Common Mistakes When Restoring Period Interior Features (and How to Avoid Them)

Period homes are generous in what they give back and unforgiving in what they take away. Get the proportions right — a cornice at the correct depth, skirting at the right height, a fireplace that suits the room — and the house settles around you. Get them wrong and something feels off, even to visitors who could not tell a Regency terrace from an Edwardian one. The damage done to historic interiors is rarely vandalism. It is well-meant work carried out quickly, with modern materials and modern assumptions.

The same handful of mistakes comes up again and again. Most are easier to avoid than to fix.

Treating a fireplace as a gap to be filled

The most common error is buying a surround by eye, then discovering it is too wide, too shallow or from the wrong period. A chunky Victorian cast-iron insert in a delicate Georgian room never quite looks right, no matter how well it is restored.

Before you buy anything, measure the opening, the width of the chimney breast and the depth of the reveal, then work out where the hearth sits — flush with the floor or raised. Look at what is left behind: scars in the plaster where a surround once sat, a stone hearth edge, soot staining on the brickwork. Old photographs of the house, if you can find them, are worth more than any amount of guessing.

Three things to avoid in particular:

• Cutting bricks away to squeeze in an oversized insert. It weakens the breast and rarely convinces.
• Sealing a redundant chimney completely. An airtight flue encourages condensation and damp patches on the chimney breast. Leave a vent, or an air gap behind a sealed plate.
• Removing a chimney breast without structural advice. It is rarely just a decorative decision.

If you plan to burn anything, the flue needs to be suitable — swept, checked, and lined if necessary. Building Regulations apply, and this is work for a competent registered installer, along with a carbon monoxide alarm. Not a job for a hopeful Saturday.

Cornices: chipping off what could have been repaired

A hairline crack or a small loss above a door is not a reason to rip out an entire run of cornice. Traditional cornices were run in situ in lime plaster, and they can be repaired the same way. For small sections, take a silicone mould from the surviving profile, cast a matching piece, and fix it in place with plaster of Paris or lime. Filler has its uses, but anything more than a shallow scratch will look flat and slightly shiny under paint.

Two other habits cause trouble. The first is sanding aggressively. Cornice plaster is soft, and the crisp edges are what make the profile read; once they are rounded off, the moulding looks tired forever. The second is paint. Fifteen coats will soften a sharp profile as surely as sandpaper will. If you decide to strip it, work gently and treat the paint as suspect — houses built before the 1960s may contain lead paint. Dry sanding and heat guns are the wrong tools. Take advice, or bring in a specialist for anything more than a small area.

Skirting boards: the biggest giveaway

Nothing announces a rushed renovation like 95mm MDF skirting under a 250mm Victorian run. Height, thickness and profile all matter, and so does keeping what you already have. Repair and splice rather than replace wholesale. Once spliced sections are filled and painted, they disappear.

Where replacement is unavoidable, match the profile rather than the price. Period profiles are widely available in pine or tulipwood. Fitting matters too: floors in old houses are rarely level, so scribe the bottom edge to the floor rather than pumping in caulk. A thin bead along the top is fine. Half a tube along the bottom will crack and look worse than the gap it was hiding.

Damp: sealing a wall that needs to breathe

Solid walls manage moisture by allowing it to move. Cement render, gypsum skim and vinyl paints stop that movement, and the moisture finds somewhere else to go — usually your skirting boards and the bottom of your plaster.

Before accepting a diagnosis of rising damp, check the boring things first: overflowing gutters, leaking downpipes, cracked render, soil or paving bridging the damp-proof course, blocked air bricks, high ground levels outside. Water running down a wall for years will soak brickwork thoroughly, and no injected treatment will help while the leak continues.

Where a wall is wet, let it dry, then reinstate breathable materials — lime render and plaster, limewash or clay paint. If damp is persistent, or if you are worried about mould and indoor air quality, take independent advice from a surveyor or a conservation-accredited professional. A free survey from a company that sells damp-proofing is not neutral advice.

Paint finishes: the right coating for the right surface

Paint is where good intentions do the most quiet damage. On lime plaster and render, breathable finishes — limewash, distemper, clay paint — let the wall dry out. Vinyl matt emulsion and acrylic eggshell do the opposite. Around a chimney breast or a solid external wall, that difference shows up within a winter.

Preparation matters as much as the topcoat:

• Use lime-based filler on lime plaster. Gypsum filler shrinks, cracks and pulls away.
• Do not paint over hollow, damp or dusty plaster. Fix it first.
• Sand lightly between coats on joinery, and keep coats thin. Thick paint rounds off the beads on panelling and the mouldings on sash windows.
• Treat pre-1960s paint as lead paint until proven otherwise. Damp-sand, use proper protection, and get specialist help for large areas.

Getting the order of work right

Most of these mistakes come from doing things in the wrong sequence. The order below saves money and heartache:

1. Investigate. Strip back a small area, measure, look for evidence of what was there originally.
2. Fix water and structure. Roof, gutters, downpipes, drainage, ground levels. Nothing else is worth doing until this is sorted.
3. Repair plaster and joinery. Splice, cast, patch and make good before any brush appears.
4. Decorate with materials suited to the substrate, once everything is genuinely dry.
5. Add the details last — hearth, insert, ironwork, hardware.

One more point worth checking early: if the building is listed or sits in a conservation area, speak to the local authority's conservation officer before removing or altering original features. Consent may be needed, and undoing work carried out without it is expensive. In practice, most conservation officers would rather help you get it right than stop you.

A slower, calmer approach

Period interiors reward patience. Photograph everything before you touch it. Keep a box of salvaged pieces, even the ones you think are useless. Test a small patch of paint or plaster before committing to a whole room, and live with a bare wall for a season before deciding how to finish it.

If a job feels beyond your skills — running in a cornice, lining a flue, dealing with persistent damp — spend the money on a specialist rather than on a cheap fix you will have to undo. The house has waited a hundred years. It can wait another month for you to get it right.

Photo: Michael D Beckwith / Pexels