How to Paint Exterior Wood Trim

When you paint your home’s trim properly, you’ll be amazed at the results you can achieve. With the right products, preparation, and application, you can have your trim looking brand new.

As with a lot of painting jobs, smart paint selection is a vital part of painting your home’s exterior trim. For a start, you must use paint formulated for exterior use rather than interior paint. Spare a moment’s thought for how much tougher the outdoor environment is; interior paint isn’t going to hold up to the punishing weather conditions that it’ll be subjected to outside.

Picking The Perfect Choice for Painting Exterior Trim

A high-quality exterior paint differs from interior paint in nearly all its ingredients, and also in the ratios between them. Paint is made up of pigments, binders, and sometimes solvents.

Purpose-blended exterior trim paint has a higher ratio of binders to pigments; this makes it more durable and weather-resistant. Exterior trim paints also tend to use more durable, inorganic pigments (like yellow umber or red oxide) for similar reasons of durability. Inorganic pigments also hold up to direct sunlight better. Interior paints use a wider range of natural pigments to offer more diverse colours, but these pigments aren’t suitable for exterior trim use.

Paints formulated for use on exterior walls also usually include glare-cutting ingredients to offset the reflective sheen that comes from the high binder ratio. When you’re painting trim, though, you want that shinier finish so that your trim pieces stand out.

Modern interior paints tend to avoid volatile solvents because these can produce fumes and pose a health hazard. Volatile solvents are less dangerous when used for exterior painting, so the right paint for your exterior trim might make use of them.

Here is what that technical information translates to when you’re selecting a paint product:

Sheen/Finish: Use a paint that offers a satin, semi-gloss or full gloss finish.

Oil or water-based: Use oil-based paints if you want the glossiest possible finish. Preparation and cleanup are more time-consuming with oil-based paints, though. Water-based trim paint is perfectly fine so long as it’s formulated for exterior use.

Paint additives: Mildewcide is probably the best additive for use in exterior paint. You’ll find this already mixed into many premium products. Don’t worry if an otherwise-ideal paint lacks mildewcide, though; you can buy the additive separately and mix it yourself.

Colour: Bear in mind that the more specific your colour needs are, the narrower your selection of appropriate products may be.

The Easiest Routine To Paint Exterior Wood Trim

The methods we’re sharing here are intended to strike the right balance between labour requirements and finish results. You don’t want your trim-painting job to eat up endless days, but you want to get the job done right! Because exterior trim has many prominent edges and corners, it tends to be the first part of your home’s exterior paint to show signs of failure (peeling, chipping, cracking, and so forth). It’s important to renew the paint on your trim because the more damaged the paint gets, the more moisture penetrates the wood.

1) Trim Cleaning

It’s difficult or impossible to put a good, long-lasting layer of paint on exterior wood surfaces if they’re not clean. Dirt, debris, and other unwanted materials all interfere with the connection between the paint and the wood, weakening their bond and leading to premature paint damage. Painting dirty wood can also accentuate unwanted imperfections in the finished product, like brush marks and rough textures.

Exterior wood trim is best washed with a mild solution of bleach and water. This will remove surface debris and also mildew. Products with trisodium phosphate are ideal for scrubbing tougher trim stains. Look for “TSP” in the ingredients list.

2) Trim Replacement

It may seem odd to place this step after washing, but this is a time-saver because the washing process is the perfect opportunity to carefully assess your trim and identify damaged pieces.

Wood trim degrades most quickly in areas where it’s subjected to moisture. Trim in need of replacement will be loose, soft, rotten, filled with holes, or blackened by mould and mildew. Be extra vigilant when inspecting the edges of your roof; soffits and fascia are often the fastest-deteriorating pieces of trim. The good news is, replacing damaged trim pieces and applying a good coat of paint is an excellent way to guard against future water damage! Just be sure to apply it correctly if it is new, bare wood.

Replacing wood trim is a job that’s well within the skill set of the average homeowner. You merely need basic carpentry tools: a measuring tape, a saw, a hammer and nails. Take a sample of your damaged trim boards with you to your local hardware retailer so that you can exactly match the dimensions required. Most wood trim is sold by the linear foot. Use your tape to measure how much you need — then add a ‘safety net’ of about 10 to 15 per cent to account for wastage.

3) Filling Seams And Holes

Joints between trim pieces, angles, corners, and small holes should all be filled with caulk to produce an even painting surface. Caulking creates flexible joints that let trim pieces expand or contract according to the changes in the weather without opening up gaps that would allow moisture in. Apply caulk and hole filler generously. Before purchasing the products for this step, confirm that they’re designed to take exterior paint.

4) Old Paint Removal

In most cases, you’re going to be applying your new trim paint over old paint. You must put a little elbow grease into removing the old, loose paint to create the smoothest possible surface for your new finish. Besides looking much more attractive, a new paint layer on top of a well-cleaned old one will be more durable. Paint removal will go a lot faster if you make a modest investment and buy a purpose-designed paint scraper. This will lift away old, flaking paint faster than any other type of blade and do less damage to your wood trim. Sand all your trim pieces after you’ve cleared away the old paint.

5) Caulk Between Trim And Walls

We already introduced the subject of caulk in point #3. Caulking the spaces where your wood trim meets the walls of your home is even more important than caulking the joints between trim pieces. If moisture gets into these gaps, it can rapidly damage both trim and walls.

During the cleaning process, check the quality of the existing caulking around your trim boards. Any dried, stiff, or cracked caulk should be removed and replaced before you start painting.

Invest in a high-quality silicone/latex caulk designed to take paint. A good caulking product properly applied will last for decades. In our professional experience, caulking all the trim on an average-sized home requires one to two dozen tubes of caulk. You may need less if you decide some or most of your existing caulk is still in good shape. Don’t worry about over-buying caulk; it never goes bad (in unopened tubes) and it can be handy to have around for spot touch-ups later.

When applying caulk, be sure to clean up drips and wipe down your caulk beads as you go. This produces a smoother surface that paint will adhere to more readily.

6) Spot Prime Existing Wood Trim

A primer coat significantly boosts the quality and durability of your final coat of paint. It seals the wood to prevent moisture intrusion and creates an ideal surface for your finish coat to adhere to. If you’re applying new paint over an old coat, don’t take chances with the paint that remains after cleaning, scraping, and sanding — go ahead and apply some fresh primer.

Some modern exterior paints are formulated with built-in primers. These can be handy when you are painting fresh wood, but a separate primer may be necessary when you are repainting existing trim.

7) Prime New Trim

All of the information in the previous point applies equally to priming new trim boards. (You’re likely to have at least a few pieces of fresh trim if you’ve been thorough about finding and replacing damaged boards.) It’s important to create a consistent primer coat for your finish paint if at all possible to bare wood. If you find yourself using different primer products, at least try to align their colours and textures, so that your final paint goes on consistently.

Remember to give your primer coat plenty of time to dry before you move on to your finish paint! This ensures the best possible bond between the two coats.

8) Apply Your New Paint

For painting exterior wood trim, brushes and rollers are the most efficient way to apply finish paint. You can get an attractive, durable finish with one well-applied coat, but two thinner coats will yield a result that looks even better and lasts even longer. The same total amount of paint will last up to twice as long if it’s properly applied in two coats rather than one.

Specific Painting Techniques And Additional Notes

* Combining Trim Painting With Bigger Jobs

If you are doing a full repaint of your home’s exterior, we have some good news: There’s no need for time-consuming masking when you paint exterior trim. Simply lay your main wall paint on first (this is typically done with a sprayer). Save the trim work until the end of the painting job.

* The Details Of Exterior Painting

Homeowners will be relieved to hear that even professionals economize with their labour when painting exterior trim. The overwhelming majority of painting jobs concentrate exclusively on the ‘front-facing’ sides of the trim boards. This means applying the chosen trim colour only on the widest, exterior-facing side of the board. The shorter edges that connect to the walls are painted with the same colour (and at the same time) as the walls themselves.

Of course, trim boards are sometimes completely painted on all visible sides. Professional house painting practitioners call this effect ‘3D’ painting. If you’re painting exterior wood trim on your own, bear in mind that aiming for 3D painting takes much more time. Masking is often required to achieve good-looking results.

* Picking The Perfect Tools

Another key element in completing a painting job in a timely fashion is equipping yourself with the right tools to apply the paint. Whether you choose a roller or a brush, a three-inch width is ideal for almost all residential trim. Smaller brushes can be useful for hard-to-reach areas, but they will waste valuable time if you try to use them for your whole paint job.

* Efficient Exterior Trim-Painting Technique

When you’re finally ready to bring paint and wood together, make sure you’re doing it in the most effective manner! Trim paint goes on faster and dries to a better finish when you apply it with the grain of the wood. (This is usually easy with trim painting because long trim boards are generally cut along the grain.) Keep the edge of your brush or roller wet and take the longest possible strokes — arm-length strokes are ideal on trim.

* Trim Painting: Do-It-Yourself Or Professional Hire?

Although we’ve done all we can to provide useful advice on trim painting here, you should be aware that it can be a very challenging do-it-yourself project, particularly on a multi-story home. Every stage of the preparatory work described above can be time-consuming, especially if your wood trim is in bad shape.

This can make it tempting to hire a professional painter to take care of your exterior wood trim. This will get the job done faster, with less risk to you and better final results. However, it will also be more expensive. Perhaps much more expensive than you expect — it may surprise you to learn that trim painting can account for up to 60% of a painter’s time on when painting exterior siding.