Clearing Drains Before the LA Basin Rains — What Changed This Year
What to do about a flat roof in North Hollywood in the first forty-eight hours, and what to leave until Monday.
After a storm the useful work happens in the first two days, and most of it is documentation rather than repair. This is what to do about a flat roof in North Hollywood once the wind drops.
What actually matters
Ponding is the beginning of most flat roof failures. Water standing more than forty-eight hours after rain is a defect, not a quirk of the building. It adds load, accelerates breakdown of the membrane, and in this climate leaves a mineral crust that holds the next rainfall in exactly the same place.
What to do in the first forty-eight hours
Document before you touch anything: wide photographs to establish the property, then close photographs of each item of damage, all dated. Drainage does not fail in the storm; it fails in the eight dry months beforehand. A drain that has been dry since April collects grit, leaves and debris, and nobody looks at it until water is coming through a ceiling. A tarp fixed through sound covering creates damage that was not there before.
How North Hollywood changes the answer
North Hollywood takes the full inland summer with very little relief after dark, and the ultraviolet load on a south-facing slope here is as hard as anywhere in the county. Asphalt ages from the top down under it: once the granules have gone the mat underneath turns brittle and starts to crack. Mostly single-storey post-war housing with later additions, which puts a transition detail in the middle of the roof where two eras of workmanship meet.
What we look at on an inspection
- Fall across the roof, and any area holding water beyond forty-eight hours
- Drain and scupper clearance, including underneath every strainer
- Membrane condition across the whole field, not only at the edges
- Flashing at every penetration, curb and item of rooftop plant
- Parapet termination and counterflashing along the full perimeter
- Insulation moisture, established by probe rather than by eye
- Evidence and quality of previous patching
Common questions
Should I get a tarp on it straight away?
Only once it is photographed, and only if it can be fixed without putting new holes through sound covering. A badly fixed tarp creates damage that was not there before.
How soon do I need to report it?
Check your policy, because most impose a reporting window. Reporting early costs nothing and protects the claim.
The honest summary
Ponding, blocked drainage and failed penetration detail account for nearly every flat roof call we take. If a quote does not mention drainage, it is a quote to recreate the same problem in a new material. In North Hollywood the thing to watch is granule loss on the sun-facing slopes, and the junction where an addition meets the original roof.
Free inspection, drone photography where access is difficult, and a written estimate with deck repair priced per sheet. No obligation.