Flat Roof Insulation Above And Between Joists

By majority the rule of thumb is that in a domestic house not flats approximately a third of the total thermal performance of insulation can be placed below the deck with two thirds above.

Flat roof insulation above and between joists.

Here the roof deck is maintained at the same temperature as the internal conditions hence warm deck roof. A cold flat roof is one where the insulation is between or between and below the roof joists. It is also suitable for retrofit with a substantial renovation of the roof. The following images provide examples of flat roof details.

This method of insulation can also be used to upgrade the thermal performance of an existing roof without affecting the waterproofing system. Alternatively battens can be secured to the underside of the. A warm flat roof is defined by insulation being installed on top of the roof deck. Good question theoretically when building a warm roof the vaper control layer goes on the warm side of the insulation.

Here the roof deck is maintained at the. The insulation is below the deck but above the plasterboard. If you put insulation under the decking and between the joists you lower the temperature of the decking and lower the due point thus bringing it closer to the danger point of being in the building. Bs 5250 2011 the british standard for the control of condensation in buildings does not recommend installing insulation between timber joists as well as above the deck.

A cold flat roof is defined by insulation being installed between and if necessary underneath the timber joists. Flat roof detail examples. The roof itself is therefore kept warm. A warm roof is defined as being when the all or the majority of the insulation is above the joists or deck.

This is used for refurbishment e g. Refurbishing an existing timber joisted flat roof which has no insulation. Warm deck insulation 1. An over and between rafter insulation solution can be a feature of a new build project.

Celotex polyisocyanurate pir foam insulation boards are easy to cut and handle. Flat roof detail masonry cavity wall flat roof insulation above and between joists. Flat roof detail masonry cavity wall flat roof insulation above and between joists. As for insulating below the joists an insulating laminate insulation bonded to plasterboard such as celotex pl4000 or a separate rigid pir insulation board finished with a separate sheet of plasterboard can be securely fixed to the joists to provide an internal finish to the roof.

Where insulation depth is restricted by the flat roof construction it may be necessary to install the roof insulation between and below the joists to create a cold deck structure. Parapet detail masonry cavity wall flat roof with parapet insulation.