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)?
That’s not figure R602.3(2).
Nope. The jack studs are for the load bearing header, not for the window frame out.
Doesn’t the window sill need jack studs like Bob’s image depicts?
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.
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).
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?
Interesting take on it. Thanks.
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.
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.
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)
[FONT=Helvetica-BoldOblique]The following is from the ABC 2006[/FONT]
[FONT=Helvetica-BoldOblique]Division 8[/FONT]
[FONT=Times New Roman]Framing over Openings[/FONT]
[FONT=Times New Roman]Openings in Non-Loadbearing Walls[/FONT]
[FONT=Times New Roman]1 [/FONT]) [FONT=Times New Roman]Except as provided in Sentence (2), openings in non-loadbearing walls shall be[/FONT]
[FONT=Times New Roman]framed with not less than 38 mm material the same width as the studs, securely[/FONT]
[FONT=Times New Roman]nailed to adjacent studs.[/FONT]
[FONT=Helvetica-Bold]2) Openings for doors in non-loadbearing walls required to befire separations with a[/FONT]
[FONT=Times New Roman]fire-resistance rating shall be framed with the equivalent of at least two 38 mm thick[/FONT]
[FONT=Times New Roman]members that are the same width as the wall plates.[/FONT]
[FONT=Times New Roman]Openings in Loadbearing Walls[/FONT]
[FONT=Times New Roman]1 [/FONT]) [FONT=Times New Roman]Openings in loadbearing walls greater than the required stud spacing shall be[/FONT]
[FONT=Times New Roman]framed with lintels designed to carry the superimposed loads to adjacent studs. (See[/FONT]
[FONT=Times New Roman]A-9.23.10.6.(3) in Appendix A.)[/FONT]
[FONT=Helvetica-Bold]2) Except as provided in Sentence 9.23.12.3.(2), where 2 or more members are used[/FONT]
[FONT=Times New Roman]in lintels, they shall be fastened together with not less than 82 mm nails in a double[/FONT]
[FONT=Times New Roman]row, with nails not more than 450 mm apart in each row.[/FONT]
[FONT=Helvetica-Bold]3) Lintel members are permitted to be separated by filler pieces.[/FONT]
[FONT=Times New Roman]Lintel Spans and Sizes[/FONT]
[FONT=Helvetica-Bold]1) Spans and sizes of wood lintels shall conform to the spans shown in[/FONT]
[FONT=Times New Roman]Tables A-12 to A-16[/FONT]
[FONT=Times New Roman]a) for buildings of residential occupancy,[/FONT]
[FONT=Times New Roman]b) where the wall studs exceed 38 mm by 64 mm in size,[/FONT]
[FONT=Times New Roman]c) where the spans of supported joists do not exceed 4.9 m, and[/FONT]
[FONT=Times New Roman]d) where the spans of trusses do not exceed 9.8 m.[/FONT]
[FONT=Helvetica-Bold]2) In loadbearing exterior and interior walls of 38 mm by 64 mm framing members,[/FONT]
[FONT=Times New Roman]lintels shall consist of[/FONT]
[FONT=Times New Roman]a) 64 mm thick members on edge, or[/FONT]
[FONT=Times New Roman]b) 38 mm thick and 19 mm thick members fastened together with a double row[/FONT]
[FONT=Times New Roman]of nails not less than 63 mm long and spaced not more than 450 mm apart.[/FONT]
[FONT=Helvetica-Bold]3) Lintels referred to in Sentence (2)[/FONT]
[FONT=Times-Roman]a) shall be not less than 50 mm greater in depth than those shown in[/FONT]
[FONT=Times New Roman]Tables A-12 to A-16 for the maximum spans shown, and[/FONT]
[FONT=Times New Roman]b) shall not exceed 2.24 m in length.[/FONT]
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.
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.
I always frame my windows, no matter how large or small, with cripples under the ends. I checked with an inspector from the local building department to get his take. In our area (north central Ohio) they will allow no cripples at the ends on windows up to 5’ wide. Anything larger they want cripples.
I just installed some Pella windows (casement) about 4.5’ wide and maybe 4’ high which weighed somewhere around 150lbs. Yes, there were some cripples under the center portion of the window sill, but shims were placed on each end and in the center, shifting all that weight onto three small piles of shims, two of which where on either side.
I agree with most others here - it may not be against code, but I would think it shows which builders care and pay more attention to detail. Minimum code is only a minimum. And it usually isn’t good enough.
Thank you for helping. Good post.
Here’s a photo from one of my recent frame inspections in the San Antonio (south Texas) area on a large national production builders home. Volume builders of course cut back on certain things for cost effectiveness, but you can see here they have the jack studs installed below window. I would write it up if they weren’t installed, but never have to, at least not til this point. As far as I’m concerned they are required.
Someone made a good point on this thread, but I don’t see the post anymore. They felt that it’s not that the image- figure R602.3(2) is incorrect but that’s it’s incomplete. The reason I agree w/ that opinion is because I remembered the Rafter construction image in the 2006 IRC. We use 2006 here. In figure R802.5.1 (pg.267) The roof frame image shows ridge, rafters, joists, purlins and it’s bracing but no collar ties which of course are required every other rafter (max. 4’ spacing) connecting rafters under ridge. So this image I’m referring to is also incomplete. I can’t get my new laptop scanning yet so I can’t post that image of roof frame in IRC that I’m referring to.
There are metal framing brackets available to support plate ends such as in OVE framing.