How Much Prep Work Is Needed Before Painting? (UK Guide)
Quick Answer
Professional painting requires 4-8 hours of prep work per standard room: filling holes and cracks, sanding surfaces, cleaning walls, masking edges, and protecting furniture. Preparation is 60-70% of the total work time. Skipping or rushing prep causes paint failure, peeling, and poor finish.
The difference between a £150 paint job that peels in months and a £250 job that lasts years is almost entirely about preparation. Professional decorators spend the majority of their time preparing surfaces rather than applying paint. Understanding what's involved helps you appreciate quality work and avoid cowboys who cut corners.
Why Preparation Matters So Much
Paint can only perform as well as the surface beneath it:
Proper prep ensures paint adheres correctly and won't peel. It creates smooth surfaces that look professional. It addresses underlying issues before they're locked under paint. It's what separates work that lasts 1-2 years from work that lasts 10+ years.
🔨 Industry Secret: Professional decorators know that rushing preparation to save 2 hours inevitably causes callbacks and reputation damage. Quality decorators never skimp on prep - it's their signature.
The Standard Preparation Process
Here's what professional decorators do before any paint is applied:
- Stage 1 - Protection (30-45 mins): Lay dust sheets, cover furniture, protect floors
- Stage 2 - Assessment (15-20 mins): Inspect walls for damage, damp, or structural issues
- Stage 3 - Repair (1-3 hours): Fill all holes, cracks, and imperfections with appropriate filler
- Stage 4 - Sanding (1-2 hours): Sand filled areas smooth, plus light sand of all woodwork
- Stage 5 - Cleaning (30-45 mins): Wipe down walls to remove dust, grease, cobwebs
- Stage 6 - Masking (45-60 mins): Tape around windows, doors, sockets, switches for clean lines
- Stage 7 - Priming (if needed, 1-2 hours): Apply primer to bare plaster or stains
Total prep time: 4-8 hours for a standard bedroom. Only then does actual painting begin.
Different Wall Conditions
Walls in Good Condition
Previously painted walls in good shape need minimal prep: light sanding to create 'key' for new paint, filling any new holes from picture hooks, cleaning to remove dust and marks, masking for clean edges. Time required: 2-3 hours for standard room.
Walls in Average Condition
Most UK homes fall into this category: multiple holes from picture hooks and shelves, minor cracks around doors and windows, scuff marks and small dings, previous paint in reasonable condition. Time required: 4-5 hours for standard room. This is 'standard' prep included in most quotes.
Walls in Poor Condition
Walls requiring significant work: large holes or damaged plaster, extensive cracking, old wallpaper to remove, water damage or stains, multiple layers of old paint, uneven surfaces. Time required: 8-12+ hours, often charged separately as 'additional prep work' at £50-£200 depending on extent.
What's Included vs What Costs Extra
Standard prep (included in base quotes):
- Filling nail holes and minor cracks
- Light sanding of surfaces
- Cleaning walls
- Masking and protection
- Spot priming of filled areas
Extra prep work (charged separately):
- Removing wallpaper (£40-£120 per room)
- Major repairs (large holes, damaged plaster) - £50-£200
- Damp treatment or mould remediation - £50-£300
- Stripping multiple layers of old paint - £80-£150
- Repairing damaged woodwork - quoted per item
Reputable services identify extra prep during photo review or initial consultation, adding these costs to the quote before work begins.
The Filler and Sanding Process
Understanding what decorators actually do:
Filling: All holes and cracks filled with appropriate filler (quick-drying filler for small holes, deeper filler for larger damage). Decorators overfill slightly as filler shrinks when drying. Multiple applications may be needed for deep holes.
Sanding: Once filler is completely dry (2-4 hours), decorators sand it perfectly flush with the wall. They also lightly sand all woodwork to create texture for paint adhesion. Fine-grit sandpaper (120-240 grit) is used to avoid scratching.
This creates the smooth, professional surface that makes painted walls look perfect.
Masking and Edge Work
Creating clean, crisp lines:
Professional decorators use high-quality decorators tape (not cheap masking tape) around all edges - windows, doors, skirting boards, light switches, sockets. They ensure tape is firmly pressed down to prevent paint bleeding underneath.
The masking process takes 45-60 minutes per room but is essential for professional-looking results. Remove the tape while paint is still slightly tacky (not fully dry) for the cleanest lines.
Primer: When Is It Needed?
Primer is essential in these situations:
- Bare plaster (new builds or after replastering)
- Extreme colour changes (dark to light or light to dark)
- Covering stains (water marks, nicotine, permanent marks)
- Painting over different surface types (wood to plaster transitions)
- After major repairs or extensive filling
Good primer costs £15-£25 per room in materials but can save you 1-2 coats of expensive topcoat paint. Professional decorators know when primer is worth using versus when it's unnecessary.
Spotting Corners Being Cut
Red flags that prep is being rushed or skipped:
- Decorator arrives and starts painting immediately (no prep time)
- Visible holes and cracks not filled before painting
- Dust and cobwebs visible before painting begins
- No masking tape used (relying entirely on 'cutting in' skill)
- Furniture not properly protected
- Paint applied directly over damaged areas
- Only one coat applied when two are standard
If you notice these, stop the work and discuss. Poor prep cannot be fixed later - the damage is done once paint is applied.
Frequently Asked Questions
Can I do the prep work myself to save money?
You can, but professional decorators work faster and to higher standards. DIY prep often misses issues or uses wrong materials. The £50-£80 saving isn't worth the risk of poor paint adhesion. However, basic cleaning and clearing rooms definitely helps.
How long does filler need to dry before painting?
Standard filler needs 2-4 hours until sandable and 6-8 hours before painting over it. Deep filler or very thick applications may need 24 hours. Professional decorators time this correctly to avoid delays.
Why does prep work cost so much of the total?
Prep is labour-intensive, skilled work that can't be rushed. It requires different materials (filler, sandpaper, primers) and tools. It's less visible than painting but more important for long-term results. Quality decorators charge appropriately for this crucial work.
What if my walls are in really bad condition?
Request a survey or photo review before quoting. Major damage may need plasterer involvement first. Some decorators offer replastering services or can recommend specialists. Address structural issues (damp, cracks) before cosmetic painting.
Flexible ways to pay
A larger decorating project doesn't have to mean one limited way to pay. Get your fixed Paint-MyRoom.com price online and choose from available payment options at checkout, including Klarna and Clearpay.
Subject to eligibility and provider terms.