SMACNA Sizing Guidelines
Under-sized gutters spill water against siding and wash away sub-grade foundation soil, causing basement flooding.
Frequently Asked Questions
Common questions regarding this calculation and code compliance
As a rule of thumb, you need at least one downspout for every 30 to 40 linear feet of gutter run, sized to handle your roof square footage.
Need Licensed Hands-On Help in Anchorage, AK?
Calculations provide the theoretical baseline, but Alaska installations face sub-zero frost lines, glacial soils, and strict municipal codes. Our licensed master technicians provide full diagnostics, inspections, and repairs:
Sewer & Drain Cleaning
Motorized cabling and hydro jetting to clear stubborn blockages and restore code fall velocity.
Sewer Line Repair & Replacement
Trenchless and excavation repair for bellied, cracked, or collapsed private sewer laterals.
Sewer Camera Video Inspection
High-definition diagnostic scoping to visually verify pipe slope, joint offsets, and root intrusion.
24/7 Emergency Plumbing Dispatch
Rapid emergency response for active municipal backups, crawlspace flooding, and fixture overflows.
Interactive Plumbing & HVAC Calculators
Drain Pipe Slope Tool
Calculate minimum fall per foot for DWV lines to avoid solid stagnation.
Grease Trap Sizing Tool
Size commercial grease interceptors based on fixture flow rates.
Septic Tank Capacity Tool
Calculate required liquid capacity for residential septic tanks.
Pipe Burst Pressure Calculator
Determine maximum working pressure and Barlow's hoop stress.