The moisture diagnosis
The starting point was a damp survey: walls measured 24% moisture content on the prevailing-wind elevations vs. 8% on the sheltered side. That 24% was killing the thermal performance of the existing render and was the reason every previous insulation contractor had walked away from quoting cavity work.
The plan was straightforward in concept, demanding in execution: apply BBA-certified ProPERLA exterior wall coating across the exposed elevations to drop water absorption below 0.5 kg/m²·h, wait two months to confirm the wall fabric had dried back, then install bonded EPS bead cavity wall insulation across the perimeter. Two stages, two seasons — done properly the first time.
What we installed
ProPERLA: full pressure-wash and biocide treatment of the existing pebbledash, two-coat ProPERLA Facade Cream applied in November (warm enough to cure before salt-laden winter winds). Coverage 88 m² across front, north-facing side and rear elevation. 25-year material warranty.
Cavity wall insulation: blown EPS bead system across the full perimeter in late January, after a December moisture re-test confirmed walls had dried back to 11% (within the manufacturer's safe-install range). 10-year insurance-backed CIGA guarantee. GBIS funded the cavity in full; the ProPERLA was self-funded at £4,400.
The outcome
Two-month post-install moisture re-survey: external walls now reading 9% — within normal range across the building, sheltered and exposed elevations alike. Internal condensation on bedroom windows: gone. The first sub-zero week in February proved the new cavity insulation: bedroom temperature held at 17°C overnight with the heating off, vs. the 12-13°C the family was used to.
Energy bill saving £620/year (cavity) plus an immediate health benefit (no more daily wiping of black-spot mould from window reveals). The customer total: £4,400 for ProPERLA, £0 for the cavity — and a property that's now genuinely fit for the next 25 years of coastal exposure.
“Three other firms had quoted cavity wall and then backed out when they saw the rain exposure. OMEGA were the first to explain why — and the first to come up with a real plan that solved the damp first and then the heat. Two winters in and the bedroom windows are dry every morning.”