I think I know what I'll be doing this weekend!
However it will take us from a patchy 100mm up to 400mm. Should make quite a difference.
Insulation on the cheap
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Bedrock Barney
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Helen, Candy's advice is good. Your house is an older house, probably built before the 30's before sarking felt was used. Where a vapour proof sarking, usually bituminous felt, has been used it is necessary to maintain a ventilation opening at the eaves equivalent to a continuous 25mm gap with at least a 50mm gap between the insulation and the sarking. With your non felted roof this would not be necessary as the wind will blow through the tiles.
The sarking felt is used to prevent wind driven rain and snow, which can be blown between the tiles, from causing dampness on the ceiling below. If there is no dampness or rain penetration or damage to the tiles leave well alone with the roof. If you are getting moisture ingress you will need to have the roof stripped and replaced using a felt under the tiles.
The best felt to use is a breather membrane such as Klober Permo Forte which allows water vapour to escape but not moisture in. This felt would be sealed at the joints to stops draughts taking heat away from the insulation. With this system no gaps at the eaves are required, indeed the eaves should be sealed as well.
You should increase the thickness of the insulation to at least the Building Regulations minimum of 250mm but it would be better to increase it too a maximum of 450mm, all at ceiling level. It is not worth it going above this thickness nor insulating at rafter level unless you are doing a full loft conversion. As others have said, don't remove the existing, install over it. There are literally dozens of different types of insulation available at different prices.
Bill, I'm taking a large trailer up to CAT next weekend to do a cob building workshop so I could collect some sheep fleeces on the way back. It will take about 10 cu m. I usually take the A44, A470, so must go quite close to you. Can you PM me with a price, please?
The sarking felt is used to prevent wind driven rain and snow, which can be blown between the tiles, from causing dampness on the ceiling below. If there is no dampness or rain penetration or damage to the tiles leave well alone with the roof. If you are getting moisture ingress you will need to have the roof stripped and replaced using a felt under the tiles.
The best felt to use is a breather membrane such as Klober Permo Forte which allows water vapour to escape but not moisture in. This felt would be sealed at the joints to stops draughts taking heat away from the insulation. With this system no gaps at the eaves are required, indeed the eaves should be sealed as well.
You should increase the thickness of the insulation to at least the Building Regulations minimum of 250mm but it would be better to increase it too a maximum of 450mm, all at ceiling level. It is not worth it going above this thickness nor insulating at rafter level unless you are doing a full loft conversion. As others have said, don't remove the existing, install over it. There are literally dozens of different types of insulation available at different prices.
Bill, I'm taking a large trailer up to CAT next weekend to do a cob building workshop so I could collect some sheep fleeces on the way back. It will take about 10 cu m. I usually take the A44, A470, so must go quite close to you. Can you PM me with a price, please?
Action is the antidote to despair - Joan Baez