How to Install Exterior Trim, Caulk It, and Paint for a Lasting Finish

First, thank you so much for the incredible wave of congratulations after our announcement yesterday. It was wonderful to share the news with you. While we’ve been trying to work through the thousands of comments, our usual afternoon post slipped, so here’s an update to make up for it. Sherry is gathering questions from the comments for Friday’s Q&A, and I’m here to report on a few more sunroom tasks we finished this week.

Three relatively small steps—adding trim, caulking, and painting—helped move our sunroom from half-finished to feeling properly complete. These jobs aren’t glamorous, but the details matter: poor trim work or messy caulk can make a nicely furnished room look unfinished. I planned to skim over the trim phase and focus on caulking and painting, but we ran into a hiccup while installing the trim that felt worth sharing. Sometimes the best lessons come from mistakes.

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We needed trim to clean up gaps where we installed a tongue-and-groove ceiling. Initially I considered a slim profile to match the room’s existing lattice-like trim and avoid the complexity of crown molding cuts. But once we installed the smaller pieces, the proportion felt off. A thin 1×2 near the ceiling and a quarter-round against the brick looked too delicate next to the chunkier 1×4 trim at the base of the triangle panels.

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Because the 1×4 was already used at the bottom to cover rough spots, we decided the entire triangle needed the same scale for visual balance. So, 24 hours after putting up the thinner trim, we removed it and replaced it with 1x4s all the way around. It’s hard to see in photos, especially before caulking and painting, but the heavier trim immediately read better in person. Hanging long boards on a ladder is easiest with two people: one holds the board while the other nails. I also used a bit of wood glue behind each piece for added hold.

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These triangle sections were a little more challenging since they required angled cuts. We used an angle finder from our Kreg Crown Pro to capture the exact nook angle, then transferred that angle to the board and cut with a circular saw. The cuts weren’t perfect, but small imperfections are easily corrected with caulk. Overall it was a fairly quick process, even with the redo.

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Next up was caulking. Sherry and I usually tag-team these finishing tasks, but outdoor caulk has strong VOCs and I didn’t want to be around that while pregnant, so I handled this one myself. In addition to caulking seams around the trim, I took the time to caulk nail holes in each ceiling plank. It took a couple hours, but the extra effort sealed everything and reduced the chance of future warping or moisture issues.

My system became pretty efficient: place a small dab of caulk at each spot, press it in with a finger (dipped in water to prevent caulk buildup on skin), then smooth with a damp sponge. The sponge makes the finish clean and speeds the job along. The change is subtle in photos, but in person the ceiling reads as much more finished once those little imperfections are addressed.

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Painting came next. We used Snowbound by Sherwin-Williams to match our existing exterior trim. At first we thought it would be quick—there aren’t many square feet of wall—but then we remembered the many-paned door and three large multi-paned windows. Painting mullions adds time. It took about four hours to apply two coats across all the panes and trim. Sherry usually handles cutting-in, but exterior paint is off-limits during pregnancy, so this time I did it myself. I tested a specialty brush made for trim work, but ultimately we preferred our usual short-handled brush.

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After the windows and door were done I painted the small wall areas with a foam roller and used an angled brush for tight spots. Finally, I applied one more coat of blue to the ceiling to hide the caulked spots. Even when caulk matches the paint, it can “flash” at certain angles, so that extra coat made the finish consistent.

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These updates aren’t flashy, but they made a big difference. Below are before and after views that show the improved, more finished look after trim, caulk, and paint.

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With those tasks crossed off, we’re closer to the part we’re most excited about: installing the tile floor. That should be starting soon, so hopefully we’ll have an update next week.

  • Rip up the old carpeting
  • Remove the sliding doors and tracks to open things up
  • Convert outlets to outdoor-safe rain-proof ones with covers
  • Add fresh casing to the openings and caulk like crazy to waterproof everything
  • Demo the old ceiling in hopes of possibly lofting it (get a pro in here for advice)
  • Remove old beams, reinforce ceiling stability, and re-route electrical for two fans instead of one
  • Prime, paint, and install our beadboard ceiling
  • Add trim around the ceiling and caulk/paint that
  • Repaint the columns & interior of the sunroom with white exterior paint (it’s currently cream)
  • Hang two ceiling fans
  • Tile the floors with an outdoor-safe, slip-resistant option
  • Get a rug, furniture, and add outdoor curtains and lighting
  • Possibly build an outdoor fireplace down the line

We went into this thinking a sunroom renovation would be simpler than a kitchen or bathroom. In reality it involved removing doors and a ceiling, replacing electrical, installing new plank ceiling, and a lot of careful trim and paint work. There are still fans and tile to install, plus the dream fireplace someday—but we’re making steady progress and learning along the way.