The 10 Best Multi-Flue Chimney Caps of 2026

Many chimneys have more than one flue: one for the fireplace, one for the furnace, maybe one for a water heater or a basement stove. When those flues sit close together, there may not be room for a separate cap on each. A multi flue chimney cap solves that with one large cap that covers them all.

This guide explains when a multi flue cap is the right choice, how to measure for one, how it mounts and what it costs.

When Do You Need a Multi Flue Chimney Cap?

You need a multi flue chimney cap when:

• Flues are too close for separate caps. Single flue caps need room around each tile for their skirts and lids.
• Flues are different heights. A multi flue cap can be ordered tall enough to clear the tallest one.
• The crown is cracked or worn. A multi flue cap covers most of the crown and keeps rain off it.
• You want one cap to maintain. One cap is easier to inspect than three.

If your chimney has one flue, or flues far apart, single flue caps are cheaper, and our pick of the best chimney cap covers the single flue options worth buying.

Single Flue vs Multi Flue Chimney Caps

Outside Mount vs Top Mount Multi Flue Caps

Outside Mount

An outside mount cap has a skirt or flanges that wrap down over the sides of the crown and fasten to the crown face or the top course of brick. It covers the whole crown. Outside mount caps work well when the crown has an overhang or a clean, square edge.

Top Mount

A top mount cap sits on the flat surface of the crown and is fastened with masonry anchors or high temperature adhesive. It covers the flues and the crown area inside its footprint. Top mount caps suit crowns with sloped or uneven edges.

Both need a sound crown. If the crown is crumbling, repair it first or the anchors will not hold.

How to Measure for a Multi Flue Chimney Cap

Accurate measurements matter, because most multi flue caps are made to order and cannot be returned.

1Step 1: Measure the Crown

Measure the length and width of the crown at the top. For an outside mount cap, measure to the outside edge. For a top mount cap, measure the flat area the cap will sit on.

2Step 2: Measure the Flue Area to Cover

Measure the length and width of the rectangle that includes all the flues, from the outside edge of the first tile to the outside edge of the last. The cap must cover this area with some margin.

3Step 3: Measure the Tallest Flue

Measure the height of the tallest flue above the crown surface. This sets the mesh height.

4Step 4: Add the Clearance Above the Flue

The lid must sit above the tallest flue with enough room for smoke to escape. Makers specify how much. Mesh heights such as 8, 10 or 14 inches are common. The Draft King BigTop stainless cap comes in 8, 10 or 14 inch mesh heights, and the copper Big Top in 9, 12 or 14 inches.

5Step 5: Note Obstacles

Note any antenna mounts, flashing, or crown slopes. Send photos to the maker with your measurements.

How Much Open Area Does a Multi Flue Cap Need?

A multi flue cap must leave enough open area under the lid for every flue it covers. Model codes based on the IRC require a cap’s open area to be at least four times the flue area. With several flues under one lid, the total open area needs to cover all of them. That is why makers set mesh heights based on flue sizes. If you add an appliance to a flue later, check that the cap still provides enough open area.

Stainless vs Copper Multi Flue Caps

Stainless Steel

Stainless multi flue caps offer the best value. The Draft King Custom BigTop lists 18 gauge 304 stainless mesh, 24 gauge flanges and a lifetime warranty on stainless, made in the USA. The HomeSaver stainless knock down cap ships flat and assembles on site, in sizes such as 9 x 13 inches with a 10 inch mesh height and 17 x 35 or 17 x 41 inches with an 8 inch height. A knock down cap is easier to carry up a ladder than a welded box.

Copper

Copper multi flue caps are the premium option. The Draft King Big Top copper cap uses a 24 gauge removable copper hood, 24 gauge copper plated stainless base flanges and 18 gauge copper mesh, with a limited lifetime warranty. Expect copper to cost several times more than stainless at the same size.

Galvannealed and Black Finishes

Some makers offer multi flue caps in galvannealed steel or with black powder coat. Draft King lists a 7 year warranty on its black powder coat finish. Galvanized steel is best limited to gas flues in mild climates.

Multi Flue Caps for Mixed Fuels

A chimney with a wood fireplace flue and a gas furnace flue can share one multi flue cap, but think about:

• Smoke re-entry. Wood smoke from one flue can be drawn down a neighboring flue if they end at the same height. Many codes and sweeps recommend the flues end at different heights or are separated by a wythe of masonry.
• Material. Wood and oil flues need stainless or copper. Choose the cap for the harshest fuel.
• Open area. The cap must serve both flues at full draft.

Ask a chimney sweep to check the setup before you order.

Multi Flue Caps and Rain Protection

Because a multi flue cap covers the crown, it is one of the best ways to stop rain getting into the chimney. The crown is a common leak point: small cracks let water in, it freezes, and the cracks grow. A cap over the crown slows that cycle.

Installing a Multi Flue Chimney Cap

Multi flue caps are heavier and larger than single flue caps, and they are fastened to the crown rather than a tile. Most homeowners hire a chimney sweep or roofer. The basic steps are:

1. Inspect and sweep the flues before covering them.
2. Check the crown and repair cracks.
3. Set the cap and mark anchor holes.
4. Drill with a masonry bit and fasten with stainless anchors, or bond with high temperature adhesive as the maker directs.
5. Check the lid sits level and the mesh is clear.

The ladder and roof safety rules are the same as for how to install a chimney cap on a single flue, just with a heavier, bulkier part.

How Much Does a Multi Flue Chimney Cap Cost?

Multi flue caps cost more than single flue caps because they use more metal and are often custom built. One cost guide puts a stainless outside mount multi flue cap at about $200 to $800 for the cap alone and $400 to $1,300 installed. Copper multi flue caps cost more, and published estimates for installed copper caps reach well above $1,000. Prices vary with size, height and region, so get a quote with your measurements.

Common Multi Flue Cap Mistakes

• Measuring the flue tiles, not the crown. The cap sits on the crown.
• Forgetting the tallest flue. If the mesh is too short, the cap will not fit.
• Mounting on a crumbling crown. Anchors pull out in the first storm.
• Ignoring open area. An undersized cap can starve draft for all flues.
• Mixing metals. Use stainless anchors with stainless caps and copper compatible fasteners with copper.

Multi Flue Cap Checklist

• Crown size: length and width, top surface and outside edge.
• Flue area: rectangle from the outer edge of the first flue to the outer edge of the last.
• Tallest flue: height above the crown.
• Mesh height: clears the tallest flue with the maker’s required gap.
• Mount type: top mount or outside mount.
• Crown condition: solid enough for anchors.
• Fuel mix: stainless or copper if any flue serves wood or oil.
• Open area: enough for every flue at once.

How High Should a Multi Flue Cap Sit Above the Flues?

The lid must sit high enough above the tallest flue for smoke to escape freely. Makers set this gap and build the mesh height to suit. As a rule, choose the mesh height that clears the tallest flue by the margin the maker recommends rather than the shortest height that fits. A cap that sits too low restricts draft and can push smoke into a neighboring flue. A cap that sits too high lets more wind driven rain in under the lid.

Can You Put a Multi Flue Cap on Flues of Different Heights?

Yes. The mesh height is set by the tallest flue, so shorter flues simply sit lower under the lid. If one flue is much taller than the rest, ask the maker whether to trim it or use a taller cap. Some chimneys are built with flues at different heights on purpose to reduce smoke re-entry between them.

Can a Multi Flue Cap Replace a Damaged Crown?

No. A multi flue cap protects the crown from rain, but it does not repair cracks or replace missing mortar. Anchors need solid masonry. If the crown is crumbling, have it repaired or rebuilt first, then fit the cap. A cap on a sound crown will help keep it that way.

Multi Flue Caps and Animals

Because a multi flue cap covers the whole crown, it closes the gaps between flues that birds and squirrels sometimes use. Make sure the skirt or base sits tight to the crown all the way around. Raccoons are the usual test of that seal, and a good chimney cap animal guard setup is built to beat them.

Multi Flue Caps in Snow Country

Large flat lids collect snow. In heavy snow areas, choose a pitched lid if offered, and a heavier gauge hood. Check the cap after big storms to make sure the mesh is clear and the lid has not bent.

How Long Does a Multi Flue Cap Last?

A stainless or copper multi flue cap that is installed on a sound crown and kept clean can last for decades. The most common failures are crown anchors pulling out, mesh damaged by animals, and coatings fading on powder coated caps. Annual chimney inspections catch these early.

Questions to Ask Before You Buy

1. How many flues are there, and what fuels do they serve?
2. What are the crown dimensions?
3. How high is the tallest flue above the crown?
4. Is the crown sound, or does it need repair first?
5. Outside mount or top mount? It depends on the crown edge and the look you want.
6. Do I need a spark arrestor?
7. Will a professional install it? Anchoring into masonry is usually a pro job.

Multi Flue Cap Features Compared

Signs Your Multi Flue Cap Needs Attention

• Rust streaks on the crown or brick.
• The lid sits crooked or rattles in wind.
• Smoke from one flue drifts into another.
• Animals or nesting material in any flue.
• Creosote buildup on the screen above a wood flue.

Have the sweep check every flue under the cap during the yearly inspection.

Quick Verdict by Situation

The Bottom Line

The best multi flue chimney cap is a stainless cap made to your crown size with a mesh height that clears the tallest flue, such as the Draft King BigTop or a HomeSaver knock down cap. Choose copper for looks. Measure the crown, the flue area and the tallest flue carefully, repair the crown first, and make sure the cap gives every flue enough open area.