What is the best underlayment for kitchen LVP flooring in NB?

The best underlayment for kitchen LVP flooring in New Brunswick is a closed-cell foam or cross-linked polyethylene (XLPE) underlayment with an attached vapour barrier, typically 1.5 mm to 2 mm thick. This combination handles NB's seasonal humidity swings, provides moisture protection on concrete and older subfloors, and adds enough cushion for comfort without compromising the click-lock connection.

Before choosing an underlayment, check your LVP product specifications. Many LVP planks sold in NB already come with a pre-attached underlayment pad on the bottom of each plank. If your LVP has this attached pad, do not add a separate underlayment on top of it. Doubling up underlayment creates too much cushion, which causes the click-lock joints to flex, separate, and eventually fail. If your LVP has an attached pad, you may still need a standalone vapour barrier (6-mil polyethylene sheeting) over concrete subfloors, but skip the foam underlayment.

For LVP without a pre-attached pad, a quality underlayment serves three purposes in an NB kitchen: moisture protection, sound dampening, and minor subfloor imperfection correction.

Moisture Protection

This is the most critical function in New Brunswick. NB's humidity swings from 15 to 25 percent in winter to 60 percent or more in summer, and concrete basement or slab subfloors transmit ground moisture year-round. A vapour barrier underlayment prevents moisture from migrating up through the subfloor and attacking the LVP core from below. Even on plywood subfloors in above-grade kitchens, a vapour barrier is good insurance in NB's Maritime climate. Look for underlayment products with an integrated 6-mil poly vapour barrier, or lay separate 6-mil poly sheeting before placing the foam underlayment.

On concrete subfloors, always do a moisture test before installing LVP. Tape a 2-foot square of plastic sheeting to the concrete and leave it for 48 to 72 hours. If moisture collects under the plastic, you have a vapour transmission issue that a standard underlayment alone may not solve. You may need a more robust moisture mitigation system before proceeding.

Recommended Products and Costs

Popular underlayment choices available at NB building supply stores include Floor Muffler (XLPE, excellent moisture barrier, $0.35 to $0.55 per square foot), QuietWalk (recycled fibre with vapour barrier, $0.50 to $0.75 per square foot), and basic cross-linked poly foam ($0.15 to $0.30 per square foot). For a typical NB kitchen of 100 to 150 square feet, underlayment costs run $25 to $100 for the material itself.

Avoid cork underlayment in NB kitchens. While cork offers excellent sound dampening, it absorbs moisture and can develop mold in NB's humid summers, especially in lower-level kitchens or homes without air conditioning. Also avoid thick, spongy underlayments marketed for comfort. Anything thicker than 2 mm under LVP causes excessive flex in the joints.

When installing the underlayment, overlap the vapour barrier seams by at least 6 inches and tape them with moisture-barrier tape. Run the underlayment up the wall edges by half an inch, which gets hidden behind the baseboard. On plywood subfloors, make sure the subfloor is clean, dry, and level within 3/16 of an inch over 10 feet. Any high spots or dips beyond this tolerance should be sanded down or filled with floor levelling compound ($30 to $80 per bag) before the underlayment goes down. Proper subfloor preparation is the foundation of a long-lasting LVP kitchen floor in any NB home.

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Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• Gionetterenovations
• Thirty Four Renovations