insulating loft, do I do the loft floor or the roof?
Discussion
I want to insulate the loft of my house soon. I went around to a mates house a while ago and he has just done his with the foil covered insulation which looks to be very good quality. However, he has used it on the underside of the roof as opposed to on the loft floor.
While this may be a bit easier for me (I have some stuff stored up there and part of the loft is already boarded)I am concerned that it might not be as efficient as putting the insulation on the loft floor. My rational is that if its on the underside of the roof, I am effectively heating the loft space!
So, in efficiency terms, whats my best option?
1. Just insulate the whole underside of the roof with foil layer type insulation.
2. Use foil layer insulation on the loft floor (this would be over the existing fiber type
insulation that is already there, and about 4 inches thick and up to the top of the joists)
3. Just cover the existing fiber insulation with another layer of fiber.
Any advice guys?
While this may be a bit easier for me (I have some stuff stored up there and part of the loft is already boarded)I am concerned that it might not be as efficient as putting the insulation on the loft floor. My rational is that if its on the underside of the roof, I am effectively heating the loft space!
So, in efficiency terms, whats my best option?
1. Just insulate the whole underside of the roof with foil layer type insulation.
2. Use foil layer insulation on the loft floor (this would be over the existing fiber type
insulation that is already there, and about 4 inches thick and up to the top of the joists)
3. Just cover the existing fiber insulation with another layer of fiber.
Any advice guys?
buzzer said:
I want to insulate the loft of my house soon. I went around to a mates house a while ago and he has just done his with the foil covered insulation which looks to be very good quality. However, he has used it on the underside of the roof as opposed to on the loft floor.
While this may be a bit easier for me (I have some stuff stored up there and part of the loft is already boarded)I am concerned that it might not be as efficient as putting the insulation on the loft floor. My rational is that if its on the underside of the roof, I am effectively heating the loft space!
So, in efficiency terms, whats my best option?
1. Just insulate the whole underside of the roof with foil layer type insulation.
2. Use foil layer insulation on the loft floor (this would be over the existing fiber type
insulation that is already there, and about 4 inches thick and up to the top of the joists)
3. Just cover the existing fiber insulation with another layer of fiber.
Any advice guys?
1 is called "warm roof" because the whole roof space is warm, but it does leave you the entire ceiling/floor surface as an area to store stuff. It will also keep any pipes in the roof space from being frozen. Downside is you have to pay for the energy to heat the roof space. Note that there should be a minimum of 25mm space between the top surface of the insulation and the underside of the roofing felt, or you could end up with condensation/damp problems.
2 don't bother, the foil will compress the fibreglass, see below.
3 this is the easiest way, but the fibreglass will collapse over time, and you won't be able to use the floor because if you lay boards over the fibreglass, it will ccmpress and be less effective.
While this may be a bit easier for me (I have some stuff stored up there and part of the loft is already boarded)I am concerned that it might not be as efficient as putting the insulation on the loft floor. My rational is that if its on the underside of the roof, I am effectively heating the loft space!
So, in efficiency terms, whats my best option?
1. Just insulate the whole underside of the roof with foil layer type insulation.
2. Use foil layer insulation on the loft floor (this would be over the existing fiber type
insulation that is already there, and about 4 inches thick and up to the top of the joists)
3. Just cover the existing fiber insulation with another layer of fiber.
Any advice guys?
1 is called "warm roof" because the whole roof space is warm, but it does leave you the entire ceiling/floor surface as an area to store stuff. It will also keep any pipes in the roof space from being frozen. Downside is you have to pay for the energy to heat the roof space. Note that there should be a minimum of 25mm space between the top surface of the insulation and the underside of the roofing felt, or you could end up with condensation/damp problems.
2 don't bother, the foil will compress the fibreglass, see below.
3 this is the easiest way, but the fibreglass will collapse over time, and you won't be able to use the floor because if you lay boards over the fibreglass, it will ccmpress and be less effective.
If you have a traditional 'cold' roof, there's limited benefit in insulating at rafter level, because the loft space is deliberately ventilated at eaves level.
If you add insulation at ceiling level (which is the logical thing to do), be aware that you can create potential problmes with condensation, if you overdo it.
Search 'loft condensation' on this forum and you'll find lots of references to me boring everyone with the details.
If you add insulation at ceiling level (which is the logical thing to do), be aware that you can create potential problmes with condensation, if you overdo it.
Search 'loft condensation' on this forum and you'll find lots of references to me boring everyone with the details.
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