Prepping walls properly: the 70% of the job you never see

If you’ve ever wondered why one painter quotes $8,000 and another quotes $5,000 for the same house, the answer is almost always preparation. Prep is the unseen 70% of every paint job, and it’s the single strongest predictor of how long the coat will last.

What proper prep looks like

Walls are washed, sanded, filled, primed and caulked. Holes and cracks are properly feathered. Bare timber is primed with a proper timber primer, not just covered with top coat. Rusty metal gets a rust-converting primer. This typically takes 1-3 days before a single coat of colour goes on.

What cheap prep looks like

A light dust-down with a broom. Filler jammed into cracks without sanding. Single coat of wall paint going straight over bare primer patches. Result: the job looks fine for 12 months, then the coat starts flaking at edges within 3 years.

How to test a painter on prep

Ask this question: “walk me through what you’ll do before any colour goes on.” If the answer is under 30 seconds, find a different painter. A painter who takes prep seriously will describe sanding, washing, filling, caulking and priming in detail.

Specific prep work to look for

• Pressure cleaning — exteriors only. Removes surface dust, salt residue, and loose paint chalk.
• Sanding — both interior and exterior. Creates surface “tooth” for paint to grip.
• Filling and patching — fills nail holes, hairline cracks, dents. Should be sanded smooth before priming.
• Caulking — silicone or acrylic gap-filling around skirtings, architraves, window frames. Often skipped.
• Priming — bare patches, stained areas, big colour changes need a primer coat before topcoat.

The painters in our network are vetted on prep approach as part of how we onboard them. Our 15 questions to ask a painter guide includes the exact prep questions to use when comparing quotes.