January 03, 2023

New Oak Ridge Tests Verify SIP Performance Advantage

Test Room with Four-Inch SIPs Blows Away 2x6 Fiberglass Construction in Controlled Side-by-Side Lab Test

"SIP room 15 times less leaky" - Oak Ridge report

A SIP test room has significantly outperformed a 2x6 stick-framed and fiberglass-insulated wall in controlled testing under identical laboratory conditions at the government's Oak Ridge National Laboratories (ORNL). Results from a carefully monitored and instrumented study in Oak Ridge's climate simulation laboratory showed that SIP construction can be far more airtight than stick-frame construction. "We can put a number on it," says SIPA Executive Director Bill Wachtler. "When it comes to stopping air infiltration and exfiltration, a properly sealed SIP building is almost 15 times better than the competition."
 

Outstripping the Test Equipment. The test setup created identical climate conditions for both rooms and measured both the air tightness and the heating energy requirement of the two rooms. Under blower door testing, a room with four-inch SIP walls, a SIP ceiling, a window, a door, prerouted wiring chases, and electrical outlets showed almost 15 times less air leakage than an otherwise identical room built with 2x6 studs, OSB sheathing, fiberglass insulation, and drywall. In fact, the SIP room was too tight for normal use of the blower door. The test protocol calls for the room to be depressurized in a range of 15 to 50 pascals of pressure, but Oak Ridge reported that "we were unable to go below the 75 pascals because the SIP room was so airtight." At 50 pascals of negative pressure, the stick-built room leaked 126 cubic feet of air per minute (CFM), while the SIP room would have leaked only 9 CFM.
 

Extraordinarily Airtight. "The CMF50 for the SIP test room was almost 15 times less leaky than that measured in the wood-frame," says the Oak Ridge report. "By comparison with the wood-framed room, the SIP room is extraordinarily airtight. These results show that, with care, a very nearly airtight construction is possible with SIPs." "The test results can be reliably extrapolated to the real world," notes the Oak Ridge study. Lab test results for the stick house very closely track the data from actual stick houses. While Oak Ridge did not have data from SIP houses to compare to the SIP test room, blower door testing data in SIPA's possession indicates that SIP houses can readily achieve natural air change rates under normal atmospheric conditions of around .05 air changes per hour (ACH), compared to a typical stick-house values on the order of .5 to 1 ACH.
 

Air Tightness Relates Directly to Durability. An integral part of the SIP building system is properly sealed joints. One reason for the high performance of the SIP test room is that the joints were properly sealed. When panel joints are sealed properly to prevent air infiltration and exfiltration, moisture is prevented from entering the building envelope and long-term durability is ensured.
 

Surprising Energy Savings. Perhaps more significantly, the room with the 4-inch SIP walls used .9% less heating energy than the stick-built room under identical conditions (an indoor temperature of 70 degrees F and an outdoor temperature of 0 degrees F). Those results were verified by continuous monitoring of temperature and heating system data.
 

R-Values are Deceiving. The implication is that building with 4-inch SIP walls, in addition to providing far superior air tightness, would more effectively meet energy code requirements than building with 6-inch stick walls. "People look at the insulation R-values for a six-inch stick wall (R-19) and a four-inch SIP wall (R-15), and they think the stick wall is four points better," says SIPA director Bill Wachtler. "But these tests prove that the stick wall is really 10% worse. Let's stop making false comparisons between the two systems. It's time to change the energy rating systems and the energy codes to reflect the true performance of SIPs."
 

SIP Walls are Competitive with Stick Framing. According to Mike Bryan of Premier Building Systems, this fact means builders can be competitive using SIPs. "Cost comparisons are often based on six-inch SIP walls versus 2x6 walls. But now we see that you can beat 2x6 walls energy-wise with a 4-inch SIP wall. And cost-wise, if you compare a 4-inch SIP wall with a 6-inch stick wall, SIPs are competitive," says Bryan. "Especially when you take into account the labor savings with SIPs, or savings on things like extension jambs and wider trim." In addition, 4-inch walls create two inches of usable space at the room perimeter compared to a 6-inch wall, which can add up to 50 or more square feet on a whole house. "Using a SIP wall buys you space for an extra closet or even a bathroom," notes Bryan.
 

Time to Revise Energy Rating Methods. The Oak Ridge testing confirms the observations from real-world measurements of identical whole houses built with SIPs and stick framing. For instance, in 1998, three identical Habitat for Humanity houses were built in Plains, Georgia. Two houses used SIP walls and roof, while the third house was built with standard stick framing and fiberglass insulation. All three houses were monitored by scientists from the Florida Solar Energy Center (FSEC).
 

Real-Word SIP House Saves 25%. "The three houses were intentionally built with their calculated energy performance (HERS score) similar to each other (all three had HERS ratings of about 83)," reports FSEC. "The frame house featured energy-related details that resulted in 5.3 air changes per hour at 50 pascals (ACH50). With the home's whole-house fan cover installed, the ACH50 dropped to 3.9, very good for frame construction. However, testing results revealed much better performance in the SIP houses with a measured ACH50 of 1.8. Considering the average indoor-outdoor temperature difference of 30 degrees F, the SIP houses saved 25% (on heating energy) compared to the frame house (during December and January 1998-1999)."
 

The Trouble with HERS. What's wrong with this picture? Obviously, the identical HERS ratings did not reflect the true difference between these houses - the ratings underestimated the actual energy-saving value of building with SIPs. Congress authorized the development of the Home Energy Rating System (HERS) so that homeowners could easily make comparisons between construction methods based on a simple numerical rating, without having to understand the construction details. The idea is to provide the market with accurate information so that the market can make wise choices. But, these identical houses received the same energy rating, even though the SIP house proved to use 25% less energy. With that real-world performance, the SIP houses deserve a HERS rating of 87, not 83. Clearly, the HERS rating, as applied in this case did not meet the intent of Congress - the identical ratings would not have helped the potential homebuyer to know that the SIP house was, in fact, a better energy buy.
 

Information taken from April 4, 2002 SIPA News Release.

February 23, 2023

Q: What is a Structural Insulated Panel (SIP)?

A: A SIP is an energy efficient structural wall system that is manufactured with a core of Styrofoam laminated to oriented strand board (OSB) or plywood. Panels are available for walls, roof and floor systems.  Special below grade panels are also available for super insulated lower levels in the ground.

Q: Why is it better to use SIP's than standard "stick-built" construction?

A: First, the use of SIP's provides a much sturdier exterior wall - approximately 2 1/2 times stronger, in fact. And, of course, the energy efficiency is far, far superior to standard 2x4 or 2x6 construction - usually averaging up to a 50% to 60% savings on your energy bills.

Q: My "stick-built" home has an R-19 rating. What makes a SIP home so much better?

A: "Standard" fiberglass insulation has the ability to settle, allow air infiltration and can actually allow for air circulation within the wall, thus reducing the actual "R" factor of the wall, usually to an actual 9 to 12 "R"-factor, NOT R-19. The SIP's we use in SIPerior Design Homes offer an "R" factor of 22. There is no settling and no air infiltration, so this is a "real" and fixed "R" factor. Plus there are fewer studs to conduct cold into your home, this is refered to as a "thermal short".

Q: Does it cost more or less to build with SIP's?

A: The initial cost of construction with SIP's might be a little bit more, but the labor is less and you'll save money on your energy bills for the life of the home! Also, the faster construction time can reduce your construction loan interest cost.

You can learn even more about SIPs here.

Q: Does the home come pre-assembled?

A: Your home will be built on-site in accordance with the plans that have been engineered specifically for your job site's requirements. Only the wall panels are pre-built and delivered to the site.

Q: How is the SIPerior Design Home delivered to the site?

A: Your SIPerior Design Home will be built on-site, and the materials will be delivered as needed. You won't see any material laying around on the job site for longer than necessary. The builder will determine the delivery schedule. All it takes is a phone call to SIPerior Designs (and the appropriate lead time) and we'll have the materials delivered in a timely manner.

Q: Where can SIPerior Design Homes be built?

A: Really, they can be built anywhere in the United States. Here's how it works: SIPerior Design will find suppliers as close as possible to your building site, such as a SIP supplier, lumber supplier, etc. Materials will be delivered from those suppliers as needed, thus reducing the handling and shipping cost typically associated with kit or packaged homes. Depending on location most interior finish materials would be supplied locally.

Q: Does SIPerior Design have its own building crew?

A: While the estimated cost of building the home is factored into the pricing schedule, SIPerior Designs does not serve as the General Contractor. SIPerior Designs provides the house plans and material package only.  Yes, our sister company, Andersen Enterprise, can provide the labor necessary to build your home and act as General Contractor.  You can, however, select any builder of your choice, or you may build the home yourself.

Q: How do we select a builder?

A: In many cases we can help you find a builder in your area who has experience building with SIP's. But any experienced builder can learn to use SIP's and technical help is available in the form of manuals, CD's and on-site assistance. SIPerior Designs is in constant contact with the builder from the beginning to the end of the project. If you're building in SIPerior Designs immediate area, our General Contracting company, Andersen Enterprise, can provide the labor necessary to build your home. There are also a number of local builders who have built many of our homes.  You may choose any builder to build your home.   

Q: How long does it take to build a SIPerior Design Home?

A: Once everything is in place, it generally takes 6-10 months to build a SIPerior Design Home, depending on it's square footage. "Everything in place" means that financing is in place, your plans have been drawn and engineered, your plans have been submitted to the Building Department and approved and your building site is ready to go. You need to allow plenty of up-front time to complete these items.

Q: Can we do some of the work ourselves?

A: That's one of the reasons SIPerior Design Homes are so popular! You may purchase just materials from us and build the home yourself; you may have a builder erect the shell only; or you can elect to have the entire Siperior home built. We would be happy to explain how these options work and discuss which method is best for you. See What's Included

Q: Can we make changes to SIPerior Design's standard plans?

A: There are lots of "standard" changes you can make to the plans. For example, you can extend the great room by four feet and the bedrooms by two feet on most models. You can add porch and/or deck. You can add a lower level on any model for a drive-under garage, additional bedrooms, family room, etc. If you want to change the configuration of the plan, that is possible for a fee. Naturally, this cost depends on the extent of the changes. Finally, there are many ways to customize your home with our "standard" selections, such as your choice of siding, roofing, cabinets, countertops, etc.

Q: What is SIPerior Designs cost per square foot?

A: SIPerior Designs provides pricing for each specific model. "Price per square foot" is a very inaccurate method of calculating the cost of a home as there are so many variables. SIPerior Design'sQuick Quote system will provide a cost for the model you select with the options and upgrades of your choice. This is a much more accurate and predictable method of calculating the cost for your home and can be produced very quickly.

Q: Does SIPerior Designs have model homes?

A: If you're in the Woodland Park, Colorado area we invite you to stop into our demonstration & model home; the Schofield model which exhibits many structural details. You'll also see dozens of pictures of homes we've built throughout the years. Once you've selected a model we're often able to send you out to a home under construction. Finally, our website has lots of photos. We add to our website photos often, so keep coming back.

Q: How many homes has SIPerior Design supplied?

A: The original Building Alternatives started business in 1985.  In 1994 they developed the PAC Home product line and supplied more than 200 homes to date.  Our general contracting company, Andersen Enterprise,  has built almost 40 of those homes, including three award-winning homes in the Colorado Springs Parade of Homes.

Q: What is the warranty on a SIPerior Design Home?

A: The materials supplied by SIPerior Designs carry individual warranties. You may refer to our warranty section for more information on these. The General Contractor is responsible for the warranty on the construction of the home and for the materials supplied outside of the SIPerior Designs materials package.

Q: Does SIPerior Design provide financing?

A: SIPerior Design does not provide financing. Customers may work with the financing institution of their choice. However, we do have several excellent banking relationships in our local area that are familiar with us and our products. Upon request we would be happy to provide this information to you. Or, you can visit their websites that are linked to their advertising on our website.

Q: What is the billing procedure?

A: You will have one contract with SIPerior Designs and a contract with your builder. SIPerior Designs requires a $2,500.00 Drawings Fee to produce the Preliminary Drawings. The Drawings Fee is non-refundable, but does apply toward the total cost of the SIPerior Designs Materials Package. Then, a 20% deposit (this is 20% of the SIPerior Designs Materials Package or $20,000 which ever is LESS) is required to have the Final Plans drawn and engineered (minus the Drawings Fee previously paid). These initial amounts are held in reserve. Once building begins, you will receive an invoice from SIPerior Designs once a month for materials delivered to the site the previous month. At the end of the building process SIPerior Designs will "draw down" the original amount that has been held in reserve. Heavily modified plans and full custom designs will require a larger fees based on the scope of work required.