Should a Reroof Replace Wall and Chimney Flashing, or Only the Shingles?
When a reroof is on the table, the shingles are the visible part of the bid. Wall and chimney flashing are the pieces that keep water out where the roof meets a wall, a chimney, or another penetration. Replacing only the shingles can be the right scope when those flashings are still sound. Replacing them can be the right scope when they are rusted, damaged, or deteriorated. The captured code does not say every reroof automatically replaces flashing that is still doing its job.
This guide is for a Mid-Missouri homeowner comparing those two scopes. It is not a drip-edge catalog, and it is not a chimney-rebuild manual. The installed products and the local authority having jurisdiction still control the work on a particular house.
Key Takeaways
- Flashing is part of the roof assembly, not a decorative trim. It is there so water does not enter at joints, permeable materials, parapets, and other penetrations.
- The captured reinstall rule is conditional. In the retrieved Missouri Modular Residential Code 2021 text, existing flashings, edgings, outlets, vents, and similar devices that are part of the assembly are replaced where they are rusted, damaged, or deteriorated.
- Sound flashing is not automatically in the tear-off pile. The same section does not say undamaged flashing must be thrown out because the shingles are being replaced.
- Wall and chimney locations are named separately from the open field. Flashings are required at wall and roof intersections and around roof openings. A field-shingle price does not answer those locations.
- Model code is not the local ordinance. Confirm the authority having jurisdiction. Columbia publishes building resources, but this capture is not a Columbia ordinance file.
Where wall and chimney flashing sit in a reroof
A reroof removes and replaces the roof covering, and it may include the underlayment and the details that tie the covering to the rest of the house. Wall flashing is the metal or other approved material where a roof slope dies into a vertical wall. Chimney flashing is the set of pieces around a masonry or framed chimney: the apron at the downslope face, the step pieces up the sides, and the counterflashing that covers those pieces. Those parts see different water than a shingle in the middle of a slope.
A proposal that says “new shingles” has not yet said what happens at those intersections. Ask whether the existing step flashing stays, whether the counterflashing is cut out and reset, and whether the cricket or saddle behind a wide chimney is in the scope. Those are scope lines, not extras invented after the tear-off starts, when the conditions can already be seen from the existing roof.
Drip edge at the eaves and rakes is a different piece. It closes the edge of the deck. It matters, and many roofs need it, but a drip-edge conversation is not a substitute for deciding the wall and chimney details. Keep the bid lines separate so a complete edge detail is not mistaken for a complete chimney.
What the captured code actually requires
Two sections in the retrieved roof-assemblies chapter are the ones this article uses. Section R903.2 says flashings shall be installed in a manner that prevents moisture from entering the wall and roof through joints in copings, through moisture-permeable materials, and at intersections with parapet walls and other penetrations through the roof plane. The following subsection, R903.2.1, says flashings shall be installed at wall and roof intersections, wherever there is a change in roof slope or direction, and around roof openings. A flashing shall be installed to divert water away from those locations. That is the “where” rule. It does not, by itself, say the existing metal on your chimney has failed.
Section R908.5, titled Reinstallation of Materials in the capture, includes the conditional replacement sentence: any existing flashings, edgings, outlets, vents, or similar devices that are part of the assembly shall be replaced where rusted, damaged, or deteriorated. The same section also limits reinstallation of damaged slate or tile and says aggregate surfacing materials shall not be reinstalled. Read the flashing sentence as a condition. Rust, damage, and deterioration are the triggers named in the capture. Undamaged flashing is not listed as something that must be replaced merely because the shingles are new.
The next captured section, R908.6, says flashings shall be reconstructed in accordance with approved manufacturer’s installation instructions. That is the control the product manufacturer keeps. NRCA manuals were not retrieved for this article, and a blog cannot supply the bending, lap, or fastening sequence for a specific chimney. The person writing the scope has to use the instructions for the shingles and flashings being installed.
The text lives in the Missouri roof-assemblies chapter on UpCodes. It is a model-code viewer titled for the Missouri Modular Residential Code 2021. It is not a determination that Columbia, Jefferson City, or any other city has adopted that wording without amendment. For a property in Columbia, start with the City’s Building and Site Development resources and ask which adopted code and local amendments apply.
How to read a proposal that only prices shingles
Put the flashing decision in writing before you compare totals. A lower bid that leaves every piece of chimney metal in place is not the same project as a bid that replaces rusted step flashing and resets counterflashing. A higher bid is not automatically more complete either. It might be replacing metal that the capture would allow to stay, or it might be the only bid that looked at the back of the chimney.
Ask for four statements on the wall and chimney lines:
- Which existing flashings were seen, and which could not be seen until the shingles come off?
- Which pieces are rusted, damaged, or deteriorated, in the words the inspector is willing to stand behind?
- Which pieces are proposed to remain, and what will happen if tear-off shows a condition that was hidden?
- Whose instructions govern the new shingles and any new flashing, and who confirms the local authority’s rules for that house?
Concealed conditions belong in that fourth answer. Counterflashing is often set into a mortar joint or a reglet. You may not know the condition of the metal inside the joint until someone opens it. The proposal should say how a change is documented, not assume the first price covered every unseen piece.
Walls, chimneys, and the rest of the roof edge
Sidewall flashing, headwall flashing, and chimney flashing are the intersections this article is about. Plumbing vents, skylights, and exhaust curbs are penetrations too, and R903.2 names penetrations through the roof plane. If a vent boot is cracked, that is its own line. Do not fold it into “chimney” or ignore it because the chimney looks fine.
A cricket or saddle above a chimney that is wide enough to stop water is a drainage shape, not a piece of step flashing. If the existing roof has no way for water to go around the chimney, replacing the shingles without addressing that geometry can leave the same ponding the old roof had. Ask whether the geometry is adequate before you argue only about metal gauge.
Our roof replacement service is where this scope belongs. Maintenance of an existing valley or a small flashing repair is a different visit. If the covering is staying, do not use a full reroof checklist. If the covering is coming off, do not stop the checklist at the shingle brand.
What to write down before the shingles come off
A reroof hides the intersections again as soon as the new covering is on. The useful record is made while the deck and the walls are visible. Ask for photos of each wall intersection and each face of the chimney after the old shingles are off and again after the new flashing is in, before the shingles cover the step pieces. Those photos should show whether the metal was replaced or left, not only the finished shingle color.
If a piece stays, the note should say why: it was not rusted, damaged, or deteriorated in the inspection. If a piece is replaced, the note should name it, such as sidewall step flashing, headwall flashing, or chimney counterflashing. A single line that says “flashing included” does not tell you which of those happened. The same note should say which product instructions were followed, because R908.6 in the capture points reconstruction to the manufacturer’s installation instructions.
Keep that record with the proposal. It is how you compare two bids that both say they roof houses, and it is how you ask a question later without guessing what was covered. It is not a substitute for the local authority’s inspection, if one is required, and it does not turn this article into a fastening pattern.
Frequently asked questions
Does a reroof always include new chimney flashing?
Not on the wording captured here. R908.5 calls for replacement of existing flashings that are rusted, damaged, or deteriorated. Flashing that is still serviceable is not given that same instruction. The inspection has to say which condition is present.
Can the roofer leave the counterflashing and only replace the step flashing?
Sometimes that is the right split, and sometimes the counterflashing is the piece that has failed. Ask which piece is damaged and how the new step flashing will be covered. A new step flashing that tucks under a cracked or loose counterflashing does not finish the intersection.
Is this decided by the shingle warranty?
The captured code points to the manufacturer’s installation instructions for reconstructed flashing. A warranty PDF was not retrieved for this article. Ask for the instructions that apply to the product in the bid, and do not treat a general warranty slogan as the flashing scope.
Compare the intersection, not only the squares
CoMo Premium Exteriors can walk a Mid-Missouri roof with this question in the scope: which wall and chimney flashings should be replaced because they are rusted, damaged, or deteriorated, and which can remain. Request a roof evaluation and ask for those lines in writing before you compare shingle prices.
