How to Install Coving and Cornices: Complete Guide
Quick Answer: Installing coving or cornice takes 2-4 hours for an average bedroom. You’ll need coving adhesive, mitre box, saw, filler, and fine sandpaper. The process involves: measuring and cutting mitres, applying adhesive to both surfaces, pressing firmly into place, and filling gaps. Plaster coving costs £2-4/metre for materials, whilst lightweight polystyrene costs £1-2/metre. Most DIYers can achieve professional results with patience and the right technique. Understanding Coving and Cornices: What’s the Difference? Before we dive into installation, let’s clarify terminology. In the UK, coving typically refers to the concave moulding that sits at the wall-ceiling junction, whilst cornice describes more ornate, decorative mouldings with complex profiles and details. Both serve the same practical purposes: hiding imperfect plaster joints, adding character to rooms, and creating visual interest. The terms are often used interchangeably, though Georgian and Victorian properties typically feature true cornices with elaborate designs, whilst modern homes use simpler coving profiles. Feature Coving Cornice Profile Simple concave curve Complex, ornate designs with multiple tiers Projection 50-127mm (2-5″) 100-300mm+ (4-12″+) Material cost £1-4/metre £5-25/metre+ Installation time 2-3 hours per room 4-8 hours per room Best suited for Modern homes, standard ceilings Period properties, high ceilings Choosing the Right Material for Your Coving Material choice dramatically affects installation difficulty, durability, and final appearance. Each has distinct advantages depending on your skill level and property type. Plaster Coving (Traditional) Plaster coving remains the gold standard for professional installations. Made from gypsum plaster, it’s heavy, durable, and produces the crispest, most authentic finish. It’s particularly appropriate for listed buildings and period properties where maintaining historical accuracy matters. Weight: Approximately 2-4kg per metre depending on profile size Cost: £2-4/metre from suppliers like Wickes or Travis Perkins Installation difficulty: Moderate to high — requires proper adhesive technique Lifespan: 50+ years with no sagging or yellowing Finishing: Can be filled, sanded smooth, and painted to perfection Polystyrene Coving (Lightweight) Polystyrene (expanded foam) coving suits DIY installations. It’s lightweight, easy to cut, and forgiving of minor mistakes. Most B&Q and Screwfix stores stock various profiles. Weight: 50-100g per metre — incredibly light Cost: £1-2/metre, making it budget-friendly Installation difficulty: Low — perfect for first-timers Lifespan: 15-20 years, may yellow slightly over time Limitations: Less durable, can dent easily, profiles look less crisp Polyurethane Coving (Modern Alternative) Polyurethane offers a middle ground: lighter than plaster but more substantial than polystyrene. It replicates ornate Victorian and Georgian profiles convincingly. Weight: 500g-1kg per metre Cost: £3-8/metre Installation difficulty: Moderate Lifespan: 30+ years, won’t yellow Benefits: Pre-primed, moisture-resistant, ideal for bathrooms Pro Tip: For properties built before 1950, always use plaster coving if you’re matching existing profiles. Modern lightweight materials won’t match the depth, shadow lines, or crisp detail of original plasterwork, which can look jarring in period rooms. Essential Tools and Materials for Coving Installation Proper preparation prevents frustration. Gather everything before starting — interrupting work to fetch tools breaks your rhythm and affects adhesive working time. Core Tools Required Mitre box and fine-tooth saw: Stanley or equivalent, around £8-15 from Screwfix Tape measure and pencil: 5m tape minimum for full room measurements Spirit level: 600mm or longer for checking alignment Filling knife: 100mm flexible blade for applying adhesive Small trowel: For working adhesive into gaps Sanding block: 120-grit paper for smoothing joints Step ladder: Stable platform essential for ceiling work Caulking gun: If using decorators’ caulk for polystyrene coving Materials Checklist Coving lengths: Calculate room perimeter plus 10% for wastage and mitres Coving adhesive: Gyproc Cove Adhesive or similar (£6-8 per 10kg bag) Joint filler: Polyfilla or Gyproc Easifill for finishing joints PVA glue: For sealing porous surfaces before adhesive application Sandpaper: 120 and 240-grit for progressive smoothing Sugar soap: For cleaning surfaces before installation Dustsheets: Protect floors and furniture from adhesive drips Similar to working with plaster beading and trims, successful coving installation depends heavily on surface preparation and accurate cutting. Step-by-Step Coving Installation Process Step 1: Surface Preparation (Critical Phase) Adhesive only bonds properly to clean, sound surfaces. This preparation stage determines whether your coving stays up for decades or falls down within months. For new plaster: Ensure plaster has fully dried (minimum 2-3 weeks). The wall-ceiling junction should feel dry to touch, not cool or damp. Apply diluted PVA (1 part PVA to 5 parts water) to seal the surface and reduce suction, preventing the coving adhesive from drying too quickly. For painted surfaces: Wash thoroughly with sugar soap to remove grease, nicotine, and dirt. Rinse with clean water and allow to dry completely. Lightly sand glossy paint with 80-grit paper to provide a key for adhesive. Wipe away dust with a damp cloth. For old coving removal: Scrape away all remnants of old adhesive with a filling knife. The surface must be flat and clean. Fill any holes or dents with filler and sand smooth once dry. ⚠️ Warning: If removing old coving from properties built before 1999, be aware of potential asbestos in adhesives and fillers. HSE guidance recommends professional testing if you’re uncertain. Never sand or break up suspected asbestos materials. Step 2: Measuring and Planning Your Layout Measure the room’s perimeter carefully. For rectangular rooms, you’ll need four straight lengths with mitred corners. Start by installing the longest walls first, then fit the shorter walls between them. Corner mitre angles: Standard room corners are 90 degrees, requiring 45-degree mitres on each piece. However, many older properties have corners that are 88-92 degrees. Test-fit your mitres before applying adhesive. Mark a guideline on both wall and ceiling, typically 10mm away from the corner junction. Use a spirit level to ensure this line is straight — wonky guidelines create wonky coving that’s visible once installed. Room Size Coving Required (metres) Number of Internal Corners Estimated Time Small bedroom (3m x 3m) 13m (including wastage) 4 2-3 hours Double bedroom (4m x 5m) 20m 4 3-4 hours Living room (5m x 6m) 24m 4 4-5 hours Large L-shaped room Calculate perimeter + 15% 6 6-8 hours Step 3: Cutting Accurate Mitres Mitre cutting separates
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