Hello,

I hope you'll excuse my ignorance, but I've got a question or two about SIP roofs. My wife and I are planning our house now. We're going to do an ICF basement, but have been going back and forth between ICF and SIPs for the first floor. Either way we're interested in SIPs for the roof. Our house is going to be a two story (or I suppose more like a 1.5). We'll have a dormer on the front and back of the house. We don't necessarily want vaulted ceilings on our second floor. Would it still make sense to use SIPs or would it be nearly as good to use the spray foam insulation with standard stick building?

With a SIP roof do the SIPs rest on top of framing? I've looked around for some pictures, but haven't really seen too many of roofs. I guess a deciding factor will be cost too. Is a general estimate about $8 sq ft?

Any other pros/cons you can give me? Thanks for any advice, I really appreciate it.

Thanks,
Nick

Nick,

Good idea with the ICF basement, particularly if you are going to use it as a living or recreational area. As for the main floor walls, ICF’s are a good choice if you live in a noisy area and would like a quieter house or in an area where high winds, flood waters, forest fires or tornadoes are a concern. ICF’s are generally thicker than SIP’s, and it’s a little more expensive ordering windows and doors with wider jams. SIP’s have a somewhat higher R-value than ICF’s. I know there’s a mass issue, but I believe that a thermal mass performs best when contained completely inside the insulating envelope. SIP’s can be assembled faster than ICF’s. Get a free estimate for each to see which one is less expensive.

You can have gabled dormers or flat roof dormers. The nice thing about the flat roof dormers is that you have so much more room inside, and they’re much simpler to build. I like SIP’s for roofs because of the high R-values and their strength and you might find that the spray foam insulation is a little pricey. SIP’s lend themselves very well to a vaulted ceiling, while making the upstairs area seem much larger. It’s also easier to screw the roof panels to beams than to trusses, as the beams are wider than trusses. I imagine if you wanted to use glulam beams to support the roof, and hang joists from wall to wall for a sheet-rock ceiling, that would be possible too. And yes, the panels rest on top of the beams or trusses. If you were to use beams, a SIP panel can span up to 14 ft, depending on snow loads.

And your estimate at $8 per sq ft for 10-1/4’ panels should be pretty close. That should include screws, glue, foam cutter, lifting plates, drawings, taxes, engineering for wind and snow loads, delivery to your site and an on site rep for assembly directions.

Steve

[email protected]
www.GrandCountySIPs.com

Steve,

When you talk about cost per square foot, is that per square foot of SIP or per square foot of heated area?

Alton,

That's roughly the roof panel price per sq. ft. It all depends on shipping costs, design costs, engineering costs, etc. And if you are going with just the roof, it's more expensive, generaly, than if you combine the roof with SIP walls. It's usually less expensive per sq ft to ship a full semi than a partial load. I really hesitated to answer that question about price per ft, because of all the variables, but I didn't think it would run much more than $8-$9 per sq ft. Probably less. Maybe more. Gabled dormers are more dificult to design and build because of all the angles and intersecting rooflines and therefore more expensive to design. A no dormer standard gabled roof would be less expesive yet. A bunch of 4'X8' panels would be more expensive than few 8'X18' panels. If you're building site is on an island, in the mountains at 9000 ft with 150 lbs per sq ft snow loads and the closest road is a jeep trial, it's going to be more expensive than a suburb of Denver. I always encourage people to get a qoute to find out what it will cost, instead of a ballpark price. If the ballparkprice is too high, people are discouraged, and if it's too low, I'm a no good son of a gun trying to drum up sales. Guesstimating is a no-win siuation. I hope that answered your question.

Steve

GrandCountySips.com

Steve,

Thanks for the help. We're definitely going to get some estimates. I understand where you're coming from about the ballpark figures. The dormers are going to the flat roof dormers. Hopefully it ends up being a fairly straightforward job. We're trying to keep it somewhat simple. Actually, the roof line is somewhat similar to the house in the pictures on your website (minus the peak over the front door).

Let me ask you one other dumb question. We've been considering going with concrete floors throughout the house. If we go with a SIP main floor, would it be possible to put a concrete floor on the second floor? I'm still not sure we even want vaulted ceilings. Where do you put your ductwork when you do that?

Thanks again for your time and information, I really appreciate it.

Thanks,
Nick

Nick,

I thought I’d just mention that the peak over the front door is a small entrance area. It makes a great area to hang coats, boots etc. It also acts like an air-lock since there is an inside and outside door, keeping the cold air and wind out of the house when we come in and out during the winter. Also, under the entrance in the basement is my boiler, water tank and electrical center.

I have an in-floor radiant heat system in my house, so the whole first floor is tubing covered by 1-1/2” of gypcrete. I put a steel beam under the floor the length of the house and put I-joists from that to the outside walls on 16” centers. I didn’t put in-floor heat upstairs, so I didn’t put any gypcrete up there. If you wanted to, I don’t really see a problem putting 1-1/2” of concrete on the second floor. You would need a steel beam to support the weight with posts from the basement in the center of the house up to the second story steel beam for support. In the SIP walls you would have the foam cut back enough to place a beam in the walls to support the steel beam at its ends. Do all the duct work before you pour the concrete and have the duct exits in front of windows against the outside walls. Talk with your HVAC guys about this. Make sure they do a thorough heat loss estimate to get the proper sized unit. If it’s too big or too small, it’s going to cost you money.

If you are living in a predominantly cold climate or a mix of hot and cold, I would advise going with SIP’s and maybe in-floor heat or a heat pump. If you’re living in a predominantly warm climate, go with ICF’s and possibly a Hallowell heat pump. Take a look at solar, as they have made some good strides in that direction, and with an energy efficient house, the price is more reasonable. Many times if the cost of the solar unit is added to your mortgage, the money you can save per month is more that the extra monthly mortgage payment.

Steve

GrandcountySIPs.com

Steve:

Thanks...RE:"Talk with your HVAC guys about this. Make sure they do a thorough heat loss estimate to get the proper sized unit. If it’s too big or too small, it’s going to cost you money. "

They (HVAC guys with SIP expereince) are pretty rare in California. Which unit(company) did you put in? Perhaps I can address it directly to their engineers...


John

WOW!!!!!! That is VERY expensive!! I just did a calc on the house I finished. It was a 3750sf heated house with 5900 sf of roof.....That came out to OVER $47,000!!! Just for the roof????????? I'm I missing something here????

Robinnc,

That's exactly why I don't like to make estimates sight unseen and no idea of what you're trying to build and encourage to get quotes with all of the pertinate information. Here's a closer way to ballpark estimate what it costs to build with SIP's. Take a house, estimate what it would cost to stick build it with 2X6 framing, add 1 to 3%, and that'll be pretty close. The last few houses we did came within 1% of the stick build estimate. Ok, let's consider your house for a moment and assume you had it stick built. Take 3750 sq ft times $135 a sq ft to build gives us a house building cost of $506,250. Now, add 1% to that gives us $511,312. So, bottom line, it might cost around $5062 more to build with SIP's, but it would cut your heating and cooling bill in half. Now, say your average heat and cooling bill is $200 a month, your ROI would be just over 2 years. Even if at $100 a month, your ROI is just over 4 years. As the price of heating fuel and electricity climb (and they will) your ROI will be even sooner.

Thank you for again pointing out the error of trying to make a blind estimate. It's kinda like asking for a car estimate. After all, they're all made out of steel and plastic. Without knowing if you want a Chevrolet Aveo5 or a gold plated Rolls Royce, and not knowing where to deliver it to, it's darn hard to make an accurate estimate. I've learned my lesson. No more blind estimates.

Steve

GrandCountySIPs.com

trigem1, I see your point and I completely understand why you wouldn't like to make a blind estimate. You don't want to scare any potential homeowners from using SIPS due to sticker shock.

On the other hand, when a future homeowner is looking into materials to see what he can possibly build with, it's also likely to scare them off when nobody wants to give them a realistic idea of what SIPS cost. People tend to shy away from unknowns.

With something like a roof, when comparing traditional methods to SIPS, one has to factor every single piece of material in that traditional roof into the equation. Every piece of OSB or plywood, every piece of roofing felt, every single truss, every inch of spray foam. When one has real numbers to crunch, then SIPS probably won't look THAT much more expensive.

What was the cost for the conventional... trusses, sheathing, insulation, etc.?

Steve, I don't know where you are but it doesn't cost anywhere NEAR $135/sf to build(actual cost) and not a cheap track home but all brick sides, hardwood flrs, granite in kitchen, etc. I am a new GC in this area.  Sounds like you might be in the NE or out west.
 A SIP roof is litteraly thru the roof expensive. The house I just finished building was the 'Middleton' by Frank Betz. The materials list says it would need 60 squares of shingles for the roof. This comes to right at 5700 sf of roof. An OSB board is 32 sf, so it would take approx. 180 sheets at 8 bucks each equals to $1440(actually at the big box stores these are going for $5.50ea now). Add maybe $1000 bucks for labor just for this OSB to install. Shingle install(labor and materials) would be around $6000.  Total $8400 bucks total......One H@llava lot less than SIPS at $47,000 bucks!!!!!!!!!!!
The wall pricing at $8sf is reasonable........but no way in H@ll are the roofs. You would NEVER recoup the extra costs in your life time!!!!!!

robinnc, it's informative for me to see you break down those numbers like that.

Now correct me if I'm wrong, but I think you forgot two major components on the traditional roof - insulation and trusses. I don't know what trusses and 5 or 6 inches of spray foam under 5700sf of roof will cost. But unless it's $38,600 then I guess the traditional roof is more economical?

One more thing - the SIP roof would need to be finished, whether it's shingles or standing seam, etc. This cost is on top of the already mentioned figures, right?

my SIP house had a 200m2 floor plan. The roof was made in 4 sections from smaller panels made on site and then lifted into place with a crane. It would have been faster to have made the roof in place as the team of 6+ lost so much time trying to acurrately align such big 'jumbo' panels due to their weight and the friction on the beams. Lift is fine, but pushing them together is a different matter. I guess it depends on the jointing system you use.

You can see pictures of the large panels going on to the roof at the bottom of the page here: http://sip-house.blogspot.com/search?label=sip

Jonty

Steel clad SIPS are your bet for any structure above ground level, your savings surpass any thing out there right now for energy savings and storm resitstance and building longgivity,Ralph...............www.Flagreenbuilder.com

Green1,

Which steel clad SIP do you use in Florida?  Here is my e-mail address if you do not want to show the brand name here.

alton at auburn dot edu             Please substitute the smybol for at and period (.) for dot.  Maybe writing my e-mail this way will hold down the SPAM.

Jelly, your're right. I did forget to add the insulation into that figure. Add another $1000 bucks.  I can't possibly see anyway a SIPS roof would pay back in anyone's lifetime.
I've also heard  that SIP roofs tend to 'pop' and 'crackle' from time to time with weather changes.  Anyone here heard this?

I don't recommend SIP roofs for every application. Some examples:

• Top floor areas w/o a true vault...
• That includes:
• - Areas with 8' - 9' ceilings...
• - Areas with 'Tray' ceilings...
• - Any area where the ceiling is lower than the plane between exterior wall and the roof ridge...
• Complex roof designs...

Now let's look at a simple 30' x 50' rectangular structure:

• 1,500 sqft on the main floor...
• 12/12 roof pitch...
• 1.5' gable overhang...
• 'Lookouts' for non-gable overhangs...
• Add two lofts and a basement, and you've got over 3,500 sqft...

53' x 22' x 2 = 2,332 x $8 = $18,656

Use SIP roofs where they are appropriate and make sense.

PanelCrafters,

I'm not trying to argue, just to learn:

I'd understood that the advantage was to eliminate the problem in sealing the ceiling levels: that there was an advantage even if the "attic" volume were not used. 
If the walls are difficult to seal properly, why wouldn't the roof structure or ceiling plane be at least as hard to seal?
Why does the ceiling height matter?
Why do effects such as a tray ceiling matter?

Very respectfully,
Larry

That wasn't the intent of my post. I was trying to show that SIP roofs can be a good solution.


If you are placing mechanicals in the attic space is one valid argument. Otherwise w/o a true vaulted situation, you are then also paying for framing or trusses to have a lower ceiling level(or you have a complex roof design). And, you would also be heating a larger space, unless you add insulation above the ceiling. Niether of which make sense to me(or probably someones budget).