Water that gets past a St. Louis flat roof soaks into the insulation and spreads sideways well beyond the entry point. Wet board loses nearly all of its R-value, adds dead load, corrodes steel deck, and will not dry out under a sealed membrane. John Beal Roofing finds it with moisture readings and core samples, maps it on a drawing, and cuts it out. Free inspections. Call (314) 429-6000.
A tenant calls about a stain in a ceiling tile. Somebody goes up, finds an open seam twenty feet away, glues it, and the stain stops. Everybody moves on. Meanwhile the insulation between the two is holding water, and it’ll still be holding water three winters from now.
That’s the whole problem with a low-slope roof. It’s a sandwich. The top of the sandwich is watertight, which means whatever gets in gets trapped, and it travels along the deck flutes and the joints between boards until it finds somewhere to show up inside.
Saturated polyiso can lose the large majority of its thermal value. You’re paying to heat and cool a building through a wet sponge, and the cold spots show up on a thermal camera as clear outlines.
Roof insulation and R-valueTrapped water sits against the top flange of a steel deck and rusts it from above. On a gypsum or lightweight concrete deck it’s worse — the deck itself softens and loses capacity.
Wet insulation is heavy. Then Missouri does what it does in February: it freezes, expands, delaminates the polyiso facer, and pops fasteners and seams from underneath.
No manufacturer will issue an NDL over known wet insulation. Cover it up and you’ve bought a warranty that won’t pay when you need it to.
NDL vs material warrantyA coating seals the top surface completely. Over wet board that traps the moisture, and on a hot afternoon vapor pressure blisters the coating right off.
Roof coatings and restorationTwo layers is the code ceiling anyway, but wet board settles the question. You can’t roof over it, so the wet areas come out no matter which direction you go.
Tear-off vs recover
We start with a walk and the interior. Where are the stains, where’s the rust on the deck underside, where’s the ceiling grid sagging. That tells us where to look hardest.
Then instruments. A capacitance or impedance meter on a grid gives us relative readings fast. An infrared scan on the right night — clear sky, dry surface, enough temperature swing — shows wet areas holding heat after the dry roof has cooled off.
Every anomaly gets verified with a core. A four-inch cut to the deck tells us layer count, board type, whether it’s actually wet, and what shape the deck is in. Then the core gets patched watertight the same day.
You get the wet areas drawn on a roof plan with square footages, so the repair or replacement scope is a number you can budget and bid instead of a guess.
Related: infrared moisture scanning, roof core sampling and leak detection.
Under a sealed membrane, no. There's nowhere for the moisture to go. Vented assemblies dry slowly and unevenly at best. Wet board gets removed.
Whatever the scan and the cores say is wet, plus a margin past the edge of the readings. That's why we map it with square footages instead of guessing a percentage.
Rough rule: once you're past roughly a quarter of the roof area, cutting and patching starts costing more than a tear-off, and you're still left with an old membrane. We show you both numbers.
Sometimes you get strong clues from stains and deck rust, but no. Interior signs point you to a neighborhood. Meters and cores find the boundary.
The inspection, photo report and written scope are free with no obligation. Core sampling on a large roof is quoted separately, and we'll tell you up front when a roof needs it.
Tell us about the property and a dispatcher will call to schedule. No cost, no obligation.
Commercial leaks do not wait for business hours. A live dispatcher answers around the clock and we get crews moving the same night.
