Chimney Cricket Rules in Massachusetts (2026)

Massachusetts requires a chimney cricket (also called a saddle) on the upslope side of any chimney whose dimension measured parallel to the ridge is greater than 30 inches. Two separate sections of the state's residential code back the rule, IRC R1003.20 for masonry chimneys and IRC R903.2.2 for any roof penetration, both adopted under 780 CMR 10th edition. Roofers still skip crickets on 32 to 48 inch chimneys, usually by scabbing on a taller back pan and hoping the homeowner does not know the difference.

If you have a wide masonry chimney, a wide metal chimney chase, or a wide skylight on a sloped roof, and you are about to reroof or re-flash, this is the code detail that decides whether that chimney leaks in ten years. Here is what the code actually requires, how tall the cricket has to be for your slope, and what to write into the contract so the crew cannot cut it.

The short answer: when is a cricket required in MA?

Anytime the chimney (or any other roof penetration) measures more than 30 inches across parallel to the ridge line, and does not itself sit on the ridge. The code does not care whether the chimney is masonry, metal, or a prefabricated chase, and it does not care what the roof covering is. Wider than 30 inches across the slope on the uphill side means a cricket is required, period.

That trigger is written into 780 CMR twice, in Chapter 9 (roof assemblies) and in Chapter 10 (chimneys and fireplaces). Either section alone would require it. Both saying the same thing is why "the inspector didn't call it out" is not a defense.

What is a chimney cricket (or saddle)?

A cricket is a small ridged mini-roof built on the upslope side of a chimney, tented up against the chimney's back wall so rain, snow melt, and debris get diverted around the chimney instead of piling up against it. The word saddle is the same thing on a wider chimney, the geometry is peaked enough to look like a saddle straddling the ridge.

Without a cricket, everything that runs down the roof toward the chimney, water, sliding snow, leaves, pine needles, roof grit from the shingles, hits the back of the chimney and either dams there or forces its way into the seam between the chimney and the flashing. In a Massachusetts winter, that seam takes a beating: freeze-thaw, ice-dam backflow, and nor'easter-driven sideways rain all attack the same back-of-chimney corner. On a chimney wider than 30 inches, a flat back pan is not enough surface to shed that volume before water finds a way in.

The 30-inch rule, and why two code sections back it up

Massachusetts adopts the 2021 IRC with amendments as 780 CMR 10th edition, which took effect October 11, 2024 and became the sole residential code in force after June 30, 2025. Two sections of that code independently require a cricket:

• IRC R1003.20 (Chimney Crickets), in the chimneys and fireplaces chapter, requires that "Chimneys shall be provided with crickets where the dimension parallel to the ridgeline is greater than 30 inches and does not intersect the ridgeline." This section governs masonry chimneys.
• IRC R903.2.2 (Crickets and Saddles), in the roof assemblies chapter, requires that "A cricket or saddle shall be installed on the ridge side of any chimney or penetration more than 30 inches wide as measured perpendicular to the slope." This section governs the roof side of the assembly, and it covers any wide penetration, chimney or otherwise. Cricket coverings shall be sheet metal or the same material as the roof covering.

Read those two sentences together. If your masonry chimney is 34 inches wide across the ridge, R1003.20 requires a cricket. If your prefab metal chimney chase is 34 inches wide, R1003.20 arguably does not apply (it speaks to masonry chimneys), but R903.2.2 does, and it still requires the cricket. Same result. The 30-inch trigger applies statewide, from Cape Cod to the Berkshires, with no local carve-out.

Under 30 inches wide across the ridge, neither section requires a cricket, and a properly built back pan with step flashing and counterflashing is code-compliant. Do not let a roofer sell you a cricket you do not need on a narrow chimney. Do not accept a back pan on a wide one.

How tall does the cricket have to be? Table R1003.20

The cricket is not just "a bump behind the chimney." Its ridge height above the roof deck is fixed by Table R1003.20 as a function of roof slope and chimney width (W, the dimension parallel to the ridge). Steeper roofs need taller crickets because the water hitting the chimney arrives with more velocity.

Roof slope	Cricket ridge height (H) as a fraction of chimney width (W)	40-inch chimney example
12:12	1/2 of W	20 inches
8:12	1/3 of W	13.3 inches
6:12	1/4 of W	10 inches
4:12	1/6 of W	6.7 inches
3:12	1/8 of W	5 inches

Two things follow. First, a "token" 2-inch bump the roofer builds up with mastic and shingles is not a cricket, it is decoration. On a 40-inch chimney on a 6:12 roof (a very common Cape or gambrel geometry in MA), the code number is 10 inches of height. Second, on steep New England capes and gambrels, the cricket gets tall enough that it needs its own proper framing, sheathing, ice barrier, underlayment, and flashing, not just a shingle drape.

The intersection of the cricket and the chimney has to be flashed and counterflashed the same way the rest of the chimney is, per R1003.20: step flashing up the sides where the cricket meets the chimney, and counterflashing let into the mortar joint or reglet-cut into the masonry above.

Cricket vs. a bigger back pan: why the shortcut fails

The single most common shortcut in Massachusetts reroofs on wide chimneys is a tall back pan. The roofer bends a piece of aluminum or copper into an L-shape 6 to 12 inches tall, tucks it under the shingles above the chimney, and calls it a day. That looks like a cricket from the ground, but it is not. Here is what actually goes wrong on a MA winter roof:

• Water hitting a flat back pan slows down and pools at the corners where the pan meets the chimney sidewall step flashing. Freeze-thaw cycles pump water sideways into that corner until the seam fails.
• Sliding snow and ice hit the back pan and either lift the top edge (if it is under-nailed) or drive water and grit up under the shingles above it. A cricket sheds sliding snow to either side.
• Leaves and needles pile up in the pan and hold moisture against the chimney all winter. Any efflorescence you see on the interior brick, usually on the first-floor fireplace face, often traces back to that.
• The pan gives you no place to run ice and water shield up and over the ridge of a real diverter. A cricket has a real ridge with membrane running up and over.

A cricket costs a few hundred dollars more to build than a back pan. On a 30-year reroof, that adder is under $40 a year. The math is not close.

Where MA chimneys leak without a cricket

The leak signatures we see most on cricket-less chimneys in Massachusetts:

• North-face wide chimney, older brick. Ice-dam backup at the eave climbs high enough on some winters to reach the chimney base. Without a cricket to divert, the water rides the back pan seam into the attic.
• Cape or gambrel with a 34 to 42 inch chimney mid-slope. Sliding snow packs into the back-pan pocket, refreezes, and drives water into the top course of step flashing.
• South-side chimney under a big oak. Debris packs into the pan, holds water, and mineralizes the mortar joints between the flashing and the brick.
• New reroof, no leak yet. These get discovered years later when the attic starts showing staining or the plaster around the flue chase bubbles. By then, the sheathing above the chimney is often rotted.

If the ceiling drywall or plaster right below the chimney has any brown staining, or the attic sheathing above the chimney is soft, the odds are very high there is no cricket up there.

What to put in the roofing or re-flashing contract

The wording that stops shortcuts is section numbers. A generic "chimney flashing" line lets the roofer install a tall back pan on a 40-inch chimney and call the job done. Write the code trigger in.

For a reroof or standalone re-flash on a chimney wider than 30 inches across the ridge, the scope should include, at minimum:

1. Cricket or saddle installed on the ridge side of the chimney per IRC R1003.20 and R903.2.2 as adopted under 780 CMR, sized to the Table R1003.20 height requirement for the actual roof slope. State the height number (e.g., "cricket ridge height not less than 10 inches for the existing 6:12 slope and 40-inch chimney width").
2. Cricket framing: dimensional lumber or plywood ribs and gussets, sheathed with a minimum 1/2-inch structural panel, fastened to the existing deck. Not shingle-drape over foam or mastic.
3. Ice barrier self-adhered membrane over the entire cricket assembly, wrapped up the chimney a minimum of 6 inches and lapped under the field underlayment on the sides.
4. Metal flashing and counterflashing at the cricket-to-chimney intersection, minimum 0.019-inch (26 gauge) corrosion-resistant metal per IRC R903.2.1, step-flashed up the sides and counterflashed into the mortar joint or a reglet cut in the masonry.
5. Cricket covering: sheet metal or the same shingle as the field per R903.2.2. On a steep enough cricket, the same shingle is fine. On a shallow cricket where the effective slope drops below 4:12, use a soldered metal pan instead of shingles.
6. No aluminum flashing in direct contact with the copper flue liner or a copper gas-vent flashing collar. Galvanic corrosion turns those seams into weep holes in about a decade.

If the bid line for "chimney flashing" is under a few hundred dollars on a wide chimney, none of the above is being priced.

How much does adding a cricket cost on a MA reroof?

A cricket built into a full tear-off reroof, on a typical 34 to 48 inch masonry chimney at a mid-slope location, generally adds a few hundred to about a thousand dollars over the equivalent back-pan chimney flashing. On very steep pitches, tall chimneys with rebuilt crowns, or crickets that require re-cutting a reglet into the masonry, that adder climbs. Standalone re-flash jobs (no tear-off) that add a cricket where none existed run higher because the crew has to open the field above the chimney, land the cricket, and blend the surrounding shingles back in. Those we usually see quoted higher than a simple re-flash without a cricket, which by itself is often in the mid-hundreds to low-thousands.

The dollar figure that matters more is the one you save by not tearing the ceiling out below the chimney in year seven. That is the whole point of the code section.

How this connects to the rest of the roof

Crickets are one code detail in a package of chimney and eave weatherproofing rules that MA roofers routinely under-spec. If you are already writing the cricket into the contract, add the underlayment and ice barrier spec at the same time, we walk through the numbers in ice and water shield code in Massachusetts. For the general chimney flashing detail (step and counterflashing on narrower chimneys where no cricket is required), see chimney flashing leaks in Massachusetts. And because a real cricket install requires opening the field above the chimney, this is one more reason we push MA homeowners away from a layover job, we cover the tradeoff in roof tear-off vs layover. For the whole reroof cost picture the cricket lands inside, see roof replacement cost in Massachusetts. The full menu of local roofing coverage lives on the Massachusetts roofing hub.

FAQ

Is a chimney cricket required by code in Massachusetts?

Yes, on any chimney whose dimension parallel to the ridge is greater than 30 inches. Two sections of 780 CMR 10th edition (which adopts the 2021 IRC with MA amendments), R1003.20 for masonry chimneys and R903.2.2 for any roof penetration, both require it. Under 30 inches wide across the ridge, a cricket is not required and a proper back pan is code-compliant.

How tall does the cricket have to be?

Per IRC Table R1003.20, cricket ridge height is a fraction of chimney width (W): W/2 at a 12:12 slope, W/3 at 8:12, W/4 at 6:12, W/6 at 4:12, and W/8 at 3:12. A 40-inch chimney on a 6:12 roof needs a cricket at least 10 inches tall.

What is the difference between a cricket and a saddle?

Practically nothing in MA usage. Both are peaked diverters on the upslope side of a chimney. "Saddle" tends to describe wider ones that straddle a ridge or a wide chimney. Code sections R1003.20 and R903.2.2 use "cricket or saddle" interchangeably.

Can the roofer just install a taller back pan instead?

No, not if the chimney is wider than 30 inches across the ridge. The code requires a cricket, not a bigger pan. A tall back pan looks similar but fails differently in a MA winter: water pools at the sidewall corners, sliding snow lifts the top edge, and debris holds moisture against the masonry.

How much does adding a chimney cricket cost during a reroof?

On a typical 34 to 48 inch masonry chimney at a mid-slope location, the cricket adds a few hundred to about a thousand dollars over the back-pan alternative in a full tear-off scope. Standalone re-flash jobs that add a cricket where none existed run higher because the crew has to open the field above the chimney.

Will a cricket stop my current chimney leak?

Usually yes, if the leak is water driving in at the upslope back-pan seam or ice-dam backup climbing to the chimney base. It will not fix a leak coming through the crown, through cracked masonry, or through a failed flue liner. If you are already seeing interior staining below the chimney on a wide masonry stack with no cricket, budget for cricket plus a crown and mortar inspection.

Get a MA roofer who codes the cricket correctly

Wide-chimney reroofs are where the cheapest bid usually loses in year eight. The MA roofers in our directory write the code section numbers into the contract by default. Tell us your town, your roof, and the chimney width, and we will route you to vetted local contractors who have built crickets on your kind of house.

Get matched with MA roofers and request quotes.