Vertical Chases in Every SIP Panel?

Conversations with those new to SIPs inevitably turn to concerns and questions on how to run electrical through structural insulated panels. Most assume that the solid core of a SIP thwarts the efforts of your electrician to efficiently run wires through walls and roof. In actuality, with a bit of preplanning and knowledgeable SIP installers, Sparky can get wires from A to B with minimal effort.


No planning and no communication with your electrician could result in this scenario.

As a standard, most panel manufacturers have predetermined the location of wire chases that meet common requirements for wiring a building.   For instance, if electrical outlets are to be placed at 16” off the finished floor, most manufacturers will place a horizontal chase at that height in all wall panels. Likewise, as electrical outlets are required above kitchen counters, it’s logical to place an additional horizontal chase in the panel at 42”-44” above the floor. Some manufacturers place an upper horizontal chase at switch height. However, my experience has shown that 99% of all switches are next to doors so I recommend a vertical chase 6” from the door edge. If the SIP designer doesn’t know which way the door swings it’s not unreasonable to place a vertical chase on either side of the door at 6” off the rough opening. This vertical chase will allow the electrician to pull wire up to the switch box and continue on to an outside light or even up to an upper floor system or beyond.

The SIP manufacturing process uses predetermined box locations to design their layout of standard chases. Many will place a vertical chase in every panel for a four foot wide panel system or every four to eight feet if it’s a jumbo panel. Hence, if you allow the manufacturer to dictate the chase layout you may have a whole lot of chases that never get used. What’s wrong with that? Now you have to seal a lot of holes in your wall system.


Here, wall and floor chases are clearly marked by the SIP installation crew.

I want my building envelope to be as airtight as possible so my approach uses a little preplanning to specify both vertical and horizontal chases only where they’re necessary. If plans change and an additional path is required there are simple methods that allow site chases to be installed in the field. My ideal factory-installed chase layout will include a vertical chase at all known switch boxes. Add to that a horizontal chase at 42” above the floor for panels in the kitchen area, and don’t forget to look for counters in other areas such as laundry rooms. Finally, I’ll add vertical chases as needed to ensure access to any remote areas or locations that don’t have any better option.

What about plugs in exterior walls? I’ll simply have my trained SIP installers site drill the plate, mark the deck for location, bore up from the bottom of the panel with a 1 ½ “ ship augers bit to a height of about 16” and then mark the panel. This simple prep will show the electrician exactly where he has access into the wall and avoids having him drill through the plate – a tough exercise when the SIP is already in place. With this procedure I keep my electrician happy and moving along with wiring at a formidable pace. The basement or crawlspace becomes the “horizontal chase” and we simply pull wire up 14” at each pre-drilled location. Have a concrete slab? This is one of the few times I’ll request a lower horizontal chase from the factory.

So when your client or builder starts talking about putting vertical chases in every panel, think like a molecule of air. Multiple pathways for air to move through your building envelope makes it more difficult to win the energy efficiency (airtightness) battle. If the paths are created by electrical chases you should plan to go back and fill or plug them all. My advice is to plan ahead with a complete electrical schematic and have chases installed only where you need them.

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SIPschool at 2015 Timber Framers Guild Annual Conference

Wrapping the Perfect Frame with the Perfect Envelope

Wrapping the Perfect Frame with the Perfect Envelope

SIPschool’s Al Cobb will be presenting a one day workshop at the upcoming Timber Framers Guild Conference in Coeur d’Alene, Idaho. Join him on Thursday, October 29 for “Wrapping the Perfect Frame with the Perfect Envelope”. Cost is $175 per person for the all-day event, which will include discussions on the following

SIP design                                                  Tools of the trade
Basic engineering                                    Manufacturing SIPs
SIP rigging and lifting                            Sealing the structure                                                  
SIP accessories                                         Connection details
Electrical preparation                            Working with the other trades
Managing a crew efficiently                 Coordination of installation
Cranes and forklifts                                Supporting the roof
Design details                                           Site fabrication
Repair and replace                                 The business of being an installer

You don’t have to attend the TFGuild Conference to take this standalone course, but why wouldn’t you? For more information, visit the 2015 Timber Framers Guild National Conference.

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Sizing HVAC for Your SIP Home

The following question was in my Inbox this morning.

Does SIPA have any contacts in the “HVAC world” regarding proper sizing of HVAC equipment for SIP homes? 

At the 2015 Annual Meeting the Structural Insulated Panel Association announced that SIPA had entered into a buying agreement with the folks at NORESCO, LLC to offer discounts and training on REM/Design software. It’s the same program used by HERs raters to perform energy modelling on any structure, not just those built with SIPs. Technically the registered “raters” use REM/Rate to generate reports pursuant to a HERs score. However, the input, training, and modelling for REM/Rate and REM/Design are exactly the same.

The benefit of using this software is multifaceted. To aid with equipment sizing, REM/Design will calculate the BTUs required to heat and cool not just the entire structure, but room by room based on orientation, windows and doors, and specific envelope characteristics. Another benefit is the program’s ability to show compliance with code, and in most jurisdictions this report will suffice as a building inspector’s assurance that the home is being built to meet the applicable building code. In addition, the program’s output can graphically show where energy weaknesses exist in a structure. This valuable information helps to cost-effectively add performance where it is needed and trim dollars where it’s allowed.

In my experience, the real benefit of using modelling software like REM/Design is to provide a third party specification of equipment sizing. The notion that all HVAC contractors use a manual J calculation to properly size the equipment package they propose is beyond laughable. It is commonplace for HVAC contractors to use rules of thumb and size the equipment based solely on square footage, resulting in multiple bids with the tonnage of A/C and the BTU output of the heating system ranging as wildly as the bid price. If a specification of size is generated by a third party (like a HERs rater) using modelling software (Like Rem/Design), the result is all your HVAC contractors bidding to a spec as opposed to their unique rule of thumb.

Many SIPA members have seen the value of offering energy modelling to their clients. I encourage you to consider adding that service to your company’s list of value-added services.

Or, get your client to call a HERs rater and they will get the benefit of:

    • Equipment sizing (with REM/Rate)
    • Code compliance verification
    • Quality assurance via site inspections and blower door testing
    • The Green addendum leading to:
      • Better appraised values
      • Better mortgage rate

 I encourage you to ask your SIP provider if they offer energy modelling. If they don’t, the easiest and quickest path is to contact a  HERs rater.

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SIPs & Passive House

SIPs have a good track record with the Passive House community and the reason is obvious. A structural insulated panel envelope (if installed properly) is very tight, and it is this inherent tightness that allows builders to meet the airtightness requirements of Passive House. I often hear about builders’ and designers’ concerns over meeting this strict requirement. A blower door test must show the envelope will leak no more that .6 air changes per hour under a differential pressure of 50 pascals (<.6ach @ 50). I’ve personally secured contracts for SIP Passive House builds by guaranteeing to meet this metric. While many builders wonder how they will ever meet a standard that requires them to build 5X tighter than the 2012 Energy Code requirements, I welcome the opportunity to show how SIPs can easily meet that goal. 

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How Low Can You Go?

I often find interesting content on RESNET‘s Facebook page and today was no exception. With the hashtag #howlowcanyougo, followers were prompted to enter noteworthy HERS scores. The question is a great one and engages people in the discussion of energy efficiency, or does it? As I have discussed in a previous post “Real Energy Efficiency Can’t Be Bought” I make the case for true energy efficiency being about the building envelope, SIPs or otherwise. Alternative energy is an effective strategy that should follow, not proceed, building energy efficiency.

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SIPs and Small Spaces

Saturday’s Cozy Cottage Workshop was standing room only, with attendees traveling as much as six hours to be here at SIPschool.

SIPschool's Al Cobb with Cozy Cottage in the background.

SIPschool’s Al Cobb with Cozy Cottage in the background.

Our outline for the three hour session was centered on two main topics: Structural Insulated Panels, and building very small structures. Also of great interest was the “wheels vs foundation” debate, sparking discussions on the relationship between code and zoning acceptance with small houses that move. Our Cozy Cottage is designed for another option – skids – but we’ll save that discussion for another post.  Presenters included Al Cobb of SIPschool and Panelwrights, Thom Stanton of Timber Trails, Robin Hayes with BuildTiny, and Jillian Zimmerman, resident-in-waiting of the Cozy Cottage.

Jillian takes attendees on a tour of her kitchen space in the Cozy Cottage.

Jillian takes attendees on a tour of her kitchen space in the Cozy Cottage.

This introduction to Building Small with SIPs intentionally emphasized the need to build a very energy efficient structure. Audience questions also generated several discussions on living off-grid. Dumpster diving for building materials has its place but you need to be thinking long and hard about your envelope if off-grid is your ultimate goal. The core components of your structure are the hardest to upgrade or replace. In a full-size home these would include the foundation, floor systems and the building envelope. Everything else can be, and routinely is, upgraded over the life of the structure. In small structures like those seen in the Tiny House movement the core elements are the same (swap trailer for foundation, if that’s what you’re using).
Our position reflects a commitment to designing and building with SIPs. This building component may be more expensive than collecting bowed and splintered 2 x 4s from the dumpster, but SIPs will provide a fast and efficient build. SIPs have significant strength advantages over stick framed structures, but the ultimate advantage in a tiny house is the comfort of living in a SIP structure and the reduced utility costs.  A truly energy efficient envelope makes the leap to off grid living with alternative energy production an affordable option. For more on this soapbox issue of mine, check out my June 2013 post “My House Isn’t Solar Ready, Yet”. And what do you think about this articulating door?

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Are SIP Homes Hurricane Proof?

In recognition of Hurricane Preparedness Week I thought I’d offer the SIP perspective on building a structure that can withstand much of what Mother Nature can dish out. SIPs have a notable history of surviving direct hits from the devastating winds of a hurricane while their traditionally framed neighboring structures often shatter into sticks.

I have been at the table with many a homeowner who recognized the advantage of building it right the first time and making the investment in a high performing building system.  This video (courtesy of SIPA) features Meg Retersdorf of Pass Christian, Mississippi discussing why her family decided to go with SIPs in the wake of Katrina. A teenager when Camille hit in 1969, she was well aware of the destruction possible with these high wind events.

A structural insulated panel’s standalone strength, the fastening details, and the design of the structure itself all combine to create a safer building envelope.  Credit to both designers and engineers should not be discounted.  A 140 + mph wind event requires that all parties be at the top of their game. SIPA Registered Master Builder: Hall & Wright Builders of North Carolina knows that building along the southeastern shoreline carries the risk of high winds and hurricane danger. Partner Bryan McGowin states “We build in the 130 and 140 mph wind zones, and our area has seen the eye of numerous hurricanes lately. Watching a hurricane in a finished SIPs house is like TV with the sound turned off: quiet, peaceful and interesting to see,” he added.

As we prepare for the arrival of the 2014 Hurricane season, I’d always recommend getting out of harm’s way as a first choice.  If that’s not an option,  I’d want to ride it out in a SIP house!


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