Ask This Old House S24E17: Lead Paint Testing, Sink Clogs, and Granite Steps for a Hill That Fought Back

Season 24, episode 17 of Ask This Old House has no single showpiece build, just three jobs that all come down to the same instinct: figure out what is actually there before you touch it. Richard Trethewey opens a trap, Mauro Henrique scratches a windowsill, and Mark McCullough digs a hole in New Hampshire clay. None of it looks heroic on camera. All of it is the part you skip at your own expense.

The through-line is prevention. Drain maintenance, lead testing, and hillside drainage are three flavors of the same question: what happens to this assembly two years from now if I get the prep wrong?

Richard Trethewey on sink clogs: it is almost never the solids

Richard starts at the kitchen sink with a trap he has loaded with a bracelet, some flossers, and plastic coffee stirrers — the kind of small stuff that slips past a strainer and settles into the U-bend because a trap has a tight radius by design. That same tight radius is what holds the water seal that keeps sewer gas out of the house, so you cannot just eliminate the bend. What you can do is open it. Most modern traps come apart by hand, and Richard's point is that this is the first place to look when a sink is slow, not the last.

The real culprit, though, is grease. He heats a pan of fat and pours it into a cold glass pipe as a demo. It coats the bottom, hardens, waits for the next pour, and thickens. Kevin O'Connor's comment about five years of Sunday morning bacon is exactly the mechanism: nothing dramatic on any given day, and a nearly closed pipe at the end. Richard notes that old galvanized and cast iron are worse offenders than smooth PVC because the interior is rougher and gives the fat something to cling to.

Hair gets its own segment because pop-up stoppers put a mechanical obstruction directly in the water stream. Swapping the pop-up for a strainer-style stopper that lifts out is one of the cheapest plumbing upgrades you can make, and a hair catcher over a shower drain does the same job without touching the fixture.

Then Richard turns to the shelf of chemical drain cleaners, and this is the part worth rewinding. He mixes lye with hair in a jug with a thermometer in it and the temperature climbs past 150°F on camera. That is what is happening inside your wall. On thin or old pipe, that heat and causticity can eat the metal, and if you later call someone to snake the line, they are now working over a caustic pool. He walks through safer alternatives: baking soda and vinegar for grease, and enzyme products that colonize the organic buildup and eat it over time. enzymes are slow, but they do not cost you a drain line. This is the same territory Richard covered in the garbage-disposal segment earlier this season (S24E15), where the appliance is fine but the way we treat it is not.

Mauro Henrique tests paint for lead, two ways

Mauro opens with the rule he works under: if the house was built before 1978, treat the paint as lead until proven otherwise. As a professional painter, he tests on almost every job because the legal and health stakes are real — lead exposure is particularly bad for young children and brain development, and Kevin and Mauro both say so plainly.

The at-home kit uses two sealed chambers, one liquid and one powder, separated by a glass ampule inside a plastic tube. You clean the blade with an alcohol wipe first, cut a notch through all the paint layers down to bare wood, then crush both chambers in sequence and shake. Rub the swab in the cut. Orange means no lead. Red or pink means positive. In the demo, Kevin pulls orange and Mauro pulls red and pink on a neighboring window — a nice teaching moment because it lets them stand side by side.

The XRF analyzer is the other half of the lesson. It fires X-rays through the paint and reads fluorescence, so it doesn't require a cut and doesn't damage the wood. It also reports a concentration number, which matters because state and local rules vary on what levels trigger which protocols. Mauro's read is that the XRF is more of an inspection or general-contractor tool than a standard homeowner purchase — the swab is what you buy, the XRF is what you call in when the swab comes back positive. Mauro's previous paint segment was about cleaning up spilled paint quickly (S24E14); this one is the other side of the same job, where you have to know what you're working on before you start sanding it into dust.

Mark McCullough installs granite steps into a New Hampshire hill

The house call is in New Hampshire — the Granite State, as Mark reminds us — and the homeowner is Pete, who built the house about a year ago. He has a beautiful fire pit in the side yard and a slope steep enough that he has taken actual falls getting to it. He even shows Mark video of one.

Mark lays out two options. Cutting straight up the steep hill would produce somewhere between eight and nine steps, require a poured footing, and demand a handrail at the end. The gentler slope he picks instead lines up with the doorway above, which makes the flow natural and lets him set thick granite treads straight into the hill. That second option is what makes this a much easier build, and it also puts the emphasis on the stone itself. Mark's last hardscape segment compared paver options by pattern and price (S24E16); this is granite in its structural role, not its decorative one.

The build itself is unglamorous and worth describing because the parts you would skip are the parts that make it last. Mark digs at least 12 inches to reach clay, then tamps the clay flat. He fills the hole with crushed stone and compacts it — the stone is drainage first, foundation second. He then sets each granite tread onto the compacted base with a deliberate bent-knee, roll-and-flip technique that he calls out explicitly: he has never hurt his back because he always bends his knees. The first tread is oriented to face the fire pit, because that is where the walk is going. He checks pitch with a 2-foot level in both directions and makes an on-site call based on the surrounding grade so water does not get caught, build up, and freeze. That last detail is exactly the kind of thing you cannot really plan from a drawing.

After the treads are set, Mark backfills them all at once, lays down landscape fabric, and drives heavy-duty stakes to hold it. Gravel goes on top, raked to meet the driveway. He leaves Pete with homework — seed the bare dirt patch, and plant a row of bushes along the driveway corner so company is naturally funneled down the new walkway and toward the fire pit instead of toward the steep side of the hill. That last suggestion is the most professional thing in the segment: the steps work, but the design only works if people choose to use them.

What the camera compresses

The three jobs are edited down, and each one hides the same kind of labor. The granite treads are set in what reads as a friendly afternoon, but moving a 40-inch slab of granite with a helper and a pair of shovels is slow, and the digging is on a slope with clay underneath. The lead swab looks trivially easy on camera, and it is — as a test. What it isn't is a plan for what to do about a positive result, which is where licensing, containment, and state rules kick in. The lye demo is the most aggressive editing trick of the episode: it visibly works on the hair, and Richard has to talk you back to the part where it also melts the pipe.

DIY Confidence Scale

Sink and drain maintenance: 5/5. Pulling a trap, swapping a pop-up stopper for a strainer, adding a shower hair catcher, and giving up bacon grease down the drain are all homeowner-level tasks. I will not be pouring lye down anything in my house.

Lead paint swab testing: 4/5. The test itself is straightforward and worth doing before any pre-1978 renovation. Scoring the surface, reading the color, and knowing you have to escalate to a professional — and to the correct disposal and containment protocols — for a positive result is where the modest skill ceiling sits.

Granite hillside steps: 2/5. If you have moved heavy stone, can dig a consistent 12-inch trench, own a hand tamper, and can read a level in two axes while thinking about drainage, this is within reach. Bring a helper. If you have never set a paver bed, this is a job to watch before you try it, and probably a job to hire the first time.

Additional Resources

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

There is a version of this episode where the granite steps are the story, but the drain segment is the one I keep thinking about. Richard's demo makes a persuasive case for the tool everyone reaches for, and then takes it away. If a slow sink is a warning, what is the correct first move in your house — a plunger, a snake, or the trap?