The hairline that opens along the top of a wall every February is one of the most misdiagnosed defects in a house. It is not a crack in the plaster; it is the junction between two surfaces that move independently, and filling it again each spring is a ritual rather than a repair. Guildford's housing runs from panelled Georgian and Victorian rooms in the town centre out to interwar and post-war suburbs, and the correct answer at that junction is different in each of them.
Establishing what is already up there
Three materials get called coving. A run cornice of lime plaster, modelled in situ against a mould, is found in the older town-centre rooms and is a conservation matter as much as a repair one. Fibrous plaster lengths, cast in a workshop and screwed up, appear in late Victorian and Edwardian work. Everything since is gypsum-cored coving or, in the worst case, expanded polystyrene stuck up with tile adhesive. Tapping and probing a hidden end with a blade settles which one is present before any decision about removal is taken.
Taking a run down without taking the ceiling
Old cornice is heavier than it looks and is often keyed into lath above. The method is to cut the paint line at both edges, work a thin blade along the wall face to release the bond, and support the length while the last of it comes free, rather than dragging it down and pulling laths with it. Fibrous sections are screwed through a hidden flange, and hunting for those screws saves a great deal of damage. Where decorative enrichment survives in good order, a short damaged section is far better spliced than replaced wholesale.
Setting out in a room with no right angles
Coving is set to a line, not to the ceiling. A gauge line is struck on the wall and a second on the ceiling at the correct projection, taken from a level datum rather than from either surface, because a ceiling that dips in the middle of a room will drag the whole run downhill if the coving simply follows it. Where the gap that leaves is uneven, it is packed and filled behind rather than exposed. A run set out properly reads as straight even in a room that is visibly not.
Angles, and why the corner is where it fails
Internal angles are the joint everybody gets wrong. A mitre cut on a box works only if the corner is truly ninety degrees, which in an old house it never is, so the second length is scribed to the profile of the first instead and eased in until it closes. External angles must be mitred, glued on both faces and reinforced from behind, since an external corner takes every knock in the room. Joints along a straight run are staggered away from the middle of a wall, where the eye lands first.
Fixing, and the crack that keeps coming back
Adhesive alone holds gypsum coving to sound plaster, but not to distemper, wallpaper or a dusty surface, so both faces are scored, dusted off and primed first. Long lengths are supported with temporary fixings until the adhesive grabs. Where the underlying movement is seasonal — a timber upper floor drying and re-wetting through the year — the honest solution is to let the junction move and to detail it so it can, rather than to fill it rigidly and repaint every spring.
Stains, gaps and what is behind the run
A brown line following a cornice on a top floor almost never originates in the room. Water backing up at the eaves and overflowing behind the fascia arrives at exactly that junction, so blocked rainwater goods are worth ruling out through experienced gutter vacuuming in Guildford before any plaster is disturbed. The wall head itself, where the masonry meets the ceiling timbers, is frequently open into the roof void, and removing a cornice exposes it — which is the sort of route examined in work carried out for Fantastic Services.
Access, dust and how the work is timed
Plaster work is charged on time and the length of run, with a second visit for filling and sanding once everything has dried. The dust is fine, travels everywhere and settles for days, so rooms are emptied rather than sheeted and a thorough clear-up afterwards is worth arranging alongside through after builders cleaning for homes in Guildford. Town-centre streets are narrow and largely permit-controlled, and long lengths of coving will not go up a tight staircase, so access is checked before delivery. The same work in neighbouring towns is handled by local handyman in Farnborough, and our nationwide service sets out the wider list of repairs available.
