Roof Cricket Installation: A Step-by-Step Guide
If you've got a chimney wider than 30 inches sitting on your roof, you've probably already dealt with the debris pile and water stains that build up on its uphill side. That's not bad luck, it's physics. Snow, rain, and leaves hit that flat vertical surface and have nowhere to go, so they pool right where your roofing material is most vulnerable. A properly built roof cricket installation solves this by redirecting water around the obstruction instead of letting it dam up against your chimney or the curb of a curb-mounted skylight.
This guide walks you through exactly how to build a chimney saddle from framing to final flashing, using the same approach our crews use on Kirkland-area homes. You'll learn how to size the cricket correctly, cut the ridge and hip rafters, sheathe the frame, and tie the water diversion structure into your existing roofing and flashing system so it sheds water instead of trapping it.
We'll cover the tools you need, the measurements that matter most, and the common mistakes that turn a cricket into a future leak point. Whether you're a hands-on homeowner or just want to know what a contractor should be doing on your roof, you'll walk away knowing what proper cricket installation actually requires.
What a roof cricket does and when you need one
A roof cricket is a small triangular structure built into the uphill side of a chimney, skylight curb, or any wide roof penetration. Think of it as a miniature roof-within-a-roof: two sloped planes that meet at a ridge and split incoming water to either side of the obstruction instead of letting it pool against the flat vertical wall. Without one, water backs up behind the chimney every time it rains, and that standing water works its way under shingles, through mortar joints, and eventually into your attic. Roof cricket installation isn't a cosmetic upgrade. It's a structural fix for a drainage problem that gets worse every season you ignore it.
Code doesn't leave this to guesswork, and neither do industry standards like the NRCA's published roofing manual. The International Residential Code requires a cricket on any chimney or roof penetration measuring 30 inches or wider (measured parallel to the ridge) when the roof slope is less than 12 in 12. You can check the exact language in the International Code Council's residential code if you want to see it in writing. Below that threshold, standard step flashing can usually handle the water volume. Above it, physics wins and you need a diverter.
A chimney over 30 inches wide without a cricket isn't a design choice, it's a leak waiting for the right storm.
How a cricket diverts water away from your chimney
Water always follows the path of least resistance. On a normal roof plane, that path runs straight down to the gutter. A chimney interrupts that path and creates a flat dead zone where debris collects and snow melts slowly, refreezing at night and expanding under your shingles. The water diversion structure of a cricket splits the flow into two channels that rejoin the main roof plane on either side of the chimney, so water never has a chance to sit still. On steeper pitches or wider chimneys, this diversion effect matters even more, since the volume of water hitting that upslope wall during one of our heavy Northwest downpours is higher than most homeowners assume.
Signs your chimney needs a cricket now
You don't need a moisture meter to spot most of these problems. Walk your attic on a rainy day or check the roof after a storm and look for these red flags:
Dark staining or streaking on the roof deck or ceiling directly below the uphill side of the chimney
Granule buildup or shingle wear concentrated in a horizontal band behind the chimney
Ice buildup that lingers longer on one side of the chimney than the rest of the roof
Visible debris pockets of pine needles, leaves, or moss collecting against the chimney base
A chimney width over 30 inches with no visible cricket or diverter structure at all
Spotting two or more of these usually means the flashing alone isn't keeping up, and a cricket is overdue rather than optional, not just another chimney leak fix and what it costs.
When a repair won't cut it
Homeowners often ask if resealing the flashing or adding extra caulk will solve the problem. It buys time, nothing more. Sealant degrades under UV exposure and temperature swings within a few years, and it does nothing to change the physics of water pooling against a flat surface. If your chimney meets the width threshold and you're seeing any of the warning signs above, the cricket itself is the fix, not another layer of patching. We walk Kirkland-area homeowners through this assessment as part of our residential roofing evaluations, because catching it early usually means a straightforward carpentry job instead of a full deck replacement after years of hidden water damage.
Step 1. Measure your chimney and roof pitch
Getting the measurements right is the single most important part of roof cricket installation. Every angle you cut later depends on three numbers: chimney width, roof pitch, and the distance from the chimney's uphill face to the ridge or nearest hip. Get any of these wrong and your cricket either sheds water into the wrong spot or sits proud enough to look like an afterthought bolted onto the roof.
Measuring chimney width and roof pitch
Start by measuring the chimney's width parallel to the ridge, right at the roof deck. Use a tape measure and record it in inches, not feet, since you'll need precision when you cut the cricket's ridge board later. Next, find your roof pitch. Set a rafter square or a pitch gauge against the roof surface a few feet away from the chimney, on an unobstructed section, and read the rise per 12 inches of run. Most residential roofs in the Kirkland area run between 4/12 and 8/12, but don't assume, measure it directly.
Get the chimney width and roof pitch wrong, and every cut you make after this point compounds the error.
Calculating cricket height and ridge length
Once you have width and pitch, calculate the cricket's ridge height using half the chimney width multiplied by the roof's rise-per-foot, converted to the same units. A cricket built for a chimney saddle typically needs a ridge height equal to or slightly greater than the roof pitch to guarantee positive drainage on both slopes. Many roofers add an extra half-inch of rise for insurance against ponding on low-slope sections.
Measurement | How to find it | Typical range |
|---|---|---|
Chimney width | Tape measure, parallel to ridge | 30 to 48 inches |
Roof pitch | Rafter square or pitch gauge | 4/12 to 8/12 |
Cricket ridge height | Half chimney width x roof rise-per-foot | 4 to 10 inches |
Cricket length (front to back) | Chimney depth plus 6 to 12 inch overrun | 24 to 48 inches |
Write every number down before you touch a saw. Homeowners who skip this step and eyeball the cut end up with a lopsided water diversion structure that dumps water toward one side of the chimney instead of splitting it evenly. If your roof has an unusual pitch break near the chimney, or the chimney sits close to a valley or hip, take a photo and note the distance to that feature too, since it changes how the cricket ties into the existing roof plane in Step 4.
Step 2. Gather the tools and materials
Before you cut a single board, lay out everything you need within arm's reach of the chimney. Climbing up and down for a forgotten tool wastes daylight and, worse, tempts you to skip a step just to finish before dark. A roof cricket installation only takes a few hours once you're set up correctly, but a disorganized job site turns that into a full weekend.
Framing tools and lumber
You'll frame the cricket the same way you'd frame a miniature roof, so most of the tools are standard carpentry gear you probably already own. Grab these before you start:
Circular saw and a fine-tooth blade for clean rafter cuts
Framing square and speed square for marking angles
Chalk line for laying out the ridge and hip cuts on your sheathing
Cordless drill with exterior-rated deck screws (2.5 to 3 inch)
2x4 or 2x6 lumber for the rafters, sized to your calculated cricket height
1/2 inch CDX plywood or OSB for sheathing the two sloped planes
Construction adhesive rated for exterior use, to lock sheathing to framing before you nail it
Use pressure-treated lumber if there's any chance moisture will sit against the framing before you get the flashing on. It costs a little more, but it's cheap insurance against the exact rot problem you're trying to fix.
Waterproofing and flashing materials
The frame keeps the cricket standing, but the water diversion structure only works once it's properly waterproofed. Don't substitute cheaper materials here. This is the layer that actually stops leaks.
Material | Purpose | Notes |
|---|---|---|
Ice and water shield membrane | Self-adhering waterproof underlayment over sheathing | Cover the entire cricket, not just the seams |
Step flashing (aluminum or copper) | Directs water at the chimney/roof junction | Match the metal to your existing flashing to avoid corrosion |
Counterflashing | Ties into the chimney masonry | Usually cut into a mortar reglet |
Roofing cement or high-quality sealant | Seals flashing edges and fasteners | Use sparingly, it's a backup, not a primary barrier |
Matching shingles or roofing material | Final surface layer | Buy extra to match cut angles without running short |
Skimp on the membrane and flashing, and the framing underneath won't matter at all.
Safety gear
Don't overlook fall protection. A cricket sits at the roof's most awkward pitch break, right where footing gets unpredictable. Wear a harness anchored to a roof anchor point, use roof jacks or a stable ladder stabilizer, and keep the work area clear of loose tools that can roll downslope. If your roof pitch exceeds 6/12 or the chimney sits near an edge, this is exactly the kind of job where a fall can happen fast, and it's worth pairing up rather than working alone.
Step 3. Build the cricket frame
Now that you've got your numbers and materials staged, it's time to actually build the cricket frame. Work off the ridge height and length you calculated in Step 1, and cut your ridge board first since every other piece references it. A cricket frame is really just two small shed roofs leaning against each other at a ridge, so if you've ever framed a rafter, this geometry will feel familiar.
Cutting the ridge board and hip rafters
Cut the ridge board to the length you calculated, then mark your hip rafters using a speed square set to your roof's pitch angle. The hip rafters run from each end of the ridge down to the roof deck at the base of the cricket, and they need a compound angle cut where they meet both the ridge and the deck. Take your time on these cuts. A hip rafter that's off by even a few degrees throws the whole plane out of alignment.
Cut the ridge board to length, square on both ends.
Cut two hip rafters with a compound angle matching your roof pitch.
Cut common rafters (jack rafters) that run from the ridge to the roof deck along each sloped plane.
Dry-fit every piece before driving a single screw.
A hip rafter off by a few degrees at the base ruins the pitch of the entire sloped plane above it.
Assembling and fastening the frame
Once the dry fit looks clean, fasten the ridge to the hip rafters with 3-inch exterior deck screws, toe-screwing at an angle for extra pull-out strength. Add the jack rafters next, spacing them 16 to 24 inches apart depending on your local roof cricket installation code requirements, and secure each one to both the ridge and the roof deck. Don't rely on screws alone at the base connection. A metal rafter tie or angle bracket at every hip-to-deck joint keeps the frame from racking under wind load or foot traffic during future maintenance.
Sheathing the two sloped planes
Sheathe both sloped planes with your 1/2 inch CDX plywood or OSB, running construction adhesive along every rafter before you nail the panels down. Trim the sheathing flush with the hip rafters using a circular saw, leaving no overhang that could trap water later. Check the whole assembly with a level once it's sheathed. A slightly warped frame is easy to fix now with a shim and nearly impossible to correct once shingles and flashing go on top.
Step 4. Set and fasten the cricket on the roof
With the frame sheathed and squared, carry it up to the roof and set it against the chimney's uphill face. This is the moment where all your Step 1 measurements either pay off or reveal a mistake, so check the fit before you drive a single fastener. Roof cricket installation at this stage is less about carpentry skill and more about patience, since a rushed placement here undermines every layer you add afterward.
Dry-fitting the cricket against the chimney
Slide the assembled cricket into position with its flat base resting on the roof deck and its vertical back edge tight against the chimney masonry. Check three things before committing: the ridge should sit level side to side, the base should make full contact with the deck along its entire footprint, and the gap between the cricket and chimney should be consistent, not wider on one end than the other. If the chimney brick has any texture or step-outs, you may need to scribe the back edge of the frame to match. Don't force a bad fit with shims alone. A gap that's packed with wood filler instead of properly scribed becomes a leak path the moment the sealant ages.
A cricket that doesn't sit flush against the chimney will leak eventually, no matter how good the flashing on top is.
Fastening the frame to the roof deck
Once the dry fit checks out, fasten the cricket permanently using this sequence:
Pre-drill through the base plate into the roof deck at 12-inch intervals along both sloped edges.
Drive 3-inch exterior deck screws through the pilot holes into the rafters below, not just the sheathing.
Add construction adhesive along the base seam before final tightening for extra grip against wind uplift.
Toe-screw the back edge into the chimney's cricket ledger board if your framing plan included one, rather than fastening directly into masonry.
Recheck level and squareness one final time, since screws can shift the frame slightly as they seat.
Never fasten directly into chimney brick or mortar joints. Masonry doesn't flex the way a wood roof deck does, and rigid fasteners there crack mortar and create new water entry points instead of solving your original problem. If your chimney's masonry is already deteriorating, that's a separate repair to handle before you finish the cricket, and it's worth a second set of eyes from a Kirkland roofing contractor if you're unsure how sound the brick actually is.
Step 5. Install flashing and waterproofing
With the frame fastened and squared, you're ready for the layer that actually does the leak-stopping work. Roof cricket installation succeeds or fails right here, since even a perfectly framed cricket leaks if the waterproofing underneath is sloppy. Work in dry weather only. Self-adhering membrane won't bond properly to damp sheathing, and you don't want to find that out during the next rainstorm.
Laying the ice and water shield membrane
Start by rolling ice and water shield membrane over both sloped planes of the cricket, extending it up the chimney face at least 6 inches and down onto the main roof deck by the same margin. Overlap seams by a minimum of 3 inches, shingle-style, so upper courses always lap over lower ones. Press the membrane firmly into every corner with a roller, especially along the hip lines where two planes meet, since trapped air pockets there create weak spots. Cover the entire cricket surface, not just the seams and edges.
A cricket wrapped in membrane only at the seams isn't waterproofed, it's decorated.
Installing step flashing at the chimney junction
Next, weave step flashing at the chimney junction where the cricket meets the masonry, working from the bottom up so each piece overlaps the one below it by at least 2 inches. Match the metal to whatever flashing already exists elsewhere on your roof. Mixing aluminum against copper accelerates corrosion through galvanic reaction, and that's a repair you'll be making again in a few years.
Set the first step flashing piece at the low point where the cricket meets the roof deck.
Work upward along both hip lines, overlapping each new piece over the previous one.
Bend each piece tightly into the corner where the sloped plane meets the chimney face.
Fasten flashing to the wood deck only, never through the metal into masonry.
Tying in counterflashing and sealing the joints
Finally, cut a reglet into the chimney's mortar joint about 1.5 inches deep and set counterflashing into it, bending the metal down over the step flashing below to create a two-piece water diversion structure that sheds water regardless of wind direction. Fill the reglet with masonry sealant rated for exterior exposure, and run a thin bead of roofing cement along any exposed flashing edges. Skip the temptation to caulk over gaps instead of cutting the reglet properly. Surface-applied sealant degrades within a few seasons, while counterflashing set into masonry lasts as long as the chimney itself.
Step 6. Shingle and finish the cricket
With flashing and membrane locked in, the last stage of roof cricket installation is putting shingles back on so the cricket disappears into the roofline instead of standing out as an obvious patch. Work from the bottom edge upward, the same direction water flows, so every course laps over the one below it. Rushing this step is where a lot of otherwise solid cricket jobs go wrong, because a shingle set at the wrong angle can funnel water sideways into a seam instead of down toward the gutter.
Shingling around the cricket's hip lines
Start your first course at the base of the cricket, laying shingles up the slope so each one bridges from the main roof plane onto the cricket's sloped surface. Cut shingles along the hip lines with a utility knife and a straightedge, leaving a clean, tight seam rather than a jagged edge that catches debris. Follow this order for a clean tie-in:
Lay the bottom course across the main roof and onto the cricket base in one continuous run.
Cut and fit shingles along each hip line, working up both sloped planes at the same time.
Weave the top course over the ridge board so no gap exists at the peak.
Nail every shingle per the manufacturer's pattern, keeping fasteners out of the flashing beneath.
A cricket that blends into the surrounding shingle pattern is doing its job invisibly, which is exactly the point.
Matching cut angles and blending shingles
Buy a few extra bundles before you start, because cutting shingles to fit a triangular chimney saddle wastes more material than a flat run ever would. Match the color lot to your existing roof, not just the product name, since dye lots vary between manufacturing batches and a mismatched patch is obvious from the street. Keep your exposure and overlap consistent with the rest of the roof so the cricket doesn't read as a different texture once you step back and look at it from the ground.
Final inspection and ridge cap
Cap the ridge board with a ridge shingle bent to match your roof pitch, sealing the nail heads underneath with roofing cement before the cap goes down. Walk the entire cricket one more time and check these items before you call the job finished:
No exposed nail heads anywhere on the sloped planes
Flashing edges fully covered by shingle overlap
Ridge cap sealed and lying flat, no lift at either end
Hip line cuts tight, with no visible gaps down to the membrane
Spray the whole area lightly with a garden hose and check your attic for moisture before you consider roof cricket installation complete.
Cost, code rules, and when to call a pro
Material costs for a single cricket run modest, but labor and complexity swing the total price more than most homeowners expect. A straightforward roof cricket installation on an accessible, moderate-pitch roof typically runs $300 to $800 in materials and labor combined when done alongside other roofing work, while a standalone job on a steep or hard-to-reach chimney can climb past $1,200 once staging, flashing, and matching shingles factor in. Budgeting for the higher end protects you from a mid-project surprise if the chimney masonry turns out to need repair too, and our roof cost estimating tool helps you scope the rest of the roof at the same time.
Scope | Typical cost range | Notes |
|---|---|---|
Cricket added during full roof replacement | $150 to $400 | Materials only marginally add to an existing tear-off |
Standalone cricket, moderate pitch, easy access | $300 to $800 | Includes framing, membrane, flashing, shingles |
Standalone cricket, steep pitch or hard access | $800 to $1,500+ | Staging, harness setup, and extra labor time |
DIY materials only | $80 to $200 | Assumes you already own basic carpentry tools |
Code requirements you can't skip
Beyond the 30-inch width trigger mentioned earlier, most jurisdictions in the Kirkland area require a building permit for any roof framing modification, including cricket construction, since it changes the load path and water management of an existing roof assembly. Check with your local building department before you cut a single rafter, because an unpermitted structural change can complicate a home sale or insurance claim later. Local amendments sometimes tighten the IRC's baseline requirements, so don't assume statewide code covers every city ordinance in Washington.
Skipping the permit doesn't remove the requirement, it just moves the problem to whoever inspects your roof next.
When a professional needs to take over
Ownership of this project shifts from a confident DIY weekend to a licensed-contractor job under a few specific conditions. Watch for these:
Roof pitch exceeds 7/12, where footing and fall risk climb sharply
Chimney masonry shows cracking or spalling that needs repair before a cricket can seal against it
Multiple roof planes or valleys intersect near the chimney, complicating the tie-in geometry
No prior framing experience, since a poorly cut hip rafter is expensive to fix after shingles go on
Qualified crews carry the fall protection, flashing experience, and code knowledge to get this right the first time. If any of those conditions apply to your home, you can request a free quote with a locked-in price, so you know the full cost before anyone climbs a ladder.
Keeping your chimney leak-free for years to come
A well-built cricket outlasts the shingles around it, often 20 years or more, because it solves the actual physics problem instead of masking symptoms with sealant. Roof cricket installation done right means correct measurements, solid framing, and waterproofing layers that overlap the way water actually flows, not just the way they look from the ground. Get those fundamentals right once, and you stop dealing with attic stains, rotted decking, and repeat repair calls every few years.
Getting there takes real carpentry skill, roof safety experience, and an eye for flashing details that don't show up until the next storm exposes them. If your chimney's over 30 inches wide and you're not confident cutting compound angles on a steep pitch, don't gamble your attic on a first attempt. Schedule a free roof inspection in Kirkland and let a crew that builds crickets weekly handle it correctly, with a locked-in price before anyone climbs a ladder.
