Insulation Between Rafters Flat Roof

I have an insulation factor of about 8 10 plus the reflectivity of the white tpo.

Insulation between rafters flat roof.

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. The old roof was tar and gravel so the switch to tpo should show significant change. Water is insulation s enemy. An over and between rafter insulation solution can be a feature of a.

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. 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. 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. It creates a breeding ground for mold and mildew and ruins the air trapping pockets that block heat flow.

Modern u value targets mean installing insulation between rafters only is rarely a viable option. 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. 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. 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.

Is there any advantage to trying to get any insulation in between the 2 8 rafters. 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. Look for water stains on the roof sheathing or damp or moldy spots on attic joists and existing insulation as a clue to where leaks might be.

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. This is used for refurbishment e g. Refurbishing an existing timber joisted flat roof which has no insulation. For example if the space beneath the rafters is going to be used for a living area then you will need to insulate the roof rafters.

Box out light fixtures. Although there are many different. Being lightweight they do not impose significant additional loads on existing structures. The insulation is below the deck but above the plasterboard.

Also there is a soffit vent but none at roof peak.