Exterior Drainage · Maryland
Exterior
Drainage
in Maryland
Every wet basement starts outside. Correcting where surface water goes is the cheapest fix — and the one most homeowners skip.
French drain installation, grading and swale correction, downspout extension routing, window well drainage, and yard drainage solutions. OBW addresses the exterior drainage conditions that drive hydrostatic pressure against Maryland foundations.
Against Wet Basements
Fix the Exterior First
How Exterior Drainage Prevents
Wet Basements in Maryland
Most Maryland basement water problems have an exterior component: downspouts dumping at the foundation, grade that slopes toward the house, or surface water that has nowhere to go but against the foundation wall. Correcting these conditions is the cheapest, most effective first step — and many homeowners skip it and go straight to interior waterproofing.
Interior drainage is the right solution when the water table itself is the problem — when hydrostatic pressure is coming from saturated clay soils regardless of how well the surface drains. But when the water source is surface runoff that can be redirected, exterior drainage correction handles it for a fraction of the cost.
OBW assesses both exterior and interior conditions during every free inspection. When exterior drainage correction will solve or significantly reduce the problem, we recommend it. When interior drainage is also needed, we scope both and let you make an informed decision.
All Services
Exterior Drainage
Services in Maryland
Every scope is written after a free inspection. No phone estimates, no commissioned salespeople.
French Drain Installation
Perforated pipe in gravel trench intercepting groundwater before it reaches the foundation.
→Grading & Swales
Re-grading to restore positive slope away from the foundation. Swale construction to direct surface water.
→Downspout Drainage
Underground downspout extensions routing discharge well away from the foundation perimeter.
→Window Well Drains
Drainage for window wells that collect rainwater and push it against the foundation wall.
→Yard Drainage Solutions
Catch basins, channel drains, and yard drainage systems for low spots that collect and hold water.
Warning Signs of Exterior Drainage Problems
Signs Your Maryland Property Has
Exterior Drainage Issues
Exterior drainage problems are visible — if you know where to look.
- Downspouts that terminate at the foundation wall or less than 4 feet away
- Grade that slopes toward the house — visible after rain as water pools at the foundation
- Window wells that fill with water after rain
- Low spots in the yard that hold water for hours or days after a storm
- Wet basement events that correlate directly with specific storm patterns or downspout directions
- Erosion or soil loss along the foundation perimeter
Exterior Drainage Questions
Common Questions About Exterior
Drainage in Maryland
Call (410) 709-7166 for questions not listed here.
Can exterior drainage correction replace interior waterproofing?
Sometimes. If your basement water problem is primarily surface runoff driven — downspouts too close, grade sloping inward, no swales — exterior correction may resolve it entirely. If the water source is the seasonal water table rising in saturated clay (very common in Maryland), exterior drainage helps but interior drainage is also needed. We assess which applies during the free inspection and recommend the right scope, not the largest one.
How far should downspouts discharge from the foundation?
At minimum 4 feet, per most building codes. We recommend 6–10 feet with an underground extension, routing to a pop-up emitter in the lawn that opens under flow. Short-distance surface discharge recirculates water back toward the foundation and defeats the purpose.
What is a French drain and when do I need one?
A French drain is a perforated pipe in a gravel trench that intercepts groundwater moving laterally through the soil and redirects it away from the foundation. It's appropriate when water is flowing toward the house through the soil profile — often visible as a wet stripe in the lawn parallel to the house. Not the same as interior perimeter drainage, which handles water that has already reached the foundation.
Does grading last?
Grading improvements settle over time, especially in Maryland's frost-heave conditions. Most grading corrections hold well for 5–10 years before they need reassessment. We typically combine grading with other drainage improvements (downspout extensions, swales) so the grade correction isn't doing all the work alone.
70 Years of Maryland Basements
Why Maryland Homeowners Choose
Oriole Over National Brands
Three generations of the Pirog family since 1953.
No Commissioned Salespeople
Our inspectors diagnose accurately — not sell the largest system. Honest assessment every time.
Lifetime Transferable Guarantee
Transfers to the next homeowner. National franchise warranties don't.
Maryland Soil Expertise
Piedmont clay, Bay water tables, freeze-thaw. Engineered for Maryland specifically.
Family-Owned Since 1953
Amber Pirog leads the same family company Frank Sr. founded over 70 years ago.
Free Inspection. Written Quote. No Pressure.
Three Steps to a Dry,
Sound Maryland Home
From inspection to completed work, most OBW jobs are scheduled within two to three weeks.
Free Inspection
A local OBW inspector visits, assesses the problem, and documents the scope. Free, no obligation.
Written Quote Same Day
A specific, itemized quote before any work is scheduled — not a vague range over the phone.
Work & Warranty
OBW's own crew completes the work and hands you the Lifetime Transferable Warranty before leaving.
Fix the Outside Before It Becomes an Inside Problem.
Free inspection. Written estimate same day. Exterior drainage scoped honestly against interior alternatives.
Family-owned since 1953 · MHIC #4247 · Lifetime Transferable Guarantee