Managing Roof Drainage on Steep Pittsburgh Lots

On steep Pittsburgh lots you need oversized gutters, extended downspouts, and sealed flashing at every valley to move water away before it pools or freezes. Skip the big-box sealant because it cracks after two winters here.

Why Do Steep Lots Send Water So Fast?

Pittsburgh hills like those in Mount Washington and the South Side pitch roofs at 8/12 or steeper. Rain hits the surface and runs off in sheets instead of soaking in. One inch of rain on a 1,200-square-foot roof dumps roughly 750 gallons downhill in minutes. That volume hits foundations hard if the first 3 feet of ground slope toward the house. Older homes in Allegheny County often lack French drains, so the water finds cracks in the masonry. Add our humid continental climate with cold winters and the runoff turns to ice along the eaves by morning.

How Does Winter Weather Change the Drainage Plan?

Cold winters here freeze the fast-moving water into ice dams within 8–12 hours after a warm spell. The dams back water under shingles and rot the deck in 2–3 weeks. Steep lots make the problem worse because meltwater from upper roofs hits lower eaves in a concentrated stream. Homeowners in Squirrel Hill and Shadyside see this every February. You need at least 5-inch gutters with 3x4-inch downspouts every 20 feet and heat cable on the first 6 feet of each run. We also route downspouts into buried 4-inch pipe that exits 10 feet from the foundation.

What Gutters and Downspouts Actually Work on These Slopes?

Half-round copper or 6-inch aluminum K-style gutters hold the volume without spilling. Downspouts must drop straight, not zigzag, or the elbows clog with leaves from the many mature trees in Regent Square and Point Breeze. Install splash blocks or extend the pipe another 4 feet past the foundation edge. On lots steeper than 20 percent grade, add a second downspout mid-run so no single pipe carries more than 150 gallons per minute. Link this work to Gutter Installation And Repair when the existing system is undersized.

What Does Proper Drainage Cost on a Steep Lot?

Expect $1,800–$3,200 for 6-inch gutters and downspouts on a typical 1,800-square-foot two-story home. Add $600–$900 for buried extensions and $450–$750 for ice-melt cable on the lower eaves. Full ice dam removal runs $300–$600 per visit when the dams already formed. These numbers cover labor and materials in Allegheny County; prices rise if the crew must work from scaffolding on a 12/12 pitch. A full roof replacement becomes the cheaper long-term fix once water has damaged more than 20 percent of the deck.

When Can You DIY Drainage Fixes?

You can clean gutters and tighten loose hangers yourself from a stable ladder. You can also screw in new downspout straps and replace cracked splash blocks. Stop at the roofline. Anything that requires walking steep slopes, cutting into flashing, or running new pipe through finished walls crosses into code territory and safety lines. Call a crew for valley work or when you see water stains inside the attic after the first hard freeze. We offer 24/7 Emergency Service if a storm clogs the system overnight.

If drainage on your steep lot is pushing water into the house, stop by our shop at 2270 Roswell Dr and we will take a look.