Structural insulated panels (SIPs) are becoming an increasingly popular choice of building material in the United States. The energy efficiency, speed of construction, and improved indoor air quality provided by SIPs are some of the main reasons.
The use of SIPs in residential construction has been increasing steadily in the past decade as homeowners and builders are becoming more aware of the benefits of SIPs. As the demand for building with SIPs increases, so have the questions regarding how they are used, why they are used, and when they are used.
In this article, we will help to answer some of the most common questions facing builders and homeowners considering building with SIPs.
Table of Contents
What are SIPs?
Structural insulated panels (SIPs) are a type of building material that consists of a foam insulation core compressed between two structural facings, typically made of oriented strand board (OSB). The foam insulation core provides high thermal performance, while the structural facings serve as a load-bearing structure, making SIPs a highly energy-efficient and robust building material.
Some contractors refer to the composition of SIPs as similar to an ice cream sandwich. The OSB sheathing acts as the chocolate wafer, with closed-cell EPS foam insulation inside as the ice cream.
SIPs can be used to construct the entire building envelope, including the foundation, walls, roof, and floor, promoting faster construction times, improved indoor air quality, and significant energy savings. Learn more about the makeup of SIPs and their many benefits in our recent post, SIPs 101.
What are the advantages of building with SIPs?
We believe that SIPs are the future of residential construction and disrupt the current construction industry by providing the following benefits over conventional construction.
Energy Efficiency:
The continuous foam insulation core of SIPs provides a high level of thermal performance, which can lead to significant energy savings. The average SIPs home in 2021 was 74% more energy efficient than a standard new construction home in the US (based on the 2021 RESNET HERS study).
Speed of Construction:
SIPs are manufactured off-site in a climate & quality-controlled environment, then delivered to the construction site where they can be quickly assembled to form the building envelope. Off-site manufacturing can lead to faster construction times, reduced labor costs, and decreased waste.
Indoor Air Quality:
SIPs create an airtight building envelope, helping to improve indoor air quality by preventing and reducing the number of pollutants and airborne contaminants entering the building. With the inclusion of adequate ventilation, SIPs homes meet and exceed national standards for Indoor Air Quality.
Strength and Durability:
The structural OSB sheathing of SIPs provides a load-bearing structure that is stronger and more durable than conventional 2x framing counterparts. Depending on the manufacturer, SIP walls and roof can carry nearly double the load of a 2″x6″ framed alternative. Overall, SIPs are an excellent option for building areas with significant snow, wind, or seismic load-bearing requirements.
Design Flexibility:
SIPs can be used to construct a wide range of building types and styles, from single-story ranch-style homes to multi-level commercial or agricultural infrastructure. The panels range in size from 4 feet to 24 feet, allowing for excellent design flexibility no matter the project’s scale.
Sustainably Sourced:
SIPs are made of renewable and recyclable resources. Fast-growth lumber (renewable) is used for OSB sheathing, and EPS foam (recyclable) is used for insulation. The studless composition of SIPs also significantly reduces the wood needed for a new construction project. Going one step further, the manufacturing of SIPs produces less waste and pollution than traditional construction methods.
Cost-Effective:
SIPs are known to be more cost-effective than traditional construction methods because of their energy efficiency, strength, and speed of construction. The upfront cost of a SIP wall or roof system may be higher than that of a standard 2x framing package, but the savings are realized over time. You’ll save on labor through expedited framing timelines. You’ll save on energy expenses for the lifetime of the structure. Lastly, you’ll save on repairs by building with strength and durability.
What are the disadvantages of building with SIPs?
While structural insulated panels (SIPs) offer many advantages over traditional construction methods, there are also some potential disadvantages to consider:
Upfront Cost Differential:
SIPs are generally more expensive than conventional building materials upfront. That does not take into consideration the improved speed of construction and lifetime energy savings.
Product Scarcity:
SIPs are not widely available in all areas and need to be ordered and shipped to the construction site. Unlike conventional 2x lumber, you cannot order SIPs from your local lumber yard. You or your general contractor will have to source the SIPs for your project from a reputable and verifiable manufacturer.
Specialized Expertise:
Installing SIPs requires some technical knowledge of the product and may require heavy equipment depending on the size and scale of the project. Once familiar with the product, the installation process can streamline framing timelines by up to 60%.
We recommend searching for a SIPA builder in your area for a SIPs installation expert.
Moisture Concerns:
We constantly receive questions about whether or not SIPs are appropriate for certain climates due to moisture concerns. The answer is simple. If not correctly sealed, SIPs can be susceptible to moisture damage regardless of the environment. You can mitigate moisture concerns by ensuring proper flashing, sealing, and ventilation during the panel installation.
SIPs Can Be Difficult to Repair:
SIPs, once installed, are difficult to repair or modify. The panels are precision cut (CNC) and engineered based on the original home plans. Therefore, thoughtful design often mitigates the need for dramatic modifications in the future. Working one-on-one with a design expert, you can plan for the future and ensure that your needs and desires are met the first time.
Are SIPs soundproof?
SIPs provide considerable sound insulation, but depending on the application, you may need to implement additional soundproofing.
The continuous foam insulation core of SIPs provides an effective barrier to sound transfer, helping to reduce the transmission of sound between rooms or between the interior and exterior of the structure. However, the thickness of the panel & foam core can affect the sound insulation properties of the SIPs.
Suppose your goal is to completely soundproof a room or particular section of your house. You may need to apply additional soundproofing materials, such as a sound-deadening board, to improve their sound insulation properties further.
Do SIPs need framing?
In many situations, SIPs do not require additional framing. The structural OSB facings provide the necessary strength and rigidity to the walls.
SIPs are designed and engineered on a project-by-project basis to carry the unique loads and distribute them proportionately to the foundation. The wall and roof panels are manufactured to specific widths, lengths, and thicknesses, which can be adjusted to match the loads and spans of the structure.
Depending on the design, certain areas of the building, such as corners, roof-wall connections, and other load-bearing areas (heavy appliances, large windows, or door openings), may require additional framing to transfer the loads properly and comply with local building codes.
Timber Frame, or Post and Beam framing, is commonly used in conjunction with SIPs for a highly resilient structure. The heavy timber elements carry a large portion of the load-bearing requirements, relieving any stress from the panels in any high load-bearing areas of the home.
Do SIP panels rot?
SIPs are not susceptible to rot. The EPS foam core of the panels is not an organic material and therefore does not retain moisture. Going one step further, the OSB facings are treated with zinc borate to resist rot, decay, and insect infiltration.
However, moisture can affect SIPs if they are not correctly sealed following the manufacturer’s guidelines or are exposed to severe water infiltration. To prevent moisture damage, it is important to properly seal all joints and penetrations in the SIPs, such as electrical and plumbing penetrations, and to ensure that the building has proper flashing, drainage, and ventilation.
You must also ensure that the SIPs are not exposed to standing water or prolonged periods of high humidity. You can mitigate threats with proper site preparation, such as grading the site to ensure adequate drainage, installing a moisture barrier on the foundation walls, and incorporating the right mechanical/ventilation system for your structure.
Can you screw into SIPs?
Yes, screws can be used to attach various items to structural insulated panels (SIPs). However, using the correct type of screws and installation techniques is vital to avoid damaging the SIPs or compromising their structural integrity. We recommend following your manufacturer’s guidelines for both screw selection & installation guidelines.
When drilling into SIPs, it is necessary to use screws specifically designed for use with the panels, such as self-tapping structural screws. SIPs screws have a sharp point and unique thread design that allows them to tap into the EPS core of the panel without damaging it.
The proper installation of screws into panels is critical. You must avoid overdriving the screws, as this can compress the foam core and weaken the structural integrity of the SIP. To prevent overdriving the screws, we recommend using a depth-sensitive screw gun or a torque-limiting screwdriver.
Spacing when attaching screws into SIPs is another crucial factor. We recommend strictly following the manufacturer’s guidelines and local building codes.
Do SIPs need ventilation?
SIPs, when appropriately installed, create an airtight building envelope, which helps improve indoor air quality by reducing the number of pollutants entering the building.
Consequently, airtight building envelopes can also trap moisture and humidity inside the building. To prevent moisture damage, it is vital to provide proper ventilation to the building. Adequate ventilation can help to control the moisture level inside the building to avoid mold and mildew growth.
We recommend a hybrid ventilation system when building with SIPs. Hybrid systems use a combination of natural and mechanical ventilation. ERVs (energy recovery ventilation systems) and/or HRVs (heat recovery ventilation systems) are critical components in any SIPs home to ensure optimal ventilation. Windows and doors are used as natural ventilation sources and should be planned (designed) accordingly to optimize natural ventilation throughout the structure.
Are SIPs fireproof?
Structural insulated panels (SIPs) are not considered to be fireproof. However, they do provide some level of fire resistance. The OSB sheathing is an engineered wood product that has been Zinc borate treated to resist fire and decay.
The continuous closed-cell foam insulation core of SIPs is fire-resistant by nature. EPS foam consumes the entire cavity between the sheathing, providing no oxygen or external fuel to the fire. However, like most objects, the foam core can burn if continuously exposed to intense heat.
Ultimately SIPs provide some level of fire resistance by slowing the spread of the flame and providing insulation to help prevent the building’s interior from overheating.
What is the R-Value of SIPs?
The SIPs used in our projects come standard with R-26 insulation in the walls and R-40 insulation in the roof. A SIP wall or roof panel can range from R-17 at 4.5″ to R-51 at 12.25″.
It’s also important to keep in mind that the R-value is just one aspect of insulation performance and that other factors, such as air tightness, vapor permeability, and proper installation, also play an essential role in the overall insulation performance of the building.
Are SIPs suitable for your project?
SIPs have demonstrated their value as a transformative building material for various new construction projects. They offer a trifecta of benefits: efficiency, cost-effectiveness, and sustainability.
Providing unparalleled insulation, bottom-line energy savings, and an expedited building process, it’s no surprise that SIPs are becoming an increasingly popular choice among builders and homeowners alike.
If you’re curious if SIPs are suitable for your next project, don’t hesitate to reach out. Our project managers will help determine whether SIPs are the right choice for your upcoming project based on your goals.
