Thinnest options for rebuilding conservatory walls

[parsman]

Hi all,
We are in the process of rebuilding the outer shell of our conservatory / extension which is currently split (partition) as a bathroom and small storage area. At present, the structure of the building consists of thin wooden Victorian walls and a lean-to felt rood. It is in a very bad state and the room is always extremely cold. We would like to replace the walls with a more solid structure, that is well insulated and would allow heavy fixtures (wall units). We were thinking of using the brick - gap (for insulation) - concrete block approach for the bottom of the walls with windows across the top 2/3 rds (not the bathroom section) but this would eat up on the very limited interior space . Are there any alternative cost effective approaches that would produce a well insulated space that is thin as possible, can handle fixtures and can cope with a lean-to tiled roof?

Thanks in advance.

 

[Deluks]

You decribe it as a conservatory with a felted roof, that it not a conservatory. If therer are big windows in there then all that glass is letting most of the heat out, so insulating the walls will do very little to retain heat. I suppose you could use single thickness blockwork with insulated plasterboard on the inside, the weight of the roof will almost certainly necessitate piers in the wall.

 

[parsman]

The felted roof was probably added later on. The idea was to remove the existing wooden / windows walls and replace it with new walls that were better insulated and strong enough for fixtures with minimal effect on space taken up internally. The amount of windows would be minimised and we would use double glazing and the door would be removed. In effect it would become a true extension rather then a quasi-extension.

http://uk.pg.photos.yahoo.com/ph/momo2007london/album?.dir=42b9re2



I was thinking of still using the or a new wooden frame, with plywood and plasterboard internally, wool insulation between the outside and inside of the walls and tilled exterior walls. The idea being that the internal plywood would strengthen / increase the holding capability of the walls

 

[Deluks]

Looking at those photos I kept expecting the door to fly open and there to be a hillbilly sitting on the bog with a target on his forehead.

If you want the timber option then go as you described but I'd use the plywood on the outside, and use foil backed plasterboard or foiled insulation.
Cover the ply with a breather membrane and battens. then you either add tiles (horizontal battens) or shiplap cladding (vertical battens) If you are rusing the existing frame though then it might for better to ply the inside. Still use membrane between outer studs/battens though.

 

[Fluffster]

Knock it down and start again. Patching it up will not add value and in no way meet current u values.
Pete