September 16

Why Prep for Commercial Painting Is So Important


prep commercial painting

The secret of a good commercial paint job is that most of the work is done before the top coat is even applied. The main reason surface preparation, or prep work, is important is because paint can’t adhere to unprepared surfaces.  The paint will peel, crack, bubble up, and flake because it is not sticking to the surface.

Bubbly paint does not do anything for curb appeal or your bottom line. Brushing or spraying paint onto an unprepared surface will look very unprofessional. Time and money will be wasted if the surface is not properly prepared. The coat of paint will not last as long as it should, so another entire paint job will be needed to fix the problem.

Contacting a professional painter to assess the surface of your building is the first step in the right direction. Prep work is a tedious and hard job. Professionals can have a knowledgeable and experienced team finish the work in a timely fashion.

What Is Prep Work?

Surface preparation for commercial painting is time-consuming work. Depending on the size of the building, it can take a while before the first coat of paint is applied.  To obtain a flawless commercial paint job, there are crucial steps in preparing the surface before any paint can be applied. Rushing the surface preparation process will only end in disaster and more cracking paint. Then you’ll have to start all over again due to a lack of patience.

Protecting Items and Surfaces       

Any surface or object that will not be painted should be covered or removed. Any portable furnishings should be relocated during the painting process. Other stationary items, like carpets or heavy appliances and furniture should be completely covered with tarps. Painters tape will protect other areas that will not be painted, such as:

  • Hardware
  • Windows
  • Gutters
  • Outlet Boxes
  • Utility Heads
  • Hose Bibs
  • Racks

Power Washing

An exterior surface of a commercial building must be thoroughly cleaned before applying paint. The best way to clean a commercial building, small or large, is to power wash it. Power washing will remove surface contaminants using pressurized water that is heated to a high temperature.

The hot temperature of the water will ensure that all the grime and contaminants are broken down; it is more effective than water that’s at room temperature.

The following surface contaminants are commonly found on the surfaces of commercial buildings.

  • Mold/Mildew
  • Dust/Mud
  • Dirt
  • Rust
  • Loose or Peeling Paint
  • Debris
  • Algae
  • Oil
  • Moss
  • Acidic substances
  • Salts
  • Grease
  • Graffiti

A clean surface is needed for good paint adhesion. If this part of the preparation is not done right, the paint will be applied to the dirt instead of the surface, resulting in an uneven surface that won’t last.

Let It Dry

Not only does paint not stick to dirty surfaces, but it also does not adhere well to wet or damp surfaces. After your building is cleaned, especially if you’ve power washed it, it can stay wet for a couple of days. Allow several days for the surface to completely dry before the next step.

Scrape It Off

All loose and peeling paint will need to be scraped off. The walls and surfaces of your building should only have either bare surfaces or well-adhered paint on them. If you leave loose or cracked paint anywhere on a commercial building, the paint job will be a complete failure.

Heavy-duty scraping jobs require a strong blade, a beefy blade clamp and a super-strong handle with a striking cap. These types of scrapers make the work of removing peeling paint go much faster.  A scraper with replaceable blades is good to have when it becomes dull.


If there are cracks at the joints or seams of the building, applying new caulking will solve the problem. Caulking prevents water from getting into your place of business potentially causing damage to the structure and its contents. It also makes the paint job look uniform.

The existing caulking must be dug out from the joints before any new caulking is applied. All siding joints and gaps need to be sealed to keep water and moisture out.

A Smooth Surface

smooth surfaces

This involves sanding down any rough exposed wood as well as feather-sanding the edge of the remaining paint that's still on the surface. 

An electric sander should be used if it’s a large surface; otherwise, smaller blocks or paper will work. If the surface is very rough, you'll need to start sanding with the medium grit and finish with fine grit.  if it's not too rough, then you can skip straight to the fine.

After the entire surface has been sanded down, the dust that forms from sanding will need to be removed for the paint to stick. Removal of dust can be done in various ways. 

  • You can wipe it all down with clean rags.
  • Blow it off with an air compressor.
  • Give it a rinse with a garden hose or pressure washer. 

If you do use water, make sure you wait until it's completely dry before applying primer or paint.

Additional Surface Fixes

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After a good power wash and removing all the old paint, more damage might be revealed. Areas of the walls or building surface might have dents or holes. If it’s a wood surface, splitting or rotting wood might show. Other issues that need attention are: 

  • Wood Surface/Components: Holes, air pockets, cracks, and other voids can be repaired with a wood filler.
  • Rotting Wood: The gray or black discoloration can be sanded away.  If the wood is soft, the shallow spots need to be dug out and filled with an exterior filler. However, if the rotting is widespread, replace the entire piece of wood.
  • Rusty Metal: This can be alleviated by cleaning off the flakes and powdery surface rust with a wire brush.  If the brush doesn’t do the job, use a drill with a wire wheel to remove the rust, then apply a primer that adheres to rusted surfaces.
  • Concrete: Holes, dented surfaces, and blemishes need a cement patching compound to fill in the dents.

Prime Time

Primer is applied to the surface to improve the adhesion of the paint. It also extends the lifespan of the paint. Since commercial buildings are made of different materials, a primer suited for the applicable surface will work best for greater adhesion.

Wood Primer

An oil-based primer is considered the best for wood surfaces.  It adheres better than other types of primer. It does take a long time to dry, allowing plenty of time for it to soak into the wood. Paint manufacturers have developed new, faster-drying technology in both oil and latex-based products. They dry quickly yet still aid in adhesion of the topcoat of paint. A good wood primer brand is KILZ Premium.

Masonry Primer

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Masonry surfaces include brick, concrete, and cement block. They are a strong choice in materials for constructing commercial buildings and can withstand all types of weather. They also must be treated differently than other materials.

Along with the normal surface prep that is required before applying exterior paint, two special factors that need to be considered for masonry are:

  1. Efflorescence
    The definition given by the Masonry Institute of America describes efflorescence as a fine, white, powdery deposit of water-soluble salts left on the surface as the water evaporates. If there is a white crystalline substance on your building’s exterior it can be removed by low-pressure washing.

    A masonry primer will help seal the surface to protect it from the elements. Many masonry primers are efflorescent-resistant and do a great job of keeping it from becoming a problem. If you want a top coat of paint to last, masonry primer is a necessity.
  1. pH Level
    Some masonry surfaces can have a high pH level which will cause adhesion problems if you apply paint directly to the surface.  A quality masonry primer will allow you to safely paint over a wider range of pH levels without risk of adhesion loss.

    Newly-constructed masonry will naturally have a high pH level, which creates a situation where normal paints and primers cannot be successfully applied. The rule of thumb is to wait for a minimum of 28 days after construction for any masonry surface to sufficiently cure before applying any coatings.

Stain-Blocking Primer

Different types of stain-blocking primers are used for common issues such as:

  • Keeping water and smoke stains from bleeding through the finish coat
  • Painting over the top of grease
  • Making a dramatic color change 

Hire the Right Commercial Painter

diamond certified

The time spent on preparing the surface of your commercial building will pay off later with a satisfactory paint job that will last for many years. The Painting Pros can handle each step of the surface prep with ease.  There is no building too big or too small for our experienced team of painting professionals.

If you’re ready to give your business a face-lift or need to hire painters for your new construction, don’t go with just any commercial painter. Go with one who has years of experience and is dedicated to the best quality results and outstanding service.

The Painting Pros is Diamond Certified, so you know you’ll be getting the quality and service you deserve. We are highly rated and recommended by customers on Angie's List, Google, Yelp, HomeAdvisor, Yahoo and more. We are also an accredited business with the Better Business Bureau with an A+ rating.


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