Thick foam board? (2023)

What thickness of foam board do I need?

A 5 mm thick foam board is the standard thickness used for presentations and for direct printing.

Because of their lightweight, durability, and convenient dimensions of 2'x8′ and 4'x8′, foam boards are simple to use. Most panels range between 3/8″ and 2.5″ in thickness, though other dimensions and thicknesses are usually available through custom order.

You can check this chart and see that a 2-inch ISO foam board has an R-value of R-11.6. If you have a rigid ISO foam board that is more than 9 inches thick, you can expect that the R-value of such board will be over R-50. This is more than enough even for attics (the best attic insulation is usually R-49).

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).

Black Foam Boards, 20x30 in.

To serve as a drainage plane, the seams in the foam sheathing must be properly taped with sheathing and flashing tapes to provide continuity of the drainage plane at joints between panels. The tapes must be durable enough to prevent ingress of water at panel joints for the life of the system.

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.

Insulation levels are specified by R-Value. R-Value is a measure of insulation's ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half. Each time the insulation layer is doubled in thickness, this rule applies.

What is the difference between blue and pink foam board?

Main Difference Between Pink And Blue Foam Boards

The two products also have the same insulating power. However, blue foam boards are manufactured by Dow Chemical Co. whereas the pink foam boards are manufactured by Owens Corning company. The boards are marketed under different brand names.

Polyisocyanurate: Known as polyiso for short, polyisocyanurate foam has the highest R-value per inch (R-6.5 to R-6.8) of any rigid insulation.

Because foam board insulation isn't flexible, it does a poor job filling the gaps and cracks that exist in walls. As a result, air passes though these areas. Air traveling in an out will bring moisture with it. This can lead to a multitude of problems such as mold, mildew and rot.

On the downside, spray foam insulation comes at a price that is considerably more expensive than fiberglass. Often times, spray foam is triple the price of fiberglass and sometimes it can be more. Applying spray foam insulation is also something that is not advised to do by yourself unless it is a very small job.

Foam boards will change colour, disintegrate or warp under much moisture or sunlight. Foam boards are not suitable for permanent outdoor displays.

Another substitute for foam board is rigid, moisture-resistant rock wool board. Unfortunately, it's also in short supply. If you can't find it at your local building center, rock wool batts are semi-rigid and can be a suitable alternative, depending on the application.

While a utility knife is the best cutting tool for thin boards, the best way to cut 2-inch foam board insulation is to use a saw. You can buy a circular saw blade designed for rigid foam, or if you really like to DIY things, you can make your own foam cutting blade using a grinder.

The major difference between Styrofoam and EPS foam blocks is that Styrofoam is made from extruded polystyrene (XPS) while EPS foam blocks are made of expanded polystyrene.

An air gap is important for shed insulation as it helps to keep the temperature inside stable and prevents moisture damage. There are a few different ways you can create an air gap, such as by using baffles or installing a soffit vent.

From what I understand, some tapes (including Tyvek tape) hold up pretty well on foamboard. I would prefer the tape to be foil faced, but it is more important that it hold up “forever”.

How do you hold foam board together?

The Basics. The most common joining technique when working with foam core is to use hot glue. It's quick, cheap and easy to use, much like foamcore itself. Glue can be used to join panels together or hold a corner joint closed.

That means that 4-inch EPS has an insulation R-value of R-16.8.

STYROFOAM/BLUE BOARD 3/4" 4'X8' DOW R-VALUE: 4.0 (SQUARE EDGE)/ P2S FACING.

8¼ ” thick, R-30C EcoTouch® Thermal Batt insulation prevents moisture damage and helps assure long roof life by providing 1" of ventilation air space between the insulation and roof deck. Easy Installation R-30C EcoTouch® Thermal Batt insulation is easy to handle and install.

Tests have shown that these laminated boards can withstand UV ray damage for a reasonably long time. That said, it's still advisable to cover any foam board insulation exposed to the Sun within 30-60 days at the most. On most projects, that's more than enough time to finish the exterior walls.

Rated at R4 per inch; EPS foam insulation boards are more permeable to air and moisture than XPS, but it doesn't retain moisture to the same extent because of it's more closed cell structure and it's breathability which lets it dry out.

EPS is resistant to water and moisture. This means that it does not absorb them and that its insulating performance is not compromised when in contact with these elements. Insulation boards made of expanded polystyrene can make a home healthier because they will not contribute to mildew formation.

The graphite in these foam boards reflects radiant heat, complementing the foam air bubbles' ability to block conductive heat. This unique function gives them a relatively high initial R-value of 4.7 per inch.

Open-cell foam in walls would not be sufficient with just 2 inches, requiring at least 3. Sprayed into attics, closed-cell foam is recommended to be between 4 and 5 inches, while open-cell foam ceiling and roof spraying should fall somewhere in the 6 to 10-inch range.

An R-value is also calculated per inch of width. Therefore, a three-inch-thick board has an R-value of 3. Blown fiberglass installed in the attic has an R-value of 2.2 per inch, so 12 inches of it would give you an R-value of 26.4 in your attic installation project.

What is the R-value of 4 inch foam board?

STYROFOAM extruded polystyrene insulation is rated at an R-value of 5.0 per inch at 75°F.

Large sheets of 1-inch to 2-inch-thick rigid foam are attached directly to the foundation wall with foam adhesive. A stud wall system, similar to those on upper levels, is built using wood or metal studs. The wall system touches the rigid foam but is held in place at the top and bottom.

The best kind of rigid foam insulation is polyisocyanurate, also known as polyiso. It has the highest R-rating of any rigid foam insulation and comes with a reflective foil on both sides, allowing it to act as a radiant barrier as well.

FOAMULAR® is a popular energy saving, moisture resistant, XPS insulation from Owens Corning. The difference between 150 and 250 is simply the compressive strength of each type.

While there are no UV rays to destroy the foam board's insulative properties, interior exposure can create a fire hazard. Therefore, to qualify a building for an occupancy permit, most jurisdictions in North America demand that a thermal barrier, like drywall, cover the foam board.

ASTM C578 standard for EPS type I is 10psi or 1,440 pounds per square ft (1 square foot is equal to 144 square inches). One square inch of Type I EPS can support 10 pounds; however, set a one square foot board on the foam and it can support 1,440 pounds.

4 Inch Styrofoam Insulation 4” Styrofoam Brand Insulation is the thickest Styrofoam that is typically… 2” Styrofoam Brand Insulation is probably the most specified rigid insulation material for use under…

The major difference between Styrofoam and EPS foam blocks is that Styrofoam is made from extruded polystyrene (XPS) while EPS foam blocks are made of expanded polystyrene.

Styrofoam is made out of styrene which is a petroleum-based product. How is styrofoam made? Through polymerization, styrene is refined into polystyrene and then a hydrofluorocarbon agent is added. This combination is then extruded and allowed to expand under pressure until it forms a foam board.

How do I calculate how much foam I need?

To determine how much foam you'll need, you need to know 2 things, the area to be insulated (square feet) and how thick you want your insulation (inches). Multiply both of these together and you get the number of board feet of insulation that you need to buy.

While R-values vary from one brand of product to another, spray foam insulation can reach R-5.5 to R-6.5 per inch. Although closed cell polyurethane insulation is a more expensive choice, it can provide a home that has six inch wall cavities with an R-value as high as R-39.

Closed cell spray foam has an R-value of R-7 per inch. In comparison, open cell spray foam has an R-value of R-3.8 per inch.