Install the vapour barrier on the warm side of the insulation (the side facing the interior of your home in cold climates) to prevent warm, moist air from condensing inside the wall or ceiling cavities. In hot, humid climates, this placement may be reversed to keep hot, outdoor moisture out.
A vapor barrier must always be installed on the warm side of your insulation based on your local climate. This prevents moisture from warm air reaching cold surfaces, which causes condensation, mold, and rot.
Don't Skip Sealing Seams, Edges, and Penetrations
A vapor barrier with unsealed seams fails at every gap. Moisture and soil gases enter through even small openings. Overlap panels by at least 12 inches and tape every seam.
Whether you need a vapor barrier for Luxury Vinyl Plank (LVP) depends entirely on your subfloor. It is mandatory over concrete to prevent moisture damage and mold, but it should never be used over wood subfloors, as it traps moisture and causes rotting.
You should avoid using a traditional, impermeable vapor barrier (like polyethylene plastic sheet) when it traps moisture instead of letting the wall system dry. If moisture gets into a wall, the barrier prevents it from escaping, leading to mold, mildew, and wood rot.
The Cons of Vapor Barrier Installation
Although vapor barriers aim to prevent moisture from entering the structure, they can also trap moisture inside. If not properly installed or upheld, this could result in the proliferation of mold and other issues related to moisture.
There are a wide number of materials available to create effective vapor barriers, including:
No, standard Tyvek cannot be used as a traditional vapor barrier. Tyvek is a housewrap designed as an air and moisture barrier. It keeps bulk water out but is highly vapor-permeable, allowing moisture to escape the wall to prevent rot and mold.
Vapor barriers and laminate flooring underlayment
If your installation is over concrete, we recommend a 6-mil-poly vapor barrier – even if the underlayment you are installing already has a vapor barrier attached.
The "Rule of 3" in flooring is a design principle that recommends using no more than three distinct flooring materials or color variations throughout your entire home. Limiting your design to three elements creates visual cohesion, prevents a chopped-up layout, and ensures smooth, intentional transitions from room to room.
If humidity stays high enough in your crawl space or basement, mold will grow — even if you have a vapor barrier in place. Installation matters enormously, too. A barrier with gaps, loose edges, or sections that weren't sealed properly can actually trap moisture rather than block it.
In basements, installing a vapor barrier on the interior wall in front of the insulation and behind the drywall will keep the basement temperature consistent and protect its contents from water vapor damage.
Salt is hygroscopic, meaning it naturally attracts and absorbs moisture from the air. When placed next to a cold window pane, it can help reduce the amount of water that collects overnight — particularly in small rooms or on single-glazed windows.
A vapor barrier should generally go on the warm side of the insulation (toward the interior of the home) in cold climates, and on the outside (exterior) in hot, humid climates. This placement prevents warm, moist air from hitting a cold surface and condensing inside your wall cavities.
Unfaced insulation is great for new construction, remodels, walls, floors, ceilings, basements, attics and crawlspaces. It's best used for interior wall applications that do not face the outside and also in rooms that don't need moisture control, like living rooms, dining rooms and studies.
Proper vapor barrier installation requires placing the material on the warm side of the wall (facing inward in cold climates, outward in hot climates). Use a minimum 6-mil polyethylene sheet (or higher for durability), overlap all seams by at least 6 inches, and completely seal the edges, cuts, and overlaps using acoustical sealant or vapor barrier tape.
In 2026, flooring trends revolve around warmth and natural textures, with cool, flat grays officially on their way out. The most popular colors include:
The wrong flooring choice can make a room look off and cause maintenance and cleaning issues. Designers say one of the worst flooring options is luxury vinyl planking for its upkeep and poor quality. Other flooring choices to avoid include mosaic tile, dark wood floors, and shiny wood flooring.
The 3-5-7 rule is a design principle that dictates grouping decorative objects, furniture, or art in odd numbers (specifically 3, 5, or 7). It breaks rigid, perfectly symmetrical pairings to create natural, eye-catching visual movement.
Whether you need a vapor barrier under Luxury Vinyl Plank (LVP) depends primarily on your subfloor. Always check your specific product's warranty requirements, but use these general rules of thumb:
3mm Moisture Lock is one of the best underlays for laminate flooring with a vapour barrier membrane already included.
While most waterproof flooring does not need a vapor barrier, there are a few exceptions. In areas with extremely high moisture levels or concrete subfloors, a moisture barrier may still be recommended.
Yes, mold can absolutely grow under a vapor barrier. While vapor barriers are designed to block moisture, any moisture that gets trapped beneath the barrier—due to a plumbing leak, groundwater seepage, or poor installation—will create a prime environment for mold to grow, out of sight.
The ZIP System and Tyvek both act as weather-resistive barriers (WRBs), but they work very differently. ZIP replaces standard sheathing and housewrap with an all-in-one coated board and taped seams. Tyvek is a breathable housewrap layered over standard oriented strand board (OSB) or plywood.
Because spray foam can trap moisture, hide the condition of the roof, make it difficult for surveyors to inspect, which means risks like timber decay, dry rot, and not forgetting increased fire risk. If you've got it or you're buying a property that does, this is something you need to know upfront.