Serving Kansas City and nearby areas
Water still sitting on your flat roof 48 hours after rain means a drain or low spot is holding it there, so get a free roof inspection and a written price set up the same day you call.
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We connect property owners in Kansas City and nearby areas, including Fairfax District, Armourdale, Village West, Edgerton, Lenexa and Olathe, with one independent local commercial roofing specialist.
The 48-hour rule
The National Roofing Contractors Association defines ponding as water that stays on a roof more than 48 hours after rain, in weather that should dry it.
Ponds freeze here
Normal January lows in Kansas City are near 19 to 21 degrees. A pond that freezes and thaws over and over wears the roof surface faster.
Typical published ranges for Kansas City. The contractor's written estimate is the price, and the inspection is free.
| Work | Typical range |
|---|---|
| Roof inspection and written priceSet up through Kansas City Commercial Roofers | Free |
| Fixing a ponding area | $70 to $750 |
| Drain repair | $70 to $500 |
| Membrane repair | $250 to $1,750 |
| Repair area | $2 to $10per square foot |
Every flat roof holds a little water after rain. That is normal. The question is how long it stays. The National Roofing Contractors Association has a simple test. If water is still there more than 48 hours after rain, in weather that should dry it, it is ponding.
Ponding does not leak on day one. It works slowly. It ages the roof surface, finds every weak seam, and adds weight to the deck. On a Kansas City roof, it also freezes in winter.
The same puddle
In the same spot after every rain.
Dirt rings or stains
On the roof where water sat and dried.
Green growth
Algae or moss in low spots.
Gravel or grit washed
Into a pile near a low area.
Ice sheets
On the roof in winter.
Water around a drain
That never fully empties.
A ceiling sag or stain
Below the low spot.
Mosquitoes or birds
Gathering on the roof in summer.
Most ponds come from one of a few causes:
Clogged drains and scuppers. Leaves, plastic bags, gravel and trash collect at drains. When a drain is slow, water pools around it. This is the most common cause and the cheapest to fix.
Crushed insulation. Foot traffic, carts and heavy gear press the insulation down. That makes a dip that holds water. Hail can crush insulation too. Paths to rooftop units are a common spot.
A sagging deck. Over time, a roof deck can deflect between supports. Water collects in the dip. The weight of the water makes the dip deeper, and the pond grows.
Not enough slope. Some roofs were built nearly dead flat, or with slope that runs away from the drains. Water has nowhere to go.
Dips around units and skylights. Heavy HVAC units and curbs can settle. Condensate lines from those units can also feed water onto the roof.
Hard spring rain. Normal May rain in Kansas City is about 5.3 inches, the National Weather Service says. A roof that drains slowly gets refilled before it dries out.
Freeze and thaw. Normal January lows sit near 19 to 21 degrees. A pond freezes at night and thaws by day. Ice spreads and pulls at seams and the roof surface. On some roof types, it wears away the mineral surface.
Summer heat. A pond in July bakes. Water and sun together speed up aging of the roof surface around the edge of the pond.
Can wait for a routine check: a small, shallow puddle that is gone in a day or two after rain, with no stain below.
Book an inspection soon: a pond that lasts more than 48 hours, a pond that grows each year, dirt rings, or green growth.
Call the same day: a ceiling that sags under a pond, water over the top of a flashing at a unit or wall, or a deck that feels soft. Pond water can come in fast when it rises above a flashing.
The inspector first finds the cause. Then the fix fits the cause:
Clear and repair drains
Clean out the drain and add a better strainer.
Add a drain or scupper
Where water has no way out.
Build up the low spot
With filler or new tapered insulation, then patch the roof over it.
Add a cricket
A small built-up ridge turns water toward a drain.
Replace crushed insulation
And the roof over it.
Fix the deck
If it has sagged, sometimes with an engineer's input.
Rebuild flashing
That sits too low near a pond.
National cost guides put most ponding fixes in the ranges in the table on this page. A sagging deck or a roof built with no slope costs more. In rare cases, a roof built flat needs new tapered insulation across a large area. Your price comes in writing after the inspection.
Many commercial roof warranties require the roof to drain. Some exclude damage caused by water that does not drain. If your roof is under warranty, read it. Ask for ponding to be noted in the written report with photos. Fixing the drainage can keep the warranty in good standing.
Take photos
Of the pond, with the date and the days since rain.
Check from a safe spot
Use a roof hatch or a window. Do not walk out on a wet roof.
Look at the ceiling
Below the low spot for stains or sagging.
Note what is nearby
Like a drain, a unit or a path the HVAC crew uses.
Find your warranty
And any old repair records.
Call (913) 347-6527 or send the form. Kansas City Commercial Roofers sets up the inspection with one independent local roofing contractor, and you get a written price.
The National Roofing Contractors Association counts it as ponding when water stays more than 48 hours after rain in weather that should dry it. Water that is gone in a day or two is normal on a flat roof.
It can. Many commercial roof warranties require the roof to drain, or exclude damage caused by poor drainage. Read your warranty and ask the inspector to note ponding in the written report.
Water is heavy. Over time, a pond can make the deck sag more, which lets the pond grow. A sagging deck or a pond that gets bigger after each storm needs a check soon.
A coating does not change where water goes. Some coatings are made to handle standing water better than others, but the low spot or slow drain still needs a fix.
Usually not. Clearing drains, adding a drain, building up the low spot or adding a cricket fixes most ponds. A full new roof is the answer only when the whole roof was built without enough slope.
