Cavity Wall Insulation in an Old House

[WullieW]

Hi
This is my first post & hope it's in the correct place, anyway my house was built in 1899, detached roughcasted and painted, the damp coarse is slate, my question is should I let one of the many company's that install cavity wall insulation do the job? I have heard that in older houses the insulation can cause dampness IS this true?
Another question I have is; being an old house the ceilings are high the same up stairs with sloping ceilings this means when looking into the loft theres not much room for loft insulation to go down either side if you know what I mean, if I installed insulation in the loft it would stop the air coming up from the cavitys, would this be a problem?
PS, My house is in Scotland south of Glasgow, the slates are nailed straight onto the sarking typycal of Scottish houses built in these days never had felt below slates, If I look into the loft in winter there is some areas with a frost coverage no water leaks just comes through from slates.

cheers
Wullie

[welsh brickie]

its a difficult question to answer.You may get condensation issues rather than damp,I would suggest if you want cavity wall insulation then go for the polystyrene ball type its better.
If you have high ceilings it would be best to insulate on the ceiling and plasterboard on top you will definatly feel it more.

[WullieW]

Thanks for the info Welsh brickie,
Wullie

[Perry525]

I have installed polystyrene ball insulation.
It is not easy to do, to make it work, you need access to the open top of the wall, so you can pour the balls in, once in they need to be agitated and compacted, otherwise over time they will settle and you will be left with an open unninsulated space at the hottest top of the wall.
If you cannot access the top of the wall, you may be able to remove some or all of the bricks from the top of the inner wall, fill and make good with either spray foam or block polystyrene.