New Builds with Drainage Issues In College Grove, TN

New Builds with Drainage Issues

in College Grove, TN

(What We are Seeing—and How to Fix It)

 

Case Study: New House, Real Problems (College Grove)

• • 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

1. 1. Split the roof into zones—don’t daisy-chain everything.
2. Solid, smooth-wall pipe for roof water (never perforated).
3. Limit 4″ laterals to one downspout (two max with steep, short runs).
4. Up-size trunk to 6″ for 3+ downspouts, long runs, or flat grades.
5. Add cleanouts at the house and at major turns.
6. Daylight to an outlet with a pop-up emitter.
7. 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.

Fixing It (College Grove Game Plan)

1. Regrade the backyard so water runs away from the wall.
2. Add a grassy swale along the rear to route flow laterally to the side.
3. Hard-pipe surface water: downspouts + catch basins to solid pipe and daylight.
4. Expose weep holes; keep mulch/soil below the brick line.
5. If seepage persists from hillside pressure: French drain at footing depth (fabric + angular rock + perforated pipe) only where subsurface flow is proven.
6. If needed, encapsulate correctly (after exterior drainage is fixed).

Red Flags for College Grove Buyers & New Owners

• • 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)

1. During a storm, film 30–60 seconds: where water starts and where it collects.
2. Fill out a form on our website and share the pictures/videos with us.
3. We will design a storm drainage plan that prioritizes the simplest, most cost-effective fixes first.

 

👉 www.excavationcon.com
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