The Wide Side of Your Chimney May Need Its Own Roof

If the wide side of your chimney faces uphill, rainwater, leaves, snow and ice all arrive at the same obstruction. A narrow chimney may shed that water around its sides without much trouble. A wide masonry chimney can hold water against its uphill wall and force a large volume toward two small corners. A chimney cricket changes that path. It is a small peaked roof built behind the chimney to divide water and send it around both sides.

This detail matters most while you are deciding between another chimney repair and a larger roofing project. New sealant around old flashing may stop a small opening for a time, but it does not change the amount of water reaching the chimney. If the roof geometry is the underlying problem, the proposal should address that geometry instead of treating every stain as a caulking problem.

Town roofing

St. Charles houses do not all present the same chimney problem. Some have a compact metal flue near the ridge. Others have a broad brick chimney on a long rear roof slope. Ranch houses can put a substantial area of roofing above the chimney. Two story houses may have intersecting roof planes that concentrate water in the same place. The useful question is not simply whether the house has a chimney. It is how much roof drains toward the uphill face of it.

A cricket resembles a short ridge set against the back of the chimney. Its two slopes divert water toward the chimney sides, where properly formed flashing carries it onto the main roof. The cricket should have a solid deck, suitable underlayment and a roof covering appropriate for its slope. Its flashing must connect with the chimney flashing rather than depend on a thick bead of exposed sealant.

The word cricket sometimes gets used loosely. A small wedge that merely fills one corner is not the same as a peaked structure that divides the water. Ask the roofer to show the proposed shape on a photo or drawing. You should be able to see where the new high point will meet the masonry and where water will leave on each side.

Width is important, but it is not the only measurement. Roof pitch, chimney position and the length of roof above it all affect the load at the back wall. A chimney near the eave may have relatively little roof feeding it. The same width of chimney near the bottom of a long slope may receive much more water. Valleys or upper roof sections can add another concentrated stream.

St. Charles weather makes that trapped area harder on the roof. Spring hail may draw attention to the shingles, while ordinary rain exposes weak flashing. Autumn leaves collect behind the masonry and stay wet. During the freeze thaw cycle, water in small gaps expands, retreats and returns. Snow can melt above the chimney and refreeze near a colder eave. A cricket does not prevent ice damming, but it can remove a pocket where water and debris would otherwise sit against the brick.

Masonry condition still matters. A cricket cannot repair cracked mortar, a deteriorated chimney cap or porous brick. Water can enter through the chimney above the roof and appear indoors near the same place as a flashing leak. Before approving roof work, ask for photographs of the chimney crown, mortar joints, flashing and the roof surface immediately uphill. The source has to be separated from the stain below.

The permit question depends on the address and the scope. The City of St. Charles, other municipalities in St. Charles County and unincorporated county areas do not share one permit counter. A reroof, structural cricket or chimney alteration may be treated differently from a small flashing repair. The contractor should identify the authority for the property and confirm what that desk requires before work starts.

What it costs

A cricket is not priced by looking at the chimney from the driveway. The roofer needs its width, the main roof pitch, the proposed cricket slope and the flashing conditions. Access also matters. A rear chimney above a steep lower roof takes more labor and protection than a chimney reached from a simple one story slope.

The written price should distinguish construction from surface repair. Building a cricket can require framing, decking, underlayment, shingles and new metal flashing. If mortar joints must be cut to receive counterflashing, that work should be named. If masonry repair is excluded, the exclusion should be equally clear. Otherwise, two bids may appear to include the same chimney work while one covers only roofing cement and the other covers a new drainage structure.

Material choice depends partly on slope. A cricket with enough pitch may use the same Atlas or Malarkey shingles as the surrounding roof. A very shallow section may need a different roofing material because shingles rely on slope to shed water. The roofer should state the cricket pitch and the proposed covering. The phrase cricket as needed does not answer either point.

Replacing a roof can be the practical time to build the cricket because the surrounding shingles and underlayment are already being removed. The roofer can inspect the deck, integrate the new framing and run the water control layers in the proper order. Adding one later means reopening a finished area and tying new flashing into existing roofing.

That does not mean every chimney needs one. A narrow chimney near the ridge may drain well with correct step flashing, back pan flashing and counterflashing. Building an unnecessary cricket adds seams and cost. The decision should follow measurements and water paths, not a standard sales package.

Decking discovered after tear off is another possible cost. Repeated wetting behind a chimney can soften sheathing even when the interior stain is small. The proposal should give a unit rate for replacing damaged decking and explain how the homeowner will see and approve that work. Photographs taken after the shingles are removed provide a clear record of what was found.

What to ask

Start with one direct question: How much roof drains into the back of this chimney? A useful answer should refer to the actual slope, chimney width and nearby valleys. It should not rely only on the age of the roof or the fact that another house has a cricket.

Then ask the roofer to mark these items on a photo or in the written scope:

• The measured width of the chimney across the uphill face.
• The pitch of the main roof and the proposed cricket.
• The type of deck and underlayment planned for the cricket.
• The roofing material to be used on the new slopes.
• How base flashing, step flashing and counterflashing will connect.
• Whether existing flashing will be removed or covered.
• Whether mortar cutting and masonry repairs are included.
• The decking replacement rate if wet or deteriorated wood appears.
• Who will confirm the permit requirement for the property address.

Ask how the contractor will inspect the chimney before calling the roof detail the source of the leak. Interior water near a chimney can come from several places. Wind driven rain can enter failed counterflashing. Water can pass through cracked mortar or a damaged cap. Condensation can form in a flue system. A roof stain below the chimney does not prove that the shingles behind it failed.

Also ask how debris will leave the pocket behind the chimney after the work. A cricket should create visible drainage paths on both sides. Those paths still need enough space to move leaves, twigs and shingle granules. If one side ends against a wall or flows directly into a valley, the transition deserves its own detail in the proposal.

If the roof is an older three tab system, consider the repair in context. Once three tab shingles have become brittle, lifting courses to install extensive new flashing can break tabs beyond the immediate work area. At that stage, a chimney rebuild on the roof may not stay confined to a neat rectangle. Ask how many surrounding courses must be removed and whether compatible replacement shingles are actually available.

Before signing, ask for one sentence that states the intended result: the new cricket will divide runoff from the uphill roof and direct it around both sides of the chimney through a fully flashed transition. That sentence gives you something more useful than a line reading repair chimney area. For an inspection and written roofing scope in St. Charles, Keys Roofing can be reached at (314) 220-2333.