Install Exterior Trim: How to Caulk and Paint It Like a Pro

First of all, thank you so much for the incredible outpouring of congratulations on our announcement yesterday. It was wonderful to share the news with you. We’ve been trying to keep up with the 3,000+ comments (seriously — thank you), so our afternoon post slipped a little. Sherry is copying questions from yesterday’s thread for Friday’s Q&A, and I wanted to share an update about the sunroom progress: three finishing steps that moved it from half-baked to genuinely finished—adding trim, caulking, and painting.

These tasks aren’t the most glamorous parts of a renovation, but they make a huge difference. Poorly installed trim and sloppy caulk can make a well-furnished room look unfinished, so paying attention to these details mattered. I intended to focus on caulking and painting, but we ran into a trim challenge that felt worth sharing. Nothing like celebrating your screw-ups, right?

We needed trim to finish off our newly installed tongue-and-groove ceiling. At first I planned to use a 1×2″ piece along the ceiling and quarter-round against the brick to match the lighter lattice trim used elsewhere in the room, while reserving a chunkier 1×4″ only where it was needed to cover rough patches. After installing everything we stepped back and realized the thinner pieces looked too puny next to the hefty 1×4″ at the bottom of the triangle. It felt visually unbalanced.

So, 24 hours after installing the trim, we removed the skimpier boards and installed 1×4″ trim all the way around each triangle so the top trim carried the same visual weight as the bottom. It’s hard to capture in photos before caulking and paint, but the change made a big difference in person. Hanging the longer pieces is mostly a two-person job: one of us held the board while the other used the nail gun. I also added wood glue behind each piece for extra hold.

Because we were working with angled sections it was a little more challenging than a typical trim job. We used an angle finder (we had one from a Kreg Crown Pro we bought years ago) to measure the angles inside the triangle, marked the boards, and cut the angles with a circular saw. Most cuts weren’t perfect, but caulk fixed the small gaps. Even with the redo, the job went fairly quickly.

With the trim up, caulking was next. Normally Sherry and I tackle this together, but outdoor caulk has strong VOCs and I didn’t want to be inhaling while carrying my baby, so I handled it solo. Besides the seams around the trim, I also caulked all the nail holes in the ceiling planks. That took a couple of hours, but it was worth it for the peace of mind—sealing everything helps prevent warping or rot from the elements and temperature swings.

I developed an efficient routine: squeeze a dot of caulk into each spot, smooth it with a finger dipped in water (to keep the caulk from sticking to my skin), then finish by smoothing the bead with a damp sponge. The sponge made a big difference in finish and speed. The before-and-after shots don’t show a dramatic visual change on camera, but in person the ceiling felt much cleaner and more finished once those little defects were addressed.

After caulking came painting. We stuck with Snowbound by Sherwin-Williams for the white trim to match our exterior, and kept the ceiling its light blue color. We underestimated the painting because the room has almost no wall area—until we remembered the 15-pane door and three 15-pane windows. That’s a lot of mullions to cut in around.

It wasn’t terrible, though. I spent about four hours applying two coats to the windows and door. I was careful to avoid getting paint on the glass to skip the tedious task of scraping panes later. We tried a new specialty brush made for this job; after both of us testing it, we actually preferred our usual short-handled brush, but it was worth experimenting.

Once the windows and door were done, I painted the walls with a small foam roller and handled tight spots with an angled brush. The final task was one more coat of blue on the ceiling to hide the caulked nail holes. Even white caulk shows up at certain angles if it’s unpainted, so that last coat cleaned everything up. Since it didn’t need cutting in, I knocked it out in about an hour while Clara was at preschool.

These finishing steps aren’t flashy, but they transformed the ceiling from “done enough” to truly complete (well, except for the fans). Below are the before and after photos that show the difference the trim, caulk, and paint made.

We’ve crossed a couple more items off the to-do list, bringing us closer to the part we’re most excited about: tiling the floor. Hopefully tile work starts soon so we’ll have another 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
  • 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 (we bought outdoor-safe tile that’s less slick than the concrete)
  • Get a rug, furniture, and maybe add some outdoor curtains and lanterns/sconces
  • Build an outdoor fireplace down the line

We went into this renovation thinking “it’s not a kitchen or bathroom; it shouldn’t take that long,” but it ended up involving removing eight doors and a ceiling, reworking electrical, installing a new ceiling plank by plank, and painting lots of trim, windows, and doors. There are still fans and tile left, plus the long-term dream of a fireplace. Turns out a sunroom renovation can be just as involved as other major rooms—who knew?