Roof leak water damage spreads from where the water gets in, down through the roof deck, rafters and attic insulation, and into ceilings and walls, and most of it happens out of sight. Stopping it takes two things: cutting off the water at the roof, then finding and drying everything it reached before mold and rot set in. If a leak is active, call NEMA Roofing at 866-631-3366.
Where does the water go once it is past the roof?
Water follows gravity and the framing, not a straight line. Each layer it passes through fails in its own way:
| Part of the house | What the water does | What you may notice |
|---|---|---|
| Roof deck (plywood or OSB sheathing) | Swells, delaminates and, if wetted again and again, rots | Dark patches on the underside seen from the attic; a soft or springy spot underfoot for the roofer |
| Rafters and trusses | Stain and, with repeated soaking, decay where water collects | Water lines on the wood; damp at the ends where they sit on the walls |
| Attic insulation | Mats down, holds water against the ceiling and stops insulating the wet area | Flattened or clumped patches; a musty attic |
| Ceilings | Stain, soften and sag | Rings, bubbles, cracks at seams |
| Walls | Water runs down inside the cavity from the top plate | Bubbling paint, swollen baseboards, stains low on a wall far from any ceiling mark |
| Eaves, fascia and soffits | Overflowing gutters and failed edge flashing soak the roof edge | Peeling paint, soft fascia boards, stains on stucco below the eave |
Because the water travels, the ceiling stain is often a long way from the hole. How roof leak detection finds the source explains how the entry point is tracked down.
How fast does a roof leak cause lasting damage?
The clock that matters most is drying. The U.S. EPA says that when wet or damp materials are dried within 24 to 48 hours after a leak, in most cases mold will not grow. Materials that stay wet past that, such as insulation packed against drywall or a cavity with no airflow, are where mold starts.
Rot is slower but cumulative. One wetting of a roof deck that then dries out rarely ruins it. A small leak that wets the same spot in every storm, all season, is how a repair turns into replacing sheets of decking and sections of rafter. That is the real cost of a leak that “only drips a little when it rains hard.”
What can you check in the attic?
If the attic is reachable and dry enough to be safe, a look with a flashlight during or right after rain tells you a lot. Step only on the framing, never between joists.
- Shiny, wet wood or drips on the underside of the deck: an active leak above.
- Dark, dry staining: an old leak; check whether it grows after the next rain.
- Daylight through the deck: an opening that needs covering before the next storm.
- Wet or flattened insulation: water is reaching the ceiling below.
- Rusty nail tips or damp across a wide area of the deck with no single wet spot: often condensation from poor attic ventilation rather than a roof leak. Worth telling the roofer, because the fix is different.
How is hidden damage repaired?
- Stop the water. A temporary cover or seal if the permanent repair has to wait for dry weather.
- Open and dry. Wet insulation comes out; ceiling or wall sections that stayed soaked are opened so the framing can dry.
- Repair the roof and what is under it. Once the covering is removed at the leak, any swollen or rotted decking is cut out and replaced, and damaged flashing and underlayment are renewed. Framing with real decay is reinforced or replaced.
- Rebuild inside last. Insulation, drywall and paint go back after the roof has proved itself in rain.
A written estimate should say how damaged decking will be handled, because its extent is only known when the roof is opened. For the ceiling part of the job, see emergency ceiling repair after a roof leak.
How do you keep it from happening again?
Most sudden leaks start as small, visible problems: a clogged gutter or valley, a cracked vent boot, a slipped tile, a lifting shingle after wind. Clearing gutters before the rainy season and having the roof looked at after strong wind catches most of them while they are cheap. The usual triggers in Southern California are covered in the top causes of roof emergencies.
Stopping leak damage with NEMA Roofing
NEMA Roofing’s five locations (Santa Barbara, Oxnard, Woodland Hills, Tarzana and Downey) put a crew within reach of homes throughout Ventura, Santa Barbara, Los Angeles, Riverside and San Bernardino counties; see our Ventura County coverage and the rest of our service areas. Our emergency roof repair service stops the water and repairs what it reached. Call 866-631-3366.
