Repainting is one of the fastest ways to refresh your home, but achieving a smooth, durable, professional finish starts long before the first coat of paint goes on. Proper preparation is essential for ensuring good adhesion, rich colour, and long-lasting results. Here’s what you need to do before repainting any previously painted surface.
Why is preparation important before repainting?
Even if a surface looks clean or the old paint appears intact, underlying dust, oils, or minor damage can prevent the new paint from bonding properly. Preparation helps you:
- Improve adhesion
- Achieve smoother coverage
- Prevent peeling or cracking
- Extend the life of your new paint job
Skipping prep is one of the most common causes of early paint failure.
What is the first step when preparing to repaint a room?
Start by inspecting the surface. Look for:
- Peeling or flaking paint
- Cracks or dents in the drywall
- Water damage or stains
- Glossy or slick finishes
- Dirt, grease, or dust buildup
Each issue requires different prep steps before repainting can begin.
How do you clean walls before repainting?
Cleaning removes oils, dust, and residue that can prevent paint from sticking.
For most walls:
- Use warm water mixed with mild dish soap
- Wipe with a soft cloth or sponge
- Rinse lightly with clean water
- Allow the surface to dry completely
For kitchens or high-touch areas, use a gentle degreaser to remove stubborn residues. Randall’s experts can recommend safe cleaners that won’t damage existing paint.
Do you need to sand before repainting?
In most cases, yes. Sanding helps smooth imperfections and improves adhesion.
You should sand if:
- The old paint is glossy
- There are visible bumps or drips
- The surface feels uneven
- You’re switching from oil-based to latex paint
Use fine-grit sandpaper (120–220 grit) and wipe away dust afterward.
How do you repair damaged areas before painting?
If walls have dents, holes, or cracks:
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Fill them with spackling compound or patching plaster
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Allow the compound to dry completely
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Sand the area until smooth
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Wipe off any dust
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Prime the repair to prevent flashing
Proper patching ensures your final coat looks smooth and uniform.
Should you remove peeling or flaking paint?
Yes. Any loose or failing paint must be removed.
- Scrape away peeling areas
- Sand the edges to blend them smoothly
- Prime the repaired spots before painting
Painting over damaged paint traps air and moisture, leading to future cracking and peeling.
Do you need to use primer when repainting?
Many previously painted surfaces still require primer, especially if:
- You’re covering stains
- The old paint is oil-based
- You’re making a dramatic color change
- You repaired damaged areas
- The existing surface is glossy
Primer helps ensure even colour, improved adhesion, and long-lasting durability. Explore high-quality primers in Randall’s Paint Collections
How do you tell if old paint is oil-based or latex?
Try this simple test:
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Dampen a cloth with rubbing alcohol
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Rub the painted surface
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If paint transfers onto the cloth, it’s latex
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If nothing comes off, it’s oil-based
When repainting oil-based paint with latex, always sand lightly and use a bonding primer.
Should you tape off trim and edges before repainting?
Yes. Taping helps create cleaner lines and protects trim, flooring, and windows while you work. Choose high-quality painter’s tape and press it down firmly to prevent bleeding.
What about removing old caulking?
If trim caulking is cracked or separating, remove loose material and recaulk before painting. Fresh caulk seals gaps and creates a polished, professional look.
When should you hire a professional painter?
If your walls have extensive peeling, moisture damage, dark stains, or complex repairs, a professional painter can prepare the surfaces correctly and efficiently. For help, visit the Randall’s Services Pageor submit a Painter Order Formto find trusted painters in Ottawa.
Get Everything You Need for a Smooth Repaint
Whether you’re refreshing a single room or your entire home, proper prep guarantees a flawless finish. Visit your nearest Randall’s location or Contact Usfor expert guidance.
Explore primers, tools, patching materials, and premium paints in our full Collectionsto prepare your surfaces the right way.
Prep right, paint right—Randall’s gives you the tools and guidance for a smooth, long-lasting finish.