SOLID WALL INSULATION
External walls are said to be ‘solid' when they consist of a single skin of masonry without a cavity. Solid walls allow much more heat to be lost than cavity walls, even if the cavity wall has a clear cavity without insulation. Solid walls can be insulated internally or externally, but in both cases it is normally a job for professionals.
Internal Insulation
It is usually only cost effective to carry out internal all insulation if there is other refurbishment work being done, such as replacing a kitchen or bathroom or external walls have to be replastered.
Watchpoint 1: Any dampness must be eradicated before installing internal insulation-it is no use hiding a damp patch behind insulation!
Watchpoint 2: Condensation occurs when warm moisture laden air meets a cold surface. In winter the internal temperature will be higher than outside and moisture is created by cooking and washing and just by the occupants breathing! Care must be taken to ensure that the insulation is properly sealed to prevent warm moisture laden air passing through to the inside face of the solid wall.
Walls can be insulated using plasterboard with rigid insulation bonded to the back , or by forming a new timber or metal stud wall inside the old solid wall. In either case, the thickness will be in the region of 100mm (four inches) to provide an appropriate level of insulation. Insulating plasterboard (also known as dry lining) will usually be slightly thinner than a stud wall. In any case it will be necessary to alter skirtings and door frames and if there is a staircase on the outside wall, then the adaptation required to insulate this wall will be very extensive and probably not cost effective.
External Insulation
Walls can be insulated externally by fixing insulation and rendering or by cladding.
Watchpoint: you may need planning permission to clad or render the outside of your house-consult your local authority.
For rendering, rigid insulation is fixed to the outside and then rendered with special render.
Cladding can be in a number of forms-clay tiles or shingles, timber boarding or even metal cladding.
External insulation is not as disruptive as internal insulation, but it will be necessary to remove and refix rainwater and soil pipes and often to alter the eaves (where the wall meets the roof). It is also necessary to insulate around windows, although the thickness of insulation here will depend on the width of the window frame
