insulating attic: gable wall

[jungle_jim01]

This may go slightly in the face of tradition but i'm in the process of insulating my attic conversion. I'm pondering about the wall. Efficiency is key, but i'm also trying to retain some of the features, such as exposed beams, stonework around windows. The wall has 3 flues running through it, 1 is used (but lined with insulated flue liner) and the other two are not used but remain open into rooms below. Any suggestions as to whether it would be useful to insulate this gable wall would be appreciated, or whether it's better to allow the warm air to flowing up the flues to warm into the room? I suspect that wit the fires being unused i'd be better off insulating. If this is the case any ideas on how i can retain some of the stonework surrounding 2 small windows?

Thanks in advance for your help.

 

[MdB]

Just a little note of warning, if you part insulate (which it sounds like you want to do) then the bits that you haven't insulated will likely suffer from condensation. You will be making most of the walls and hence the room warmer which will mean there will be a bigger temperature differential between them and the parts uninsulated, especially the windows and window surrounds.

We have dramatically improved the insulation in the floor, roof and front wall of our house. We are now seeing lots of condensation on the windows in the front of the house even though they are sealed double glazed units (old units though). The back of the house is still uninsulated and hence the walls are cold which has meant I've being spending today removing mould off the walls. A bit depressing considering it was only redecorated less than two years ago.

The plan is to upgrade the insulation in the back of the house in the next year and upgrade the windows (hopefully to oak) when we can afford it.

 

[jungle_jim01]

interesting problem i hadn't thought about...thanks for the advice. so what about an adjoining wall? (we're end of terrace) Presumably that wouldn't need insulating and condensation wouldn't be a problem?

 

[Lime]

Condensation is a major problem when insulating an old house.
The most problematic condensation is where it is unable to seen.
The living area will usually have an atmosphere with a high moisture content that will condense out onto any solid surface that is cooler than the air.
With older houses there is yet another source of moisture, namely from the house structure itself.
The insulation normally prevents air flow (otherwise it would not work) so condensation and damp is often trapped and can build up on the house structure behind the insulation.

In many situations the application of insulation will cause problems in the future no matter what you do.

 

[MdB]

interesting problem i hadn't thought about...thanks for the advice. so what about an adjoining wall? (we're end of terrace) Presumably that wouldn't need insulating and condensation wouldn't be a problem?

It depends on how hot your neighbours keep their house. I have a friend that has never switched their heating on (mid terrace upstairs flat) as their neighbours provide all the heat that they need.

 

[jungle_jim01]

so it sounds as though the best option may be to compromise between efficiency and condensation problems and leave the walls although i will plaster over most of the stonework.

 

[AMc]

Unless you're planning on plastering with lime then you will reduce the breathability (vapour permeability) of the wall using gypsum plaster. If it were me I would consider insulated plasterboard over a batten/stud framework and deal with the potential condensation if it happens.

Notionally working on more than 25% of the thermal element (aka the wall) to add a plaster finish means you should upgrade it to meet the current building regulations minimum which would require a substantial amount of insulation. Not telling you what to do, but making you aware Part L1B may apply.