College Grove Drainage Assessment: Water Reaching a New Home
At this College Grove property, the rear ground sat above the finish floor, water entered through the garage into the crawlspace, and low spots held water in the yard. This article records the problems observed and the proposed drainage plan; it does not document a completed repair.
What We Found at the College Grove Property
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- Foundation: CMU/block walls
- Negative Grading: Finish floor sat ~1 – 2 ft below exterior grade at the rear
- Symptoms: Water through the garage into the crawlspace, active mold, musty odor
- “Encapsulation” used: Foam on walls + loose vapor barrier (not a sealed system)
- Weep holes: Buried by raised dirt/mulch against veneer brick
- Pooling Water: Low spots in the yard not draining
Bottom line: The back of the house was too low; grade fell toward the foundation. Water went inside.
Why New Builds Get Drainage Wrong
- Rushed final grade (checkbox, not engineering)
- Low finish floors on sloped lots
- Buried weep holes (mulch/soil against brick)
- Band-aid fixes labeled “encapsulation” (without exterior water control)
- Warranty dynamics: delay and deflect until time runs out
The Smoking Gun: All Downspouts into One 4″ Line
During our assessment, most downspouts tied into a single 4″ main. In heavy rain it backed up so water overflowed out of the gutters. That is not a gutter failure—it is a pipe capacity and layout problem.
Why a single 4″ pipe failed here
- Too much roof area collecting in one pipe. Stack multiple downspouts in one area and it chokes.
- Long, flat runs + corrugated pipe = high friction / low flow.
- No relief path so water climbs up the downspout.
Roof drain design rules that work
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- Split the roof into zones—don’t daisy-chain everything.
- Solid, smooth-wall pipe for roof water (never perforated).
- Limit 4″ laterals to one downspout (two max with steep, short runs).
- Up-size trunk to 6″ for 3+ downspouts, long runs, or flat grades.
- Add cleanouts at the house and at major turns.
- Daylight to an outlet with a pop-up emitter.
- Keep grates/inlets clear—especially in leaf season.
Key takeaway: Roof drainage is a system. Correct pipe size, slope, and routing stop overflow, erosion, and crawlspace wetting.
Proposed Drainage and Grading Plan for College Grove
- Regrade the backyard so water runs away from the wall.
- Add a grassy swale along the rear to route flow laterally to the side.
- Route surface water through a drainage system: downspouts + catch basins to solid pipe and daylight.
- Expose weep holes; keep mulch/soil below the brick line.
- If seepage persists from hillside pressure: French drain at footing depth (fabric + angular rock + perforated pipe) only where subsurface flow is proven.
- If needed, encapsulate correctly (after exterior drainage is fixed).
Red Flags for College Grove Buyers & New Owners
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- Puddles or soggy band along the foundation
- Soil/mulch (covering weep holes)
- Musty odor or soft floors above crawlspace
- Gutters overflowing during heavy rain
- Builder says “landscaping” or “settling”
Costs, Timing, and Middle TN Reality
- Hard-pipe + basins: usually the most cost-efficient for surface water.
- Regrading + swale: moderate cost; big impact when the house sits low.
- French drain at footing depth: highest excavation/stone cost; use only for verified groundwater.
What to Do Next (Fast Diagnostic)
- During a storm, film 30–60 seconds: where water starts and where it collects.
- Fill out our project request form and share the pictures/videos with us.
- We will design a storm drainage plan that prioritizes the simplest, most cost-effective fixes first.
👉 www.excavationcon.com
Take back control of your property.
For a completed local project with a follow-up visit, read about Jacqueline’s French drain project in Franklin.
