Engineered vs solid hardwood: which one your house can actually take

Solid hardwood is one piece of wood. Engineered hardwood is a slice of the same wood glued to a stable core. Every real difference follows from those two sentences — including the ones the trade gets wrong in both directions, because “engineered is the cheap one” and “solid lasts forever” are each about half true.

The construction, in the only detail that matters

Solid is milled from a single board. The common thickness is 3/4 in (19 mm), with 5/16 in and 1/2 in also sold. It has a tongue and a groove, and it is nailed or stapled down to a wood subfloor.

Engineered is a veneer of real hardwood — anywhere from 0.6 mm to 6 mm — bonded to a core of cross-banded plywood or, at the cheaper end, high-density fibreboard. The plies run at right angles to each other, and that is the entire trick: the core physically restrains the veneer from moving across the width of the board.

A 3/4 in solid board carries roughly 1/4 in of wood above the tongue. That is its sanding budget, and it is what people mean when they say solid lasts a lifetime. On an engineered board the sanding budget is the veneer, minus whatever you cannot take off without reaching glue.

How many times it can actually be refinished

• 3/4 in solid: a properly done sand-and-refinish removes well under a millimetre, so the realistic answer is four to six times across the floor’s life. Spaced fifteen or twenty years apart, that is longer than most people own the house.
• Engineered, 4–6 mm veneer: two or three sandings. For refinishing purposes it behaves like a solid floor, and it is priced accordingly.
• Engineered, 2–3 mm veneer: one careful sanding, by someone told it is 2 mm before they start.
• Engineered, under 2 mm: never. Most click-together engineered sits here, often at 0.6 mm. Screening and recoating is the only option, and a hard factory finish limits even that.

So ask for the veneer thickness in millimetres, and ask for it specifically. “Wear layer” on a hardwood spec sheet sometimes means the veneer and sometimes means the finish, and the two differ by a factor of a hundred. Where the manufacturer publishes it, it is in the spec table on the product page; where it is missing, ask us and we will pull the technical sheet.

Canadian humidity is the real argument

Wood moves with moisture content, not with temperature. That distinction is the whole of this section. In February, a forced-air furnace running against −25 °C outdoors can drag indoor relative humidity down into the teens; the same house in July can sit above 60% before the air conditioning catches up. A wood floor goes through that full cycle every year of its life.

A solid board dries in winter and shrinks across its width, so thin gaps open between boards and close again in summer. That is seasonal behaviour rather than a defect, which is why installation guides put a humidity range — usually 35–55% — on the first page. Movement is proportional to width: the same percentage of shrinkage across a 7-inch board opens more than twice the gap of a 3 1/4-inch strip.

The cross-ply core in an engineered board resists that movement, which is the strongest argument for it in this country. It is not immunity — soak it and it will still cup, and an HDF core behaves more like laminate than like plywood when water reaches it. But through an ordinary Canadian winter, engineered stays put where solid tells you exactly what the humidity has been doing.

Concrete, condos, and why engineered took over

You cannot nail into a slab. Solid over concrete means building a plywood subfloor on sleepers first, which costs money and eats an inch and a half of height — and below grade it is not a sensible idea at any price. Engineered can be glued straight to a slab or floated over an underlay, and that, rather than any story about quality, is why it dominates over concrete.

Test the slab before either. An in-situ relative humidity probe or a calcium chloride test gives you a number, and adhesives are rated to a maximum; skipping it is how a glue-down floor releases two years later. A meter waved at the surface is not a test.

Condos add a rulebook to the slab: a finished-floor-height limit, an impact-sound requirement the board enforces, and an approved-underlay list that matters more than the flooring choice does. Get the underlay approved in writing before you order, because a floor that fails the building’s sound requirement comes back up at your expense.

Radiant heat

Radiant is an engineered floor’s home ground, because engineered is what manufacturers approve for it. The rules are consistent across brands: a surface temperature cap around 27 °C (80 °F), a slow ramp up and down over several days at each end of the heating season, a floor sensor rather than an air thermostat, and the same 35–55% humidity range — a warm floor dries wood from underneath as well as from above.

A thinner floor also conducts better. A thick plank over a thick insulating underlay fights the system you have already paid to install. Solid over radiant is not universally forbidden, but it is a narrow, brand-specific case — narrow boards, often quartersawn, and only where the manufacturer approves it in writing. Do not assume it.

Where solid is still the better buy

• Above grade, on a wood subfloor, staying put for twenty years. The ability to sand it flat and change the colour once, in year eighteen, is worth real money.
• Narrow strip flooring. A 2 1/4 or 3 1/4 in solid is the cheapest hardwood per square foot and the most dimensionally forgiving thing in the category.
• Matching or extending an existing floor. In an older house you can lace new solid into old, sand the whole floor together, and end up with one continuous surface. No prefinished product can do that.
• A site-finished look. Sanding and finishing in place gives a monolithic floor with no micro-bevel between every board. Some people do not care. The ones who do, care a lot.

Where engineered is not a compromise

• Over any slab, at any level of the house.
• In a condo, where the slab, the height limit and the sound rule all point the same way.
• Over radiant heat, where it is usually the only approved wood option.
• In wide boards. Past about 5 inches the stability of the core matters more than what the board is made of. Wide solid is doable, but it tightens your humidity control and often calls for glue assist as well as fasteners.
• Whenever the veneer is 4 mm or thicker — at that point it is a real hardwood floor on a better core, and it is priced like one.

What our catalogue can and cannot tell you

Our flooring lines include 3,210 hardwood products that carry a price. The median hardwood listing is $194.18.

Read both narrowly. The count is the Hardwood category as our suppliers file it: it does not separate engineered from solid, it does not know a veneer thickness, and nothing in it answers the question this article is about. It is a sense of scale — the construction is on the individual product page, and where it is not, ask us.

The median is per listed unit — per box, per bundle, per piece — so it is not a per-square-foot price and should never be held against a per-square-foot showroom quote. Divide by the coverage printed on the carton before comparing anything to anything.

The buying checklist

1. Answer the subfloor question first: slab or wood, above grade or below. It settles the material more often than taste does.
2. If it is a slab, test it and write the number down. Give it to your installer before they quote.
3. Ask for veneer thickness in millimetres on engineered, or board thickness in inches on solid. Refuse to accept “wear layer” as an answer.
4. Ask what the core is. Plywood and HDF are not the same product and do not behave the same way when water finds them.
5. Choose the finish for how you plan to maintain it. A UV-cured aluminium-oxide finish is very hard and very difficult to spot-repair; a hardwax oil is softer, needs upkeep, and repairs in place.
6. Treat Janka as a rough guide. The commonly published figures put American walnut near 1010, red oak near 1290, white oak near 1350 and hickory near 1820 — but a softer species with a good finish and felt pads will outlast a hard one in a house where nobody takes their boots off.
7. Plan the humidity. A hygrometer costs less than a box of hardwood and turns an argument about whether the winter gaps are “normal” into a number.
8. Order samples. And know the terms if one has to go back — 30 days, unused and in the original packaging, a 15% restocking fee may apply once the refund assessment is complete, and return shipping is yours to pay.

Shop what this guide covers

• engineered hardwood — cross-ply cores, for slabs, condos and radiant.
• solid hardwood — one piece of wood, for a dry wood subfloor above grade.
• matching hardwood stair noses and matching hardwood mouldings — order them with the floor, in the same lot.
• made-to-order hardwood — when the species, grade, width and finish you want are not a stock line.
• Janka, and what it does not tell you — the rating this comparison keeps running into.