When it comes to building in Los Angeles, Title 24 requires strict thermal performance standards for walls, roofs, and façades. Foam boards are a strong choice because they deliver solid R-values, resist moisture, and reduce thermal bridging. Options include EPS, ISO, Poly, and XPS boards.

By matching the right foam board with the local climate—coastal, valley, or urban—builders can hit Title 24 targets while improving efficiency and comfort across Los Angeles projects.

What Is Foam Board Insulation?

Foam board insulation consists of rigid panels made from plastics such as expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate (polyiso). The U.S. Department of Energy notes that the insulating effectiveness of any material is measured by its R‑value (higher R‑values mean greater resistance to heat flow). 

Rigid foam boards trap gases in closed‑cell structures to deliver high R‑values in thin profiles, making them ideal for exterior wall sheathing, roof decks, and below‑grade applications. Because they are continuous across studs and rafters, they minimize the thermal bridges that waste energy.

Types of Rigid Foam Boards

Expanded polystyrene (EPS): EPS is the most common continuous insulation used in California homes. It delivers about R‑4 per inch and is cost‑effective for large areas. EPS boards should be protected from prolonged moisture exposure; graphite‑enhanced versions (GPS) bump the R‑value to around R‑5 per inch.

Extruded polystyrene (XPS): XPS boards provide R‑5 per inch and are manufactured with a closed‑cell structure that absorbs significantly less water than EPS. Because they maintain their R‑value when wet and resist damage during freeze–thaw cycles, XPS panels are well-suited to coastal areas where fog, rain, and salt spray are concerns.

Polyisocyanurate (polyiso): Polyiso delivers the highest R‑value in its class—around R‑6 per inch. Its higher thermal resistance means thinner walls and more usable interior space. Polyiso boards are available with different facer types that provide water‑resistive barriers or vapor permeability as required by climate and code. Polyiso also maintains dimensional stability and passes stringent fire tests.

Title 24 Requirements and the Role of Continuous Foam

California’s updated energy code shifts the focus from cavity insulation alone to the effective R-value of the entire wall assembly. In Los Angeles, builders must meet a U-factor of 0.065 across all climate zones. This can be challenging because traditional wall assemblies with only batt insulation often fall short. Continuous foam board insulation provides the most direct path to compliance while also reducing bulk and improving performance.

Continuous insulation doesn’t just help Los Angeles projects pass code, it provides long-term benefits. By minimizing air leaks, preventing moisture intrusion, and cutting heat loss through framing, foam board systems make homes more comfortable, reduce operating costs, and keep projects both efficient and compliant.

Choosing the Right Foam Board for Los Angeles Climates

The city of Los Angeles contains different microclimates which range from wet coastal areas to dry inland valleys. Matching insulation type to the environment and project helps maximise performance.

• Coastal zones: The materials used for salt air and marine fog protection need to be able to withstand moisture. XPS features a closed-cell structure which provides better water resistance than EPS and keeps its R-value stable when exposed to moisture. Polyiso boards that include water-resistant facers work properly in coastal stucco system construction.
  
  

• Hot valleys: Inland areas experience high summer temperatures. Polyiso’s high R‑value per inch (around R‑6) keeps walls thin while maximising thermal resistance. Continuous foam wrapping significantly reduces heat gain and cooling loads by eliminating thermal bridges. Pair polyiso or thicker EPS boards with lighter stucco or siding to meet code without increasing wall thickness.
  
  

• Retrofit façades: When upgrading older structures, continuous exterior foam offers an easy way to boost energy performance without gutting interior walls. EPS and polyiso panels can be fastened over existing sheathing; furring strips create a drainage plane behind new cladding. For historic homes or seismic upgrades, low‑density EPS offers flexibility, while XPS provides added moisture protection.

Installation Tips

Rigid foam boards must be installed correctly to realise their benefits:

1. Plan continuous coverage: Ensure foam boards cover the entire exterior without gaps. Stagger seams and tape joints to create an air‑ and water‑resistive layer. Install furring strips or special fasteners designed for attaching stucco or siding over foam; thicker insulation may require extended screws or specialty clips.
   
   

2. Address moisture management: In coastal areas, choose boards with low water absorption (XPS) or moisture‑resistive facers. Use properly flashed windows and doors; add a drainage plane behind cladding to allow any incidental moisture to escape.
   
   

3. Avoid thermal bypasses: Seal penetrations, edges, and transitions. Foam board alone is not a vapor barrier; pair it with appropriate housewrap or integrated weather barrier to meet code.
   
   

4. Consider roof and foundation insulation: Rigid foam boards can insulate low‑slope roofs and foundation walls. Polyiso boards on roofs deliver high R‑value while reducing roof thickness; XPS boards below grade resist water and maintain thermal performance.

Sourcing and Delivery in Los Angeles

Supply Ontime provides reliable delivery across the Greater Los Angeles area. Customers can count on:

• Same-Day or Scheduled Delivery
  The company provides same-day delivery service for urgent framing needs and allows customers to schedule deliveries in advance for bigger projects. The system delivers materials at the exact time construction workers need them which prevents delays and maintains project timelines.
  
  

• Flexible Unloading Options
  Deliveries can be handled in multiple ways depending on the site. Truck Bed delivery works for lighter items, Curbside delivery keeps drop-offs simple within 5 feet of the truck, and White Gloves service places materials at the doorway for added convenience.
  
  

• Clear Delivery Rates
  Pricing is weight-based and transparent, so there are no surprises. Customers know upfront what it will cost to have materials delivered, whether it’s a small order under 20 lbs or a large shipment requiring specialized handling.
  
  

• Convenience at Drop-Off
  The delivery process needs to remain simple for all delivery options that customers select. The materials can be unloaded from the truck either by placing them at the curb or by staging them at the first entrance of the building. The system provides flexibility which enables construction teams and homebuilders to concentrate on building activities while avoiding logistical concerns.

Final Thoughts

Foam board insulation functions as a reliable material for achieving Title 24 energy standards throughout Los Angeles even though it lacks visual appeal. The installation of continuous EPS, XPS or polyiso panels around walls and roofs allows builders to remove thermal bridges while reaching higher R-values and fulfilling building codes at the same time. The wall assembly system will deliver comfort to users while achieving energy efficiency and market leadership through correct installation of well-designed systems and dependable local materials.