I'd be grateful for some advice on this issue.
Detached house was built 1996-7 under a version of the Building Regs that permitted use of thermal block for the inner skin rather than cavity wall insulation. As a result we have been seized on by the retro-fit industry for free retro insulation under the current Government/utility co scheme.
The insulation proposed is the glued polystyrene bead and neighbours have already had this done, without problems so far. I am aware from this forum and other sources that the "glued bead" method is more satisfactory than "loose bead" or "fibrefill". I was brought up to believe that the cavity is there for a purpose (I am a civil engineer rather than a builder) but I am not in an exposed location (urban Surrey) so am not too worried about rain penetration (or should I be?)
These houses are on a former industrial site with possibility of pockets of landfill gas; for this reason they have suspended precast concrete floors with underfloor ventilation via brick-sized grilles just below dpc. Can anyone advise me of the typical detail here: is there any possibility that the cwi could end up blocking the underfloor ventilation? Is the cavity normally concrete filled up to dpc?
Also I have seen on this forum a calculation of the change in U-value resulting from cavity wall insulation on a brick/cavity/thermal block wall. The improvement was small and brought the U-value up to not much more than the equivalent of a traditional cavity wall WITH cwi.
So all in all, I have lived in this house for nearly 20 years and am wondering if it actually worth it? Any views?
Detached house was built 1996-7 under a version of the Building Regs that permitted use of thermal block for the inner skin rather than cavity wall insulation. As a result we have been seized on by the retro-fit industry for free retro insulation under the current Government/utility co scheme.
The insulation proposed is the glued polystyrene bead and neighbours have already had this done, without problems so far. I am aware from this forum and other sources that the "glued bead" method is more satisfactory than "loose bead" or "fibrefill". I was brought up to believe that the cavity is there for a purpose (I am a civil engineer rather than a builder) but I am not in an exposed location (urban Surrey) so am not too worried about rain penetration (or should I be?)
These houses are on a former industrial site with possibility of pockets of landfill gas; for this reason they have suspended precast concrete floors with underfloor ventilation via brick-sized grilles just below dpc. Can anyone advise me of the typical detail here: is there any possibility that the cwi could end up blocking the underfloor ventilation? Is the cavity normally concrete filled up to dpc?
Also I have seen on this forum a calculation of the change in U-value resulting from cavity wall insulation on a brick/cavity/thermal block wall. The improvement was small and brought the U-value up to not much more than the equivalent of a traditional cavity wall WITH cwi.
So all in all, I have lived in this house for nearly 20 years and am wondering if it actually worth it? Any views?