Rigid Foam Board Insulation: Pros and Cons (2023)

FAQs

Rigid Foam Board Insulation: Pros and Cons? ›

Disadvantages. Rigid foam insulation in wall cavities must be tightly fitted to stop air infiltration. Joints between sheets and boards must be taped to prevent air flow. Rigid foam is susceptible to sunlight.

Disadvantages. Rigid foam insulation in wall cavities must be tightly fitted to stop air infiltration. Joints between sheets and boards must be taped to prevent air flow. Rigid foam is susceptible to sunlight.

Common polystyrene foam insulation board is easy to burn, and toxic smoke produced by combustion. Even adding a flame retardant, the combustion can only reach B grade. 3. Material strength is poor, prone to crack and insulation shedding phenomenon is relatively common.

More effective insulation

With R-values ranging from 3.6 to 8.0, rigid foam sheathing has much better insulation per inch than other materials (i.e. plywood has an R-value of 1.25 and fiberglass batts have an R-value of 3.14).

Vapor barriers are often installed in basements and crawl spaces to prevent ground moisture from leaking in. In houses with spray foam insulation, however, vapor barriers are not necessary.

In some cases, PIR rigid foam insulation may be combined with other types of insulation, such as batt insulation. In these situations, it may be necessary to use a vapour barrier to ensure proper moisture control and prevent moisture from building up between the insulation layers.

Typical Insulation Lifespan

The International Association of Certified Home Inspectors states that spray foam insulation, wrap tape and housewrap insulation can last for more than 80 years. At the same time, cellulose, loose-fill, foamboard, loose fill and rock wool insulation can last up to 100 years.

Because of its resistance to moisture, foam board insulation is a great choice whenever and wherever there is a chance it could get wet, such as: an exterior foundation, inside a basement against the foundation, and on the outside of a house beneath a house wrap.

Foam board insulation provides good thermal resistance and reduce heat conduction through structural elements, such as wood and steel studs, according to the U.S. DOE.

How long does rigid foam insulation last? ›

Due to its firmness and water resistance, rigid foam insulation will generally last 100 years or more.

The R-value of rigid foam insulation varies based on the materials used and how many layers are installed. For example, our polyiso rigid foam boards have R-values between 6.5 and 6.8 per inch. If two layers are installed, it doubles the R-value and cuts heat/conditioned air loss in half.

Drywall, either Standard or Fireguard, is normally used for this purpose because of its low cost and fire-resistant qualities. Other wall coverings may be available that will meet the criteria for fire protection but they will likely be more costly and sometimes more difficult to install.

Fiberglass batt is considered to be the best insulation for attics. Compared to other insulation materials, it is the cheapest and easiest to install. Fiberglass batt is also incredibly energy efficient, as it helps to slow the spread of hot and cold air.

When compared with other insulation products, spray foam insulation offers the highest R-Value per installed inch. Because spray foam will completely seal and insulate the “building envelope”,, allowing for the ultimate in thermal protection (and R-Value). Spray foam can be closed-cell or open-cell.

With R-values reaching R-10 for a 2-inch board, foam board doesn't have nearly the insulating capacity of even standard R-13 fiberglass insulation. But foam board's tight-pore resistance to moisture makes it the favored product on exterior walls over highly porous fiberglass or rockwool.

Most panels range between 3/8″ and 2.5″ in thickness, though other dimensions and thicknesses are usually available through custom order.

Interior foam keeps the framing cooler for most of the year (particularly in cold, wet climates), which reduces the drying potential and requires perfect flashing and siding details. Exterior foam keeps the framing warm and dry, which makes the wall more tolerant to occasional leaks because the wall can dry.

ALL FOAM SHOULD BE COVERED BY A THERMAL BARRIER WHEN USED INSIDE A HOME.

How flammable is rigid foam insulation? ›

Rigid polyurethane and polyisocyanurate foams will, when ignited, burn rapidly and produce intense heat, dense smoke and gases which are irritating, flammable and/or toxic.

You need 2" of continuous closed cell foam to eliminated the need of a vapour barrier otherwise don't bother with foam.

Yes, you absolutely should wax your foamie. But, there are certain techniques and considerations that should be taken into account when waxing foamies. In this article, we'll discuss how to properly wax a foam surfboard, the best practices for doing so, and the best products on the market for foamies.

A popular rigid insulation choice, XPS features an initial R-value of R-5 per inch. That said, the long term R-values of this foam board decline over time. For example, after just 5 years, an XPS board will see its R-value fall by 10%, and even more going forward.

Left uncovered these boards' physical and insulative properties begin to weaken. First, their color fades, then the foam core suffers from powder chalking, and finally, the R-values deteriorate. To protect XPS foam boards from degradation, they must be covered within 60 days at the most.

The bigger the surface area, the thicker the foam board must be. For sizes of 100 by 140 cm upwards, you should choose 10 mm thick foam board, for which the maximum surface area is 140 by 300 cm. The 10 mm thick foam board has more body, due to its greater rigidity.

Fiberglass Insulation

Fiberglass is the most common type of insulation used for residences because it is by far the best, particularly for hot climates. Here's why: Fire-retardant – Fiberglass insulation is fire-retardant, making it an ideal choice for homes in dry climates and areas prone to fire.

Fiberglass Insulation

This type of insulation material is widely available and comes in various shapes and sizes. For cold climates, Loose-fill Fiberglass Insulation is the best as it has an R-Value of 60.

Yes, foam board insulation is an excellent complement to batt insulation. Foam board insulation can add insulation and eliminate thermal bridging when used in wall and ceiling assemblies insulated with batts. It can potentially replace the vapor barrier and house wrap as well.

What is the best type of rigid foam insulation? ›

Polyisocyanurate. Also known as ISO or polyiso, this is considered the eco-friendly option when it comes to rigid foam insulation. This contains roughly 9% recycled materials and has a higher R-value, at 6.5 per inch on average.

Using air-permeable insulation with rigid foam

The easiest way to create the necessary air gap is to install wooden spacers (3⁄4 in. or 1 in. sq.) in the corners of each stud bay. These vertical spacers need to be tacked to the framing, up against the siding.

While some types of rigid insulation can stand up to water and moisture, most lose some of their thermal resistance as they become more saturated. Despite the closed-cell structure of EPS, XPS, and polyisocyanurate, water can still be absorbed into the gaps between each bead.

Aerogel insulation offers the highest R-value of any insulating material at less weight and thickness—ideal for construction, refineries, pipelines, and thin-gap thermal barriers.

With an R-value of 13.1 for a 2" thick sheet only two 2" sheets are required to achieve R-25. 2. Extruded polystyrene or XPS (foam is usually pink or blue) XPS has an R-value of 5 per inch of thickness requiring 5" of insulation to achieve R-25.

Type 1 polystyrene insulation has a typical thermal resistance value or R3. 7/in., while Type 2 polystyrene insulation has a minimum thermal resistance value of R4. 0/in. Type 1 is moulded bead polystyrene.

When building or renovating a high-performance building envelope there are really three main kinds of rigid foam panels you are going to have to choose from - Polyisocyanurate known as Polyiso (PIR), Extruded Polystyrene (XPS) - often called Styrofoam - and Expanded Polystyrene (EPS).

This application is not typically recommended for the following reasons: Rigid foam board pieces are difficult to fit snugly between studs so you would have to spray foam to fill any gaps. Unlike loose-fill or batt, foam board insulation can't easily be cut to perfectly contour around pipes or wires.

Rigid foam board, especially foil-faced polyisocyanurate, creates a vapor-impermeable barrier, so the wall would have limited drying potential.

What is the best insulation for an old attic? ›

If you check with the North American Insulation Manufacturers Association, they'll assure you that fiberglass or mineral wool is definitely your best choice for attic insulation.

Excess insulation in the attic can make a house too tightly sealed and block vents. If airflow is blocked, moisture can't escape. If moisture accumulates in the attic and comes into contact with warm air, that can allow mold to grow, which can result in serious respiratory problems in people.

Relatively inexpensive and simple to install, batt insulation works well in attics and can be a good choice if you're hoping to DIY your insulation project. It's sold in rolls and installed in strips that can be cut to fit small spaces. The average price per square foot for batt insulation is about $2 to $4.

Exceptional moisture control: Spray foam fills a space better than rigid board, making it a better insulator against moisture. This can be valuable in humid climates. Longevity: Insulation can be complicated to replace, but spray foam is designed to last a long time.

Spray foam insulation is fantastic at insulating, but it's not the best insulation for soundproofing. Open-cell spray foam performs better at sound absorption than closed-cell. It will reduce noise between rooms and homes and has a similar effect to hitting a drum with a kitchen sponge.

Cavity wall insulation is the easier and cheaper method of insulating your property and is typically the approach on houses built after 1920. This method involves filling the cavity between the two layers of bricks that make up your outside walls.

It is rigid, brittle, relatively hard and has excellent gamma radiation resistance, good electrical properties but has poor chemical and UV resistance.

Expanded polystyrene foam boards are made with air bubbles that stop heat transfer. Unfortunately, those same air bubbles collect moisture which leads to mold and mildew growth. Solution: Rigid foam board insulation products are actually made to be water resistant.

Rigid polyurethane and polyisocyanurate foams will, when ignited, burn rapidly and produce intense heat, dense smoke and gases which are irritating, flammable and/or toxic.

Rigid foam board insulation has enormous benefits, including high R-values, continuous insulation wrapping your home, and moisture control. Other benefits include preventing thermal bridging, controlling moisture, preventing air leaks, and using on both sides of the wall or ceiling.

What are the disadvantages of polystyrene foam? ›

Polystyrene is slow to degrade, and if disposed of improperly, the foam can leach chemicals into the environment harming water sources. Polystyrene manufacturing is an enormous creator of hazardous waste. Furthermore, polystyrene manufacturing greatly contributes to global warming.

The key difference between rigid foam insulation and traditional insulation is, as you might expect, the strength of the material. Unlike batt and blown insulation, rigid foam won't blow or shift out of place once it's installed. It also is water and pest resistant, making it perfect for basements and crawl spaces.

When to use foam board insulation? Because of its resistance to moisture, foam board insulation is a great choice whenever and wherever there is a chance it could get wet, such as: an exterior foundation, inside a basement against the foundation, and on the outside of a house beneath a house wrap.

Foam board can be used to insulate any exposed cavity in your home from the top to the bottom, and even the walls if you are remodeling and the drywall is down. It can also be installed in the open cavities of your pole barn.

While some types of rigid insulation can stand up to water and moisture, most lose some of their thermal resistance as they become more saturated. Despite the closed-cell structure of EPS, XPS, and polyisocyanurate, water can still be absorbed into the gaps between each bead.

Foam insulations commonly contain toxic flame retardants, and spray foam contains asthma-causing isocyanates. These products are also petroleum-based and can have significant impacts on communities throughout the manufacturing process.

Yes, absolutely. If you put spray foam insulation in a building, it needs a thermal barrier. That's what separates it from the occupied spaces. If there's a fire in the building, a thermal barrier keeps the combustible spray foam from the flames to increase fire resistance.

It's completely non-toxic and won't create any off-gas into your home as foam products do. This means that it won't lose R-value over time and allows for better air quality.