Yes, we install rigid foam board insulation in San Jose and the Bay Area for garages, slabs, foundation walls, exterior walls and commercial buildings. Most garage jobs take one to two days, and commercial jobs are scheduled around your project. We work with polyiso, XPS and EPS and pick the board that fits the job.
Rigid foam board packs a lot of insulation into a thin, stiff panel. It does not sag, it handles moisture better than fibrous insulation, and it can be installed in places batts and blown-in cannot go: under a concrete slab, against a foundation wall, over the outside of a wall before siding, or across a commercial roof deck. When the seams are taped and the edges sealed, a board layer also acts as an air barrier.
Studs conduct heat right past cavity insulation. A continuous foam layer covers the studs and breaks that path.
Types of rigid foam we install
| Board | R-value per inch | Strengths | Common uses |
|---|---|---|---|
| Polyiso (foil-faced) | About R-5.6 to R-6.5 | Highest R per inch, foil face can act as a radiant barrier | Commercial roofs, walls, cathedral ceilings |
| XPS (extruded) | About R-5 | Strong moisture resistance, compressive strength | Under slabs, foundation walls, below grade |
| EPS (expanded) | About R-3.6 to R-4.2 | Lowest cost, versatile | Exterior walls, roofs, garage walls |
How we install rigid foam board
- Scope and materialWe confirm where the board is going, the target R-value, any plans or energy compliance requirements, and choose polyiso, XPS or EPS.
- Surface prepSurfaces are cleaned and checked. On walls and ceilings, we lay out the board to minimize cuts and seams.
- Cut and fastenBoards are cut tight around windows, doors, outlets and penetrations and fastened with the right fasteners or adhesive for the surface.
- Tape and sealSeams are taped and edges and gaps are sealed with foam, so the layer works as an air barrier, not just insulation.
- Ready for coverIn occupied spaces and garages, foam board has to be covered with a code-approved thermal barrier like drywall. We coordinate so the next trade can follow right behind us.
Where rigid foam solves problems other insulation cannot
Thermal bridging through studs
Wood studs make up a meaningful share of a wall and insulate far worse than the cavity insulation between them. Heat walks right through them. A continuous layer of foam over the outside of the wall covers the studs and cuts that loss. ENERGY STAR recommends R-5 to R-10 insulative sheathing when replacing siding in the Bay Area climate zones.
Garages and converted spaces
Garages turned into gyms, offices or workshops, and garages under bedrooms, are some of the most uncomfortable spaces in Bay Area homes. Rigid foam on the walls and ceiling adds real R-value without eating the room. If the garage walls are open framing, batts or a combination with board may be the better value.
Slabs and foundations
Batts cannot go under concrete. XPS can. It is the standard choice under slabs and against foundation walls on additions, ADUs and new construction.
Commercial roofs and walls
We do commercial as well as residential work. Polyiso is a mainstay on low slope commercial roof assemblies, and board insulation is common on tilt-up, block and metal building walls. For metal buildings with condensation issues, also see spray foam.
What affects the cost of rigid foam insulation
- Board type and thickness needed to hit the target R-value
- Square footage and number of cuts around openings
- Wall, ceiling, roof or below grade application
- Seam taping, sealing and air barrier requirements
- Commercial scheduling and site access
Send plans or have us walk the space and you will get a written estimate with the board, thickness and R-value spelled out.
Contractors and builders: we work with GCs on new construction, additions and commercial projects. Call (408) 401-3152 to get on the schedule.
When rigid foam is the right call
- You are replacing siding or stucco and want insulation over the whole wall
- A garage is being turned into a gym, office or workshop
- An addition or ADU needs insulation under the slab or on the foundation
- A commercial roof or wall assembly specifies board insulation
- You need high R-value in a thin space, like a low ceiling or shallow wall
Working with the rest of the build
Rigid board almost always sits between other trades: framers and roofers before us, siding, stucco or drywall after. We coordinate the schedule, leave the surface ready for the next trade, and make sure seams and edges are sealed before anything covers them, because nobody gets a second chance once the siding is on.
We install foam board on homes, ADUs and commercial buildings in San Jose, Santa Clara, Sunnyvale, Milpitas, Fremont, Hayward, Redwood City and throughout the Bay Area.
Frequently asked questions
Which foam board has the highest R-value?
Polyiso has the highest R-value per inch, about R-5.6 to R-6.5. XPS comes in around R-5 per inch and EPS around R-3.6 to R-4.2. Which one is best depends on where it is going, not just the number.
Is rigid foam good for garage walls and ceilings?
Yes. It adds a lot of R-value in a thin layer and resists moisture. In a garage it must be covered with an approved thermal barrier, typically half inch drywall, for fire safety.
What is the difference between XPS and EPS?
XPS has a higher R-value per inch and better moisture resistance, which is why it is common under slabs and against foundations. EPS costs less and is widely used on walls and roofs. We match the board to the application.
Can foam board go on the outside of my walls?
Yes. Installed as continuous insulation over the sheathing before new siding or stucco, it stops heat from leaking through the studs themselves. It is best done when siding is already coming off.
Does rigid foam need a vapor barrier?
Foam board already slows vapor, and foil-faced polyiso acts as a vapor barrier on its own. Whether you need anything extra depends on the wall or roof assembly, and we follow the plans and code.
Do you install rigid foam on commercial jobs?
Yes. Rigid board is common on commercial roofs, tilt-up and block walls, and in warehouses and shops. Call with your plans or scope and we will price it.
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