Repair a collapsed living-room plaster ceiling and recreate damaged decorative mouldings while protecting the existing cornice.

Official description

The scope of works comprises the reinstatement of an approximately 1.75 m × 2.35 m section of collapsed lath and plaster ceiling in the living room in flat 3, 31 Pembridge Square, following the previous debonding and detachment of the plaster, understood to have resulted from a suspected leak from the water pipes above. The affected area includes sections of decorative plasterwork, including ornamental elements resembling swags/festoons and ribbon bows. A number of fragments of these decorative mouldings were damaged or lost when the ceiling collapsed. However, the majority of the existing decorative plasterwork remains intact and undisturbed. It should be noted that the area requiring reinstatement is likely to be larger, at approximately 2.0 m × 2.65 m, owing to debonding along the edges of the collapsed section. The indicated area is approximate, and the final extent will be determined by the actual area of plaster debonding confirmed by a tap survey. The affected plaster will therefore need to be removed back to sound, well-adhered material to provide a suitable bond between the retained existing plaster and the new plaster. The existing cornice shall be retained and protected throughout the reinstatement works. Laths: Sound historic laths will be retained wherever practicable, with removal restricted to decayed sections and areas requiring access for the inspection and repair of pipework within the floor zone. Reinstatement shall only commence once the source of water ingress has been identified and rectified, and the structure above has sufficiently dried out. Any replacement laths will comprise untreated sawn timber, matching the existing laths in section, spacing and fixing method. Plaster: The ceiling will be restored using a traditional three-coat lime plaster system, comprising a hair-reinforced base coat worked through the laths to create secure nibs, followed by an intermediate coat and a final finishing coat. The plaster composition shall be determined following an assessment of the surviving historic material, including verification of any gypsum content in the original finishing layer. Proprietary pre-mixed gypsum plasters and modern bonding agents shall not be used. Ornaments: Any missing plaster ornaments will be carefully replicated using moulds taken from surviving examples of the same pattern in unaffected areas of the ceiling. Cast elements will be made to match the existing material, profile and detailing, and secured using traditional fixing methods with non-ferrous fixings. Particular care will be taken to ensure that the repaired areas integrate seamlessly with the retained historic fabric. Completion: The new plaster will be allowed to carbonate fully before decoration and will subsequently be finished with a breathable paint system compatible with lime plaster. Photographic records will be taken before, during and upon completion of the works, with a copy submitted to the Council for its records.