SIP VERSUS SOUTHERN PINE LUMBER (Roof Framing compared with typical roof 20 psf Live Load + a 10 psf Dead Load with an L/240 deflection limit )
SIPs are known for #1 energy performance and #2 speed of construction* versus the more common stick framing. (*BASF did a SIP versus stick time and motion study in 2006 with the results summarized in this next chart)
But there is a third aspect - #3 Strength, where SIP also beats 'Stick' framing.
The following are the facts gleaned out of the Southern Pine Council's latest Span and Load Charts versus published SIP span and load data. Let's start with the most common roof framing method which is 2x6 spaced anywhere from 16" to 24" apart using either No.2 or No.3 SYP.
2x6 - No.2 : 16"o.c. spacing - maximum span 13'-5" -- OR -- 24"o.c. spacing - maximum span 11'-0"
2X6 No.3: 16"o.c. spacing - maximum span 10'-2" -- OR -- 24"o.c. spacing - maximum span 8'-4"
6.5" SIP (5.5" CORE) DBL 2X SPLINE ESTIMATED MAXIMUM SPAN ~ 17.5 FEET!
SIPS WIN VERSUS 2X6 FRAMING BY ~30% !
Do you frame with 2x8's or 2x10' rafters?
2x8 No.2: 16"o.c. spacing - maximum span 17'-1" –OR --24"o.c. spacing - maximum span 13'-11"
2X8 No.3: 16"o.c. spacing - maximum span 12'-10" –OR --24"o.c. spacing - maximum span 10'-6"
8.25" SIP (7.25" CORE) WITH BLOCK SPLINE MAXIMUM SPAN ~ 17 FEET BUT WITH DBL 2X SPLINE MAXIMUM SPAN ~ 22 FEET!
SIPS WIN VERSUS 2X8 FRAMING BY ~28%!
2x10 No.2: 16"o.c. spacing - maximum span 20'-3" – OR -- 24"o.c. spacing - maximum span 16'-6"
2X10 No.3: 16"o.c. spacing - maximum span 15'-7" –OR -- 24"o.c. spacing - maximum span 12'-9"
10.25" SIP (9.25" CORE) ) WITH BLOCK SPLINE MAXIMUM SPAN ~ 18 FEET
Stick framing SP No.2 2x10 at 16" o.c. wins this one!
BUT A 10.25" SIP WITH DBL 2X SPLINE HAS A SPAN OF 24* FEET (with a higher load of 20 psf LL + 20 psf DL)!
*(Actual limit is the SIP's maximum 24’ panel length)
SIPS WIN VERSUS 2X10 FRAMING BY ~20%!
SIP (AN ENGINEERED WOOD PRODUCT) WINS THIS STRENGTH CONTEST EASILY!
But don't worry about the very-green carbon-sequestering Southern Pine Industry - because the SIP OSB skins are made from Fast-Growth-Pine!