Most yard drainage problems start on the roof. Before adding drains in the lawn, it is worth knowing whether the gutters can carry what the roof collects.
How much water a roof actually sheds
A roof is a large impervious surface, and a heavy Piedmont thunderstorm puts a great deal of water through it in a short time.
All of that water arrives at a small number of downspouts, concentrated into narrow streams — which is why the ground beneath them erodes.
The steeper and larger the roof plane feeding one downspout, the more concentrated the flow.
Big roof areas draining to few downspouts is the classic setup behind a wet foundation and a scoured bed below.
Signs the system is undersized or blocked
Water sheeting over the front edge of the gutter in heavy rain.
Water overshooting at valleys, where two roof planes concentrate flow into one spot.
Downspouts that gurgle, back up, or run full and slow.
Erosion, splash marks on siding and a trench in the mulch directly below a downspout.
Staining or plant damage along one section of gutter, usually where a joint is leaking.
What to change
Adding downspouts to split a long gutter run is often more effective than replacing gutters entirely.
Larger gutter and downspout sizes, and a properly sized outlet at each drop, help where flow is genuinely too high.
Valleys benefit from a diverter or an additional drop nearby.
Guards reduce clogging but do not increase capacity, and some types reduce it. Clean gutters remain the cheapest improvement available.
Getting it away from the house
Capacity means nothing if the water is released at the foundation. Every downspout should discharge into a solid buried line running well away from the house.
That line needs continuous fall and a proper outlet — a daylight opening or a pop-up emitter — with an animal guard on the end.
Never connect roof water into a perforated drain near the foundation; it delivers the water straight back into the soil you are trying to keep dry.
Southern Style Turf & Design pipes downspouts underground and builds the outlets across the Lake Norman area, and will point out gutter capacity problems worth a roofer's attention.
Frequently asked questions
How many downspouts does a roof need?
Enough that no single one carries an excessive roof area. Water spilling over gutter edges in heavy rain is the practical sign there are too few.
Do gutter guards help with drainage?
They reduce clogging from leaves, which matters on wooded lots. They do not add capacity, and some designs reduce it.
Should downspouts be buried?
In almost all cases, yes — in a solid pipe with fall to a proper outlet well away from the foundation.
Want this looked at on your property?
We give free, no-pressure on-site estimates across Denver, Mooresville, Cornelius, Davidson, Huntersville and Troutman.
