Dorma Cladding

Alias_Omega

We are looking to change the cladding on the dorma parts of the house. Its currently some form of T&G wood which has seen better days. The plan was to have the wood removed, insulation boards installed, waterproof membrane then PVC (White) cladding installed over the top.

We have had 3 quotes, and they are vary.

1) £700. Remove wood, install insulation and then make some form of frame?, then install cladding.

2) £300. Remove wood, install 25mm solid board insulation, install waterproof membrane, install PVC cladding (using correct start, stop and corner pieces).

3) £900. Remove wood, install insulation, install 18mm Marine Ply, install waterproof membrane, install cladding. The Marine Ply will strengthen the dorma...


We think that No 2 is the best quote, as currently there is no Marine Ply on the dorma. Its been standing for 30+ years and its still good.


Its just a bit chilly in there, and the best way to update the insulation is from the outside..

Ideas?

andyhop

£300 has to be a mistake, there's easily that in material

Furts

Technically, none of the options are correct. But I accept the post may for brevity, or perhaps the contractors have not given exact details.

A typical detail would be, ideally foil backed plasterboard on a polythene membrane, insulation between the studs - depends what timber you have there, say 100mm Celotex, breather membrane, ventilation, then cladding.

Your current construction has worked because it can breath. If you clad with tight fitting pvc then condensation and sweating will be an issue. I know thousands of homes are done like this including my neighbours, but over time the problems will arise. Plus, to do properly, the plasterboard inside the room will need renewing to fit the polythene membrane.

Alias_Omega

Polythene Membrane will be fitted on the outside, after the insulation. Is this wrong?

ie..

Plasterboard --> Studs --> 25mm Insulation --> Polythene Membrane --> UPVC

Furts

Yes the detail is wrong. The membrane should be to stop moisture from your room getting into the structure - hence behind the plasterboard. Then the moisture which is in there naturally can breath in accordance with the changing weather. This will be through the breather membrane located behind the pvc cladding. This area should be ventilated to allow this moisture to escape.

This is all basic building principles that have been around for the last thirty years. There will be alternatives - I am just giving the basics. However, the fact that none of your quotes seem to have addressed these issues does concern me and should concern you.

In essence, be alert and beware of cowboy builders.

Alias_Omega

3) had waterproof membrane. Read breathable.

ceredigion

uPVC _pale_
:idea:
Marley eternity Cedral Weatherboard

Alias_Omega

^^

Wont match guttering, UPVC door etc..

ceredigion

^^
There's no accounting for taste

Alias_Omega

^^

Its okay, if we don't like it. It can be removed and Marley fitted.