Question 1

How does polyisocyanurate rigid foam compare to XPS board insulation for R-value retention in cold New Brunswick winters?

Accepted Answer

Polyisocyanurate (polyiso) loses significant R-value in NB's cold winters, while XPS maintains consistent performance — making XPS the better choice for exterior applications in our Climate Zone 6 conditions.

Polyiso's Cold Weather Performance Problem

Polyiso rigid foam is rated at R-6 to R-6.5 per inch at laboratory test temperatures (around 75°F/24°C), but its R-value drops dramatically as temperatures fall. At 20°F (-7°C) — a typical winter day in New Brunswick — polyiso delivers only about

Question 2

How do I properly tape and seal the seams of rigid foam board insulation I installed myself in a Moncton home?

Accepted Answer

Properly sealing rigid foam seams is critical for maintaining the thermal barrier and preventing air leakage — gaps as small as 1/8 inch can reduce your insulation's effectiveness by 25% or more. The key is using the right tape for your foam type and ensuring clean, dry surfaces for maximum adhesion.

For XPS rigid foam (pink or blue board), which is most common for basement applications in Moncton homes, use Tyvek tape, Zip System tape, or high-quality foil tape specifically rated for foam boar

Question 3

Are there NB Building Code requirements for the thickness of rigid foam board used in Campbellton basement walls?

Accepted Answer

The NB Building Code requires R-17 to R-20 for below-grade basement walls, but doesn't specify rigid foam thickness directly — it's the R-value that matters. For Campbellton's cold northern climate, you'll want to hit the higher end of this range.

To meet code with rigid foam in Campbellton, you'll need 3.5 to 4 inches of XPS (extruded polystyrene) at R-5 per inch, or 4 to 5 inches of EPS (expanded polystyrene) at R-4 per inch. XPS is the better choice for Campbellton basements because it maint

Question 4

What is the total installed cost comparison between polyiso and XPS rigid foam board for insulating a Saint John NB foundation from the exterior?

Accepted Answer

For exterior foundation insulation in Saint John, XPS rigid foam will cost approximately 15-25% less than polyiso and is the better choice for NB's cold climate. XPS typically runs $2.00-$4.00 per square foot installed versus polyiso at $2.50-$5.00 per square foot installed.

Why XPS is Superior for Saint John Foundations

The cost difference becomes more significant when you consider performance in New Brunswick's climate. Polyiso's R-value drops dramatically in cold temperatures — while it's r

Question 5

How does rigid foam board perform against moisture in coastal NB areas like Shediac? | Insulation IQ?

Accepted Answer

Coastal communities in New Brunswick — Shediac, Bouctouche, Cap-Pelé, Baie-Verte, and the broader Northumberland Strait shoreline — face an insulation challenge that inland cities like Fredericton and Woodstock don't contend with to the same degree. Salt-laden air, higher average relative humidity, wind-driven rain, and freeze-thaw cycling near the ocean all combine to create an environment where moisture management is arguably more important than raw R-value. Rigid foam board handles these cond

Question 6

Can I use rigid foam insulation in a cathedral ceiling in New Brunswick? | Insulation IQ?

Accepted Answer

Rigid foam insulation is not only compatible with cathedral ceiling assemblies in New Brunswick — for many situations, it's the most effective solution available, and in some configurations it's the only approach that fully solves the technical challenges a cathedral ceiling presents in Climate Zone 6. That said, doing it correctly requires understanding a few non-negotiable principles around ventilation, vapour control, and R-value minimums.

The core challenge of a cathedral ceiling is that, u

Question 7

Is foil-faced rigid foam better than unfaced for New Brunswick basements? | Insulation IQ?

Accepted Answer

For New Brunswick basements, the choice between foil-faced and unfaced rigid foam board matters more than most homeowners realize — and in most situations, foil-faced polyisocyanurate (polyiso) or foil-faced XPS offers distinct advantages that make it the preferred choice along basement walls.

Foil-faced rigid foam uses a reflective aluminium facing laminated to one or both sides of the foam core. That facing serves two functions simultaneously: it acts as a radiant barrier, reflecting heat bac

Question 8

Does rigid foam board create a moisture barrier on NB foundation walls? | Insulation IQ?

Accepted Answer

Rigid foam board does act as a significant vapour retarder on New Brunswick foundation walls, but whether it functions as a full moisture barrier depends on the type of foam used, how it's installed, and what you mean by moisture barrier. Understanding this distinction is critical for avoiding condensation problems, mould growth, and long-term structural damage in a climate as demanding as New Brunswick's.

All three major types of rigid foam — EPS (expanded polystyrene), XPS (extruded polystyre

Question 9

What is the cost of rigid foam board insulation per sheet in Saint John NB? | Insulation IQ?

Accepted Answer

Rigid foam board insulation prices in Saint John and throughout New Brunswick have remained relatively stable following the volatility of recent years, though regional supply chain factors and the local building supply market do create some variation compared to central Canadian pricing. Understanding what you should expect to pay per sheet — and what drives those price differences — helps you budget accurately and evaluate quotes.

The most commonly purchased sheet size is 4 feet by 8 feet (4x8

Question 10

What R-value does 2-inch rigid foam provide and is it enough for NB code? | Insulation IQ?

Accepted Answer

A 2-inch sheet of rigid foam insulation provides varying thermal resistance depending on which type you choose, and understanding these differences is essential before deciding whether it meets New Brunswick's building code requirements. Expanded polystyrene (EPS) at 2 inches delivers approximately R-8, extruded polystyrene (XPS) provides roughly R-10, and polyisocyanurate (polyiso) achieves approximately R-12 to R-13 at the same thickness. These are nominal values — polyiso in particular loses

Question 11

How do I seal joints between rigid foam boards in my Dieppe basement? | Insulation IQ?

Accepted Answer

Sealing the joints between rigid foam boards in your Dieppe basement is one of the most important steps in achieving an effective air barrier — and it's a detail that gets skipped or done incorrectly far too often. Air leakage through unsealed foam board seams can dramatically reduce the effective performance of the insulation, allow warm interior air to reach the cold foundation wall, and create conditions for condensation and mould growth in the wall cavity. Getting this right matters especial

Question 12

Is polyiso rigid foam board effective in cold New Brunswick temperatures? | Insulation IQ?

Accepted Answer

Polyisocyanurate, commonly called polyiso, is one of the most efficient rigid foam board products available — but it has a well-documented performance characteristic that New Brunswick homeowners and builders need to understand before choosing it for cold-climate applications. The short answer is: polyiso is excellent in many NB applications but should be used carefully in locations where it will be continuously exposed to very cold temperatures.

The thermal drift issue with polyiso is real and

Question 13

Can rigid foam insulation be used under a basement floor slab in NB? | Insulation IQ?

Accepted Answer

Rigid foam insulation under a basement floor slab is not only possible in New Brunswick — it is one of the most important and underutilised insulation measures available to NB homeowners, particularly in new construction. In Climate Zone 6, the ground beneath a basement slab sits at a relatively stable temperature of around 6–10°C year-round, but in winter that is still cold enough to create a significant heat sink when an uninsulated concrete slab is in direct contact with it. Adding rigid foam

Question 14

How do I attach rigid foam insulation to concrete foundation walls in Moncton? | Insulation IQ?

Accepted Answer

Attaching rigid foam insulation to concrete foundation walls in Moncton requires a bit more care than most homeowners expect, primarily because concrete is porous, can be damp, and doesn't accept fasteners the way wood framing does. The good news is there are several reliable methods, and the right choice depends on whether you plan to leave a stud wall in front of the foam or attach it independently.

The most common approach in Moncton basements is to use construction adhesive designed for foa

Question 15

Can I use rigid foam board insulation on the exterior of my Fredericton home? | Insulation IQ?

Accepted Answer

Yes, exterior rigid foam board insulation is not only possible on a Fredericton home — it is one of the most effective upgrades you can make in New Brunswick's cold Climate Zone 6 environment. Fredericton routinely sees winters with sustained temperatures well below -20°C, and exterior continuous insulation addresses thermal bridging through your wall studs in a way that cavity insulation alone simply cannot.

How exterior rigid foam works is straightforward in principle: rigid foam panels are f

Question 16

Does rigid foam board need to be covered with drywall in NB basements? | Insulation IQ?

Accepted Answer

Yes, in the vast majority of New Brunswick basements, rigid foam board insulation must be covered with a thermal barrier — and 12.7mm (½-inch) drywall is the standard material used to satisfy that requirement. This is not an optional finishing step; it is a fire protection requirement under the National Building Code of Canada as adopted in New Brunswick, and it applies to any exposed foam plastic insulation used in a space accessible to building occupants.

The reason comes down to the combusti

Question 17

How thick should rigid foam board be on a New Brunswick foundation wall? | Insulation IQ?

Accepted Answer

Foundation wall insulation is one of the most cost-effective upgrades a New Brunswick homeowner can make, and getting the thickness right directly determines how comfortable your basement is and how much you pay to heat it. The New Brunswick Building Code — which adopts the National Building Code of Canada — requires a minimum of R-10 for basement walls in most residential applications under Part 9, but that is a minimum, not a recommendation. For Climate Zone 6, which covers essentially all of

Question 18

What is the difference between XPS and EPS rigid foam for New Brunswick homes? | Insulation IQ?

Accepted Answer

XPS and EPS are both rigid foam board insulation products used extensively in New Brunswick homes, but they differ in manufacturing process, performance characteristics, environmental impact, and cost. Choosing between them is not simply a matter of picking the cheaper option — the application location and moisture conditions in NB's Climate Zone 6 environment make certain properties much more important depending on where in the house you are insulating.

XPS (Extruded Polystyrene) is manufactur

Rigid Foam Board