Any rough framers have a 2009 IRC? I have a question.

[Nick Gromicko]

My question has to do with figure R602.3(2) on page 152.

Don't the ends of the window sill need jack studs under them (not just along side them)?

[Bob Elliott]

Just so we can all follow.

[Nick Gromicko]

That's not figure R602.3(2).

[Nick Gromicko]

Here is figure R602.3(2) from the 2009 IRC. See anything wrong with their drawing?

[Stephen W. Stanczyk]

Nope. The jack studs are for the load bearing header, not for the window frame out.

[Nick Gromicko]

Doesn't the window sill need jack studs like Bob's image depicts?

[Stephen W. Stanczyk]

Personally I would not call it out. The sill is non load bearing. Just there to frame out the window. In Bobs picture, they are using those as a jack stud all the way through the sill to the header.

[Nick Gromicko]

Nails only hold wood together, they are not meant to be used to carry a load (even if the load is only a window) like the horizontal nails holding up the ends of the window sill are doing in the IRC's figure R602.3(2).

[Tim Spargo]

I know the diagram you speak of Nick.. it shows the sill to be what would appear toe-nailed to the jack with cripples under it. The only thing that I would say is correct in *that* diagram is that the Jack is not intersected. I'm in CA, and haven't ever nailed at least one full trimmer or jack stud under a beam.. period, and tightly to boot.

I have however seen many times in practice where the sill is simply face nailed to a cripple below it that is *nailed directly to the jack*, meaning no sandwich as in Bob's illustration.

There are requirements for openings over 60" and having double trimmers and a single king.. but again, at least one full length jack/trimmer under the beam. When we used a second Jack as shown in Bob's diagram, and sandwich a sill between the pieced Jack, we'd call it a sub-sill and nail another sill on top of it. Lotta wood, eh?

I think the Sill and Sub Sill methods tie into the trades of years past as the top Sill would be SLOPED... remember the 2 x 6 and 8 sloped sill window opening's?

[Nick Gromicko]

Interesting take on it. Thanks.

[Tim Spargo]

And just as I replied.. there's that illustration..

I'd agree that it's correct in CODE, but incorrect in practice. The only time that I would see a sill framed like the one pictured, is right before I nailed a piece of framing next to each jack and under the sill. IMO, it's more incomplete than incorrect.

[Nick Gromicko]

One of the reasons I noticed it was because the dead load of a wall is calculated by including the additional load of any windows (about 8psf) which would mean the horizontal nails holding up the ends of the sill plate are carrying some load, albeit not very much.

Thanks for your insight.

[Jim Hime]

The IRC R301.2.1.1 Design Criteria via the American Forest and Paper Association (AF&PA) - Wood Frame Construction Manual for One-Two Family Dwellings (WFCM) also shows wall framing without a jack stud at the sill ends.

The perimeter of a window is fastened to the framed opening. In my area we add the jack studs as common practice and habit. A wall is built on the foundation and then stood up. The extra jack stud generally aids in keeping the window opening from torquing from the frame (depending on the amount of labor onsite). The lack of the jack studs at the sill ends has no real value to the load-bearing of the wall. The lack of these jack studs can increase wall insulation and decreases thermal bridging. (Green Building)

[Brian A. MacNeish]

[quote=jhime;786811]The IRC R301.2.1.1 Design Criteria via the American Forest and Paper Association (AF&PA) - Wood Frame Construction Manual for One-Two Family Dwellings (WFCM) also shows wall framing without a jack stud at the sill ends.

The perimeter of a window is fastened to the framed opening. In my area we add the jack studs as common practice and habit. A wall is built on the foundation and then stood up. The extra jack stud generally aids in keeping the window opening from torquing from the frame (depending on the amount of labor onsite). The lack of the jack studs at the sill ends has no real value to the load-bearing of the wall. The lack of these jack studs can increase wall insulation and decreases thermal bridging. (Green Building)[/quote]

Optimum Value Engineered (OVE) framing saves labour/materials up front and allows for more efficient walls with less low R-value framing and more lower cost but better R-value insulation; the average overall R value of the wall goes up. The OVE concept has been around for 25-30 years now.

[Nick Gromicko]

In my area we add the jack studs as common practice and habit.

Same here in my area.

Many windows require that you install shims between the bottom of the window and the ends of the sill, which would mean shimming against a framing member that is nothing but end nailed if the jacks studs were missing.