Preparation has a major effect on adhesion, finish quality and long-term coating performance. House painting preparation is not one fixed checklist. Interior drywall, older plaster, exterior wood, masonry and stucco can each require different cleaning, repairs, sanding and primer decisions depending on their condition and previous coatings. A professional painter assesses those conditions first, then prepares each surface only as much as needed to create a sound, consistent base for the new finish.
Professional painters allocate more than 50 percent of any project's total time to preparation, not to painting, because the prep sequence determines whether the finish lasts a decade or fails within a season.
Prep a House for Painting
Importance of House Painting
House painting is one of the most important home maintenance projects. House painting upkeep and caulking help protect a home from weather damage caused by water and sun. Neglecting obviously peeling exterior paint can lead to high siding replacement costs.
Importance of Preparing your Home for Painting
Preparing a home for painting is not only important, but it saves time and money. It ensures that the paint adheres properly to the surface and lasts longer. According to CMHC's guidance on home maintenance and investment protection, properly maintained painted surfaces are among the most cost effective ways for Canadian homeowners to protect long term property value, and correct preparation is what keeps those surfaces maintainable for years.
Interior Painting Preparation Tips: Why the Prep Work Is More Than Half the Job on Any Toronto Painting Project
The most common reason interior paint jobs fail early is not the paint product: it is the preparation sequence. Paint applied over a greasy wall bonds to the grease, not the wall. Topcoat applied over unfilled cracks reveals those cracks through the new film within the first heating season. Paint applied over a glossy existing finish without sanding loses mechanical adhesion at the highest contact points within months. Each preparation step exists because skipping it produces a specific, predictable failure mode in the finished surface.
Professional painters at Home Painters Toronto allocate more than 50 percent of any interior project's total time to preparation, not to painting. For the full list of preparation errors that produce early paint failure, see our guide on common painting mistakes to avoid.
Prep the Right Way for Painting Interior
- Remove smaller objects
- Move larger objects out or to the room's center
- Unscrew the outlet and light switch covers
- Put painter's tape around windows, doors, and baseboards
- Lay down drop cloths
The smaller objects include wall hangings, curtains, and items inside the larger objects. A covering is thrown over any large objects in the room's center. Ceiling fans and lights need to be taken care of too. Taking off the fan blades and covering the fixture with plastic protects them. For recessed lights, removing the bulb and pulling the fixture's trim down a bit, then releasing the cover and taping plastic over it, ensures no paint damage.
How do I Prepare the Exterior of my House for Painting
- Wash the house — washing the house gets the dirt off and makes it easier for the paint to stick to the walls, same as scraping off the loose paint, then sanding and priming repaired areas
- Scrape off any loose paint
- Make any repairs
- Sand
- Re caulk if needed
- Apply painter's tape to doors and windows
- Put down drop cloths
- Prime if needed
How Much Paint for Home Painting?
A rough rule of thumb is that 1 gallon of paint will cover about 350 square feet.
More paint will be needed when painting bare drywall which absorbs more paint, painting several coats, or covering old paint that is darker. The first step in preparing a home for painting is to estimate how much paint is needed for the project.
How to Prep a House for Painting Project
How do Professional Painters Prep?
Professional painters do a lot of prep work before they start painting a home. It is not just the paint that makes a house look beautiful. Home preparation is a crucial step to ensure lasting quality, durability and beauty. Below are some tips for preparing the house for painting interior from our resident painting experts at Home Painters Toronto.
Remove Hardware before painting
When preparing a home, the first step once ready is to remove all hardware from the walls such as:
- Electrical plug covers
- Cable and phone outlet covers
- Curtains
- All pictures and artwork
- Nails
- Light fixtures if painting the ceiling
Splatter Prevention
Paint is messy, so prepping a house before starting to paint requires drop sheets all along the walls and floors. Taping them down keeps them in place. Painter's tape is applied around all moldings, window frames, and door frames to prevent stray paint.
Any furniture is removed if possible and if not, tightly covered to protect it. Furniture that cannot be removed should be organized in the center of the room to keep the areas around the walls clear.
Wall Preparation for Painting
- Many people make the mistake of starting to paint after removing hardware and laying drop sheets and tape. But preparing a home for painting has not finished yet.
- It is very important to prepare the walls to ensure imperfections are fixed and achieve the most durable hold for the paint. Our drywall repair and installation service handles all hole and crack repairs before any painting begins.
- Whether tackling a house painting job or hiring someone, always ensure that proper paint preparation is executed before starting any house paint job
- Inspect walls for cracks and holes. Repair any damage with a spackling compound using a putty knife. Spread the compound over the defect several times and scrape off the excess.
- Allow it to dry according to the product's instructions. Then use fine grit sandpaper (150 to 200 grit) and smooth it out until there is a seamless transition to the original wall.
- Wash the walls. Washing the walls is very important to remove grease and dust which will seriously compromise the life of the paint if this step is ignored. If the walls are very dirty a chemical cleaner like Tri Sodium Phosphate may be needed to start.
- After, rinse all walls with clean water and a sponge. Allow walls to properly dry before applying primer or paint.
Cleaning Walls and Surfaces Before Interior Painting: What Professional Painters Use and Why
Interior Painting Preparation Tips: Why TSP Substitute Is the Professional Standard for Wall Cleaning in Toronto
Tri Sodium Phosphate (TSP) and its residential substitute (TSP substitute) are the professional standard for wall cleaning before interior painting because they chemically cut through cooking grease, fingerprint oils, and household cleaner residue that soap and water does not dissolve. Grease on a wall surface is not visible to the eye in most cases, but primer applied over grease bonds to the grease layer rather than to the wall, and the grease releases through thermal cycling and daily use, taking the paint film with it. According to Health Canada's guidance on VOCs in indoor environments, wall surfaces in kitchens and other cooking adjacent rooms accumulate airborne grease and cleaning agent residue that requires chemical degreasing, not just wiping, to fully remove before any painting begins.
The correct cleaning sequence is: apply TSP substitute solution with a sponge or cloth to all surfaces that will receive paint, rinse thoroughly with clean water, and allow to dry fully before any sanding or priming begins. The drying step is essential: applying primer to a surface that is still damp from cleaning produces adhesion issues at the sections where moisture was present.
Wall Preparation Before Painting
Use sandpaper or a sanding block to dull uneven surfaces, wipe away dust with a damp cloth and let dry thoroughly. Smoothing walls before painting is necessary for surfaces previously painted with a gloss or high gloss paint. For previously painted water based paint, sand with a fine grit sandpaper.
How to Paint Walls Like a Pro
Painting doesn't have to be a job strictly for professionals. With the right tools and preparation, excellent results are achievable on an interior wall.
Filling Holes and Repairing Surfaces Before Painting: The Right Materials for Each Damage Type
What Grit Sandpaper to Use Before Painting Walls
Grit selection for wall sanding before painting follows a simple rule based on what the sanding needs to accomplish. For dulling an existing gloss finish to provide mechanical adhesion for primer, 120 to 150 grit is the correct range: coarse enough to break the sheen across the full wall area efficiently, fine enough not to leave visible sanding scratches that show through the topcoat. For sanding filled nail holes and crack repairs until smooth and flush with the surrounding wall, 150 to 200 grit is the correct range. For a final sanding pass on previously textured or rough surfaces before a smooth topcoat, 220 grit provides the smoothest possible base.
Grit selection matters: 120 to 150 grit dulls an existing gloss finish, 150 to 200 grit smooths filled cracks and nail holes flush, and 220 grit provides the smoothest base on rough or textured surfaces.
Professional Painting Tips and Tricks
Wait for Dry Weather
Humidity means drips and slow drying, so avoiding painting on a rainy day produces better results. If painting must happen when humid, taking time to work carefully and taking advantage of slow drying paint to correct errors before moving on to the next coat produces a better finish. Overworking wet paint shows when finished.
Do a Thorough Visual Inspection and Prep
Any cracked, flaking or peeling areas need to be lightly sanded or scraped (and then thoroughly rinsed) before applying new primer and paint, because the weight of the new coat will pull the old paint loose. Painting over failed surfaces wastes time and money. Greasy spots also need washing with soap, followed by a rinse with clean water. Otherwise, wiping down with a damp cloth ensures that paint will have a clean, dust free surface to stick to.
Buy High-Quality Brushes, Roller Covers, and Painter's Tape
Good brushes and roller covers give excellent coverage so time and paint are not wasted on reapplication. High end painter's tape is the real deal when it comes to sealing out drips and blurs.
Know Your Nap
The more texture a wall has, the thicker the nap needed on a roller cover so it can reach into crevices and give complete coverage. A thick nap works for painting concrete walls, while a thin nap is preferred for drywall. Going with a nap that's too thick may create texture where it is not wanted.
Protect Anything You Don't Want Painted
Covering floors, furniture, and hardware before beginning a paint project produces consistently better results. Drop cloths are a must and small plastic sandwich bags secured with tape are an easy way to protect door knobs.
Paint From Top to Bottom
After cutting in edges at the ceiling and baseboard using a brush, use a roller to apply paint from the ceiling downward. Drips and spatter are painted right over as work progresses down the wall. Once an area starts to dry, it is best to leave it alone. Going back over drying sections can leave marks and colour streaks on the paint's surface.
Priming Before Painting: Why Primer Is Not Optional and Which Type to Use
Primer Selection for Different Surfaces in a Toronto Home
Standard acrylic primer is the correct specification for new or previously painted drywall in good condition. Alkali resistant primer is required for original plaster walls in Toronto heritage homes, where the lime content of the plaster remains chemically active and standard acrylic primer does not create a chemically stable bonding layer. Shellac based stain blocking primer is required at any surface with permanent stains (marker, nicotine, water staining) where the stain will bleed through any standard primer.
Skipping primer on bare drywall produces visible sheen variation in the topcoat because the drywall absorbs paint at different rates at the joint compound sections vs the paper facing. Skipping primer when changing from a dark to a light colour requires additional topcoats that collectively cost more than the primer coat would have. For a full guide on primer types, see our guide on picking the right type of interior paint.
How to Prep a Stucco House for Exterior Painting
Cost of Professional Interior Painting with Full Prep in Toronto in 2026
Home Painters Toronto is WSIB compliant, fully insured to $5 million in general liability, and all interior painting is backed by a lifetime warranty. Preparation is included in every quote. All prices below are in CAD and exclude HST. For the full cost breakdown, see our interior painting cost guide.
| Scope | Estimated Cost (CAD) | Notes |
|---|---|---|
| Interior room (living or dining room, standard prep) | $400 – $900 | Full prep included: TSP clean, repair, sand, prime, two topcoats; eggshell or satin finish |
| Interior room (bedroom) | $400 – $800 | Low or zero VOC products standard; full prep included |
| Heritage plaster room (Victorian or Edwardian home) | $500 – $1,100 | Alkali resistant prime on all plaster; crack fill; additional prep time |
| Drywall repair before painting (holes, cracks) | $150 – $600 | All repair complete before any primer is applied |
| Exterior stucco repaint (prep, prime, two coats) | $2,000 – $8,000 | Full stucco crack repair; acrylic prime; elastomeric topcoat; coverage calculated at stucco rate (200 sq ft per gallon) |
Frequently Asked Questions About Interior and Exterior Painting Preparation
Professional painters follow a consistent sequence: remove all hardware, apply drop cloths and painter's tape, clean all surfaces with TSP substitute solution to remove grease and dust, inspect and repair all cracks and holes, sand filled sections and any glossy surfaces, apply the correct primer for the specific substrate, and apply topcoat only after primer has fully dried. The preparation sequence takes more than 50 percent of the total project time on a quality interior paint job.
Yes. Walls accumulate grease, dust, and cleaning agent residue over time that soap and water does not fully remove. TSP substitute solution applied with a sponge or cloth removes grease contamination that would otherwise prevent primer from bonding to the wall surface. Primer applied over a greasy wall bonds to the grease layer and peels when the grease releases. Rinsing with clean water and allowing the wall to dry fully before primer is applied is required after cleaning.
For dulling a gloss finish before primer, 120 to 150 grit is the correct range. For sanding filled nail holes and crack repairs flush with the surrounding wall, 150 to 200 grit is correct. For a final sanding pass on rough or textured surfaces before a smooth topcoat, 220 grit provides the smoothest base. Wiping away all sanding dust with a damp microfiber cloth before primer is applied prevents dust particles from becoming embedded in the finish.
A rough rule of thumb is that 1 gallon of paint covers approximately 350 square feet of flat wall surface. Bare drywall absorbs more paint than previously painted surfaces, requiring more product per square foot. Dark to-light colour changes require additional coats. For stucco and textured surfaces, the coverage rate is approximately half that of flat surfaces: assume 200 square feet of stucco coverage from a gallon rated at 400 square feet.
Yes, in most cases. New drywall requires primer to even out the porosity difference between the paper facing and joint compound sections. Previously painted walls with a glossy finish require bonding primer after sanding. Original plaster in Toronto heritage homes requires alkali resistant primer to neutralize the lime chemistry. Any surface with stains (marker, nicotine, water damage) requires shellac based stain blocking primer. Skipping primer on any of these surfaces produces a specific failure mode that costs more to correct than the primer coat would have. For a full guide, see our overview on picking the right type of interior paint.
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