Serious Condensation

[jumpeyspyder]

Hi

I moved into my current property about 4 years ago (mid terrace with natural stone slate roof.)
The attic space was boarded and artexed.
There was no insulation and the room was very cold. After the first winter I pulled down the ceiling, installed some urethane insulation board.

To ensure that there would be an air gap (above the insulation) I added battens to the sides of the joists as spacers.

The attic now smells of damp!! I am guessing that there are no vents I had assumed that this would have already been done.

I'm skint and my wife is expecting our second baby in early August.

Does anyone know any cheap solutions or what is the best way to get a contractor without ending up with a cowboy???

 

[Darkrob_DIY]

Hey,

Sounds to me like the damp has been caused by interstitial condensation in that the warm moist air from inside the building rises up into the attic space and through the insulation, eventually condensing on the cold surfaces of the roof - which can lead to rot etc. Therefore i would suggest that one option available to you would be to install a vapour barrier on the warm side of the insulation as this will prevent any moisture from reaching the cold surfaces of the roof - http://monarflex.icopal.co.uk/Products/vcl/index.htm

Other option would be to have vents installed in the roof at the eaves as these vents wll provide cross ventilation of the roof space - getting rid of the warm moist air and replacing it with cooler less moist air from the outside the building. Im not too sure about the cost of this option although it would be dearer than a vapour barrier.

Hope this helps !!

R Critchley

 

[McD]

Forget the vapour barrier, sounds like a lot of work and interference on the inside (something you dont want in your position).

Basically you need the air gap vented. Contact your local building control and they will give you the current guidelines for both eves and apex (there is a given amount of millimetres per metre at both) then contact a roofer and have them comply with this.

This is a small job which would only take a day (depending on the size of roof).

I've just done a similar job with 120 mm of kingspan between the rafters followed by 25mm of kingspan underneath and boarded with foilbacked plasterboard. When I spoke to building control they said that as I did not need to comply with the regs, the air gap of 50mm was not that critical (I have 47mm) but the vents are, given that I have felt underneath the slates and nowhere for any condensation to go.

 

[jumpeyspyder]

Thanks for the replies Darkrob & McD.

The vapor barrier would have been useful before I plastered the ceiling, but I'm not sure I fancy pulling down the ceiling and the associated mess.

I should be able to get Apex vents, but I'm not sure about the eaves as their is no overhang or soffit and the front of the house is cut stone .
(The bottom tiles bed straight onto the wall into a cast iron gutter)

I guess this this leaves me with some kind of tile vent or reroofing using a breathable membrane such as tyvec.

I assume the vents will be the cheapest option any comments or ball park costs would be appreaciated as I don't know if this kind of work should cost me £100 , £1000 or £10,000

Thanks

 

[McD]

As an example my roof is 9 metres long and had 12 vents put in it. Its stone built with cast iron gutters (sounds similar to yourself).

It took a day and cost just under £300.

Basically the guys moved the slates aside, cut a hole with a core bit, fixed the vent and moved the slates back.

The roof has felt over sarking with ballachullish slates.

Re the vapour barrier, the insulation I put in was sealed with aluminium tape with foil backed plaster board, however I have been advised that condensation will still form and that in the absence of a breathable membrane, vents would be required.