700 mm vs. 120 mm Oak Flooring: Cost & Value
A 700 mm oak board is exceptionally wide for flooring, so first confirm that 700 mm is the board’s width and not its length. Compared with 120 mm boards, it may cost more to buy, prepare for, and install. Compare full installed quotes for the same oak, grade, construction, finish, and work scope. Moisture control, flatness, waste, and movement gaps affect long-term value.
“Before comparing prices, I ask buyers to confirm the measurement and compare the whole flooring system, not just the board,” is the advice I give when reviewing estimates. That matters here: a 700 mm-wide plank is about 27.6 inches across, while 120 mm is about 4.7 inches. A seller may use 700 mm to describe board length instead. Ask for a product specification sheet before requesting bids.
Confirm the board size and compare like with like
The board width affects appearance, sourcing, installation demands, and risk, but it does not determine total cost by itself. First confirm whether each measurement is width or length. Then match the products by oak species, grade, solid or engineered construction, finish, wear layer, and installation method.
The table shows what to investigate. These are cost drivers, not fixed price premiums: local supply, product quality, room layout, and site conditions change the final quote.
| Cost or value factor | 120 mm-wide oak | 700 mm-wide oak |
|---|---|---|
| Sourcing and selection | Often easier to find in standard ranges; confirm local availability | Unusually wide; confirm that the stated dimension is width and verify stock, grade, and product details |
| Material price | Compare the quote for the exact product and finish | May carry a premium for material, grading, milling, or handling; request a written price |
| Installation | Standard methods still depend on product instructions and subfloor condition | May need tighter flatness and moisture control; installer experience with wide boards matters |
| Cutting and waste | Depends on room shape, board lengths, pattern, and defects | Also depends on layout and product; do not assume wider means less waste |
| Future repairs | Replacement boards may be easier to source, but match and availability still matter | A matching board may be harder to source; ask about spare stock and future refinishing |
| Seasonal movement | Wood still expands and contracts as conditions change | Movement across a wide board may be more visible; correct moisture control and clearances are important |
A fair comparison uses the same room area and the same scope. Ask each contractor to list material quantity, waste allowance, subfloor work, moisture testing, installation, transitions, trim, and disposal separately. If one quote omits preparation, it may look cheaper without covering the same job.
Compare total installed cost, not board price
Installed cost includes the flooring and the work needed to make it suitable for the room. It may also include waste, delivery, subfloor repairs, moisture control, trim, and transitions. Because these items vary by site and product, use contractor quotes rather than treating a general price range as a guaranteed budget.
Use this basic estimate:
Flooring quantity to order = measured floor area × (1 + waste allowance)
Estimated project total = flooring + delivery + preparation + moisture system, if required + installation + trim and transitions + other written scope items
For example, a 500-square-foot room with a hypothetical 8% waste allowance needs 540 square feet of flooring. This is a math example, not a recommended allowance for either board width. Ask the installer to explain the allowance based on the room plan, board lengths, pattern, grade, and expected cuts. Do not accept a vague “standard waste” line without asking how it was set.
| Quote item | Question to ask |
|---|---|
| Board price and quantity | Is the price per square foot, and does the quantity include stated waste? |
| Subfloor work | What measured problem is being corrected, and how is the work priced? |
| Moisture testing or mitigation | Which test and product are specified, and what result triggers added work? |
| Installation labor | Does the price cover the chosen method, layout, and wide-board handling? |
| Transitions and trim | How many are included, and are they priced by item or by length? |
| Change orders | Will added work require written approval before it begins? |
Building on this, compare the installed cost per square foot by dividing each complete written estimate by the same measured room area. Keep upgrades and unknown repairs separate. A low initial price can lose its advantage if it excludes required subfloor correction or moisture protection.
Substrate Inspection, Flatness & Moisture Preparation
The substrate is the surface that supports the oak floor, such as a wood subfloor or concrete slab. It must be sound, clean, dry within the flooring system’s limits, and flat enough for the selected product. Test and inspect it before ordering or installing; a membrane cannot correct an active leak or unstable surface.
For a wood-framed floor, check that the plywood or OSB is dry, sound, securely fastened, and suitable for the flooring system. Find and correct movement, loose panels, and squeaks. On concrete, use only an oak product and adhesive system approved for slab installation, including its specified moisture-control system.
A common flatness target is no more than 3/16 inch in 10 feet (4.8 mm in 3.05 m) or 1/8 inch in 6 feet (3.2 mm in 1.83 m). The manufacturer may require a tighter tolerance, especially for very wide boards. Ask the installer to measure and record the floor, not simply describe it as “good enough.”
Measure the moisture content of the flooring and wood subfloor with a calibrated meter. As a common NWFA-based screening limit, the difference should generally be no more than 4 percentage points for strip flooring under 3 inches wide and 2 points for wider flooring. Confirm the product-specific limits and acclimation method. For concrete, use ASTM F2170 in-situ relative humidity and/or ASTM F1869 moisture vapor emission rate when the adhesive system requires it. There is no universal safe RH or MVER limit. Follow the published limits for the flooring, adhesive, and mitigation system; 75% RH or 3 lb/1,000 square feet/24 hours is not a universal pass line.
Do not install over a wet, contaminated, unstable, or out-of-tolerance surface without the specified correction or mitigation. Fix leaks and structural movement first. A moisture barrier does not make an unsuitable substrate sound.
Oak Board Installation: Adhesive, Fastener & Layout Precision
Installation method means the approved way to secure the floor: nail-down, staple-down, or glue-down. The product instructions set the method, tools, fastener or adhesive details, and site conditions. Wide boards call for particular care with flatness and moisture; ask the installer to identify the exact product instructions used for the job.
For a fastened floor, confirm the specified nailer or stapler, fastener type, and spacing. For glue-down work, confirm the approved adhesive and trowel notch, open time, adhesive transfer, and moisture limits. Do not substitute a different adhesive or fastening pattern without approval. Tile mortar and tile slip-resistance criteria do not apply to oak flooring.
Follow the product’s delivery, acclimation, and room-condition requirements rather than assuming a fixed number of days is right for every floor. Record site conditions and test results. During installation, check layout, board selection, fastener placement or adhesive transfer, and the required clearance at walls and fixed objects.
Transitions, Movement Clearances & Structural Deflection Compliance
Movement clearance is the open space left at room edges and fixed objects so a wood floor can respond to changes in humidity. The product instructions set the required gap. A half-inch (13 mm) is a common starting detail, not a universal rule; room size, installation method, and seasonal humidity range can change what is needed.
Keep the required gap clear beneath trim. Do not trap a floating floor under fixed cabinets, tight transitions, or trim. Fit transitions without pinning the floor, and size clearances according to the manufacturer’s directions. If a wide board is held rigidly at a wall or transition, seasonal expansion can contribute to buckling or joint failure.
Ask the contractor to confirm the structural design and the flooring maker’s requirements. L/360 is a common tile criterion, not a universal hardwood acceptance rule. Do not use a tile standard as a substitute for the wood-floor manufacturer’s requirements or project-specific structural review.
Maintenance, Finish Care & Long-Term Dimensional Protection
Lifecycle value includes the cost of care, the finish, and the chance of future repair, not only the purchase price. Follow the flooring maker’s cleaning and humidity guidance. Keep the care instructions and product details with your project records so future maintenance and repairs can match the installed floor.
Wide oak can show cupping, crowning, or gaps when moisture differs across a board or changes over time. That does not mean every wide board will fail; it means moisture control and correct installation matter. Do not treat a membrane or adhesive as a fix for an active leak, excessive slab moisture, or an unsuitable base.
Before signing, ask whether the finish can be refinished and what limits apply. For engineered oak, confirm the wear-layer details and the manufacturer’s refinishing guidance. Also ask how long matching boards will be available and whether buying spare material is practical. Keep the product name, lot information, test results, adhesive or mitigation details, and care instructions.
Two budget scenarios: how to read contractor estimates
These scenarios show how to compare bids, not market prices. Actual costs depend on the product, region, room, and site findings. I use the same room area and scope in both cases so the difference is visible.
| Scenario | What the estimate should show | Budget decision |
|---|---|---|
| 500 sq. ft. of 120 mm oak | Product and quantity, stated waste basis, preparation, installation method, transitions, and any moisture work | Use as a baseline only if it covers the same work and product quality as the other bid |
| 500 sq. ft. of 700 mm oak | The same scope, plus confirmation of board width, wide-board experience, flatness checks, and product-specific moisture limits | Compare the complete total and the risk controls, not just the added board cost |
For either scenario, request a site inspection before treating the bid as final. If a contractor expects added preparation, ask for the measured condition, proposed repair, unit cost or fixed price, and written approval process. This makes unexpected add-ons easier to judge and negotiate.
Conclusion: choose the width that fits the whole budget
The 120 mm option is often simpler to source and handle, while 700 mm boards may have added material and installation demands. Neither width is automatically the better value. Confirm what “700 mm” describes, compare equivalent oak products, and price the same complete scope. Then weigh appearance and sourcing against preparation, moisture risk, repair options, and the written warranty.
Quick quote checklist:
- Confirm whether 700 mm is width or length.
- Match species, grade, construction, finish, and wear layer.
- Require a measured waste allowance and itemized preparation costs.
- Ask for flatness and moisture checks, plus the applicable product limits.
- Get added work approved in writing before it begins.
- Keep test results, product details, and installation records.
Frequently asked questions
Is 700 mm too wide for oak flooring?
Not automatically, but it is exceptionally wide. Confirm the product is designed for flooring and follow its requirements for substrate flatness, moisture, installation, and movement clearance.
Could 700 mm refer to board length instead of width?
Yes. Check the product specification sheet for width and length separately before comparing prices or ordering material.
Does 700 mm oak cost more than 120 mm oak?
It may cost more because of material, grading, milling, handling, or installation needs, but there is no fixed premium. Compare written, like-for-like installed quotes.
Which width needs more flooring waste?
Neither width has a universal waste rate. The room layout, board lengths, pattern, grade, and cuts affect the amount. Ask the installer to explain the stated allowance.
What flatness should I ask for?
A common target is 3/16 inch in 10 feet or 1/8 inch in 6 feet. The flooring maker may require a tighter tolerance, particularly for very wide boards.
How should a wood subfloor’s moisture be checked?
Use a calibrated meter on both the flooring and subfloor. Confirm the product requirements; common screening limits vary by board width and do not replace manufacturer instructions.
How should concrete moisture be tested?
Use ASTM F2170 and/or ASTM F1869 when required by the adhesive system. Follow that system’s published limits; there is no universal safe reading.
Can a membrane fix a damp slab or moving subfloor?
No. Use only an approved moisture-control system, and first correct leaks, structural movement, or other substrate problems.
How much expansion space should oak flooring have?
Follow the product instructions. Half an inch is a common starting detail, not a rule for every room or installation method.
What should I get in writing before work starts?
Get the product and quantity, waste basis, preparation, tests, installation method, transitions, total price, change-order process, and applicable warranty terms.
(This article was written by one of our staff writers, Richard Bennett. Visit our Meet the Team page.)