Proposed works
Reason for works
The main concern for this building is moisture stress. Secondary concerns are increasing comfort and reducing energy bills. As the moisture stress is associated with the entrance road, it appears some element of public works is advisable.
Design
The creation of the new ‘major renovation’ standard has implications for what measures a homeowner of an existing dwelling not listed on register of protected structures may consider. In brief, renovating more than 25% of the surface area of an existing dwelling (where that includes some form of wall insulation) triggers the requirement for a cost-optimal improvement which is identified as 125 kWh/m2. TGD-L:2018. Section 2.3.1 states “Where more than 25% of the surface area of the dwelling envelope undergoes renovation the energy performance of the whole building should be improved to Cost Optimal level in so far as this is technically, functionally and economically feasible.”
The proposed minimum works are focused primarily on attic insulation and resolving the rising damp problems moisture problems at the front of house. It is suggested that no insulation works should be carried out to the façade or ground floor until the causes of the rising damp have been resolved and moisture levels have stablised to an acceptable level.
The proposed maximum works cover a wider range of insulating and energy efficiency measures on the basis that moisture has been dealt with adequately. The suspended timber floor to front of dwelling has been insulated as is, rather than changed to an insulated solid floor as per Findlater Street to facilitate drying.
For whatever reasons it happened, Irvine Terrace has no footpath, and the road is only a few millimetres between the inside floor level. It appears that there is a centre camber to the road encouraging the movement of surface water towards the terrace. This appears to be significantly stressing the rubble brick and stone solid walls of this Victorian terrace; see images of Irvine Terrace on a wet day. A survey should be undertaken of the moisture conditions of all dwellings on this terrace. Perhaps the footpath would be lowered somewhat and a lower road level created or perhaps, by investigating local drainage, the falls and outlets would be altered to ensure rainwater is directed away from the houses. Alternatively, the following measures are suggested to reduce the moisture stress:
- A continuous French drain should be installed at the face of the wall locally lowering the water table and reducing residual moisture near the wall. Drainage channel or gullies may also needed on the other side of the road (at bottom of large embankment); a simple example of a French drain is a perforated pipe at the bottom of a gravel-filled trench
- A wide, high quality channel drain should be installed to drain the road surface for the full length of the terrace, removing free flowing surface water from the wall.
Works of this nature require engagement by property owners and the local authority.
Energy use, grants and tax relief
See Energy analysis below to understand the energy efficiency impact of the various works.