Greetings! This forum has been an invaluable resource for researching modern building practices. Thank you. I'm starting construction on a new home (North Alabama) very soon. I've decided on SuperiorWalls for my walkout basement and am looking hard at SIPs construction for my home. The home is 1800 heated sq ft main level and 1100 in the walkout basement (53 linear feet of exposed wall on walkout basement) plus a 25x25 garage. The home is a modern design with "shed" style roofs that nicely lend themselves to vaulted SIPs construction. I have one estimate from a contractor for 100% stick construction as follows. Framing materials $32,000 Misc material-nails $1,717 Framing labor $25,000 Insulation: $3,000 Total: About $62000. My SIPs estimate came in at $56,000 including vaulted roofs and delivery. But I will have to add to that the cost of the uninsulated 25x25 garage which will be of stick/truss construction - I'm guessing 6 to 10k? I also have to add the cost of interior walls to that. Another 3 or 4k perhaps? So, about 68k total to build my house out of SIPs compared to 62,000 for stick construction. But for that additional money, I get no surprises - I know what the cost will be ahead of time. I get a much higher R value (R23 for walls, R30+ for roof) which reduces the tonnage for AC and, of course, heating/cooling bills. Plus, the house is "dried in" in two days shaving weeks off construction time which will save money in loan interest. Am I missing anything here? The two quotes I've received so far seem to be high. Are my quotes about what you'd expect? Attached is a file with the mail level and basement on one page.

Hi Jim,

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Does the SIP pricing include installation? Are all of the prices with or without the floor framing?

What type of SIPs? Metal, OSB?

RichM

Would you mind telling us which SIP company gave you the quote?

Sorry, Rich.

The SIPs price includes delivery and crane/setup. I would have to supply the laborers. They are 4.5" OSB SIPs.

Stupid me, I had not considered that the "stick" price includes flooring. The SIPs quote does NOT include flooring. That makes the price difference between SIPs and sticks even wider. Don't know that I can justify that.

The SIPs quote was only one quote from one highly-recommended SIPs provider that is within 2 hours driving time from my location. I'm expecting other quotes soon.

I can't see how to attach a JPEG to this message.

Alton, the provider of my quote was SipsOfTheSouth dot com. The constructed a house in my area (Florence) and the owners are singing their praises. I've also been impressed with their level of service thus far but I *think* their prices are considerably higher than I anticipated.

Jim,

Can we assume that the SIP roof panels are thicker than the 4.5" wall panels?

RichM

richm,

Yes, the roof SIPs are 8.5" thick (R30ish) as opposed to the 4.5" walls (R17ish).

Jim,
Some thoughts to help you along the way:
You've chosen a "superior" basement system that has similar High-Performance attributes as does a SIP system. I'm willing to wager that you can find a significantly cheaper basement in poured walls or CMU. Therefore, how do you justify the Superior walls system over the inferior competition and not see at least the same advantage of SIPs over sticks?

You have chosen wisely with SOTS. They are both reputable and capable. Keeping that in mind, when you get competing quotes, I urge you to verify similarities in all quotes. Are you being quoted a fully CNC fabricated package with lumber? Do all quotes include drawings, delivery, installation accessories, and installation assistance? One of the advantages of dealing with a "Full Service" dealer like SOTS is that you get a complete package.

Your dream of a smaller and more affordable HVAC system will only be realized if you engage a third party to do energy modelling and create a equipment sizing specification. Without that piece of the puzzle, you are at the mercy of "Old school Rules of Thumb"! The secret to sizing is to use a professional who understands high performance and approved modelling software.

In furthering my above point, I wonder if you have spoken to a HERs rater yet. If not, you're stacking the deck against yourself before the job even begins.

If you have begun a relationship with a rater, you are aware of all the good things they can offer including proving similarities in performance. What I'm saying is that your rater can define a level of performance that your stick framer should match so that you are comparing apples to apples. Let's see if your framer is willing to commit to meeting the 2015 MEC and guaranteeing a blower door test of less than 2 ACH@50. I'm willing to bet he wouldn't touch that specification with the material and labor number that he has already quoted.

Lastly, why are you (Like so many others) looking at "first cost & not "total cost"? Unless you plan to build and sell the house within a few years, you are ignoring the biggest advantage of a SIP structure. You SAVE money every month in utility costs over code minimum stick framed house. Hence, if you run the numbers of a mortgage (I'm assuming you're not paying cash for this house) you will usually see that an upfront increase in building cost converted to a monthly payment is less than the utility savings created by your intelligent choices made right now.

OK, this is lastly as well. You will not dry that house in in two days with a SIP package!

If you want to know what else you're missing, we can talk about:
the green addendum
proper appraisals for high performance homes
energy efficient mortgages
proper ventilation
etc.


Regards,
acobb

Also,

If you take out the Sip roofs and put a roof truss system on your house instead - where does that bring your cost?

Are the R values of the traditional built house and the SIP walls similar? Are you looking at thermal bridging?

I'm currently going through the same price quote process .... looking at ICF's or Superior Walls for my Walkout basement and SIPS vs Traditional Stick for my home. I'm heavily leaning towards SIPs because I do plan on living in this home for 15+ years.

"Lastly, why are you (Like so many others) looking at "first cost & not "total cost"? "

I don't think I stated I was looking at "cost first." I have a budget that I cannot exceed. My research tells me that SIPs ought to cost "about " or "a little more" than stick but with extraordinary benefits. My first quote was at least double the cost of stick construction and that goes against everything I've read.

Fortunately, I have found a couple of other suppliers that are in line with what I expected. My last quote was from Panel Wright and was more than 20k less expensive.

"If you take out the Sip roofs and put a roof truss system on your house instead - where does that bring your cost? "

The roof panels on my first quote are about 20k.. That would be a vaulted roof that is already insulated, of course. My truss quote comes in a 5k for the trusses. To that, I have to add insulation (perhaps $500 for 1800sq ft?) and osb sheathing (25 sheets) about $1000. Total truss material cost of $6500. Gonna have to add a little labor to both but, as it stands now, truss construction will save me at least 10k.

BUT! Some of my numbers are quite jibing. I think the first quote overestimated the roof square footage. They have 3800 sq ft and I only have 2400 sp I'm studying that a little more.

Another quote I received suggested that if I use trusses for my roof, I could still use "single sided" (nailbase) SIPs panels. However, I am not seeing the benefit of those sips versus a simple assload of insulation above sheetrock in a truss system.

So, the journey continues.

Thanks all. I'll still be post here as I get more info.

Cheapest route = truss roof with blown in cellulose

Where SIPs rule over truss systems is:

• SPEED - one can have a fully enclosed & insulated roof within 2-3 days vs weeks or months later with a truss system
  
• STRENGTH - trusses are toothpicks in high winds vs SIPs which are 3-4 times stronger
• AIR TIGHTNESS - much harder to seal a truss attic space
• CONDITIONED ATTIC - no need for gable, attic, ridge, soffit vents
  
• CATHEDRAL CEILINGS - the proper way to insulate and seal a cathedral ceiling 
• INSTANT SOFFIT/OVERHANGS - no need to frame out and build soffits, SIPs make instant soffits
  

The above points is what you pay extra for in a SIP.

It's not clear to me what happens to OSB roof SIPs after the asphalt shingles get old (or any other leak) and the OSB rots here and there.

Posted By jonr on 15 Dec 2014 11:36 AM
It's not clear to me what happens to OSB roof SIPs after the asphalt shingles get old (or any other leak) and the OSB rots here and there.

The goal of any roof sheathing is to keep it dry. SIPs are no different. The roof underlayment is key.

Asphalt shingles are not supposed to be the water barrier. The underlayment is supposed to do that. Peel & stick is the best choice for keeping the roof sheathing/SIPs dry and rot free.

Posted By Lbear on 15 Dec 2014 04:56 PM

Posted By jonr on 15 Dec 2014 11:36 AM
It's not clear to me what happens to OSB roof SIPs after the asphalt shingles get old (or any other leak) and the OSB rots here and there.

The goal of any roof sheathing is to keep it dry. SIPs are no different. The roof underlayment is key.

Asphalt shingles are not supposed to be the water barrier. The underlayment is supposed to do that. Peel & stick is the best choice for keeping the roof sheathing/SIPs dry and rot free.

Actually ....... shingles (properly installed ) are the primary water barrier, the underlayment is the "secondary" water barrier

Actually.... Chris is right about the shingles and the advice to use peel and stick is only applicable in the deep South. Without a clear understanding of building science that's geographically applicable, you can often be mislead by on-line forums such as this. Placing a vapor barrier (Peel & Stick membrane) on the wrong side of your assembly is a really bad idea! Regardless of the type of panel, trapping moisture in your assembly can lead to all types of moisture related issues.

Al Cobb
SIPschool.org
training and consulting for the SIP industry

Peel and stick would be safe with a vented design (another OSB layer above the SIP). How does it work when you remove old shingles - does the P&S get damaged and need replacing too?

Of course adding a vent/gap and P&S starts to up the cost even more (as compared to a vented attic/truss/cellulose/OSB/tar paper/shingles design).

Posted By acobb on 16 Dec 2014 10:44 AM
Actually.... Chris is right about the shingles and the advice to use peel and stick is only applicable in the deep South. Without a clear understanding of building science that's geographically applicable, you can often be mislead by on-line forums such as this. Placing a vapor barrier (Peel & Stick membrane) on the wrong side of your assembly is a really bad idea! Regardless of the type of panel, trapping moisture in your assembly can lead to all types of moisture related issues.

Al Cobb
SIPschool.org
training and consulting for the SIP industry

SIP roofs CANNOT breathe or dry to the exterior once you place a standing seam metal roof on them. So it makes sense to use a peel & stick membrane underneath the metal roof since it will protect and seal the OSB from water infiltration.

Lbear,
your original comment about using peel & stick was used in conjunction with asphalt shingles. In that scenario, (without back-ventilation and in the majority of North America) you have offered bad advice as it relates to SIP assemblies.

A peel & stick membrane acts as a vapor barrier as it has zero permeability. Therefore, if we follow your specification and the codes requirement of a vapor barrier (SIP tape) on the inside in all climate zones north of Florida, we have the worst of all possibilities. Zero capacity to dry! You have designed an assembly with a vapor barrier on both sides!

I agree that a standing seam roof (Or any other non- self-ventilating cladding) that is installed directly on the roof assembly greatly reduces the assemblies ability to dry. However, it's capacity is not reduced to zero until we apply peel & stick. The detailing of installation MUST be geographically driven. A standing seam roof in Georgia may work very well applied directly to the SIP. However, in Vermont the reduced capacity to dry would suggest an installation detail that uses some form of back-ventilation. Once again, your blanket statement does not qualify a climate zone or the applicable building science.

The proper detailing of any high performance assembly pays as much or more attention to drying than it does to keeping bulk water out. By definition, a high performance wall or roof assembly has a "Reduced Capacity to DRY" because of the air-tightness associated with maximum energy efficiency. In climate zones 4 and above, one must be very careful with the detailing to create an environment that promotes drying. The use of self-ventilating cladding and/or back ventilating is the best way to ensure durability of the structure and eliminate moisture related problems.

This discussion is equally applicable to all types of SIPs and all types of assemblies. I stand by my statement that it's a really bad idea unless you're building in a climate zone that does not require a heating system. In that case, your vapor barrier goes on the outside of the structure and your assembly can dry to the inside.

Al Cobb
SIPschool.org
training and consulting for the SIP industry

Regarding roof construction:
http://www.buildingscience.com/documents/insights/bsi083-mea-culpa-roofs/view?utm_source=Building+Science+Corporation+List&utm_campaign=8b06c95e02-BSC+Newsletter+Issue+%2375&utm_medium=email&utm_term=0_194890bc8c-8b06c95e02-63876805

What little research I found suggests that a standing seam metal roof does allow small amounts of air flow (ie, isn't an effective vapor or air barrier). It's not like the metal is glued to the decking and the seams are caulked. Same for asphalt shingles.