At a glance: Completed 2026-09-03: copper dormer & flat tpo roof tie-in repair on Buckland Hall Road, St. Louis, MO 63131. Office: St. Louis, 314-429-6000.
Three materials meeting in one corner
This home has a detail you see on many larger houses in west St. Louis County: a shingled dormer on the back of the house, trimmed in copper flashing, sitting right next to a flat roof covered in TPO. Shingles, copper and single-ply membrane all behave differently. Shingles shed water by overlapping, copper lasts for generations but moves with heat, and TPO is a sheet that has to be sealed at every edge. Where all three meet, the details have to be done exactly right.
Along the rear dormer, the TPO had pulled loose from where it should have been sealed up the side of the dormer. With the edge open, water running off the shingles and copper could get behind the membrane.
Why TPO edges let go
TPO is a heat-welded single-ply membrane that is very good at keeping water out across the flat field of a roof. Its weak points are its edges, where it turns up a wall or another surface and has to be glued and mechanically held. Sun, heat cycling and building movement slowly break that bond if the edge was not fastened with a termination bar. Once the top edge peels down even an inch, every rain runs behind it.
Opening up the dormer side
The crew removed the shingles along the dormer where it meets the flat roof. That exposed the copper flashing and the top of the TPO turn-up, so the crew could see exactly where the membrane had separated and how far back it was open.
Cleaning the copper
Copper develops a patina and collects dirt and old sealant. TPO bonding adhesive will not grip a dirty or oily surface, so the crew cleaned the copper flashing where the membrane would bond to it. Proper surface prep is what decides whether an adhesive bond lasts a season or many years. The copper itself was in good shape and was kept, which preserves the look of the house and avoids replacing an expensive material that still has decades of life.
Reattaching the TPO the right way
With the surfaces clean, the crew applied TPO bonding adhesive to the membrane and the substrate and pressed the turn-up back into place. Then a termination bar was installed across the top edge. A termination bar is a rigid metal strip fastened through the membrane every few inches. It clamps the edge so it cannot peel down again, even if the adhesive weakens over time. The top of the bar is sealed so water cannot get behind it.
New shingles over the finished tie-in
Finally, new shingles were installed back along the dormer, lapping over the top of the termination bar area and the copper so water runs over the joint and out onto the flat roof instead of into it. Layering in the right order, membrane under, metal in the middle and shingles over, is what makes the corner watertight.
Why we did not just caulk it
A loose TPO edge is often patched with a bead of caulk or a strip of tape. That can hold for a few months, but it does not address why the edge pulled away. Reattaching with adhesive and clamping with a termination bar fixes the cause.
Flat roof sections on 63131 homes
Many homes in the 63131 area, around Town and Country, Des Peres and Frontenac, have flat or low-slope sections over additions, sunrooms and rear porches. These tie into the main roof at walls and dormers, and those joints are where most leaks start. We work on TPO, EPDM, modified bitumen and coatings, so we can repair the flat roof and the steep roof in the same visit.
Roofer near me in St. Louis, 63131
If you are searching roofer near me in St. Louis County, our St. Louis office serves 63131, 63122, 63141 and the surrounding area from our headquarters in Maryland Heights. Call 314-429-6000 or 1-800-564-6232, day or night.
We will show you photos of the problem and explain the repair before any work starts.
Lifetime workmanship warranty
The tie-in repair on Buckland Hall Road is covered by our lifetime workmanship warranty on the work we did. If the corner we rebuilt leaks, we come back and fix it.
Signs a flat roof tie-in is failing
Inside, watch for stains on the ceiling or wall right under where a dormer or upper wall meets the flat roof. Outside, look for membrane that has slumped or wrinkled at the base of a wall, a visible gap at the top edge of the turn-up, or old caulk peeling away. Ponding water right against the wall after rain also puts constant pressure on that edge. If you can slide a finger behind the top of the membrane, the bond is gone.
Caring for copper flashing
Copper is one of the longest-lasting flashing materials made, and on a well-kept home it can outlast several shingle roofs. It naturally darkens and can turn green over time; that patina protects it and does not need to be removed except where a new bond is being made, as on this job. Avoid letting steel nails or galvanized parts touch copper, because the two metals corrode each other. When we work around copper, we use compatible fasteners.
Why the order of layers matters
Every roof detail comes down to one rule: the upper layer always laps over the lower layer, so water running downhill never meets an edge it can slip under. At this corner, the TPO turns up and is clamped, the copper sits over it, and the shingles lap over the copper. Getting that sequence right is the difference between a corner that stays dry for decades and one that leaks again next spring.
What the crew did, step by step
- Removed shingles along the rear dormer where it meets the flat TPO roof.
- Inspected the copper flashing and the loose TPO turn-up.
- Cleaned the copper flashing so the adhesive would bond.
- Applied TPO bonding adhesive and pressed the membrane back into place.
- Installed and sealed a termination bar across the top edge of the TPO.
- Installed new shingles back over the tie-in.
- Cleaned up and hauled away all debris.
Questions homeowners in St. Louis ask about this repair
What is a TPO roof?
TPO is a single-ply white membrane used on flat and low-slope roofs. Its seams are heat welded.
What is a termination bar?
A metal strip fastened along the top edge of a membrane to clamp it in place so it cannot peel loose.
Can TPO be glued to copper?
Yes, with clean surfaces and the right bonding adhesive, backed up by a termination bar.
Did you replace the copper flashing?
No. The copper was in good condition, so it was cleaned and kept.
Do you repair flat roofs in St. Louis County?
Yes. Call our St. Louis office at 314-429-6000.
Why do flat roofs leak at walls and dormers?
Those edges are where the membrane has to turn up and be sealed, and that bond is the first thing to fail.