The insulation of a roof from the outside allows to keep all the space to arrange the attic of the house, not to mention that it is more efficient, since it presents little risk of thermal bridges, but it is a question of 'a heavy operation.
Preparation of the operation
It is essential first to remove the cover (remove the tiles), then to clean the rafters, to treat them and to replace those which are damaged. Calculations must also be made to ensure that the frame will be able to support the weight added by the insulation.
Installation of insulation
This insulation can be achieved by attaching panels of extruded polystyrene or lined with glass wool to the frame. The most used method is called "sarking". It consists first of all in fixing the interior siding of your choice on the rafters, provided that it resists fire and possibly humidity. The insulating panels are then laid in staggered rows, with tight and alternating joints to avoid thermal bridges. We start every other row with half a panel, and the work is done from bottom to top, going from one side of the roof to the other. You can then optionally install an under-roof screen, then the assembly is fixed to the rafters by nailed or screwed battens, in compliance with the regulations. This done, all you have to do is put the cover down again.> Ask for a roof insulation quote