Karndean Rigid Core Installation: A Step-by-Step Checklist (Plus Real Korlok Select Price Lessons)

I've been handling Karndean orders and installations for about seven years now. Personally made (and documented) 11 significant mistakes totalling roughly $4,800 in wasted budget. The worst one? Mis-specified the underlayment for a rigid core job on a 1,200 sqft commercial space — $3,200 redo plus a 1-week delay. Now I maintain our team's Karndean rigid core installation checklist to prevent others from repeating my errors. This guide is for distributors, installers, and contractors who need to get it right the first time.

Also, because I know half of you googled "shower shoes" and "epoxy floor coating" alongside Karndean — quick note: I'll connect those at the end. And yes, someone once asked me how to clean a stainless steel sink after an LVT install. I'll cover that too.

Before You Start: When This Checklist Saves You Time

This checklist applies when you're installing:

• Karndean Rigid Core (Korlok Select, Knight Tile, Van Gogh) over concrete, plywood, or existing tile
• Any Karndean loose lay or glue-down that requires strict subfloor prep
• Working with a distributor or installer who's new to Karndean's specific requirements

Total steps: 6. Follow them in order. Skip one, and you risk callbacks.

Step 1: Subfloor Moisture & Flatness Check

Most buyers focus on the flooring design — the herringbone, the wood grain — and completely miss subfloor moisture. That's the classic outsider blindspot. I once approved a job based on a quick RH test… and the results came back at 90% RH. (Should mention: Karndean requires ≤75% RH for concrete, or a vapor barrier.)

Do this:

• Perform three calcium chloride tests per 1,000 sqft. If you don't have hard data on your slab's moisture, assume it's borderline.
• Flatness: Use a 6ft straight edge. No gaps over 1/8 inch. Fill low spots with a self-levelling compound. I'd say 90% — nah, closer to 85% of installers skip full flatness checks.

Reference: Karndean's installation manual (Section 2.1) states: "Subfloor must be clean, dry, smooth, and structurally sound."

Step 2: Acclimation — Don't Trust the Box Labels

I wish I had tracked how many times boxes arrived with dates that were clearly wrong. What I can say anecdotally is that about 15% of our rigid core orders needed extra acclimation time.

Karndean requires the flooring to acclimatise in the room (65-85°F, 30-60% RH) for 48 hours. But here's the step most people forget:

• Open the boxes and fan out the planks. Don't just stack them.
• Measure the temperature of the flooring itself, not just the room air. A concrete slab can be 10°F colder than ambient.

Step 3: Choose the Right Underlayment (or None)

For Karndean rigid core (Korlok, Knight Tile), many installations don't require a separate underlayment — the attached pad handles it. But over existing tile or for sound reduction, you might need one. I made the mistake of specifying a standard foam pad that trapped moisture. Cost: $890 in redo plus a 1-week delay.

Checklist:

• Use only Karndean-approved underlayments (e.g., Karndean Acousti-Pebble).
• Vapour barrier is mandatory over concrete slabs in grade-level or below-grade.
• If existing subfloor is epoxy floor coating (I've seen it): check adhesion. Epoxy must be well-bonded and free of contaminants. Otherwise, pour a self-leveller over it.

Step 4: Laying Pattern & Expansion Gaps

Even after choosing a nice herringbone pattern, I kept second-guessing. What if I staggered the planks wrong? The two weeks until the first install were stressful. Didn't relax until I saw the floor actually locked together.

Practical tips:

• Stagger end joints at least 6 inches for rigid core.
• Leave a ¼-inch expansion gap along all walls, pipes, and doorframes. (I once forgot at a doorway — had to remove three planks.)
• For Korlok Select: click-lock system requires a slight angle (25-30°) when connecting long sides. Many installers try to force it flat — that breaks the tongue.

Step 5: Price Reality Check for Korlok Select

Everyone asks "what's your best price?" The question they should ask is "what's included?" For Karndean Korlok Select, here's what I've seen on invoices over the past 12 months:

• Material cost: $3.50–$5.00 per sqft (distributor pricing, East Coast, Q2 2024–Q1 2025). Expect higher for premium designs.
• Add-ons: Adhesive for glue-down edges (some jobs require it), transition strips ($15–$40 each), and baseboards.
• Installation labor: $2.00–$4.00 per sqft for standard click-lock; add 50% for herringbone.

Hidden cost: Sample fees. I've seen clients order 10+ samples at $5 each before committing. That adds up. I wish I had tracked that more carefully — my sense is it's around $50–$80 per project just in samples.

Step 6: Final Cleaning & Protection

After locking the last plank, resist the urge to walk on it for 24 hours (especially for glue-down edges). Then clean with a damp microfiber mop — no harsh chemicals. (Oh, and if you're wondering how to clean a stainless steel sink after an LVT install? Same rule: mild soap, soft cloth, no abrasive pads.)

One last thing: shower shoes. In bathrooms, Karndean rigid core works beautifully. But don't install it directly under a shower — use waterproof shower liner first. The term "shower shoes" came from a client who wanted non-slip footwear for the wet area. We installed Karndean with a textured finish, and it's worked great for two years.

Common Mistakes I've Seen (and Made)

• Expansion gap too small — Causes buckling in summer humidity. Rule: ¼ inch minimum, and don't fill with silicone (use baseboards to cover).
• Click-lock not fully engaged — Check every joint by running a putty knife along the seam. If it catches, it's not locked.
• Using the wrong transition strip — Karndean has specific profiles for rigid core. A standard T-mold can crack under the thickness.
• Ignoring subfloor fasteners — Screws or nails left proud will telegraph through the vinyl. Use a scraper to find them (I missed one on a $3,200 order — had to replace a plank).

"What was best practice in 2020 may not apply in 2025. The fundamentals haven't changed, but the execution has transformed — especially with rigid core click systems. Always verify against Karndean's latest installation guide."

Disclaimer: Price data based on my experience with Northeast US distributors from January 2024 to January 2025. Actual prices vary. Always get current quotes.