Crawl space drainage in Greensboro

Outside first, always

Most crawl space water starts as rain on the roof or yard. Before any interior drain is considered, the outside should be checked:

North Carolina's residential code also calls for the site to be graded so water drains away from the foundation, and for walls to be damp-proofed where outside grade is higher than inside grade.

Interior drainage options

When water still reaches the crawl after exterior fixes, interior drainage moves it to a safe exit.

• Grading to low spots. The crawl floor is shaped so water flows to one or more low points.
• Drain to daylight. If the lot slopes, a solid pipe can carry water from a low spot out to grade downhill.
• Interior perimeter drain. A trench along the inside of the foundation with perforated pipe and gravel, leading to a sump or daylight.
• Sump basin and pump. Where gravity cannot do the job, water collects in a basin and is pumped out.

For closed crawl spaces, NC code calls for low spots to drain to daylight or a sump pump, and for crawl drains to be kept separate from roof gutter drains and foundation perimeter drains.

Source: NC closed crawl space provisions (R409), as published by Johnston County Building Inspections. Confirm the current edition with your local inspections office.

Piedmont clay complicates drainage

Clay soils drain slowly and can hold water against the foundation for days after a storm. They also swell when wet and shrink when dry. In much of Greensboro, a drain that would be optional on sandy soil becomes necessary. Clay also makes trenching heavy work, which affects cost.

Signs your crawl needs drainage work

• Standing water after storms.
• Mud or wet soil in the same low area every time it rains.
• Water stains or mineral deposits on block walls.
• A crawl that never dries out between storms.
• Sagging or wet insulation near one wall.

Cost references

HomeGuide lists an interior crawl space drain system at about $800 to $3,000, including trenching, gravel, pipe, and a pump. See our cost guide for sources and how drainage fits into the total.

Keeping drainage working

• Clean gutters at least twice a year, especially in fall when Greensboro's oaks and maples drop leaves.
• Check that downspout extensions are still attached after mowing.
• Look for water in the crawl after a heavy storm, at least once a year.
• Test the sump pump if you have one.
• Keep the daylight outlet clear of leaves, mulch, and soil.

For drainage work, see our crawl space encapsulation services in Greensboro. We serve Pleasant Garden, Jamestown, Gibsonville, Reidsville and nearby. Related: sump pumps and standing water.

A note on French drains outside

Exterior French drains along the foundation can help in some situations, but they are a bigger excavation job and can clog over time if not built with proper fabric and outlet. In many Triad crawls, the combination of gutter and grading fixes plus interior drainage is more practical. We explain the trade-offs for your lot.

How we decide between daylight and a sump

If the lot falls away enough that a pipe from the crawl's low spot can reach open ground downhill with a steady slope, a drain to daylight is simple and has no moving parts. If the lot is flat, slopes toward the house, or the run would be very long, a sump is usually the better choice. Some crawls use both.

Keeping drains working

Drains need occasional attention. Check that the outlet of a daylight drain is open and not buried by mulch, leaves, or soil. Clear grass and roots from the end of the pipe. After a heavy storm, look in the crawl to confirm water is not ponding where it used to. If you have a sump, test it by pouring water into the basin and watching it cycle.

Outside, keep gutters clean, especially in fall when oaks and maples around Greensboro drop leaves, and make sure downspout extensions stay attached after mowing. Most crawl drainage problems start or get worse at the gutters.

Crawl drainage questions

Do I need a crawl space drain?

If water still reaches the crawl after gutters, downspouts, and grading are fixed, an interior drain to daylight or a sump is usually needed.

Can crawl drains connect to my gutter drains?

NC closed crawl rules call for crawl drains to be kept separate from roof gutter drains and foundation perimeter drains.

How much does an interior crawl drain cost?

HomeGuide lists about $800 to $3,000 for an interior crawl space drain system, including trenching, gravel, pipe, and a pump.

Why is drainage harder on Greensboro clay?

Clay drains slowly and holds water against foundations, so water lingers after storms. Trenching in clay is also heavy work.

What maintenance does crawl drainage need?

Clean gutters, keep downspout extensions attached, check the crawl after big storms, test the sump pump, and keep the outlet clear.

Is a drain to daylight better than a sump?

When the lot allows it, a drain to daylight has no moving parts. On flat lots or lots sloping toward the house, a sump is usually needed.

How do I maintain a crawl drain?

Keep the outlet clear of mulch, leaves, and roots, check the crawl after heavy storms, and test any sump by pouring water into the basin.