Shared walls turn one leak into two problems
The walk streets running inland from The Strand are the densest housing in Hermosa Beach. No vehicle access, no side yards, and in most cases no gap at all between one building and the next. Units are separately owned and share a party wall, which is a fine arrangement right up until water gets into it.
When it does, the leak has one origin and two victims. The owner on the dry side watches a stain appear on a wall they have never touched. The owner on the wet side sees nothing, because the water is traveling away from them. Both are certain it started next door, and until somebody measures, both are guessing.
What air testing settles that a visual check cannot
Air sampling counts what is actually airborne in a defined space and compares it against an outdoor control taken the same day. Run in both units and in the shared stairwell, the numbers show where concentrations are highest and how they fall away with distance. That gradient is what points at an origin.
It answers three things that come up constantly on these blocks:
- Is there a problem, or is it a smell? Older walk street buildings hold odors from decades of damp that has long since dried. Counts separate an active source from a memory of one.
- Which side is it coming from? Concentration gradients across a shared wall are the closest thing to a directional answer available without opening that wall up.
- How far has it traveled? Spores move on air, and this housing is stacked vertically as well as pressed together horizontally. A ground floor source can register two floors up a stairwell.
Why the walk streets behave differently from the rest of town
There is no service access. Everything comes and goes through the front. Plumbing and drainage ended up wherever it could be run, and past repairs were made from whichever side was reachable at the time. Those access constraints explain a lot of what we find now.
Sun does not reach the ground. Buildings three and four stories tall stand close enough that lower floors and the passages between them stay shaded and damp through the day. Surfaces that never fully dry stay hospitable.
Ocean air is constant and it is salty. It works on fasteners, flashing and sealant far faster than inland air does. Junctions that were sound ten years ago are not necessarily sound now.
How a test is run
Samples are collected on calibrated pumps over a fixed interval so volumes are comparable. Interior samples are taken in the affected space and in at least one unaffected space in the same building. An outdoor control is mandatory, because indoor counts mean nothing without the day’s ambient reading to measure them against.
Everything goes to an accredited independent laboratory. The report gives counts by genus, the control figures, and a plain reading of what the comparison shows. It is written to be handed straight to a neighbor, a board or an insurer without needing translation.
Independent, and here it matters more than usual
Golden State Mold Inspections does not perform remediation. On a shared wall that independence is not a nicety, it is the only reason the result carries weight. A test paid for by one owner and run by a company that also sells the repair is not a document the other owner has any reason to accept. Ours is.
Questions from walk street owners
My neighbor will not let anyone in. Can you still test?
Yes, though the answer comes out less precise. Testing your unit and the shared stairwell still establishes whether you have a problem and roughly where counts rise. Pinpointing an origin across a party wall works far better with access to both sides.
Will the report say whose fault it is?
It reports measurements and what they indicate. It will state where counts were highest and what that suggests about the source. It does not assign legal liability, and any report claiming to should be treated with suspicion.
Our building has an HOA. Who normally pays?
That turns on your governing documents and usually on whether the source sits in common area or exclusive-use area. Establishing where the source actually is tends to be the step that settles it, which is why testing generally comes before the argument rather than after.
How long do results take?
Laboratory turnaround is typically a few business days. The visit itself is a matter of hours.
Where a shared-wall dispute involves building work, the age of the structure matters as much as the damp. Asbestos surveys before renovation work are a legal requirement on much of this housing. Our full coverage of the town is set out under how we work throughout Hermosa Beach.
Getting to us from The Strand
From The Strand at Pier Avenue, head east on Pier Avenue, turn left onto Valley Drive and continue north as it becomes Ardmore Avenue. Turn right onto Rosecrans Avenue, left onto Sepulveda Boulevard, right onto Grand Avenue, then left onto Lomita Street. We are at 204 Lomita Street, El Segundo, CA 90245. Call (310) 525-0619.