. This is then covered with a further weatherproofing layer. Insulation is placed in between the joists underneath the roof surface above.

Insulation material is placed on top of the roof rather than in between the ceiling and the decking. With an inverted warm roof construction put ballast usually graded pebbles or concrete paving slabs on top of the insulation in order to keep the insulation down in the event of wind. A cold flat roof is one where the insulation is between or between and below the roof joists. The insulation is below the deck but above the plasterboard.

There are many different types and installation methods out there along with a lot misinformation about which products offer the greatest energy savings. Green roofs a green sedum or grass roof can also be put onto a flat roof provided it can take the weight. Roof types the various types of roofs found on homes sheds garages and other buildings fall into one of the following categories. To insulate a flat roof with a concrete deck we recommend a warm deck construction method where the vapour control layer is sandwiched between the concrete deck and a layer of rigid pir insulation boards.