Hello PPUK,
At the risk of stirring up some ardent opinions I am going to broach the subject of external wall insulation. We only have about 15 sq metres of wall that needs insulating and several square metres of the wall is taken up by two large casement windows so material costs for this part of the project shouldn't be too onerous regardless of which solution we go for.
As I mentioned in another thread I just can't come to a decision about the best way forward. As you can see from the photo the base of the wall is at two heights which is making the solution less straightforward. Long story short but the excavation of the ground levels uncovered not only very shallow clay drainage pipes that necessitated further excavation and replacing with new pipes but part of the rear wall was build with not much in the way of footings. The area that is stepped up was done so that the single skin brick wall could be underpinned and stabilised with concrete. 80mm XPS was used as shuttering for the concrete with the understanding that this would at least provide some insulation and stop water sitting against the wall. So a quick decision was made and we have now ended up where we are.
The red line in the photo shows where the slate DPC is in the double skin brick wall and the blockwork section that bricked up a redundant doorway; the rest of the wall does not have a DPC. Internally the top of the Geocell-insulated limecrete floor is at about the height of the DPC. The plan has always been the insulate and render and this is something I am hoping to be able to undertake as soon as the weather is more accommodating.
The insulation and render buildup can only be about 50mm (I will install 60-80mm of IWI but that is a subject for another day
). I have considered cork board insulation as it should be more resilient in an area that gets a lot of weather and not a lot of direct sun most of the year. I have also looked into insulating plasters but as discussed in an earlier thread they often require professional installation to get the quoted lambda values.
Finally, I am unsure about what to do below DPC and would like to hear about people's experiences. The insulation and render manufacturers/suppliers suggest an XPS plinth that can then be rendered but won't that just trap moisture behind the XPS? As you can see from the photo the brick wall below DPC suffers from a lot of moisture travelling up from the ground so I am reluctant to simply trap that moisture behind an XPS plinth. Or perhaps I am mistaken and this is not what will happen? Later this year the area will be paved and ACO drains installed so this should hopefully help with some of the ground moisture.
If you have got this far listening to my ramblings, thank you. As always, thoughts and recommendations are very much welcome and encouraged.
At the risk of stirring up some ardent opinions I am going to broach the subject of external wall insulation. We only have about 15 sq metres of wall that needs insulating and several square metres of the wall is taken up by two large casement windows so material costs for this part of the project shouldn't be too onerous regardless of which solution we go for.
As I mentioned in another thread I just can't come to a decision about the best way forward. As you can see from the photo the base of the wall is at two heights which is making the solution less straightforward. Long story short but the excavation of the ground levels uncovered not only very shallow clay drainage pipes that necessitated further excavation and replacing with new pipes but part of the rear wall was build with not much in the way of footings. The area that is stepped up was done so that the single skin brick wall could be underpinned and stabilised with concrete. 80mm XPS was used as shuttering for the concrete with the understanding that this would at least provide some insulation and stop water sitting against the wall. So a quick decision was made and we have now ended up where we are.
The red line in the photo shows where the slate DPC is in the double skin brick wall and the blockwork section that bricked up a redundant doorway; the rest of the wall does not have a DPC. Internally the top of the Geocell-insulated limecrete floor is at about the height of the DPC. The plan has always been the insulate and render and this is something I am hoping to be able to undertake as soon as the weather is more accommodating.
The insulation and render buildup can only be about 50mm (I will install 60-80mm of IWI but that is a subject for another day
). I have considered cork board insulation as it should be more resilient in an area that gets a lot of weather and not a lot of direct sun most of the year. I have also looked into insulating plasters but as discussed in an earlier thread they often require professional installation to get the quoted lambda values.Finally, I am unsure about what to do below DPC and would like to hear about people's experiences. The insulation and render manufacturers/suppliers suggest an XPS plinth that can then be rendered but won't that just trap moisture behind the XPS? As you can see from the photo the brick wall below DPC suffers from a lot of moisture travelling up from the ground so I am reluctant to simply trap that moisture behind an XPS plinth. Or perhaps I am mistaken and this is not what will happen? Later this year the area will be paved and ACO drains installed so this should hopefully help with some of the ground moisture.
If you have got this far listening to my ramblings, thank you. As always, thoughts and recommendations are very much welcome and encouraged.