XPS Insulation Installation

It’s important to insulate your home to maintain a comfortable living space. Also, insulating your house will reduce utility bills. There’re numerous insulation products available today.

One of the easiest insulation to install is extruded polystyrene (XPS). XPS insulation has a high thermal resistance.

For instance, an XPS rigid foam insulation measuring 2 inches thick has a thermal resistance of R-10. It’s lightweight and versatile, making it great for insulating ceilings and walls. However, it also has a few limitations.


XPS Insulation Installation


Properties of Polystyrene

XPS sheets are available in various sizes. They come in a length of either 5 or 8 feet and a width ranging from a minimum of 16 inches to a maximum of 4 feet.

Also, the sheets are available in various options including unfaced, covered with a foil facing, or laminated with plastic. Lamination increases strength whereas the facing improves water resistance. However, neither lamination nor facing changes the R-value of an XPS sheet.

XPS sheets are available in several colours, with the most common ones being pink, green, and blue. The colours represent the manufacturer.

However, different colors don’t affect the areas of application of the sheets. Also, the colours don’t affect the sheet’s insulating quality.


Installing XPS Insulation

Insulating interior masonry such as block or concrete is very simple when using rigid foam. XSP insulation rigid foam outshines other kinds of rigid foam with respect to ease of installation.

Other insulation materials such as spray foam, batts, and blown-in fiberglass require drilling furring strips into a wall.

On the other hand, XPS insulation installation is quite simple. You only need to glue the insulation on a wall. However, you should use foam-safe glue as advised by the manufacturer.

Inappropriate glue may cause the foam to melt. If you want to install XPS sheets successfully, ensure the sheets fit snugly together. Also, seal the joints with the recommended seam tape.


Filling Ceiling and Wall Cavities

XPS foam is ideal for enhancing the insulation of interior ceilings and walls. To insulate rafter, joist, and stud cavities, you’ll need to cut the foam to fit tightly in the wall cavities. Ensure they fit flush with the framing.

Since the insulation of a wall depends on how well it blocks airflow, ensure you fill any wall cavities with expandable insulation foam. For deeper cavities, you can enhance their insulation by inserting two layers of XPS foam.


Cutting XPS Sheets

Although you can easily cut a ½ inch XPS sheet with a regular utility knife, you’ll need a sharper object such as a drywall saw or table saw to cut thicker sheets.

If you want to cut the sheet with your utility knife, it’ll help to place a straightedge over the cutting line. Next, score the cutting line about ¾ inch deep.

Upon scoring it, snap it by placing it on a flat table, with the scored side facing upward and the cutting line placed approximately 1 inch away from the table.

Snap it firmly downward to break along the cutting line. Trim off any rough edges on the sheet with the help of a utility knife.


Exterior Use

Due to its thickness, a 2-inch XPS sheet isn’t ideal for exterior sheathing not unless structural supports such as furring strips are installed.

You can install thinner XPS sheets, such as those with a thickness not exceeding 1 inch. Also, you’ll need to install an exterior siding over the XPS sheets.

However, XPS rigid foam doesn’t have a lot of structural strength. Also, XPS sheets don’t offer the strength needed to hold the siding’s weight.

Consult with your local building authority for further details about the kind of extra support that’s needed before using XPS foam as exterior wall sheathing.



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