How To Correctly Prep Exterior Trim For Painting

How To Correctly Prep Exterior Trim For Painting


Knowing how to correctly prepare exterior trim for painting, will ensure final paint coating it's lasting protection & quality. Listing all acceptable steps preparing trim for upcoming paint coatings, which benefit outside trim in many ways.

Understanding paint on wood trim is the first thing to fail, it's proper prep is the utmost importance, for lasting adhesion, & paint protection.

Special care needs to be dealt concerning trim boards, laying out what you need to be aware of, so that paint lasts longest time possible.

Most outside wood trim is found around windows, doors, fascias, & corner boards. Also exterior trim is found with skirting boards, bats. Typically painted a contrasting color, different than main field color.

How To Paint Exterior Trim Like A Pro


Outlining proper preparedness, painting your exterior trim like a Pro

To professionally paint trim outside sufficiently, first steps listed below must be followed.

Guiding you to clean, inspect, scrape, caulk, fill, and prime all areas needing your attention.

  • Pressure wash exterior siding & trim
  • Inspect exterior trim
  • Scrape outside trim showing failure
  • Caulk all exposed trim outside
  • Fill all holes, gouges, intentions
  • Prime, scraped trim, or bare wood

Pressure Wash Exterior Trim


First, let me say pressure washing should not be trying to peel paint. Thinking you can skip an important next step, as I will explain further in article.

Using a high pressure washer, cleaning siding & trim. keeping spray tip at least 2' away from surfaces, you are only trying to remove any dust, dirt, or grime. No telling how many birds have bombarded your siding over the years. All of which needs to be cleaned.

Pressure washing is probably the most enjoyable, easiest step preparing your exterior trim. Similar to washing your new car or truck in a driveway. Never having to worry breaking a sweat. Also fun, but besides not getting too close, you'll want to work from the top down.

If You Don't Have A Pressure Washer, Can Always Rent One

Even if you cannot see this dust, dirt, or bird droppings, it's there. As giving you a prime example. Have you ever gone to the car wash, rinsing off your fairly clean car or truck, seeing all the dirt coming off? Same goes for your exterior siding & trim.

Giving your outside surfaces a quick rinse, is like having a clean slate or canvas to work with. Similar to an artist's cleaned canvas, but only on a grandeur scale.

Inspecting Exterior Trim


Well, you've been actually inspecting trim, while you've been pressure washing. Seeing any troubled areas. Where paint is really peeling off, or worse, visibly witnessing decay, mold, or mildew.

Visibly Inspect Trim For Problem Areas

Key tip is allowing exterior to properly dry, 24 - 48 hours before any hand scraping begins.

Reason for this wait is dried paint is much easier to scrape than wet. Less likely to damage trim even more, scraping, or wire brushing old paint, when wood has dried back out.

Using a 5 Way painter's tool, you can go around as many areas as you can, tapping on paint. If hearing a hollow sound under paint surface, even though paint is still intact, chances are, you have air pockets. And this leads to the next step, preparing your trim like a Pro.

Scraping Old, Failed Paint


Do I really need to scrape paint before painting trim?

Generally speaking No, you don't. Only remove all old paint that is showing signs of failing. These signs again are paints not properly adhering, cracked, bubbled, blistered, or peeling. As this is one of the main reasons paint fails.

I know scraping paint is not on your highest priority of things to do, but it is at the utmost importance, if you want your new paint coating to last. Matter of fact, paint that is currently lifting up, or will lift up in the next 6 months, will continue to do exactly that.

Basic Hand Scrapers Work Well

Scraping off old, cracked, failed paint off of exterior trim is a must. Just as it is, hearing air pockets underneath where you've inspected, testing painted surfaces.

As you scrape paint off your trim, just imagine it could be worse. Thinking you could be scraping paint off of a ship, with insurmountable areas to scrape. So scraping paint off of your trim is a lot less, but has to be done, just the same.


Whether or not you have a fresh new paint coat. Even does not matter what grade or quality of paint you're using. Old failed paint can cause even the best lifetime paints to fail, if failed paint not properly removed.

Using a wire brush works well in many areas of trim. Hard to reach surfaces, or grooved trim pieces, a wire brush is the answer.

Painting Exterior Trim That Is Currently Peeling

One of the main reasons you've decided painting exterior trim that is currently peeling, knowing it's only going to get worse, not better. Not only does all failed paint need to be scraped, but is good rule of thumb to ascertain the reason causing it in the first place!

Hopefully, you don't have a lot of paint to scrape, but every home is different.

Trim is notorious finding failed paint for a number of reasons. Painting exterior trim that is currently peeling will not last the duration of paint's warranty. Removing failed paint is extremely important for new paint's proper adhesion.

Caulking All 90 Degree Cracks



Just about homeowner's primary consideration of exterior's proper preparation for painting trim, is caulk and sealants. 9 times out of 10 every exterior paint job includes some amount of caulk, especially for trim.

All You Need Is A Good Tube Of Paint-able Caulk & Caulking Gun

Removing old dried, cracked out caulk is your first step. Following by caulking with a high grade caulking sealant. Caulk all cracks, 90 degrees, where trim board meets another. This keeps out water penetration, as paint just wont bridge these gaps.


Using a high grade latex paintable silicone sealant, we either use Sherwin-Williams® 1050 or  is designed for masonry, but works well on trim & siding, where any movement might take place later.

Filling Holes, Gouges, Indentations


If you have holes from woodpeckers, gouges from a lawnmower hitting bottom edge of trim board, or a golf ball making a dent on the side of your house, listen up.

These imperfections must be cared differently than filling with caulk. What best fills gouges, or indentations is Crawfords® Exterior Spackle.

Reason for this is not only does it dry quickly, but dries a flat finish. Putting on a new satin exterior paint will eventually go to a flat finish. Crawfords® Exterior Spackle will never show or stand out being a different finish years to come, as finish coats age.

Allowing Exterior Spackle to dry, normally within an hour or less, sanding is very easy, with a medium to fine sanding block. After sanding, all your exterior trim is ready for the final step in preparation.

Prime Bare Wood Trim


You're almost done preparing exterior wood trim for painting. Applying a high bonding latex primer will do several good things for wood trim.

Have A High Bonding Exterior Primer?

Not only will primer appropriately seal wood trim, but allow final paint have a better surface to grab, for proper adhesion.


Top Exterior Primers For Trim

Sherwin-Williams™ Extreme Bond Primer

For surfaces that require a greater degree of adhesion than our standard primers can offer, Extreme Bond Interior/Exterior Primer is up to the challenge. Designed for coating hard, glossy surfaces like tile, glass panels and plastic piping with minimal surface preparation. Can be tinted and is compatible with a full range of finish coat products.

KILZ® General Purpose Primer

KILZ® GENERAL PURPOSE EXTERIOR is a fast-drying latex primer and sealer, specifically formulated for outdoor use. It minimizes problems caused by surface texture and porosity differences. It’s ready to brush, roll or spray and can be topcoated after one hour with latex or oil-based paint.


Glidden™ Gripper Primer

Gripper Interior/Exterior Primer & Sealer is a premium acrylic primer and sealer designed to meet the variety of challenges experienced in the residential, commercial and multi-family markets for a multi-purpose primer. This fast-drying, all-purpose, bonding primer and sealer is suitable for interior or exterior application with its excellent adhesion to a variety of surfaces. Ideal for use on properly prepared interior or exterior wood, masonry, plaster, wallboard, cement, brick and stucco.

PPG™ Pittsburgh Primers

Choose from a range of professional-quality interior and exterior acrylic latex primers that are quick-drying, feature excellent adhesion and have great hiding and sealing qualities.

Simply, any bare wood requires primer first. Reason is exterior primers bond to wood much better than typical exterior paint coatings. Also understanding your standard exterior paints grabs to primers much better than to bare wood.

Knowing how to paint exterior trim like a Pro, requires following tips listed above. Preparing your surfaces withstanding any weather comes it's way.

Masking Trim


Masking certain surfaces outside before painting exteriors is indeed a step, but not for trim. Reason masking trim is not a suggested step prepping your wood for painting, is how an exterior painting job is actually completed.

Have a 3M hand masker?

When painting exteriors, masking windows, roof, & concrete, spraying field or body first, it's not only good, but quicker to over-spray on trim boards themselves. Painting sides of trim the field or main color, coming back, front facing trim with it's different color.

Therefore, not only this saves time, but giving your fascia trim an additional coat during this overall process.

So masking trim is not a preparation step painting exterior trim, but is a very integral part painting complete exterior. In that painting trim is typically done by brush & roll.

Caring For Your Exterior Trim


These important steps preparing exterior trim coincide, painting complete exterior homes as well. Keep this in mind though; If trim is showing age, probably your entire house needs a fresh coat also. Additional information can be found as to, most exteriors painted, trim also siding is painted same time.

Need To Replace Trim?

Summarizing how to correctly prep your exterior trim for painting involves a few key steps or processes. Cleaning off all surfaces, gives you a clean slate to work with.

Trim Replacement

If fascia, corner boards, skirting boards, or bats too damages to repair, guess what? It's much easier just to replace them.

Followed by giving a good bird-eye view of wood trim's integrity, having a good, solid substrate. If any areas need attention, either replace trim boards, or scrape old flaking paint off, filling any mil thickness differences.


To Summarize Prepping Exterior Trim For Paint

Sanding filler, caulking edges where trim meets another substrate, allowing to dry. Another key step preparing trim for paint is priming.

Priming all bare wood, caulking, fillers, sealing trim, allowing primer to properly dry. Once primer has dried, trim is ready repainting exterior trim, looking brand new.

However, in most cases trim does not need replacement. Peeling paint will give the appearance trim boards are baked and done with. So giving careful attention to your trim on an ongoing basis is the first important step, caring for your exterior trim.

Hope this helps you with your exterior trim, & if so please like, share, comment, and/or ping below!

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[…] must be sanded for a fine smooth finish. These fillers fill voids, makes everything nice a smooth, preparing wood siding and trim for the best exterior paint brand you've […]


[…] Correctly repainting exterior wood trim is one of the most important areas painting, because more eyes are directed to these areas. Making sure trim boards having no signs of moisture, and all peeling paint has been removed. Critical steps to take, painting over old exterior paint, making them look brand new, not seeing previous paint coats applied years before. […]

4 years ago

I am a DIY homeowner that always back paint any NEW exterior trim with a good primer before installing it, My thinking is Hey! I am sealing /protecting the wood surface area! Yea I know that will not be exposed to the elements that get wet and sun-dried over and over again but what about the back side that should the caulking fail and moisture gets behind the trim that takes forever to dry out could that be a recipe for mold wood rotting from the back side out? Totally surprised I do not see anyone bring this up, Maybe… Read more »


[…] primer will properly bond to wood trim, without any concern of it ever coming off. Once it's applied, trim primer allows a much better […]

Patti K
Patti K
1 year ago

I sure hope I’m doing this correctly. The only thing I’m doing differently is using Behr paint and primer. I sure hope I’m doing this job again next year! lol