Under a nail-down engineered or solid wood floor the layer is a vapour retarder, not a foam pad. Lauzon's installation guide describes a wood subfloor vapour barrier as recommended for nailed or stapled floors, Appalachian's solid guide asks for a vapour retarder in the 0.7 to 1 perm range, and the NWFA describes #15 asphalt-saturated felt as a Class II vapour retarder. That paper is what hardwood underlayment means once the planks are fastened down. A concrete slab changes the build-up again, and for solid wood the answer can be that the floor does not belong there. We stock the paper, the membranes and the floors, and this guide prices them from our underlayment collection.
What actually goes under a nail-down wood floor
A nailed floor is fastened through the layer underneath it into the subfloor, so that layer has to be thin, stable and able to pass a fastener. The wood makers name paper, not cushion. Lauzon's guide states that for nailed or stapled installations a wood subfloor vapour barrier is recommended. Appalachian is more specific: a vapour retarder with a 0.7 to 1 perm rating in all cases, with Aquabar B as the recommendation.
The same guide removes two things people often have on hand. Over a wood subfloor it does not allow an impermeable retarder at a perm rating of .7 or less, naming 6 mil polyethylene film, because that can trap moisture in the subfloor. It also does not allow common red rosin or building paper that is not asphalt saturated. A #15 asphalt-saturated felt, which the NWFA describes as commonly used as a Class II vapour retarder, is the kind of paper these guides point at.
So the rule for a nailed floor is to match the paper to the floor maker's specification, and we confirm the right paper or retarder for your product at quote.
Why a foam or cork roll is the wrong layer to nail through
An acoustical pad is designed for a floor that floats. The NWFA's installation guidelines are blunt about what happens when it does not: unless the flooring manufacturer directs otherwise, installers should not nail through an acoustical underlayment system. Two reasons are given. The fasteners compromise the IIC and STC ratings the pad was bought for, and most of these materials are not designed to hold a fastener.
Our quote sheet treats nail-down wood the same way. An underlayment line appears only for laminate and engineered click floors, at $50.00 per 200 sq ft roll, and a nail-down wood quote carries no roll at all. The pads we sell belong to floating installations, and our guide to underlay for laminate flooring compares them because that is where they earn their place.
If a wood manufacturer's guide names a specific acoustic system and tells you to fasten through it, follow that guide and bring it to us.
What we stock in the underlayment aisle
Four of our underlayment products cover the usual floating-floor jobs. The sizes below are the ones written on the product titles:
| Roll | Size on the label | Price |
|---|---|---|
| Goodfellow DMX 1-Step Underlayment | 44" x 27'5" roll | $97.00 |
| Goodfellow 2mm Silver Underlayment Pad | 200 sq ft roll | $18.00 |
| Top Floorings Depot 3-in-1 Green Underlayment | 200 sq ft roll | $25.00 |
| Top Floorings Depot 2mm Cork Rubber Underlayment | 3' x 2' pieces | $4.99 |
Prices checked October 23, 2026.
The DMX roll is the one with a maker's description we can point to for concrete. The maker's current FAQ page describes the 2.0 version of that roll as compatible with vinyl plank flooring, laminate flooring and engineered hardwood, and says no plywood or OSB underlayment is needed because it installs directly over clean, level concrete. Because it replaces the plywood, there is nothing in that build-up to nail into, so the floor above it floats.
We also stock a silicone vapour shield paper at $40.00. Whether it is the right paper for your floor depends on the perm rating the maker's guide asks for, which we check before the quote goes out.
Over a concrete slab the build-up changes
A slab is not a nail base, so the question stops being which paper goes under the planks and becomes what the planks are fastened to. The NWFA's guidance for a wood subfloor over concrete is that the vapour retarder is placed over the concrete slab and underneath the wood subflooring, and that with adequate moisture control below the subfloor no second retarder is needed on top of the plywood. In practice: retarder on the concrete, plywood on the retarder, fasteners into the plywood.
Lauzon adds a reading to take first. Its guide caps the moisture evaporation rate for concrete at 3 lbs per 1000 ft2 /24 hrs on a calcium chloride test, and above that it calls for a sealer or retarder suited to the installation. A slab that fails the reading is a moisture-control job before it is a flooring job; our guide to a vapour barrier in a basement covers what a wet slab means for a below-grade room.
Solid wood is where the answer can simply be no. Appalachian's solid guide allows installation on grade or above grade, marks the basement as No in its recommended-use table, and describes the method as exclusively stapled or nailed. A basement slab, or a condo slab with no plywood over it, is not a surface that guide nails into.
Our three European Oak engineered floors are nail-down as well, so over a slab they need the same plywood build-up: retarder, plywood, fasteners.
When the slab is in a condo
Your building's own rules come before the floor does, because they decide whether a nailed assembly is accepted at all. Check them before you order and send us the document if you have one. Nail-down installation in a condo is priced after viewing, and we confirm the figure on your written quote.
Our nail-down floors, with box prices
The four floors in this section are all listed as nail-down in our catalogue. Each price is the current box price, and the last column is box price divided by box coverage:
| Floor | Box price | Box coverage | Per sq ft |
|---|---|---|---|
| European Oak Silver Beige, 6 1/2 inch wide, 2mm top layer | $80.76 | 20.24 sq ft | $3.99 |
| European Oak Titanium Grey, 7 1/2 inch wide, 3mm top layer | $85.25 | 19.42 sq ft | $4.39 |
| Lauzon Authentik Red Oak Nostalgia, 4 1/4 inch wide, solid | $169.83 | 17 sq ft | $9.99 |
| Lauzon Exclusive Hard Maple Kenya, 4 1/4 inch wide, solid | $99.80 | 17 sq ft | $5.87 |
The engineered floors run from $3.99 to $4.39 per sq ft at 19mm (3/4") thick and wire brushed, and what separates Silver Beige from the two 7.5 inch floors is width and top layer, 2mm against 3mm. European Oak Grey Manor is the same 7.5 inch, 3mm build at the same $4.39 per sq ft in a different tone. The solids run from $5.87 to $9.99 at 4 1/4 inch wide and 19mm (3/4") thick, so the same box coverage can carry very different money.
A wider plank shows fewer seams and more grain, which is part of why the 7.5 inch floors cost more per sq ft than the 6 1/2 inch one at the same thickness. The top layer is the other half, and our wear layer thickness guide explains what a 2mm top layer gives you against a 3mm one.
What 500 sq ft of nail-down wood comes to
Labour for a nailed floor is priced on the measured area plus a 5% waste allowance, and the wood is bought in whole boxes. Take a 500 sq ft house:
- Waste-adjusted area = 500 sq ft x 1.05 = 525 sq ft.
- Boxes = 525 sq ft divided by the coverage in one box, rounded up to a whole box.
- Material = boxes x box price.
- Installation labour = 525 sq ft x $2.00 per sq ft, the same rate whether the floor is engineered or solid.
- HST = 13% of material plus labour.
| 500 sq ft house | Silver Beige | Hard Maple Kenya | Red Oak Nostalgia |
|---|---|---|---|
| Waste-adjusted area | 525 sq ft | 525 sq ft | 525 sq ft |
| Boxes needed | 26 boxes (526.24 sq ft) | 31 boxes (527 sq ft) | 31 boxes (527 sq ft) |
| Material | $2,099.76 | $3,093.80 | $5,264.73 |
| Installation labour | $1,050.00 | $1,050.00 | $1,050.00 |
| Material and labour | $3,149.76 | $4,143.80 | $6,314.73 |
| HST (13%) | $409.47 | $538.69 | $820.91 |
| Material and labour with HST | $3,559.23 | $4,682.49 | $7,135.64 |
| Per sq ft of floor | $7.12 | $9.36 | $14.27 |
Two things fall out of that. Nail-down labour is $2.00 per sq ft for engineered and for solid in a house, so the gap between $3,559.23 and $7,135.64 on the same 500 sq ft is material rather than installation. The line missing compared with a click floor is the underlay roll, because our quote sheet adds one only for laminate and engineered click.
These figures leave out delivery, old-floor removal and trim, which are added on your written quote because they depend on the address and on what is coming out. They also assume a flat, sound subfloor; levelling and subfloor repair are quoted after we see the floor. For the plank itself, our engineered hardwood thickness guide explains what 19mm (3/4") buys you.
Frequently asked questions about hardwood underlayment
Do you need underlayment under a nail-down hardwood floor?
Not a pad. What the wood makers ask for is a vapour retarder over the wood subfloor, paper-thin and easy for a fastener to pass through. Lauzon recommends a wood subfloor vapour barrier for nailed or stapled work, and Appalachian sets a perm rating, so the layer follows the floor's own guide rather than what is on sale.
Can I nail through a foam underlay?
Only if the flooring manufacturer directs it, which is the exception the NWFA guidelines leave open. A standard foam pad is not designed to hold a fastener, and its sound rating is compromised once nails pass through it.
What is the difference between underlayment and a vapour retarder?
Underlayment is the general word for whatever sits between the finish floor and the subfloor. A vapour retarder is one specific job, slowing moisture vapour coming from the subfloor, and under a nailed floor it is the whole layer. Under a floating floor the underlayment is often a pad, and some pads carry a moisture layer too.
Does engineered hardwood need a different underlay over concrete?
The slab changes the assembly, not the paper. The NWFA puts the retarder on the concrete with the wood subfloor over it, and the nails go into that plywood. Our engineered floors are nail-down, so a concrete room needs the plywood layer first, or a floor that floats instead.
Can solid hardwood be installed on a concrete slab?
Not with Appalachian's solid guide, which puts the floor on grade or above grade, rules basements out in its recommended-use table, and calls the method stapled or nailed. For a slab room the practical route is engineered wood over a plywood build-up, or a floating floor over a membrane.
Get a hardwood installation quote in Toronto and the GTA
Send your room measurements and a few photos of the subfloor, and tell us which floor you are considering. We will confirm the paper or retarder its maker asks for and price the job from there: request a quote online, or bring your plans to the showroom.
Top Floorings Depot
3781 Victoria Park Avenue, Unit 1, Toronto, ON M1W 3K5
www.topfloorings.com
Call: 416-499-0117
Text: 416-770-8819