hi
i'm retrofitting 150mm of rigid foil backed recticel insulation into the ceiling, sloped roof and dormer timber frames.
i'm installing 50/100mm between timbers depending on where i can still achieve the 50mm air gap, and then overboard with 50/100 depending on what is installed underneath, then seal any joins with foil tape which will provide the vapour barrier in those areas
anyway, thought i finally had the plan sorted and have the first 50/100mm in everywhere now apart from the lower dwarf walls.
behind the dwarf walls i've packed in 200mm of knauff insulation between the floor joists and run another layer of 170mm on top. i've packed the gap between the lower ceilng, floor and joists so that the insulation is approx 300mm back under the room floor, which i hoped would essentially seal the ends of the floor (we've also had a rewire, i've spoken to the spark and all cables are rated to pass through the insulation as shown)
i was going to add some more timber from the purlin to the floor then install the final pieces of insulation between and begin the overboarding.
my thinking before was 370mm insulation would work as it did in my previous house loft (which had no vapour barrier etc just a shed load of yellow insulation) as essentially the gap behind would mimic that. but now after some googling i'm worried that i should also have some kind of vapour barrier between the joists, then the knauff on top? at the minute it is just the plasterboard from the ceiling below
(pic shows opposite dormer as i'd only started installing the inusltion in there)
the roof has been replaced and a modern breathable membrane installed, also all the ridge tiles are a venting system (thats what the roofer told me anyway). will this help or negate the need for a vb?
also would installing soffit and wall vents behind the dwarf wall help with airflow? Potentially a wall vent in this area
google is obviously a wonderful thing, however a lot of information out there is contradictory and some say that installing a vb above a celing can actually cause mould/damp in some cases.
any advice welcome, many thanks
i'm retrofitting 150mm of rigid foil backed recticel insulation into the ceiling, sloped roof and dormer timber frames.
i'm installing 50/100mm between timbers depending on where i can still achieve the 50mm air gap, and then overboard with 50/100 depending on what is installed underneath, then seal any joins with foil tape which will provide the vapour barrier in those areas
anyway, thought i finally had the plan sorted and have the first 50/100mm in everywhere now apart from the lower dwarf walls.
behind the dwarf walls i've packed in 200mm of knauff insulation between the floor joists and run another layer of 170mm on top. i've packed the gap between the lower ceilng, floor and joists so that the insulation is approx 300mm back under the room floor, which i hoped would essentially seal the ends of the floor (we've also had a rewire, i've spoken to the spark and all cables are rated to pass through the insulation as shown)
i was going to add some more timber from the purlin to the floor then install the final pieces of insulation between and begin the overboarding.
my thinking before was 370mm insulation would work as it did in my previous house loft (which had no vapour barrier etc just a shed load of yellow insulation) as essentially the gap behind would mimic that. but now after some googling i'm worried that i should also have some kind of vapour barrier between the joists, then the knauff on top? at the minute it is just the plasterboard from the ceiling below
(pic shows opposite dormer as i'd only started installing the inusltion in there)
the roof has been replaced and a modern breathable membrane installed, also all the ridge tiles are a venting system (thats what the roofer told me anyway). will this help or negate the need for a vb?
also would installing soffit and wall vents behind the dwarf wall help with airflow? Potentially a wall vent in this area
google is obviously a wonderful thing, however a lot of information out there is contradictory and some say that installing a vb above a celing can actually cause mould/damp in some cases.
any advice welcome, many thanks
