A porte cochere is the covered drive that runs out from the side of a house so a car can stop under cover. In Ladue, where large lots often put the garage well away from the front door, these roofs are common enough that a homeowner may not think of them as roofs at all. They are roofs. They have their own surface, their own edge, their own gutter or none, and they are attached to a wall that belongs to the main house. When the house roof is replaced, the porte cochere roof is either part of that job or it is left with a joint that will start leaking within a few seasons.
This page is for the homeowner who has been told the covered drive is just a canopy, and who wants to know what to settle before a quote is signed.
Town roofing
Most porte cochere roofs on older Ladue houses are low-slope or gently pitched. They shed water more slowly than the steep main roof, so small faults show up as ponding or staining before they show up as drips. The surface may be built-up roofing, modified bitumen, or shingles laid on a shallow deck. The material matters less than the detail where the canopy meets the house wall. That joint needs counter-flashing set into the masonry or into a groove cut in the brick, with the top edge of the flashing tucked under the wall's own weather layer. If the canopy was built with a ledger bolted to the wall and the flashing was only caulked, the first hard freeze will open the joint, because water gets behind the caulk, freezes, and pushes the seal apart.
The drive edge is the second place to look. Snow that slides off the main roof lands on the porte cochere and sits there until it melts. In a St. Louis winter that melt runs back toward the wall during the day and refreezes at night, which is how ice builds at the drive edge and pushes water uphill under the shingles or membrane. A roofer who looks only at the flat field of the canopy and not at that edge has not looked at the part that fails.
Hail is the third concern. Spring and early summer hail falls close to straight down, and a porte cochere is often the lowest roof on the house, close to the drive. Its surface can take dents that the steep roof above it never shows. Check it on the same walk as the main roof, and photograph it from the drive and from a ladder placed where the crew would stand, so the record shows the same angle the next inspector will use.
Columns need their own look. Where a column meets the canopy beam, water sits in the joint at the top. Where the column meets the drive, splash and winter salt fall on the base. Neither is a roofing task on its own, but both decide how long the beam holds the roof edge, and a roof quote that ignores the beam is incomplete.
What it costs
The price of a porte cochere roof depends on the area of the canopy, the pitch, whether the canopy is decked or open rafter, how many columns and beams the crew has to work around, and what happens at the wall joint. A canopy with a clean masonry wall and a simple gable end is a different job from a canopy tied to a stone chimney, a bay window and a second story above it, even if the square footage is close. Ask the roofer to price the wall joint and the drive edge as separate lines. If the quote shows one number for the whole canopy and no line for the flashing, the flashing is probably included in a number that is too small to cover it.
Ask also whether the price includes the gutter on the drive side. Many canopies have no gutter, and water runs straight off onto the paving and the cars. Adding one changes the scope, the hanger spacing and the way the downspout ends, and it should be a named item rather than a sentence in the notes.
Permits are a separate question. Whether a roof attached to the house needs a permit, and whether the work needs an inspection afterward, is decided by the municipal permit desk for your address. Missouri does not license roofers at the state level, so the desk's requirements are the ones that apply to the work on your house. Ask the roofer what the desk requires for this specific canopy, and ask to see the answer in writing before the schedule is set.
What to ask
Start with the wall joint. Ask how the flashing is set into the wall, whether it is counter-flashing in a groove or a surface piece held by caulk, and what happens at the top of the flashing where it meets the house's own roof. A specific answer names the materials and the detail. A vague answer says the joint will be sealed.
Ask what happens at the drive edge in winter. A good answer describes the drip edge or the gutter line, the slope toward the drive or away from it, and the membrane or shingle lap at the edge. A weak answer is a sentence about the edge being finished properly.
Ask how the crew will reach the canopy. A porte cochere sits on the drive, which is where the trailer, the dumpster and the cars are. Ask where the ladder will stand, which part of the drive will be closed, and whether the cars will need to move during the work. The answer changes whether the drive is usable on the days the canopy is open, and it should appear on the schedule.
Ask who inspects the canopy once the work is finished and whether the permit desk requires that inspection. Ask whether the roofer will leave the photographs of the wall joint, the edge and the beam connections, taken before the cover goes on. Those photographs are the record of what was built, and they are yours to keep.
Finally, ask for the scope in writing with the canopy listed separately from the main roof. If it is folded into a single square count, ask the roofer to show the square count for the canopy alone. A porte cochere that is measured as part of the house roof often ends up with the wrong material, the wrong flashing, or no flashing at the drive edge, and the homeowner finds out in the first hard rain.