Insulation Between Roof Joists

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

Insulation between roof joists.

A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel. Improving your home s energy efficiency rating. Install batting between the attic s floor joists. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe.

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. Box out light fixtures. When you use solid insulation board to create a warm loft the key thing to remember is ventilation you must keep a 50mm gap between the roof and the rigid insulation board. Other benefits of roof insulation include.

Consider using high density r 30 batts which are as thick as r 25 batts but fit into 2x10 framing. Good question theoretically when building a warm roof the vaper control layer goes on the warm side of the insulation. Convenience polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials. 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.

The batting material must be faced and at least as thick as the joists are wide so the batting is nearly flush with the top of the joists. Being lightweight they do not impose significant additional loads on existing structures. Uneven or sloppy application however can make the insulation ineffective and unsealed open cell insulation can absorb moisture causing the roof to rot or leak. This will depend on the construction on your roof and if it is a refurbishment whether the roof tiles are going to be removed.

The main difference between the two is the location of the insulation. Once up at roof level the between rafter boards can be cut accurately to fit the rafter spacings. 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. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

Water is insulation s enemy. 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. A warm roof is where it is above and between the rafters so the rafters are kept warm.