Reading a drying log: what justifies each day of equipment

A drying log, or dry log, is the document that sits behind the equipment lines on a water-damage invoice. It covers the dehumidifiers, the air movers, and the number of days they ran.

I write these for the office I run, and I read a lot of them. This guide is for the people on the other side of the page: adjusters reviewing a claim, homeowners trying to understand their bill, and contractors checking their own work before it goes out.

Start with what the log is for

A dry log has one job: to show why the drying took as many days as it did.

That sounds obvious, but many logs miss it. They print a grid of readings, day after day, and stop. Readings alone rarely explain the length of a job. A column of numbers going down tells you the drying worked. It does not tell you why it needed six days instead of three.

So when you open a log, ask one question first. Does this document explain the days, or does it just record them?

The first thing to look for: equipment math

The strongest support for the days is arithmetic you can redo yourself. A good log shows:

Chamber volume. How much air space was being dried.
Dehumidifier sizing against the class of loss. How much water removal capacity the job called for, given how wet and how widespread the damage was.
Air mover count against the affected surface area. How many units the wet surfaces needed.

If those numbers support the equipment and the days on their own, that is the best evidence a log can carry. Check the math. If it works, the rest of the log is supporting detail.

The second thing: the conditions on site

Sometimes the equipment math does not carry the whole job. Then the log should show the real conditions that made drying slower. Every one of these genuinely lengthens a dry, and every one can be checked:

Outdoor temperature and humidity on those dates. Humid weather slows drying.
Occupancy. A house with people living in it behaves differently from an empty one.
Building materials and how saturated they were. Dense or soaked materials give up water slowly.
Airflow restrictions from the layout. A tight layout is often why a crew added or moved equipment partway through.

A log that leans on conditions should name them with dates and sources. The outdoor line, for example, can come from hourly observations at the nearest airport weather station, which anyone can look up.

How it should read

A good log states the conditions and lets you reach the conclusion. It does not print a heading that says "Justification" and then argue. It reads like a record, because it is one.

If a log reads like a sales pitch, read it more carefully.

Where the numbers come from

Every reading in a log came from somewhere. On many jobs, the readings exist only as photographs of instrument displays. In that case the log is transcribed from the photos, not pulled from a database.

When I build a log that way, each reading gets one row: which photo, which instrument, which scale, a note, and a confidence level. Anything not fully legible is recorded as displayed, with the limitation stated.

Two details are worth checking as a reader:

Which mode the meter was in. The same handheld meter can show relative humidity, wood moisture, or a relative scale. The mode indicator has to be read off the display. Without it, the number is only "as displayed."
How grains per pound were calculated. Where the instrument shows its own mixing ratio, use that. Where it does not, the log should say the value was computed.

Things that look like evidence but are not

Dehumidifier run-hour panels. A run-hour meter looks like perfect proof of how long a unit ran. It is not. Crews rarely reset the timers between jobs, so a unit can arrive with hours from its last job still on the clock. A run-hour figure cannot date an install or prove a duration unless something independent dates the install.

What does date a job: photo capture times, install and removal records whose printed address matches the claim, and the first and last capture dates on the photo project.

Missing days in the middle. Many jobs are photographed on install day and removal day, with little in between. That gap is not a defect. Equipment installed on day one and removed on day eight was in the house on day five whether anyone photographed it or not. A careful log reports that gap as it is. It does not fill it with readings nobody took.

The honesty rules

This is the part I care about most, and the part I would look for first if I were reviewing someone else's log.

Modeled values are labeled on the same page. If a stretch of the drying curve is estimated rather than measured, the log says so right there, not in a footnote.
Verified readings beat curves. Where a real reading exists, it wins over any model.
Unattended days are reported as they are. So are areas that were not drying.
No selected readings. Pick the evidence that best explains the days, but only from evidence that is true. Never choose readings to reach a number.
No dropped days. A day that is inconvenient stays in.
No figure that no instrument produced.

A dry log that gets checked and holds up is worth more than one that only reads well, because the carrier checks.

Why one fixed format helps everyone

The office I run uses one report format for every drying log: the same nine sections, the same table shapes, the same rules about where each number came from. Only the job's own facts change.

There is a practical reason. Carriers reduce invoices for "no supporting dry logs." A format that has already been through review is easier to read than a new one, even a better one. For the reader, it means you learn where everything is once. For the writer, the next report is assembly instead of design.

A quick checklist for reviewers

When a drying log lands on your desk:

Does it explain the days, or only record them?
Does the equipment math work when you redo it?
Are the site conditions named, dated and sourced?
Is every reading traceable to an instrument and a photo?
Are modeled spans and unattended days labeled where they appear?
Does anything rely on a run-hour panel to date the job?

A log that passes those six questions is one you can trust.

Written by Farough (Frank) Darakhshan, who writes the final invoices and drying reports for the office he runs. More about me: Farough Darakhshan.