Question 1

What is rigid foam board insulation used for?

Accepted Answer

Rigid foam board is a panel product installed in continuous sheets rather than stuffed into cavities. In Southwest Florida it's most often used as continuous exterior insulation over sheathing or masonry, on roof decks beneath the roofing assembly, on the interior face of concrete block walls, and under slabs. Its defining advantage is that it covers framing members instead of stopping at them.

Question 2

What's the difference between EPS, XPS, and polyiso?

Accepted Answer

EPS (expanded polystyrene) is the most economical at roughly R-3.6 to R-4.2 per inch and drains well, making it a common choice below grade and under slabs. XPS (extruded polystyrene) delivers about R-5 per inch with higher compressive strength and low water absorption. Polyiso offers the highest R-value per inch — roughly R-5.6 to R-6.5 — and is the usual choice above roof decks and on walls where every inch of thickness counts.

Question 3

Why does continuous insulation matter on a block home?

Accepted Answer

Most Naples homes are concrete block, and concrete conducts heat readily. If you only insulate between furring strips, every strip becomes a thermal bridge carrying heat straight through the wall — which can measurably reduce the assembly's effective R-value compared to its nominal rating. Rigid board applied as a continuous layer covers those bridges, so the wall performs much closer to its rated value.

Question 4

Can rigid foam board be combined with spray foam?

Accepted Answer

Yes, and the combination is powerful. Closed-cell spray foam handles air sealing and fills irregular cavities and penetrations, while rigid board provides an uninterrupted continuous layer across the framing. Using both lets you hit high effective R-values in assemblies with limited cavity depth — particularly valuable in retrofits where you can't simply build a thicker wall.

Question 5

Does rigid foam board need a thermal or ignition barrier?

Accepted Answer

In most interior applications, yes. Foam plastic insulation generally must be separated from occupied space by a code-approved thermal barrier — commonly half-inch gypsum board — with different requirements for attics and crawl spaces. This is a detail inspectors check closely, so we specify and install the correct barrier as part of the job rather than leaving it as someone else's problem.

Rigid Foam Board Insulation in Naples, FL

Thermal Bridging: The R-Value You Paid For but Never Got

Rigid Board Types We Install

EPS & XPS Board

Polyiso Board

Rigid Foam Board Insulation FAQs

Stop Losing R-Value to Thermal Bridging