Historic buildings rarely give up their secrets willingly. Lime plaster, in particular, holds a layered history: coats of limewash, repairs in gypsum, patches of cement, and the original substrate beneath. Before a trowel touches the wall, it pays to make a careful record. Photographs, sketches and written notes are not paperwork for its own sake. They are the memory of the building, and they will guide every decision you make once conservation work begins.

Why Record Before Repair?

Repair starts with understanding. Once lime plaster is stripped from a wall, the evidence it held is gone: the thickness of each coat, the way the laths were fixed, the aggregate in the mortar, the profile of a moulding, the pattern of cracks. Recording before work begins gives you a baseline. It helps you distinguish original fabric from later repairs, and it shows how the building has moved, settled and dried over time.

• Protect original fabric: a record proves what was there if questions arise later.
• Inform specifications: matching a lime mortar or plaster relies on knowing what was used originally.
• Spot patterns: cracks, damp and salt damage often relate to construction, not just decoration.
• Guide craftspeople: clear images and notes reduce guesswork on site.
• Support consent: conservation officers and listed building applications benefit from methodical evidence.

Photographs: Framing the Evidence

Photographs are the quickest way to capture a wall, but they need discipline. Start wide, then move closer. Take an overall shot of the room or elevation, a mid-range view of the area to be repaired, and close-ups of specific details. Include a scale rule or tape measure in every close-up, and add a north arrow or a note of orientation. Raking light from a torch or low sun reveals texture, hollows and fine cracks that flat lighting hides.

Before cleaning or removal, photograph the surface as found. Capture edges where plaster meets timber, stone or brick. Record lath, wattle and daub, brick nogging, or whatever substrate is exposed. Photograph previous repairs, especially cement patches and gypsum skim coats, because their extent matters. Keep a note of the date, location and photographer for each image, and back up the files the same day. Avoid filters and heavy editing; colour accuracy matters when matching limewash or plaster.

Sketches and Measured Drawings

A sketch forces you to look more closely than a camera does. You do not need to be an artist. Simple plans, elevations and cross-sections, drawn to a rough scale, will capture relationships that photographs miss. Use graph paper or a measured drawing app, and note dimensions in millimetres. Show the build-up of plaster coats: limewash, fine stuff, coarse stuff, scratch coat, lath or substrate. Mark cracks, hollow areas, delamination and repairs.

• Plan: show the room layout, wall positions and extent of repair areas.
• Elevation: record heights, openings, mouldings, rails and datums.
• Section: draw through the plaster build-up and substrate to show thickness and keying.
• Details: use a profile gauge for mouldings, cornices and reveals, then trace the profile onto card.

Label each drawing with the building name, room, date and a reference number that matches your photographs. A sketch made on site, even a rough one, often proves more useful than a perfect drawing made later from memory.

Notes That Capture the Detail

Written notes tie everything together. Record the basics first: date, weather, room, elevation, and who is making the record. Then describe what you see. Note the colour, texture and thickness of plaster. Identify aggregate if you can: sharp sand, soft sand, crushed brick, ash, chalk or shell. Look for hair, straw, hay or other fibre. Note the binder: lime putty, hydraulic lime or something else. Record the number of coats and the order in which they were applied.

Condition notes matter just as much. Is the plaster blown, hollow, friable, damp, stained or salt-laden? Are there cracks, movement, insect damage or rot in the timber behind? Note any previous repairs, including cement, gypsum, modern fillers, paints and sealants. Record tool marks, keying patterns, and the way laths are fixed. If you uncover something unexpected during work, stop and add it to the record before covering it again.

Storing and Sharing the Record

A record is only useful if it can be found. Give every photograph, sketch and note a clear file name and reference number. Keep a master index with dates, locations and descriptions. Store digital copies in at least two places: a local drive and a secure cloud folder. Print a set for the site file, and keep a copy with the building's maintenance log. Share relevant material with your plasterer, conservator and conservation officer before work starts.

As work progresses, update the record. Photograph each stage of repair, note the mixes and methods used, and record any original fabric that is uncovered. This living document becomes a specification for future maintenance and a safeguard for the next generation of custodians. It also helps you match lime plaster and limewash accurately, so repairs blend rather than shout.

Recording historic building details is a small investment of time that pays back many times over. It respects the fabric you are about to touch, and it gives everyone involved a clearer path through the work. Pick up a camera, a pencil and a notebook before the scaffolding goes up. Your future self, and the building, will thank you.