Homeowner Guides

Wood moisture readings: what the numbers on your report mean

Inspectors quote moisture content percentages like everyone knows the thresholds. Here are the ranges that matter and what each one obligates you to do.

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wood moisture readings: what the numbers on your report mean Hampton Roads
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Guardex wood moisture readings: what the numbers on your report mean

Cities served

2026

Founded

Same week

Response

NPMA-33

Reports

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Inspections come with photos, moisture readings, and a written plan you can price out.

NamePhoneEmailProperty addressCity or countyZIP codeProperty typeWhat do you need?Best time to reach you

What are you seeing?

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The mechanism

The ranges

Wood moisture content is measured as a percentage of the wood's dry weight. Framing in a healthy conditioned space in this climate typically reads in the low teens.

Under 15 percent — normal, no action
15 to 19 percent — elevated, worth monitoring and correcting the source
20 percent and above — decay fungus can establish; correction is not optional
28 percent and above — free water present; expect active decay and possible structural loss

Where the reading is taken matters

A single number for a whole crawl space is not useful. Readings should come from the sill plate, band joist, several floor joists at different points, and the subfloor, with the wettest locations noted. A crawl space can read fine at the access and be saturated at the far corner under a bathroom.

What to ask your inspector

Ask where each reading was taken, what the ambient relative humidity was, and whether the wettest readings line up with a plumbing fixture, a downspout, or a low spot in the grade. That correlation is the whole diagnosis. If nobody can tell you why the wet spot is wet, you are being sold a treatment instead of a repair.

Services referenced

Crawl Space Moisture Control Structural Wood Repair Crawl Space Encapsulation

Pests referenced

Wood-Decay Fungus Powderpost Beetle

Key takeaways

Wood moisture content is measured as a percentage of the wood's dry weight. Framing in a healthy conditioned space in this climate typically reads in the low teens.

From the pest library

Old House Borer

Hylotrupes bajulus

Identification

Oval exit holes about a quarter inch across in softwood framing, with rippled gallery walls and coarse powdery frass. Larvae are often heard as a rasping or ticking sound in quiet rooms.

Why it is here

It attacks seasoned softwood framing — the pine used across the region's older housing — and higher moisture accelerates development.

Activity by month

Full old house borer guide Browse the pest library

Coverage

This applies across the whole region

Guardex Pest Control service area map covering Wood moisture readings: what the numbers on your report mean — Hover a city to see the local pest-pressure note.

Guardex runs routes across Hampton Roads, Virginia — from the Oceanfront and Sandbridge through Norfolk, Portsmouth, and Chesapeake, up the Peninsula to Newport News, Hampton, and Poquoson, and west into Smithfield, Carrollton, and Isle of Wight County.

Contact

Email: ops1@guardexva.com
Hours: Monday–Saturday, 7:00 a.m. – 7:00 p.m.
Region: Hampton Roads, Virginia
Reports: NPMA-33 / WDI on request

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