Gravois Corridor Rowhouse Roofs: Ask Each Roofer Who Owns the Shared Parapet

Rowhouses and duplexes along the Gravois corridor often share more than a wall. Where two buildings meet, the masonry between them can rise a few courses above the roof line as a parapet, and the flashing, coping and cap at that wall can serve two houses at once. When one owner calls for a roof, the bid may cover only the side of the parapet that owner can see, and the other side goes unpriced. Before you compare totals, you need each roofer to say who owns that wall, who pays to flash it, and who signs off when the work is done.

This is a comparison question, not a judgment about any one contractor. Two bids can look nearly identical on the page and still answer the parapet question differently. One roofer may treat the shared wall as the neighbor's problem. Another may price it in full. A third may simply not mention it. The gap usually shows up later, in the first winter, when a freeze pushes water into a joint nobody priced.

Why the shared parapet is a different roof

A standard roof bid measures planes and counts squares. A parapet is a vertical wall at the roof edge, and where it sits on a party line, the roofing work has to stop or continue at a boundary that is also a property line. In older St. Louis brick, the coping on top of that wall is often stone, terra cotta or metal set in mortar. Mortar joints open with freeze and thaw cycles. Water that gets behind the coping runs down inside the wall, and the damage often shows up on the other owner's ceiling, not yours.

Hail season adds a second reason to ask. A hail strike on a shared parapet cap can crack the coping or open a joint without changing the shingles on either roof. If the bid says nothing about the cap, a later storm review may read the damage as an existing condition or as a line for the other owner. Neither answer helps you if the repair was never written down.

Ice matters too. Snow that sits against a parapet on the north face can melt and refreeze in the joint, pushing mortar apart over a few winters. The cap is also where flashing terminates, so a missed tie-in at the parapet can leak even when every shingle on both slopes is sound.

Roofer comparison

Start by making each roofer answer the same four points in writing. Do not accept a verbal yes on any of them. The points are narrow on purpose, so that you can line the answers up side by side.

• Who owns the wall. Ask whether the parapet is listed as shared, as yours, or as the neighbor's, and whether the roofer has seen a survey, deed or prior permit that says so.
• What is priced on your side. Ask for the linear feet of coping, flashing and counterflashing your bid covers, and whether the price stops at the centerline of the wall.
• What happens on the neighbor's side. Ask whether the roofer will touch their half, whether they need the neighbor's written permission, and what they will do if the neighbor refuses.
• Who signs the finished joint. Ask who inspects the tie-in before the crew leaves, and who you call if water shows up on the wall later.

A roofer who answers all four without a pause has likely done this before on rowhouse blocks. A roofer who asks you to confirm the wall line before the walk is doing useful work, because a wrong line on a bid becomes a dispute later. A roofer who says the parapet is not part of the roof has told you something as well. Write that answer down next to the question it answers, and check that the same question comes back the same way on the second visit.

Keys Roofing writes its scope with photos and measurements, then puts that document in the homeowner's hands before any work starts. That paper is the thing to compare across bids. If one bid has a photo and a measurement of the shared wall and another has a line that says "flash parapet", the first one is easier to hold to.

What it costs

The shared parapet is usually priced as its own set of lines, not folded into the field shingles. Coping replacement is often billed by the linear foot. Counterflashing cut into brick is billed by the foot as well, and the mortar reglet may be a separate charge if the brick needs cutting. Sealant and any repointing sit on their own lines. A bid that lumps all of this into one "wall work" figure makes comparison nearly impossible, so ask the roofer to split it.

Ask who pays for materials on the neighbor's side if the work crosses the line. A common arrangement is that each owner pays for their own half, with a written agreement signed by both before the crew starts. Some roofers will ask for a deposit on the shared portion. That is a reasonable request if the amount and the release terms are written, and a warning sign if they are not.

Scaffolding or a ladder setup can add cost when the parapet is above the reach of a standard eave ladder. Ask each roofer how they plan to reach the coping. A roofer who intends to lean a ladder on a mortar cap has not thought the job through. A roofer who sets staging on your side only may still need the neighbor's yard for the second side, and that access is also a written line.

When you compare totals, take out any lines that are the neighbor's responsibility under a written agreement, then compare what remains. Do not set a bid that includes the whole wall beside a bid that includes only your side. The numbers will look far apart for a reason that has nothing to do with the quality of the work.

What to ask

Bring these questions to every roofer on your list, in the same order, and write the answers in the same folder.

1. Is the parapet between my house and the neighbor's listed as shared, and what document shows that?
2. Where does your bid stop along the wall line, and how many linear feet of coping and counterflashing does it cover?
3. Will you need the neighbor's written consent to work on their side, and what happens if they do not sign?
4. How will you reach the coping, and does your price include staging or ladder setup for that wall?
5. Who inspects the tie-in between the new flashing and the existing brick before the crew leaves?
6. If water shows up on the wall after a freeze, which of you do I call first, and how do I reach you in writing?

Pay attention to the order of the answers as well as the content. A roofer who answers the first question in detail and then goes vague on the consent question has shown you where the risk sits. Log that, and ask it again on the second visit.

If you are unsure whether your wall is shared at all, your deed and the public property records are the places to start, before any roofer walks it. The roofer should not be the first to tell you where your property line runs. Your job is to hold each roofer to the same line, so the bids can be compared on the same wall.

For a written walk-through of your parapet, call Keys Roofing at (314) 220-2333 and ask each of the four points above. The answer to each one should be on paper before you choose.