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Jack studs continuous from header to sole plate?

B

bgingras

Registered User
Joined
Jan 6, 2010
Messages
184
Location
Massachusetts
I thought it was in the code somewhere, IRC 2009...jacks to be continuous from header to plate? I have a job where all of the jacks are broken to support the sills.
 
R602.3.............Studs shall be continuous from support at the sole plate to a support at the top plate to resist loads perpendicular to the wall. The support shall be a foundation or floor, ceiling or roof diaphragm or shall be designed in accordance with accepted engineering practice.

Exception: Jack studs, trimmer studs and cripple studs.........
 
The jack studs are placed under the end of the header. There is also one or more king studs adjacent to the jack studs that run from the top of the sill plate to to bottom of the top plates. In some cases a joist hanger can transfer the header reaction to the king studs and there is no need for a jack stud.

The primary role of the king stud is to resist the out of plane window loads generated by the door or window. Multiple king studs may be required as the opening width grows.
 
i always split my jack studs and have no problem with it as an inspector. I am amazed at the number of studs criples doubles put into the walls, first as a waste of material, second lowern the insulation value of the wall.

I would like to see the header and jack table revised to not require double jacks under headers less than 8 feet
 
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Thank you, it appears this is more of something that was "preferred" in another municipality and not actually a code requirement.
 
TheCommish said:
I am amazed at the number of studs criples doubles put into the walls, first as a waste of material, second lowern the insulation value of the wall.
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One reason for all that extra wood is to give nailing surface for casings etc.

Long ago I worked with an old carpenter who always put his door header jacks all the way to the floor.
 
jim baird said:
One reason for all that extra wood is to give nailing surface for casings etc.Long ago I worked with an old carpenter who always put his door header jacks all the way to the floor.
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i have head that, and it maybe true with wide casings, 2.5" raily extends past the jack stud split or striaght and if the casing was wider it sem to me that nailing is not required at the extreem outer permiter is not needed.,
 
jim baird said:
Long ago I worked with an old carpenter who always put his door header jacks all the way to the floor.
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I worked for an old contractor that framed exclusively with hot dipped galvanized nails. They bend easy and pull hard.
 
The reason that this is preferred is due to the difference in the wood shrinkage. In the direction of loading your jack will shrink 1%, your header will shrink 2-3%, but your sill will shrink 11% or more. It could cause problems with drywall cracking as the lumber dries out.
 
tmurray said:
The reason that this is preferred is due to the difference in the wood shrinkage. In the direction of loading your jack will shrink 1%, your header will shrink 2-3%, but your sill will shrink 11% or more. It could cause problems with drywall cracking as the lumber dries out.
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Just curious on where this information comes from. The sill shrinking 11% seems a bit excessive.

Why would the sill shrink so much? I've done a LOT of remodels and have never noticed any shrinkage like that.

On a standard 2X4 width that would be 3/8 of an inch. But who am I to question?
 
That was a joint study done by the Canada Mortgage and Housing Corporation and the National Research Council (Canada). Actually about 5/32 of an inch 2x4 is the nominal size, actual size is 38mm x 89mm. 38mm x 0.11 = 4.18mm X 0.03936996 = 0.16" x 32 = 5/32".

When are you guys going to join the rest of us in using a base ten measurement system anyway?
 
tmurray said:
That was a joint study done by the Canada Mortgage and Housing Corporation and the National Research Council (Canada). Actually about 5/32 of an inch 2x4 is the nominal size, actual size is 38mm x 89mm. 38mm x 0.11 = 4.18mm X 0.03936996 = 0.16" x 32 = 5/32".When are you guys going to join the rest of us in using a base ten measurement system anyway?
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We used to be proud to be a bit different and American, now for some reason our leaders keep saying we are bad bad peeps who need to change. Just don't get it.
 
We use a base ten! Whatever the heck that is! It's just the American base ten...... No really, there are too many old timers, like me, that have been so used to our system that it would be total chaos for me to try to change my way of thinking.

Okay let's look at it this way... 11% is just a smidgen over one tenth. Soooo take a 3.5 INCH :) piece of wood.

Divide that into ten equal parts, would you agree that each part would be .35 inches?

.35 is just a smidgen over 1/3 of an inch.. agree?

Divide one inch into 3 parts which is pretty darn close to 3/8 of an inch...agree?

Don't you just love this redneck math? :)
 
1-1/2" sill height x 0.11 = .165". Your math is correct, but your height is off.

Of course you could just be messing with us like the guy that says, "if a cubic foot of water weighs 62.5 lbs, and there are 7.48 gallons per cubic foot, how much does a pound of water weigh?"
 
Mule said:
We use a base ten! Whatever the heck that is! It's just the American base ten...... No really, there are too many old timers, like me, that have been so used to our system that it would be total chaos for me to try to change my way of thinking.Okay let's look at it this way... 11% is just a smidgen over one tenth. Soooo take a 3.5 INCH :) piece of wood.

Divide that into ten equal parts, would you agree that each part would be .35 inches?

.35 is just a smidgen over 1/3 of an inch.. agree?

Divide one inch into 3 parts which is pretty darn close to 3/8 of an inch...agree?

Don't you just love this redneck math? :)
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Our building code is in metric, but anytime you do any inspections everything you talk to someone about is imperial. You learn a couple dirty conversion factors really quick, or you end up looking awful stupid when you dont know 1800mm is 6'.

Yeah, as GBrackins said you're thinking about the sill in the wrong orientation.
 
Same here bgingras, we allow jacks to be broken by sills - R602.3 Design and construction: exception
 
GBrackins said:
1-1/2" sill height x 0.11 = .165". Your math is correct, but your height is off. Of course you could just be messing with us like the guy that says, "if a cubic foot of water weighs 62.5 lbs, and there are 7.48 gallons per cubic foot, how much does a pound of water weigh?"
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About 1/50th of a 50 lb. box of nails.
 
Mule, did you use a folding stick ruler that fits in your bibs or a Stanley tape measure for those measurement? ;)

Jacks split by the window sill, pretty common construction practice here.

pc1
 
gbhammer.. Yep...I be one of those!! :) And I also like to fish for carp!

I can't believe you guys would think that I would mess with yall!

Pc... Started out with a folding stick in my bib but quickly went to one of them thar metal spring loaded one that hung on a belt. Then I found out the leather tool belts was better than sliced bread. Then I learned that you need the individual leather bags and not the ones attached to the belt already. The ones attached to the belt would dump all of the nails out when you was climbing up stuff.

OH! It was actually a Lufkin.

I was one of those that had to figure the length of rafters with a framing square. Didn't even know there wan any other way! :)

Now back on track... We allow jacks to be broken by sills too!
 
this is a good shrinkage calculator;

http://woodbin.com/calcs/shrinkulator.htm

11% would not be normal wood or normal conditions. I plugged in loblolly pine, pretty high shrinkage, and got 7.4% tangential... you don't get to pick which lumber face gets to be radial and which is tangential, I make that choice with the big saw, you can get either on either face, or some blend between. Mule's example is valid, do you regularly see studs shrink 3/8" in width, no, the numbers are off as is the application.

Shrinkage begins at around the fiber saturation point which for average wood is around 25% and continues down to oven dry. I recieve wood at 19% and it reaches equilibrium moisture content at 8-12% depending on where in the house it is. This is a smaller slice of that total shrinkage range.

I'm coming up with a heavy 1/32"
 
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in elimentry school the teaches tlod me we woud be using the metric system by the time i gruadet high school in 1975
 
What a rediculus quesion - obviuosly a pound of water weighs?????????????????

Wait what was the question?

And yes we do use a base 10 system. 10" = .83333333333333'

As for the other issue discussed here

I used to work too, but now I do plan review.
 
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