You may recall our Preliminary SIP Mfg Evaluation in early December. After speaking with the various manufacturers about their basic process, product and market differentiators I owed them more detailed plans to give us a quote for the two homes. I just finished contacting the manufacturers and delivering the plans to each of them for quote.
The plans spec out 2×6 framing on 24″ centers with bat insulation (R19 walls / R30 roof) which is what Level 5 will be quoting for a baseline cost. If we were to go with stick framing we would most likely not use traditional bat insulation methods. At the very least we would caulk and seal all joints prior to installing the insulation and at the most we would use a full spray foam or blow-in cellulose insulation. I would probably lean towards a hybrid system of spray foam in a half-inch space between the framing and exterior sheathing, with a more traditional and less expensive insulation in between the framing. More on these options later…
While I was initially very excited about using SIPs for these homes, some doubts have crept in that I am looking forward to addressing in more detail with the manufacturers. One of the main issues is our party walls in Philadelphia that must achieve a 2 hour fire rating in between new homes. One and possibly even two layers of SIPs will most likely not solve this requirement. The other issues is how to support the roof panels. If an extensive beam or truss system is required it will increase our material costs, effect our interior appearance and increase the need for traditional framers on the jobsite. As we get farther away from a full SIP home and closer to a 50-50 hybrid of SIP and traditional framing I get less excited as I envision the cost savings from efficiency starting to deteriorate…
Lastly, I have received some conflicting opinions on SIP assembly, sealing and exterior cladding that I am hoping to clear up and educate the team further on as we are all fairly new to SIPs and have no personal experience with a SIP project in Philly.
9 comments ↓
Just got off the phone with Dan from SureTight and he said they have a detail to use two 4.5″ SIPs with a small air gap in between to achieve a 2-hour fire rating.
Hey Chad,
Johns Manville has a pretty cool product called “Spider” - it’s a blow-in technology that seals pretty much every nook and cranny. Not sure of the cost, but it seems highly efficient. If the SIPs aren’t an option - or if you need to augment the SIPs with traditional stick framing - you might consider this route.
Here’s a link: http://www.specjm.com/products/sprayin2/spider.asp
I’ve never personally used this product, so I can’t vouch for it.
You might want to check out:
www.thermocoremo.com
Their Polyurethane SIPs have the highest fire
rating in the industry.
The “Spider” product could certainly be one of our options if we went stick framed. I looked up vendors and they actually carry it just down the street from our site.
Thermocore looks nice but they are a bit outside of the 500 mile radius we are trying to stay in. Staying close to home reduces transportation which helps with LEED and cost. We are also trying to support businesses that are as local as possible.
I was given this link for the detail on achieving a 2 hour fire rating - http://www.suretight.com/suretight_pdfs/SIPS-19.pdf
Hi Chad,
We have the same issue here in Baltimore with the party walls. Dan (form Suretight) provided us with the same detail. We actually took a trip up to the Pittsburg area to tour the factory about two weeks ago and found it very informative. I’d suggest taking a few of your team members for a similar trip. It helps to clear up a lot of issues when you view the panels in their various stages of production.
We’ll be submitting our plans for review shortly and should have another comment on this subject in short order.
Ray,
Thanks for the info. Good to hear someone is using SIPs in a similar urban application. I’d like to visit the factory once we decide. Not sure if we’ll be able to get the whole team to go. Looking forward to more updates from your project.
Why can’t you use the GWB systems - the ones with aluminum break away clips on either side of the rated shaft wall. Then you just build your narrow sips wall against it. I doubt you will beat that for cost - this is the lowest common denominator.
I think this is what’s spec’ed in the plans now. I’m not that familiar with the system.
If I understand you correctly, you are suggesting traditional framing using the GWB system for the party wall only and SIPs for everything else?
Its not quite traditional framing - uses a system of H shaped studs to hold extra thick GWB panels that create a 2hr wall. Its located inbetween two conventional walls, so if there is a fire on one side, then only the one side will fall down. It was designed for stud construction - I’m not sure how it would adapt to SIPs.
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