I am looking into insulating my solid walled extension (of a 1936 cavity walled house – not sure of the date of the extension) in the next few months to make the bedroom more habitable for a new arrival!
At the moment the room is very cold and I suspect it has a damp problem – there is polystyrene lining paper on the walls which is coming away slightly in places. Not sure if this is due to general condensation in the room or whether there is penetrating damp through the external wall. At the moment the room is used as a junk room and I haven’t had a chance to investigate thoroughly yet.
Wall Construction:
I believe the solid wall is twin skin so I guess around 9" thick (?). I have several vented bricks in the wall that can be seen externally but have no opening inside – I have tried to find out what these are for by searching the internet for various construction techniques but can’t find anything that might match. I am wondering whether there is a small cavity behind the plaster that needs venting to prevent damp? The funny thing is the vents aren’t very regular on the walls – clay brick vents for each floor on wall1; none on wall 2 (although it has a 1st floor sash window and maybe the gap around the window was used as a vent – subsequently blocked up with sealant!); 1 metal vent cover on ground level only on wall 3 (and a ground floor sash window with sealed up gaps, plus a kitchen door); wall 4 is the original external cavity wall that is now an internal wall. I would appreciate any theories anyone might have on this!
When I installed a vent for a tumble dryer in the kitchen downstairs I noticed there was a corrugated black fibrous liner fixed to the solid brick inner face with plaster applied directly to this. My assumption was that this was a damp proof liner. I’m fairly sure there wasn’t a cavity behind it (referring to my comment above) other than that caused by the corrugations themselves.
Insulating:
I have looked at the various techniques and have come across the woodfibre boards method (internal) - e.g. Pavatex/Pavatherm/Diffutherm. These are supposedly good for the environment (recycled materials, clean energy used in production and they lock up carbon), breathable (no vapour barrier needed and no special ventilation required), resilient to damp (work even when damp and can act as a moisture buffer to keep internal air quality good), good acoustic indulation properties, improve the thermal mass of the structurem, and are non-toxic. They are more expensive than conventional materials though and require special plaster to maintain the breathability.
Has anyone here had any experience with these?
Should I just go the conventional route? Laminated thermal plaster board or separate insulation + plaster board? What thickness?
Can anyone give any advice on how I should proceed with respect to the construction of my extension walls? i.e. should I remove all existing plaster and liner and start from inner face of brick? Would I still need the vents or could I block these up?
If I have a penetrating damp problem would woodfibre be OK to use (breathable) or would I need to fix the damp problem first? Or maybe maintain a vented cavity?
Is DIY installation possible? I am fairly competent at general DIY but I have never done dry-lining before (I would get someone in to do the plastering anyway)? Would a general builder be able
Any advice would be appreciated.
At the moment the room is very cold and I suspect it has a damp problem – there is polystyrene lining paper on the walls which is coming away slightly in places. Not sure if this is due to general condensation in the room or whether there is penetrating damp through the external wall. At the moment the room is used as a junk room and I haven’t had a chance to investigate thoroughly yet.
Wall Construction:
I believe the solid wall is twin skin so I guess around 9" thick (?). I have several vented bricks in the wall that can be seen externally but have no opening inside – I have tried to find out what these are for by searching the internet for various construction techniques but can’t find anything that might match. I am wondering whether there is a small cavity behind the plaster that needs venting to prevent damp? The funny thing is the vents aren’t very regular on the walls – clay brick vents for each floor on wall1; none on wall 2 (although it has a 1st floor sash window and maybe the gap around the window was used as a vent – subsequently blocked up with sealant!); 1 metal vent cover on ground level only on wall 3 (and a ground floor sash window with sealed up gaps, plus a kitchen door); wall 4 is the original external cavity wall that is now an internal wall. I would appreciate any theories anyone might have on this!
When I installed a vent for a tumble dryer in the kitchen downstairs I noticed there was a corrugated black fibrous liner fixed to the solid brick inner face with plaster applied directly to this. My assumption was that this was a damp proof liner. I’m fairly sure there wasn’t a cavity behind it (referring to my comment above) other than that caused by the corrugations themselves.
Insulating:
I have looked at the various techniques and have come across the woodfibre boards method (internal) - e.g. Pavatex/Pavatherm/Diffutherm. These are supposedly good for the environment (recycled materials, clean energy used in production and they lock up carbon), breathable (no vapour barrier needed and no special ventilation required), resilient to damp (work even when damp and can act as a moisture buffer to keep internal air quality good), good acoustic indulation properties, improve the thermal mass of the structurem, and are non-toxic. They are more expensive than conventional materials though and require special plaster to maintain the breathability.
Has anyone here had any experience with these?
Should I just go the conventional route? Laminated thermal plaster board or separate insulation + plaster board? What thickness?
Can anyone give any advice on how I should proceed with respect to the construction of my extension walls? i.e. should I remove all existing plaster and liner and start from inner face of brick? Would I still need the vents or could I block these up?
If I have a penetrating damp problem would woodfibre be OK to use (breathable) or would I need to fix the damp problem first? Or maybe maintain a vented cavity?
Is DIY installation possible? I am fairly competent at general DIY but I have never done dry-lining before (I would get someone in to do the plastering anyway)? Would a general builder be able
Any advice would be appreciated.