Damp and Condensation Monitoring Log

Who this is for

A dated record of a damp problem while you work out what is causing it. Each line takes the room, the spot, whatever your meter or hygrometer showed, the weather outside and what you saw with your own eyes.

Owners and tenants watching a patch that may or may not be spreading, landlords answering a complaint, and anyone gathering evidence before a surveyor, a builder or a letting agent gets involved.

What this helps you track

• Where the problem is, described precisely enough to find again
• The readings you took, on the dates you took them
• What the weather was doing, since condensation and rain leave different patterns
• What was tried — heating, ventilation, a repair — and whether it changed anything
• A dated run of entries, which is what a surveyor or an agent will ask for

How to use it

1. Write the property, who is keeping the log and what instrument you are using at the top; readings only compare if they come from the same device.
2. Take readings at roughly the same time of day and in the same spot each time, and describe the spot exactly — 'north wall, just above the skirting, left of the window' rather than 'the corner'.
3. Record the outside weather in a few words. A wet week and a cold still night produce very different damp.
4. Write what you can see: staining, black spots, peeling paper, water running down glass, a smell.
5. Note what was done that day — window opened, heating on, extractor run, dehumidifier emptied — so cause and effect can be compared later.
6. Photograph anything visible on the same day and give the photograph a file name you write in the note column.

Formats

• Printable PDF (A4 and US Letter)
• Fillable PDF with form fields
• Fill in online, saved in your browser

The printable is laid out inside a box that fits both A4 and US Letter, so the two files are identical and neither one is scaled. The fillable PDF has real form fields. The online version keeps what you enter in your own browser and builds the completed PDF on your device.

How to print

Download the A4 or US Letter file to match the paper in your printer, open it in a PDF reader and print at 100% — not "fit to page", which shrinks the writing space. Both files leave a 14 mm margin, which clears the unprintable edge on home printers. To print the online version with your entries in it, use the Print this sheet button, which prints only the sheet and none of the page around it. More on printing.

Questions

What reading should I be aiming for?

The log does not say, and neither should any sheet: acceptable readings depend on the instrument, the wall, the season and the standard being applied. Record what you measure and let a surveyor interpret it.

Is this proof of a problem?

It is evidence, not proof. A dated run of readings and photographs taken by the person living there is far better than a memory, but the diagnosis belongs to somebody who can inspect the building.

Do I need a moisture meter?

No. Plenty of useful logs are kept with nothing but a date, a description and a photograph. Leave the reading columns blank if you have no instrument.

How long should I keep it up?

Long enough to cover different weather. A problem that only appears in cold still weather looks like nothing at all in a dry fortnight.

Can a landlord and tenant both keep one?

Yes, and it is often worth doing. Two logs of the same rooms rarely disagree about dates, and dates are usually what is in dispute.