Question 1

What thickness of plywood subfloor is required under ceramic tile in a second-floor NB bathroom?

Accepted Answer

For a second-floor bathroom in New Brunswick, you need a minimum 1-1/8 inch (28mm) combined subfloor thickness under ceramic tile, typically achieved with 3/4 inch plywood subfloor plus 1/2 inch cement board backer.

The structural requirements for tile installation are more demanding than other flooring types because ceramic and porcelain tiles are rigid and will crack if the subfloor deflects under load. In NB's older housing stock, many second-floor bathrooms have 5/8 inch or 3/4 inch plywood

Question 2

How much does it cost to add rigid foam insulation under a basement subfloor system in New Brunswick?

Accepted Answer

Adding rigid foam insulation under a basement subfloor system in New Brunswick typically costs $3-$8 per square foot installed, depending on insulation thickness, access conditions, and whether you're building a new subfloor system or retrofitting an existing one.

This type of insulation upgrade makes excellent sense in New Brunswick's climate. Our long heating season (October through April) means basement floors stay uncomfortably cold without proper thermal separation from the concrete slab.

Question 3

What are the signs that subfloor water damage has spread to the floor joists in a NB home?

Accepted Answer

Water damage that has spread from the subfloor to floor joists creates serious structural concerns that require immediate professional assessment. In New Brunswick's Maritime climate, this progression happens faster than in drier provinces due to our persistent humidity and slower drying conditions.

Visual indicators are your first warning signs. Look for dark staining or discoloration on exposed joist edges in basements or crawl spaces — this appears as brown, black, or gray streaking that was

Question 4

What subfloor ventilation is needed under a raised floor system in a damp NB crawl space?

Accepted Answer

Proper subfloor ventilation in a damp NB crawl space requires cross-ventilation with foundation vents spaced every 8-10 feet around the perimeter, plus vapour barriers and moisture management to prevent flooring problems above.

In New Brunswick's Maritime climate, crawl space moisture is one of the most serious threats to flooring performance. Spring snowmelt, summer humidity, and our high water table create persistently damp conditions under raised floor systems. Without adequate ventilation,

Question 5

How do I insulate a subfloor over an unheated crawl space to prevent cold floors in a Bathurst winter?

Accepted Answer

Insulating the subfloor over an unheated crawl space is essential in Bathurst's harsh winters, but this falls outside flooring installation and into general construction and insulation work. For comprehensive guidance on crawl space insulation, vapor barriers, and thermal bridging solutions, I'd recommend connecting with insulation and general construction professionals through the New Brunswick Construction Network.

However, I can share how cold subfloors directly impact your flooring choices

Question 6

What is self-levelling compound and when do I need it for NB flooring?

Accepted Answer

Self-levelling compound is a cementitious mixture that you pour over an uneven concrete or wood subfloor to create a flat, smooth surface for flooring installation. It flows out like thick pancake batter, finds its own level through gravity, and hardens into a stable, flat surface — typically within 4–24 hours depending on the product and thickness. In New Brunswick, where many homes have older concrete basement slabs and aging wood subfloors, self-levelling compound is one of the most commonly

Question 7

Should I remove old vinyl before installing new flooring or can I go over it in NB?

Accepted Answer

In many cases you can install new flooring directly over old vinyl in New Brunswick, but there are critical conditions that must be met — and one safety issue that could change your approach entirely. The decision depends on the age of the vinyl, its current condition, and what type of new flooring you plan to install.

The most important consideration is asbestos. Vinyl flooring and the black adhesive (known as cutback adhesive) used in NB homes built before 1986 commonly contain asbestos fibre

Question 8

Do I need underlayment for every type of flooring in my NB home?

Accepted Answer

No, not every flooring type requires a separate underlayment — but in New Brunswick's Maritime climate, some form of moisture protection is needed for almost every installation, especially over concrete. The answer depends on your flooring type, subfloor material, and whether you are installing above or below grade.

Here is a breakdown by flooring type for NB conditions.

Laminate flooring always requires underlayment. Laminate's HDF core is vulnerable to moisture from below, and the floating i

Question 9

How do I deal with moisture coming through my NB basement concrete slab?

Accepted Answer

Moisture migrating through a basement concrete slab is one of the most common flooring challenges in New Brunswick, and addressing it before installation is absolutely essential. The Maritime water table sits close to the surface across much of the province, and concrete is naturally porous — it acts like a giant sponge, wicking moisture vapour upward continuously. If you install flooring directly over a damp slab without proper moisture management, you are setting yourself up for mould, mildew

Question 10

How flat does a subfloor need to be for LVP installation in NB?

Accepted Answer

Your subfloor must be flat to within 3mm over a 2-metre span (roughly 1/8 inch over 6 feet) for luxury vinyl plank installation — and in New Brunswick's climate, hitting this tolerance matters even more than in drier provinces. LVP is a thin, semi-flexible material that conforms to whatever is beneath it, so every bump, dip, and ridge in your subfloor will eventually show through the finished floor.

To check your subfloor's flatness, lay a long straight edge (a 6-foot level or a straight 2x4) a

Question 11

What causes soft spots in subfloors of older New Brunswick homes?

Accepted Answer

Soft spots in older NB subfloors are almost always caused by moisture damage — either rot in the subfloor sheathing, deterioration of the floor joists below, or a combination of both. New Brunswick's Maritime climate makes this one of the most common structural issues in the province's older housing stock, and it should never be ignored.

The most frequent cause is prolonged moisture exposure from below. Older NB homes often have crawl spaces or basements with inadequate or missing vapour barrie

Question 12

How do I test concrete moisture levels before flooring installation in New Brunswick?

Accepted Answer

Testing concrete moisture before flooring installation is one of the most important steps in any NB basement or slab-on-grade project — and skipping it is gambling with thousands of dollars. New Brunswick's Maritime water table and seasonal moisture cycles make this step even more critical here than in drier provinces.

There are three main testing methods, each with different levels of accuracy and cost.

The calcium chloride test (ASTM F1869) is the most widely used quantitative method for NB

Question 13

What is the cost of subfloor repair in a New Brunswick home?

Accepted Answer

Subfloor repair in a New Brunswick home typically costs $1-$5 per square foot depending on the type and extent of damage, with most whole-room repairs falling between $500 and $3,000. The wide range reflects the reality that subfloor problems vary enormously — from minor re-screwing to full structural joist repair.

Here is a breakdown of common subfloor repair costs in the NB market for 2025-2026. Minor repairs such as re-screwing loose plywood panels to eliminate squeaks, patching small damage

Question 14

Can I install new flooring over old board subfloors in a pre-1970s NB home?

Accepted Answer

Yes, you can install new flooring over old board subfloors, but not directly — you will almost certainly need a plywood overlay first to create a smooth, stable surface. Pre-1970s New Brunswick homes commonly have diagonal or straight-laid board subfloors made of 1x6 or 1x8 spruce or fir boards, and while these are structurally sound in most cases, they are too uneven and gappy for modern flooring materials.

The gaps between old boards are the primary problem. Individual boards shrink and swell

Question 15

What type of subfloor preparation is needed for tile installation in NB?

Accepted Answer

Tile installation in New Brunswick demands the most thorough subfloor preparation of any flooring type — and getting it right accounts for 60-70% of a tile job's long-term success. A poorly prepared substrate is the number one reason NB homeowners see cracked tiles and failed grout within one to three years of installation.

The substrate underneath your tile must be structurally rigid, perfectly flat, and resistant to moisture movement. For wood-framed floors (the majority of NB homes), this me

Question 16

How do I level an uneven concrete basement floor before installing flooring in NB?

Accepted Answer

Levelling an uneven concrete basement floor requires self-levelling compound for most NB basements, though the approach depends on how severe the unevenness is and what flooring you plan to install on top. Minor imperfections under 6mm can often be addressed with a floor patch compound and a straight edge, while larger dips and slopes need a full self-levelling pour.

Before you touch the concrete with any levelling product, moisture testing is the critical first step in every New Brunswick base

Question 17

Do I need to replace my plywood subfloor before new hardwood in my older NB home?

Accepted Answer

Not necessarily — many older NB homes have plywood subfloors that are perfectly serviceable for new hardwood, but they need careful inspection first. The answer depends on the plywood's thickness, structural condition, moisture content, and flatness, all of which are particularly important given New Brunswick's challenging humidity cycles.

Start by checking what you actually have underneath your existing flooring. Many NB homes built before the 1970s have diagonal board subfloors rather than pl

Question 18

What moisture barrier should I use on a concrete slab in my NB basement?

Accepted Answer

For NB basements, a 6-mil polyethylene vapour barrier is the minimum requirement under any flooring, but the best choice depends on your flooring type, moisture test results, and how your basement will be used. Maritime moisture conditions make this decision more critical in New Brunswick than in most other provinces.

Concrete basement slabs in NB continuously release moisture vapour upward — our water table sits close to the surface in many communities, and the concrete never fully stops trans

Question 19

How do I fix squeaky subfloors before installing new carpet in my NB home?

Accepted Answer

Squeaky subfloors are caused by movement between the subfloor panel and the floor joists, and the best time to fix them is before new carpet goes down — once carpet is installed, repairs become far more difficult and disruptive. In New Brunswick's older housing stock, subfloor squeaks are extremely common and typically worsen with the province's seasonal humidity cycles.

The squeak itself comes from either nails that have worked loose from the joist (the nail slides up and down in the wood as y

Subfloor & Preparation