Flat Roof Insulation Between Rafters

Alternatively battens can be secured to the underside of the joists and gmw fitted between these in much the same way as between the main roof joists.

Flat roof insulation between rafters.

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. The old roof was tar and gravel so the switch to tpo should show significant change. A cold flat roof is one where the insulation is between or between and below the roof joists. 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.

I have an insulation factor of about 8 10 plus the reflectivity of the white tpo. Breathing roof with low resistance lr underlay with this option insulation fully fills the rafter space without an airspace between the insulation and type lr underlay. Modern u value targets mean installing insulation between rafters only is rarely a viable option. Is there any advantage to trying to get any insulation in between the 2 8 rafters.

Refurbishing an existing timber joisted flat roof which has no insulation. The insulation is below the deck but above the plasterboard. 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. 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.

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. 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. Also there is a soffit vent but none at roof peak. An over and between rafter insulation solution can be a feature of a.

Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. 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. 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. Being lightweight they do not impose significant additional loads on existing structures.

Should i leave out the soffit vent. 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. Insulation between the rafters can be designed in two ways. No ventilation is required for these types of roofs.