Tom's Caulk Bible, Richard's Air Switch Disposal, and Kevin Builds with the Toys and Colors Kids – Ask This Old House Season 24 Episode 15

Season 24, episode 15 of Ask This Old House opens with a workbench covered in caulk tubes and ends with Kevin O’Connor in a feather boa. In between, Richard Trethewey installs a garbage disposal without a wall switch, using a puff of air to control the motor. The common thread isn’t tools—it’s prep. Every segment rewards the homeowner who reads the instructions and doesn’t skip the boring first step.

Tom Silva on Caulk: Latex, Acrylic, Silicone, and the Goo That Never Gets Hard

Tom walks Kevin through four caulk families with the clarity of someone who’s scraped out a hundred failed tub joints. He starts with plain latex—an interior painter’s workhorse for filling the gap where baseboard meets wall. Tom wants primer on the wall first, before the bead, so the caulk gets better adhesion. It’s a small rule that most people skip, and it’s the kind of detail that makes his advice stick.

For exterior work, Tom moves to an acrylic caulking with silicone added. The acrylic brings adhesion across materials, while the silicone offers some water resistance. But the real reason to switch outside is movement: wood and trim expand and contract, and the caulk has to follow. If the bead cracks in the first season, it wasn’t the right product.

Then there’s 100% silicone. Tom only trusts the real thing, not the modified blends. It’s the choice for wet spots—where a shower meets a tub, for instance—because it’s fully waterproof. The tradeoff: you can’t paint it, so you’re stuck with whatever color you squeeze out of the tube. That’s why it comes in a dozen shades.

The fourth material gets Kevin’s attention: butyl. “This is what you want to use,” Tom says, holding up a tube of the dark, sticky sealant. It stays soft for years and adheres where other products fail—metal gutters, expansion joints in tile floors, gaps that move. Butyl is messy, Tom warns. He pushes a bead onto the test board and you can see why. The stuff grabs everything, including the back of your hand.

Tom’s lesson gets the same sustained, gear-driven treatment as his combination-square segment a few seasons back (Ask This Old House Season 23, Episode 4), where he spent a full act on a single tool. Here the tool is a caulk gun, and he’s just as insistent on prep. He shows Kevin the little hole in the gun’s handle that’s meant to snip the nozzle tip—press the trigger, and a built-in cutter trims the plastic at a clean angle. Tom pulls his bead rather than pushing it, and Kevin notes that after all these years, “you’ve always been a pull kind of guy.” Calling him “pops” lands because we’ve seen this relationship work over hundreds of repairs.

The biggest takeaway is a warning: don’t caulk over existing silicone. The new stuff won’t stick. “It’ll look good for about an hour,” Tom says. Instead, scrape the old bead with a razor blade, clean the surface with lacquer thinner or denatured alcohol, let it dry, and only then apply fresh sealant. That kind of restoration beats a second trip to the home center.

Richard’s Air Switch Garbage Disposal: No Electricity, Just a Puff of Air

Emily’s newly renovated kitchen has stone counters, a big island, and a missing garbage disposal. Richard arrives to fill the gap, and the space under the sink is already wide open with electrical rough-in waiting. That makes the plumbing the main job, but Richard has a twist: he’s adding an air switch so the disposal won’t need a wall-mounted electrical control.

He starts by unboxing a ¾-horsepower continuous-feed disposal. Most units today are continuous feed, meaning you flip a switch and they run until you turn them off. The older batch-feed design, which required a special magnetic lid, is fading. But a continuous-feed model demands some kind of switch accessible near the sink. Here, Richard pulls out a small black button connected to a thin tube. The tube carries a puff of air down to a relay box that plugs into the wall outlet; the disposal plugs into that box. Press the button, and a burst of air closes the circuit—no line-voltage wiring near water.

To demonstrate, Richard shows the air switch working while the disposal is unplugged, just so Emily can hear the internal click. It’s a simple demo, but it makes the safety point clear. Then he demonstrates the disposal running, and the growl of the empty chamber is a reminder that the unit is, in fact, a rugged appliance.

The installation itself is standard in most respects, but two moments stand out. The mounting flange assembly uses plumber’s putty on the sink side and a spring clip underneath. Richard lets Emily apply the putty and push the flange down while he tightens the lock ring—a rare instance of a homeowner actively turning a wrench. Then comes the hardest part: drilling a hole through the granite countertop for the air switch button. Richard tapes the stone surface, marks the spot, and uses a carbide-grit hole saw. The tool is slow and needs steady pressure. Watching from the other side, you see the core emerge, and Richard’s careful approach avoids a single chip.

After the plumbing connections (drain elbow, p-trap modifications) and the dishwasher discharge adapter, the test is a brief whirring sound and Emily’s genuine smile. Richard gets a fake text from his doctor and exits with “We’ll see you. Better there.” It’s a throwaway joke, but it works because of his deadpan delivery.

Kevin Builds a Dress-Up Closet with the Toys and Colors Kids

The episode’s final act brings Kaden and Wendy, the young hosts of the popular online channel Toys and Colors, to the workshop. They want a dress-up closet for their costumes, and Tom Silva has drawn up simple plans: a pine cabinet with a hanging rod on the right and three shelves on the left, the whole thing sitting on an apron that gives it a furniture look.

When Lee Gilliam had his toddler help spread sand in a lawn regrade earlier this season (Episode 8), the involvement was more about charm than skill. With Kaden and Wendy, Kevin goes all in: ear protection, safety glasses, and a thorough walkthrough of the miter saw. He reminds them that “there is no more important safety rule than to wear these”—a line that’s become a quiet mantra on the show. Wendy cuts the apron pieces herself, lining up the blade with a pencil line and holding the board tight against the fence with her hand well clear of the blade. Kevin names the parts of the saw, explains the two-trigger start (thumb slide and grip trigger), and lets her work. Kaden watches and calls out encouragement.

For joinery, Kevin introduces pocket screws. He shows the jig, drills the pocket, and then lets each kid drive a screw. Kaden gets the clack-clack sound of the drill’s clutch, meaning the screw is tight. Kevin explains the name: not because you sneak them in your pocket, but because the screw sits in a pocket drilled into the wood at an angle.

After assembly, they prime. Kevin’s “prime first” mantra echoes Tom’s earlier point about priming walls before latex caulking—consistency across the house. Only once the primer dries do they break out the colors, painting the closet a bright, cheerful blue. The payoff is the dress-up moment: the kids load the closet with costumes, then dress Kevin in a feather boa and knight him “Pops.” It’s playful, but the closet is a real piece of furniture. Any adult with a miter saw and a pocket-hole jig could build the same thing in a weekend.

DIY Confidence Scale

Caulking like Tom – Easy, if you follow the prep. Primer before latex, scrape before silicone, choose the right product for the joint. The mistake most people make is grabbing one tube for everything. A careful painter can handle all four categories once they know the rules.

Garbage disposal with air switch – Intermediate. The plumbing modifications (drain elbow adjustments, p-trap rework) assume some experience, and drilling through granite demands a carbide-grit hole saw and a steady hand. The air switch wiring is plug-and-play, but if your under-sink electrical isn’t already in place, you’ll need an electrician. Emily’s installation benefited from that roughed-in box; yours might not.

Dress-up closet – Accessible for a weekend woodworker with a miter saw and a pocket-hole jig. The cuts are straight, the joinery is straightforward, and the material list is short. The children in this segment worked under close supervision, and an adult working alone should follow the same safety habits: eye protection, hearing protection, and no shortcuts on the jig.

Additional Resources

• Watch the full episode on PBS
• Official This Old House episode page

What you don’t see on camera: the mess of butyl sticking to Tom’s fingers, the tedious cleanup of silicone before Richard’s perfect bead, or the primer the kids probably got on their elbows. All three segments share a quiet theme: successful home improvement isn’t about the tool. It’s about the prep you do before anyone sees the finished work.