A bead of roof cement can stop water for a while. That does not mean the leak has been repaired. Sealant is exposed to heat, ultraviolet light, rain, ice, and movement every day. In St. Louis, a sealed joint can be hot enough to soften in July and frozen solid during a January cold snap. The materials on either side keep moving. Eventually the bead shrinks, splits, or pulls loose.
The useful question is not whether a roofer can add more caulk. It is why the roof depends on caulk at that location. A lasting repair usually requires correcting the joint, flashing, fastener, or roofing detail beneath it. Sealant may still be part of the finished work, but it should not be the only thing keeping water outside.
Leak and repair
Roof sealant has legitimate uses. It can cover an exposed fastener head, seal the top edge of certain flashing details, or protect a small joint that cannot be folded or lapped. Manufacturers also specify compatible sealants for particular accessories. The problem begins when someone uses a surface bead in place of the physical overlap that should direct water down the roof.
Water should normally be controlled by layers. Shingles overlap lower shingles. Step flashing overlaps the course below it. A pipe boot fits around the pipe and extends beneath the roofing above it. Counterflashing covers the upper edge of base flashing. Each piece sends water onto the next lower surface. Gravity does most of the work.
Caulk tries to control water by adhesion. It must remain bonded to two surfaces while those surfaces expand, contract, vibrate, and collect dirt. That is a difficult job on a roof. Freeze and thaw cycles make it harder. Water enters a small separation, freezes, expands, and opens the separation farther. Hail can bruise an old sealant bead or loosen the material around it. Ice near the eave can also hold water against a joint longer than ordinary rainfall does.
One common warning sign is a thick mound of black roof cement around a vent, chimney corner, or wall intersection. Another is a series of different colored beads showing that the area has been sealed repeatedly. Those layers can hide the original defect. They can also trap water and make removal messy. Adding one more coat may postpone the drip without showing where water enters.
A proper repair starts by removing enough roofing and old sealant to see the assembly. The roofer needs to determine whether the metal is present, whether it overlaps correctly, whether fasteners are exposed, and whether the wood below remains sound. Wet or deteriorated decking will not hold a fastener properly. A new bead over soft decking does nothing to restore that connection.
The necessary work depends on what is found. A vent repair may require a new boot installed beneath the upper shingles. A sidewall repair may require individual pieces of step flashing woven into the shingle courses. A metal flashing joint may need to be cleaned, refastened, and sealed with a product compatible with the metal and surrounding roofing. An abandoned penetration should usually be removed and the roof covering rebuilt across the opening instead of filling the hole with cement.
The condition of the surrounding shingles matters. Warm, flexible shingles can often be lifted carefully to reach a flashing flange. Cold or aged shingles are more likely to crack. That is one reason a repair that looks simple from the ground can require a wider work area. On an older three tab roof, especially one around 18 to 20 years old, brittle tabs, exposed fiberglass, widespread granule loss, and previous patches may make another isolated repair poor value. Age alone does not decide it, but the roof has to tolerate being opened and put back together.
Weather affects the repair appointment too. Some sealants require dry surfaces and a particular temperature range. Shingles are easier to manipulate on a mild day than during a freeze. An emergency application may be appropriate to slow active water entry, followed by permanent work when the roof is dry and the materials can be installed correctly. The written scope should distinguish those two visits.
What it costs
The tube of sealant is rarely the important cost. You are paying for access, diagnosis, removal, compatible replacement materials, and the time needed to rebuild the detail. A low roof with a clearly exposed fastener is different from a steep roof where several courses must be opened around a chimney or wall.
Ask for a fixed repair price when the condition can be seen before work begins. If the roof must be opened to expose concealed flashing or decking, the proposal should state what is included and how additional material will be priced. For example, it can identify the included repair area, the number of shingles expected to be replaced, and a unit price for deteriorated decking discovered beneath them.
Matching the exact color of an older shingle may not be possible. A repair can be watertight and still remain visible from the yard. Sun exposure changes the color of installed shingles, and a current Atlas or Malarkey product may not look identical to an older course. Ask to see the proposed replacement before work begins if the repaired slope is prominent.
A very small sealing visit may cost less than rebuilding the surrounding detail, but compare the scopes instead of comparing only the totals. One proposal may describe cleaning and coating an existing joint. Another may include removing shingles, replacing flashing, inspecting the deck, installing new underlayment, and weaving replacement shingles into the field. Those are different repairs with different expected service.
Permit requirements also vary across the St. Louis area. St. Louis County has many municipal permit desks, and incorporated cities can apply their own requirements. A small maintenance repair may be treated differently from replacement of decking or a larger roof section. The contractor should identify the municipality for the property and confirm whether that desk requires a permit for the stated scope.
What to ask
Start with one direct question: What is the sealant covering? The answer should identify a physical roof component. Terms such as pipe flange, step flashing, counterflashing, apron flashing, fastener, underlayment, or shingle course tell you what will actually be examined. An answer that consists only of adding roof cement does not explain the leak path.
Then ask whether the old material will be removed. New sealant bonds poorly to loose, dirty, cracked, or wet material. Removal also gives the roofer a chance to inspect the joint instead of burying it. Complete removal is not always practical without damaging adjacent roofing, but the scope should say how the surface will be prepared.
Useful questions for the written proposal include:
- Which roofing or flashing pieces will be removed?
- What new pieces will be installed beneath the surrounding shingles?
- Will the decking be visible during the repair?
- How will deteriorated decking be priced if it is found?
- Is the proposed sealant compatible with the roof material and metal?
- Will photographs show the area before opening, while open, and after completion?
- Is this an emergency seal or the completed repair?
- Will the repaired area look different from the existing roof?
- Does the municipality require a permit for this scope?
Photographs are particularly useful when the repair will be covered before you can see it. A finished picture of black cement proves only that black cement was applied. The middle photograph should show the flashing position, fastener placement, underlayment, and condition of the exposed deck. That is the part of the work you cannot inspect after the shingles are back down.
Also ask what would cause the contractor to stop and revise the scope. Rotten decking, missing step flashing behind siding, a cracked vent pipe, or shingles that break during careful lifting can change the work. A clear change procedure keeps a small repair from turning into an unexplained invoice.
If water is entering now, protect the room first. Move belongings, place a container beneath the drip, and keep clear of a sagging ceiling. Do not climb onto a wet, icy, or steep roof to spread sealant. Call Keys Roofing at (314) 220-2333 and describe where the water appears, when it appears, and whether that roof area has been sealed before. Ask for the permanent repair and any temporary water control to be listed separately.