Do-It-Yourself How-To: Installing XPS (Extruded Polystyrene) Foam-board Insulation


How to Properly Install XPS Foamular Extruded Polystyrene Foam Board Insulation PanelingXPS (extruded polystyrene) foam-board is an excellent insulating material for basements because of its versatility and its built-in moisture barrier. It is installed and supplemented with Tyvek insulation tape and “Great Stuff” spray insulation in this how-to. Learn how to properly insulate your exterior walls before your basement finishing project. XPS insulation is expensive, yes – but it’s not only easy to install, it also has it’s own vapor barrier and is moisture-resistant. It’s a fantastic insulation material. This article will provide tips for installing XPS insulation.



 Examples of Installed XPS Insulation with Photos

XPS Insulation Installed in Basement Remodeling Project in Morristown NJ
XPS Extruded Polystyrene Insulation Installed in Basement Finishing Remodel in Morristown NJ

ABOVE: XPS (Extruded Polystyrene) Insulation Installed in Unfinished Basement Remodel in Morristown NJ

The photos above show our use of XPS insulation installed along the exterior masonry walls in a Morristown, NJ basement finishing remodel. The tongue-and-groove XPS Insulation panels were taped at the seam with Tyvek brand insulation tape and gaps were filled with GreatStuff brand expanding foam insulation. We then installed the framing over the 2″-think panels. At R-5 per inch, these XPS insulation panels provide a moisture-resistant R-10 insulation with its own vapor barrier that will hold up even when exposed to standin water.


Extruded Polystyrene, XPS, foam-board insulation
Rough XPS Foam-Board insulation supplemented with “Great Stuff”
The Madison, New Jersey home above had an unfinished basement that had been previously framed out with 2’x3′ studs** (see note below) against masonry walls. The homeowner wanted to finish and remodel the basement in order to add living space to the home and increase property value. Basement finishing is a trending remodel with a high ROI, and properly insulating your home with XPS foam board insulation is crucially important. CraftPro offers affordable basement finishing, and it is a cost-effective way to not only boost selling value but to essentially add another finished floor to your home. Once the room is properly insulated and the walls and ceilings are finished the possibilities for your finished basement are virtually endless. But first, you want to make sure your exterior walls are properly insulated. Using XPS insulation is the best way to achieve proper basement insulation. This article will teach you basic XPS insulation installation techniques from the professionals at CraftPro Contracting.

XPS foam board insulation   XPS Insulation Product Information:

We used “Owens Corning” brand ‘Foamular 250’ Extruded Polystyrene (XPS) foam-board panels. These rigid, foam panels each contain hundreds of millions of densely-packed closed cells that provide exceptional thermal insulation. Extruded polystyrene (XPS) Foamular panels are also virtually impervious to moisture, unlike other plastic foam insulation products, preventing loss of R-value due to moisture penetration.

Also, the product’s built-in rigidity means it can be scored and snapped, cut, or sawed with common tools. Sagging and settling are never a problem. It retains its long-term R-value year after year, even following prolonged exposure to water leakage, humidity, condensation, groundwater and freeze/thaw cycling. XPS foam-board insulation also contains a minimum of 20% certified recycled content, certified GreenGuard Indoor Air Quality for Children and Schools, Energy Star Seal and Insulate Program, and is NAHB Green approved. We used 2″ thick foam-board so that it fit between the nominal 2’x3′ studs. At R-5 per inch, that’s R-10 insulation for the exterior walls.
** NOTE **: When framing a basement it is best to use to standard 2″x4″ lumber or steel framework, and the bottom plate (the framing that touches the floor) should be pressure-treated lumber. 2″x3″ framing lumber is rarely used anymore because of its tendency to warp (bend and bow) over time.

 How to Install the XPS Insulation Foam Panels:

Simple Installation Process:

The foam-board was cut to fit inside the studs and glued directly to the masonry using paneling adhesive specifically formulated for foam panel insulation like XPS Foamular. Even though the product is very easy to score-and-snap, saw and otherwise cut with common tools, there are always small gaps. In order to thoroughly insulate the exterior masonry walls the seams where the panels meet were taped with Tyvek insulation tape. We also used “Great Stuff” insulating foam sealant. This product sprays into gaps and cracks, expands and dries to a rigid, airtight seal that insulates and minimizes condensation. When XPS insulation is deeper than 1.75″ it does not require a moisture-barrier, so none was used here. After the XPS insulation, these walls are now insulated, virtually airtight, moisture-resistant and ready for Sheetrock.

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Find me, Richard D’Angelo, President of CraftPro Home Improvements and this article’s author on Google+. You can also visit CraftPro on Google+ and join our community of home improvement, maintenance and renovation professionals.



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