Flat Roof Insulation Between Rafters

It allows insulation to be installed in a watertight roof either after the roof covering has been fixed on a new build or without disturbing an otherwise sound existing roof covering as part of a renovation.

Flat roof insulation between rafters.

The old roof was tar and gravel so the switch to tpo should show significant change. Cold deck roof a cold deck roof is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof. Kingspan 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 insulation is below the deck but above the plasterboard.

Insulation between the rafters can be designed in two ways. A warm deck roof is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation. An over and between rafter insulation solution can be a feature of a. Is there any advantage to trying to get any insulation in between the 2 8 rafters.

Modern u value targets mean installing insulation between rafters only is rarely a viable option. To protect the roof from the potential of condensation occurring unseen within the construction it s important to remember that the layer of insulation installed over the rafters should as general rule be double the thickness of the insulation layer between the rafters. This is used for refurbishment e g. In this blog post we will be looking at insulating pitched roofs and why putting insulation just between the rafters isn t a viable solution.

Where the insulation does not fill the total rafter depth the low emissivity foil facings can gain additional thermal benefit from the air spaces they face. The underside of the rafters in this case will need to be finished with a suitable vapour control layer vcl and plasterboard to provide a suitable internal finish to the roof. No ventilation is required for these types of roofs. Pitched roof rafter level.

On new build or replacement pitched roofs the ideal build up would be insulation fitted over and then between the rafters giving a big boost for airtightness image credit. A cold flat roof is one where the insulation is between or between and below the roof joists. Should i leave out the soffit vent. I have an insulation factor of about 8 10 plus the reflectivity of the white tpo.

Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. Refurbishing an existing timber joisted flat roof which has no insulation. Also there is a soffit vent but none at roof peak. The general advice we give is that you should always insulate between and above the rafters or between and under the rafters on our u value calculator we don t give an option for putting insulation between the rafters.