I'll soon be having my house built from SIPs but I'm balking at the price of the SIP roof panels as it's almost twice the cost of the wall panels in terms of $/sqft. As well, there's the increased risk of OSB roof rot, as well as the need to fur out the underside of the SIP roof for fire sprinklers, canned lights, etc. Since my design calls for a near flat roof, I'm considering an i-joist framed roof with osb/plywood sheathing glued/nailed/caulked to the top wall plates, similar to how you would frame a floor within the SIP walls (without rimboards). Insulation would then be exterior overlapped layer of XPS rigid foam glued to the sheathing followed by the roofing. Would this work? Will I be able to have an air tight structure with this manner? OR should I just pony up for the SIP roof? :unsure:

Have you priced metal skinned SIPs for the walls and roof?  The EPS core types usually cost less than polyurethane cores.  There is no worry about the OSB SIP roofs when using metal skins.

there is no difference in metal skinned SIPs if they are used in walls or roof, thickness is the only factor that changes cost

Unfortunately, metal skinned sips cost more than the osb counterparts, due to the metal skin...

Hey Chris, do your metal roof SIPs have internal reinforcements like OSB roof SIPs?

Leon,

Where will you be building?  Some of us might know products or installers for your area.

No our steel SIPs do not required to have any internal supports, hence the name "Structural" , these 2 steel 10" thick SIPs are supporting the car and are clear spanning 16 feet.

The OSB skin EPS type SIPs that I know about require structural support at every joint.  This type of structure replaces EPS (insulation).  In other words, the structural support creates thermal paths.  However, some OSB skin polyurethane SIPs do not require dimensional lumber at the joints.  Check with your local suppliers about what is needed for their systems.

If any of you can recommend reasonable and affordble installers near Redmond, WA (Seattle), that would be great! That is one drawback as I am having a hard time finding a suitable installer that isn't simply saying the cost of labour will be the same as stick framing. The OSB SIPs that I am looking at don't normally have structural supports at the joints; they are glued and then connected by flat splines; no thermal bridging there, similar to how the steel SIPs tongue and groove. However, for roof SIPs, they are a bit different if there are spans 24ft, then there must be internal supports, which is what I find increases the roof SIPs costs. I guess this could be avoided if I have shorter spans but at the increase of more beams every 16ft.

Hey Chris, Do you have any steel sips that can span more than 16 feet?

What kind of finish is necessary for a metal sip roof? It is waterproof in and of itself right? So what do you put on top of it? and do you still insulate the attic?

Posted By Leon Hui on 31 Jan 2012 02:39 PM
Hey Chris, Do you have any steel sips that can span more than 16 feet?

Leon;
Yes of course the panels will span more than 16ft. I was simply demonstrating the strength of the panels with out any internal support

Posted By cathsand on 31 Jan 2012 04:39 PM
What kind of finish is necessary for a metal sip roof? It is waterproof in and of itself right? So what do you put on top of it? and do you still insulate the attic?

Metal SIPs can be used for the finished surface on "simple" gables, hips & mono-pitched roofs. No valleys!!, the T&G seams will need to be taped with an eternabond type tape. The SIP home in Haiti (previous post) were bare panel roof.
Or any conventional finished roof may be applied if desired.

Posted By cmkavala on 31 Jan 2012 05:00 PM

Leon;
Yes of course the panels will span more than 16ft. I was simply demonstrating the strength of the panels with out any internal support

Would a wood truss roof at 16" OC spacing be weaker or stronger than a metal SIP roof?

What is the best R-Value one can get with a metal SIP roof?

Does a SIP need to be vented?

How does one install a T&G ceiling or drywall ceiling onto a metal SIP roof?

Can one install a standing seam metal roof on top of a metal SIP?

With 30-40 degree diurnal temperatures within less than 15 hours, how much expansion would a metal SIP roof experience and how bad would the "popping" be?

Posted By Lbear on 31 Jan 2012 05:22 PM

Posted By cmkavala on 31 Jan 2012 05:00 PM

Leon;
Yes of course the panels will span more than 16ft. I was simply demonstrating the strength of the panels with out any internal support

Would a wood truss roof at 16" OC spacing be weaker or stronger than a metal SIP roof?

What is the best R-Value one can get with a metal SIP roof?

Does a SIP need to be vented?

How does one install a T&G ceiling or drywall ceiling onto a metal SIP roof?

Lbear;
The question about truuses is too broad,would depend on a lot of variables.
No SIPs do not need vented
To Install T&G ceiling , you would first fur-out with 3/4" furring strips, drywall can be screwed directly to the SIP skin or if wiring is needed, then first fur down with 3/4" wood strips or 7/8" steel hi-hat furring
a 12" thick steel SIP is R-51

Posted By cmkavala on 31 Jan 2012 05:31 PM

Lbear;
The question about truuses is too broad,would depend on a lot of variables.
No SIPs do not need vented
To Install T&G ceiling , you would first fur-out with 3/4" furring strips, drywall can be screwed directly to the SIP skin or if wiring is needed, then first fur down with 3/4" wood strips or 7/8" steel hi-hat furring
a 12" thick steel SIP is R-51

If the T&G ceiling utilizes a fur-down, would there be a chance that moisture would settle in-between the metal SIP and T&G?

Have you seen them install a metal standing seam roof ON TOP of a metal SIP? If so, is there any expansion issues?

With 30-40 degree diurnal temperatures within less than 15 hours, how much expansion would a metal SIP roof experience and how bad would the "popping" be? This is a big sticking point with me, I am still not confident that the popping issues have been resolved but I am open to inspect and learn.

If the T&G ceiling utilizes a fur-down, would there be a chance that moisture would settle in-between the metal SIP and T&G?

Have you seen them install a metal standing seam roof ON TOP of a metal SIP? If so, is there any expansion issues?

With 30-40 degree diurnal temperatures within less than 15 hours, how much expansion would a metal SIP roof experience and how bad would the "popping" be? This is a big sticking point with me, I am still not confident that the popping issues have been resolved but I am open to inspect and learn.




Our typical installation is steel furring and drywall, we have never seen, experienced or heard of moisture in the airsapce, nor can conceive that ever being problematic since furred air space is same temperature/humidity as the interior space, it is all inside the insulated envelope
We install standing seam roofs over our SIPs often,
we like to use a polyshield self stick membrane, then screw SS to SIPs.
While I would expect to hear expansion/cotraction in the standing seam, I have never had any customer call backs for popping? It is a non issue for us.If it is going on the air space may be muffling the noise

Seems like they should make a sip roof panel that looks like standing seam.

Posted By cathsand on 31 Jan 2012 09:51 PM
Seems like they should make a sip roof panel that looks like standing seam.

Kingspan does.  See http://www.kingspanpanels.us/produc...fault.aspx

I really like their 900 high rib roof!! Is that stuff practical/affordable for residential? Talk about eliminating trades!

Kingspan is not really made for the residential market, standing seams spaced 42" apart are very industrial looking and ther valley flashing details are problematic