How to Identify 150 mm Hardwood Floorboards
A 150 mm hardwood floorboard is usually described by its nominal face width, about 5.91 inches, not by the full width including its tongue. Measure several boards, inspect an exposed edge for construction, and check the product records for species, thickness, and profile. Then verify the subfloor and moisture conditions before choosing an approved installation method.
Would you rather confirm the board you have before planning the work, or discover after installation that its width, construction, or moisture needs were different than expected? The label “150 mm” is a useful starting point, but it does not identify every detail needed to choose or install a floor.
I start by separating what can be measured from what needs documentation. A tape measure can help check a board’s face width; it cannot reliably confirm species or whether a hidden core is engineered. The steps below help you check both the boards and the conditions they will meet.
Identify 150 mm Boards: Face Width, Construction, and Profile
A 150 mm board is generally sold by its nominal face width: about 5.91 inches. The actual exposed face can differ by product, so check several boards and compare your measurements with the manufacturer’s specification. Width alone does not confirm wood species, solid or engineered construction, thickness, or profile.
Measure the face width and profile
Face width is the width of the board’s usable top surface, rather than its full width including the tongue. Measure across the flat face, perpendicular to the board’s length. If the board has bevelled edges, record what you measured and note the bevel; different measuring points can produce different readings.
Use a ruler or tape measure and check at least three boards. Measure in millimetres, and record the results rather than rounding each one to 150 mm. Also record thickness and length. The tongue-and-groove section, click profile, or other joining edge can extend beyond the face, so it should not be counted as exposed face width.
| What to check | How to check it | What the result tells you |
|---|---|---|
| Face width | Measure the top face across several boards | Whether the product is consistent with a nominal 150 mm width |
| Overall width | Measure from the outer edge to the opposite edge, including the joint profile | The full board profile, not necessarily its stated face width |
| Thickness and length | Measure the board and compare with the product record | Whether the sample matches the listed dimensions |
| Edge profile | Inspect the long edges for tongue-and-groove, click, bevel, or square edges | What joining system the board uses |
Check construction, species, and finish
Solid flooring is made from wood through its thickness. Engineered flooring has a hardwood wear layer over a core made from cross-ply wood or another layered construction. If an end or concealed edge is available, inspect it for continuous wood grain or visible layers. Do not rely on a photograph, surface colour, or grain pattern alone to identify species or construction.
Check the product label, invoice, or manufacturer’s technical sheet for species, construction, nominal width, thickness, finish, and installation instructions. “Prefinished” describes a finish applied before installation; it does not identify the wood species or core. If the records are missing, ask the supplier to confirm the product details in writing.
Next step: Keep a sample and a record of its measured dimensions. Use product documentation to confirm the nominal size and construction before planning the installation.
Inspect the Subfloor, Moisture, and Structural Support
The subfloor is the surface that supports the finished floor. It must be sound, flat enough for the selected product, and within the product’s moisture limits. Wide boards can be more sensitive to moisture-related movement, so a dry-looking surface alone is not proof that the site is ready.
Check flatness and condition
First identify the subfloor: wood, concrete, or another approved base. Look for loose panels, movement, cracks, high spots, low areas, and signs of water damage. Check flatness with a straightedge or the method named by the flooring maker. A commonly used wood-flooring benchmark is no more than 3/16 inch in 10 feet, about 4.8 mm in 3 metres, but the selected product may require a tighter tolerance.
Do not assume that a flat surface is structurally sound. Wood framing must meet the flooring system’s structural needs. L/360, a measure of how much a floor deflects under load, is a common minimum reference for flooring work, not automatic approval for every product or building. Ask the flooring manufacturer or a qualified building professional when framing, movement, or damage is in doubt.
Test moisture using the correct method
Use a calibrated moisture meter to test both wood flooring and a wood subfloor. Follow the manufacturer’s limits for each material and for the permitted difference between them. Do not apply one moisture limit to every species, product, or site; the required readings depend on the flooring system and its instructions.
For concrete, use the in-situ relative humidity (RH) or moisture vapour emission rate (MVER) test specified for the product. RH measures moisture inside the concrete; MVER measures moisture released at the surface. There is no universal adhesive-safe threshold. Compare test results with the limits for the flooring and the specified adhesive, if used.
| Site check | Useful method | Decision point |
|---|---|---|
| Wood subfloor moisture | Calibrated moisture meter | Compare readings and permitted difference with product instructions |
| Concrete moisture | Specified in-situ RH or MVER test | Confirm readings meet the flooring and adhesive limits |
| Flatness | Straightedge or manufacturer-approved method | Correct out-of-tolerance areas before installation |
| Structural support | Inspect floor condition; seek qualified review if uncertain | Do not install over an unsound or inadequately supported base |
Next step: Record the test method, readings, and date. If moisture is high or the subfloor is damaged, resolve the cause before covering it.
Choose the Installation Method, Transitions, and Expansion Clearances
The right installation method depends on the board’s construction, its profile, the substrate, and the manufacturer’s instructions. A 150 mm width does not by itself determine whether a floor should be nailed, stapled, glued, or floated. Confirm that the complete system is approved for your product and site.
Match the method to the product and substrate
Nailing or stapling may be suitable for a product approved for fastening to a suitable wood subfloor. Glue-down installation requires a product approved for it, a compatible substrate, and the specified adhesive. Floating installation requires a board and underlayment approved for that system. Do not infer compatibility from the board’s appearance or from the fact that another floor used the same method.
On concrete, confirm that the flooring is approved for glue-down or floating installation. Use only the adhesive, underlayment, or moisture-control system named or approved by the product maker. A membrane or underlayment cannot make an unsuitable substrate acceptable, repair active water intrusion, or correct a floor that is too uneven.
Plan clearance, transitions, and movement breaks
Wood changes size as moisture conditions change. Follow the product instructions for clearance at walls and fixed objects, along with any requirements for transitions or movement breaks. There is no single expansion gap that suits every product, room, or layout. Do not cut away required clearance because the boards appear stable on installation day.
Wide boards make moisture control especially important. Excess moisture or seasonal humidity change can contribute to cupping, gapping, or adhesive failure. These outcomes are not inevitable, but they are reasons to verify the site conditions and follow the flooring maker’s limits rather than relying on a generic installation rule.
Next step: Have the product instructions, substrate test results, and installation plan available before work begins. If one of those does not match, pause and confirm the correct system.
Protect, Maintain, and Verify the Floor Over Time
Protection starts before installation and continues while the floor is in use. Keep the product within the maker’s stated storage and site conditions, and condition or acclimate it only as directed. After installation, protect it from construction traffic and moisture, then follow the recommended care instructions.
Use records and careful handling
Store boards as instructed and keep them away from known leaks or wet work. Do not assume that every hardwood floor requires the same acclimation period; follow the directions for that product and site. During construction, use the protection method recommended by the flooring maker, and avoid trapping moisture beneath coverings.
After installation, retain the product name, batch or lot information if available, and installation records. These details help if you need to check the finish, obtain matching boards, or review a performance concern. Clean the floor with products approved for its finish, and respond promptly to spills or water leaks.
Field scenarios: what the checks reveal
These examples are diagnostic scenarios, not claims about a particular job. They show why measuring width alone is not enough.
- A board measures close to 150 mm, but the tongue adds extra width. Record the face and overall width separately, then compare the face measurement with the product sheet. This helps distinguish a nominal face width from the full profile.
- An exposed edge shows layered construction. The board is likely engineered, but confirm the core and wear-layer details from the manufacturer. The construction affects which installation methods are approved.
- Concrete appears dry, but the moisture test exceeds the product limit. Delay installation and address the moisture condition. A surface that feels dry does not replace the specified RH or MVER test.
- The room is ready, but the subfloor has a high spot or movement. Correct the subfloor condition before installing. A moisture barrier does not fix flatness or structural problems.
Next step: Recheck the floor against the manufacturer’s care and inspection guidance, especially after a leak or other unusual moisture event.
Frequently Asked Questions
Is 150 mm the same as 5.91 inches?
Yes. 150 mm converts to about 5.91 inches. The stated width may be nominal, so check the product specification and measure the face.
Should I measure the tongue when checking width?
No. Measure the usable top face separately. Record the full width including the tongue only if you also need to document the board’s overall profile.
Can a photo confirm that boards are 150 mm wide?
No. A photo lacks a reliable scale and does not show the full edge profile. Measure the board or check its product records.
Can I identify the wood species by colour or grain?
Not with confidence. Appearance can offer clues, but finish, lighting, and natural variation can change how wood looks. Confirm species with product documentation.
How can I tell solid hardwood from engineered hardwood?
Inspect an exposed end or concealed edge. Solid wood has continuous wood through its thickness; engineered flooring has a hardwood wear layer over a layered core. Verify the construction with the maker.
Is 3/16 inch in 10 feet a universal flatness rule?
No. It is a common wood-flooring benchmark, not a rule for every product. Follow the selected floor’s flatness requirement, which may be tighter.
Is there one safe moisture limit for concrete?
No. Use the RH or MVER test required by the flooring and adhesive makers, then compare the result with their stated limits.
Does an underlayment fix a damp or uneven subfloor?
No. It may be part of an approved flooring system, but it does not correct active moisture intrusion or an out-of-tolerance surface.
Can every 150 mm hardwood board be nailed down?
No. Nail or staple only when the product and substrate are approved for that method. Other boards may require glue-down or floating installation.
What information should I confirm before buying?
Check nominal face width, actual dimensions, species, solid or engineered construction, thickness, profile, finish, installation methods, and the product’s moisture and subfloor requirements.
(This article was written by one of our staff writers, Michael Roberts. Visit our Meet the Team page.)
