How to Measure a Chimney for a Custom Cap

Every custom cap we build starts with the same handful of numbers. Get them right and the cap drops on like it grew there. Get them wrong and you're buying a second cap, because a cap cut to your dimensions isn't something we can put back on the shelf.

Figure out which kind of chimney you have

Masonry chimneys are brick or stone with clay flue tiles sticking out the top. Framed chases are the wood-built boxes, usually wrapped in siding, with a metal pipe inside. It matters because they take different products. A masonry chimney usually gets a rain cap or a shroud that sits on the crown. A framed chase gets a chase cover, which is a flat top with hemmed edges and a corner-to-corner cross-break folded in so water sheds off instead of ponding in the middle.

The measurements we need

For most caps on our order form it comes down to base length, base width, and overall height. Measure the outside of the chase or crown in both directions, corner to corner, with a steel tape. Don't measure the old cap's rusty skirt and call it good. Rust swells metal, and plenty of old caps were ordered wrong in the first place.

If it's a chase cover, we also want to know where the pipe sits. Measure from two sides of the chase to the center of the flue so the hole lands where the pipe actually is. And grab the pipe's diameter while you're up there.

Old chimneys are rarely square

On masonry that's been through fifty Indiana winters, measure both ends of each side. If the two numbers disagree, give us both. We'd rather build to the real chimney than to an average. Photos help too. Stand back far enough to get the whole top in frame and shoot each side.

Add a quarter inch to both sides

We tell everybody the same thing: take your two base measurements and add a quarter inch to each one. A cap built a hair big still drops over the chase and sits right. A cap built a hair small doesn't go on at all, and now you're waiting on a second one while the flue sits open. That quarter inch costs you nothing.

Height matters more than people think

Overall height decides whether the cap clears the flue tile and how the chimney reads from the street. A tall Knight or Lighthouse pot makes the chimney part of the look. A Low-Profile Hip stays out of the sightline on a wide chase. Tell us how much tile sticks up above the crown and we'll make sure whatever style you pick clears it.

Replacing a cap that already fits

If the old cap fit fine and just rusted out, measure it and send us those dimensions. We'll match it. This is the fastest path there is, and it's a good time to switch material while you're at it. We build caps in Kynar-coated steel, stainless, aluminum, and copper, and stainless on an exposed chimney never needs repainting.

Once you have your numbers, call 765-432-4157 with the flue size and the chase dimensions and we'll get you a quote. Or pick your style on the chimney caps page and put the dimensions straight into the order form. Either way it's built here in Kokomo, five days from your deposit.