Loft Insulation Between Roof Joists

Rolls of mineral wool can be used if the joists in your loft are regular.

Loft insulation between roof joists.

Alternatively battens can be secured to the underside of the. The first layer of wool is placed between the joists and then a second layer is placed at right angles which covers the joists and also makes the insulation up to the correct depth of 270mm. Lay mineral wool between the joists and then fit rigid insulation boards across the joists with floorboards on top. You can also add rigid foam insulation under the rafters which adds r value and eliminates thermal bridging through wood rafters.

If the loft is going to be used as living space then the insulation should be placed at rafter level to create a warm roof. Insulating between the joists of your loft will keep your house warmer but make the roof space above colder. 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. But if you plan to use your loft for storage only then a conventional cold roof option where the mineral wool insulation rolls are placed in between the ceiling joists above the top floor.

A vent baffle should be installed between the insulation and the roof decking to maintain the ventilation channel. But if you simply fill the spaces between the joists with insulation and then board over the top you won t achieve an adequate depth of loft insulation. Joists are the horizontal beams which make up the floor. To increase the thickness of your roof insulation layer you can.

Some old loft insulation installations can easily feature as little as a single layer of around 100mm insulation between the ceiling joists. Cold deck or cold roof is where the insulation is below the roof deck and the associated joists. We would always recommend having a breathable membrane in place between the tiles and the rafters too to allow the roof to breathe. Consider using high density r 30 batts which are as thick as r 25 batts but fit into 2x10 framing.

What about storage space. The most common solution to top up existing loft insulation levels is to lay glass mineral wool insulation over the top of the existing insulation within the ceiling joists although if this is in. Flat roof insulation always requires professional insulation and damp roofs require professional assessment before work can be carried out.