Moisture meter and infrared camera screening

We use a moisture meter and, where useful, an infrared camera to screen for signs of moisture, missing insulation and heat. They help us decide where to look more closely. They do not replace looking, and they do not tell us what is inside a wall.

This page describes what each tool does and, as important, what it does not do.

The moisture meter

A moisture meter measures the moisture content of a material, mainly wood and drywall, at or near the surface. There are two kinds.

• Pin meters push two small pins into the material and measure electrical resistance. They leave tiny holes, and we use them only where it is acceptable, such as on exposed framing in a crawl space.
• Pinless meters read through the surface with a sensor, without making holes. They read a zone below the surface, and so are used on finished walls, floors and window sills.

We use a meter in places where water tends to appear: below windows, around exterior doors, at the base of walls, near plumbing fixtures, on joists in a crawl space, at the underside of roof sheathing in an attic, and along balcony walls.

What a reading means

A high reading means that the material is wetter than we would expect. It does not tell us how long it has been wet, why, or whether it is still getting wet. A dry reading today does not rule out an intermittent leak. Different materials read differently, and metal, foil and some finishes give false readings. We compare a suspect spot with a reading on a similar material nearby.

The infrared camera

An infrared camera, which is often called a thermal imaging camera, shows differences in surface temperature as a colour picture. It does not see through walls and it does not show moisture directly.

What it can help with:

• spotting areas where insulation seems to be missing or settled, when there is a clear temperature difference between inside and outside
• showing patterns that suggest a wet area, such as a cooler zone on a ceiling or wall where evaporation is cooling the surface
• finding warm spots at electrical connections and panels that are under load
• tracing hydronic heating lines in a floor or air leakage around windows and doors

What affects it

The camera is only as good as the conditions. It works best when there is a difference of several degrees between inside and outside temperature. In mild or sunny weather, differences are small, and the pictures are less useful. Direct sun on a wall, reflective surfaces, furniture and blinds, can all mislead. An area that looks different is a place to investigate, and not a defect.

What it cannot do

• It cannot see inside a wall, or measure moisture content.
• It cannot identify mould, or tell mould from a stain.
• It cannot tell us how long a leak has been present.
• It cannot prove that something is fine.

How the two work together

On an inspection, the thermal camera may flag a cool patch on a ceiling. The moisture meter is used on that patch, and we look at the roof or plumbing above. If all three agree, we have a likely leak and write it up with a rating. If they do not, we describe what we saw and say that it needs monitoring or a closer look.

When we use them

A moisture meter is part of how we work on most inspections, in the places listed above. An infrared camera is used where it is likely to help, and on request as an add-on. It is useful for:

• a condo or townhouse with a history of leaks, or from the envelope era
• a house with a suspicious ceiling or wall stain
• a basement or crawl space with a damp feel
• older houses where we want to check how much insulation is in the walls and the attic
• buyers who want an extra look at one concern

What happens after

If the tools point to something, the report gives the finding, the reading or image, and what we recommend. Often that is a specialist: a roofer, a plumber, an envelope consultant, or a restoration contractor who can open the wall and look. Opening a wall is outside the scope of an inspection.

A fair warning

Marketing for thermal imaging sometimes suggests that it finds everything. It does not. It is a screening tool. We use it because it is quick and non-invasive and sometimes shows something we would have missed, and we tell you the limits each time.

Booking

Phone or send a request and tell us what you want checked. We will say whether the tools are likely to help in your case, given the season and the building.