Patio Drainage and Water Management in New Hampshire
Most patio failures aren't concrete failures — they're drainage failures. Water under the slab is what destroys patios in New Hampshire. Here's why drainage matters and how we plan it.
Water Is the Enemy
The cracks and heaving that destroy patios in New Hampshire are almost always caused by water under the slab. Water gets into the soil, freezes, expands, and pushes the patio up. Then it thaws, and the ground settles. Repeat that dozens of times per winter, and any base that holds water will shift.
That's why drainage isn't an afterthought — it's part of the base engineering. If water can't get away from the slab, the base will fail no matter how well it's compacted.
How We Plan Drainage
During your consultation, Patrick reads how water moves across your property. Where does runoff go? Where does it pool? Are there downspouts dumping water near the patio area? Is the property flat or sloped?
Based on what he sees, the drainage plan might include:
- Grading the base to move water away from the slab
- Installing drainage stone and pipe behind retaining walls or under the sub-base
- Directing downspouts away from the patio area
- Sloping the patio surface itself — a slight grade so water runs off, not pools
- On sloped or lakefront lots, managing water running downhill toward and under the patio
Flat Lots vs. Sloped Lots
On a flat lot, drainage is about moving water away from the slab — grading the base and surface so water has a path off the patio. On a sloped lot, it's about managing water running downhill — which can run under the base and undermine it from below. Sloped lots require more drainage engineering, and that's part of the base plan.
Lakefront Drainage
On lakefront properties, drainage has an extra dimension: runoff management. Water that runs off your patio and yard goes toward the lake, and shoreland rules govern how that's managed. We plan lakefront drainage in line with NH shoreland rules — both to protect your patio and to protect the lake.
Ask About Drainage
If you're talking to a contractor about a patio, ask how water will move away from the slab. If the answer is vague, that's a red flag. Drainage is fundamental to a patio's survival in New Hampshire.
Want a drainage plan built into your patio? Book a free consultation.
Book a free consultationAbout the author
Patrick St. John owns and runs Elite Outdoor Services in Hancock, New Hampshire. He's on every site — walking the yard, running the equipment, and walking the finished patio with you. He writes these articles because he'd rather you ask than wonder.
Ready to talk about your project?
Book a free consultation. Patrick walks your yard and gives you a straight answer — no pressure.