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Old 02-20-2011, 08:24 AM   #1
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Proper fix for floor joist


Found a crack in our floor joist and I want to make sure it is properly repaired. The joist is just under a 12 ft span. The crack from knot to hole for wiring is 5 ft. I consulted with a recommended contractor and want to make sure the everything is done right. I felt that it would probably need to be sistered but he informed me I could fill the crack with liquid nail and put screws thru the joist to stabilize it. I performed the repair he recommended but feel some what unsure it is correct. I feel like I should just sister the whole joist but wanted to see others opinion. Also I really don't want to have to jack it up to level it out. Is that necessary or just if the joist makes the floor sag?

http://s1114.photobucket.com/albums/...3DIMG_0531.jpg

http://s1114.photobucket.com/albums/...3DIMG_0532.jpg

http://http://s1114.photobucket.com/...3DIMG_0533.jpg

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Old 02-20-2011, 08:34 AM   #2
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Proper fix for floor joist


For future use, you want to drill holes for wiring in the center of the joist or beam, not towards the top or bottom. The top of the joist is in compression, the bottom is in tension, the center is the neutral axis and carries no force. That crack is due to improper location of the holes for the wiring.

As for the fix, you can sister a joist, or you can do what was suggested by the contractor, but there is a good chance you will get cracking in the other joists due to the improper placement of the wire holes. So look on the bright side, you are getting plenty of practice for the future.

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Old 02-20-2011, 09:06 AM   #3
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Proper fix for floor joist


X2.......whoever drilled those holes should be disarmed.......

Good lesson here for everyone

Holes HAVE to be drilled in the MIDDLE of the joists!!!!!!

Now tell your contractor to sister new joists and then redrill in the center for your wires.

Good luck
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Old 02-20-2011, 09:26 AM   #4
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Proper fix for floor joist


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Originally Posted by simp82 View Post
Found a crack in our floor joist and I want to make sure it is properly repaired. The joist is just under a 12 ft span. The crack from knot to hole for wiring is 5 ft. I consulted with a recommended contractor and want to make sure the everything is done right. I felt that it would probably need to be sistered but he informed me I could fill the crack with liquid nail and put screws thru the joist to stabilize it. I performed the repair he recommended but feel some what unsure it is correct. I feel like I should just sister the whole joist but wanted to see others opinion. Also I really don't want to have to jack it up to level it out. Is that necessary or just if the joist makes the floor sag?

http://s1114.photobucket.com/albums/...3DIMG_0531.jpg

http://s1114.photobucket.com/albums/...3DIMG_0532.jpg

http://http://s1114.photobucket.com/...3DIMG_0533.jpg
Is this a new house or addition?
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Old 02-20-2011, 09:44 AM   #5
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Proper fix for floor joist


It is the basement of our house not an addition. The house was built in 2006.
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Old 02-20-2011, 10:36 AM   #6
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Proper fix for floor joist


The building code states that holes should be drilled at a minimum two inches from the edge of the joist and no larger than 1/3 the depth of the joist. The holes that I see are small and far enough from the edge to be no big deal. Glue and screws is a goofy idea. Sister the joist.

What size are the joists? What species and grade? What is the spacing? The size, number and location of the knots on several of the joists looks less than ideal. What is the room above? Is there heavy furniture, a water bed or a wall being supported? The split appears to be a shear failure of the joist which indicates it was overloaded.

There is no need to jack up the floor if it isn't sagging. It appears that the joists are 2x8 at 16" on center which would allow a span of 12'10" for a grade of #2 for most species, so these joists are near their maximum span.
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Old 02-20-2011, 12:29 PM   #7
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Proper fix for floor joist


The 2003 building code reads as follows:


The 2003 International Residential Code covers this:
not exceeding 8 feet (2438 mm).
R502.8Drilling and notching. Structural floor members shall
not be cut, bored or notched in excess of the limitations speci-
fied in this section. See Figure R502.8.
R502.8.1 Sawn lumber. Notches in solid lumber joists, raf-
ters and beams shall not exceed one-sixth of the depth of the
member, shall not be longer than one-third of the depth of the
member and shall not be located in the middle one-third of
the span. Notches at the ends of teres shall not exceed
one-fourth the depth of the member. The tension side of
members 4 inches (102 mm) or greater in nominal thickness
shall not be notched except at the ends of the members. The
diameter of holes bored or cut into member shall not exceed
one-third the depth of the member. Holes shall not be closer
than 2 inches (51 mm) to the top or into member the member, or
to any other hole located in the member.Where the member
is also notched, the hole shall not be closer than 2 inches (51
mm) to the notch.
R502.8.2 Engineered wood products. Cuts, notches and
holes bored in trusses, laminated veneer lumber, glue-laminated-
members or I-joists are not permitted unless the effects
of such penetrations are specifically considered in the design
of the member.
R602.6Drilling and notching—studs.Any stud in laminated members
wall or bearing partition may be cut or notched to a depth not
exceeding 25 percent of its width. Studs in non bearing parti-
tions may be notched to a depth not to exceed 40 percent of a
single stud width. Any stud may be bored or drilled, provided
that the diameter of the resulting hole is no greater than 40 per-
cent of the stud width, the edge of the hole is no closer than 5/8
inch (15.9 mm) to the edge of the stud, and the hole is not lo-
cated in the same section as a cut or notch. See Figures
R602.6(1) and R602.6(2).
Exceptions:
1. A stud may be bored to a diameter not exceeding 60
percent of its width, provided that such studs located
in exterior walls or bearing partitions are doubled and
that not more than two successive studs are bored.
2. Approved stud shoes may be used when installed in
accordance with the manufacturer’s recommenda-
tion.
R602.6.1 Drilling and notching of top plate.When piping
or ductwork is placed in or partly in an exterior wall or interior-
or load-bearing wall, necessitating cutting, drilling or notch-
ing of the top plate by more than 50 percent of its width, a
galvanized metal tie of not less than 0.054 inches thick
(1.37mm) (16ga) and 11/2 inches (38mm) wide shall be fas-
tened to each plate across and to each side of the opening
with not less than eight 16d nails at each side or equivalent.
See Figure R602.6.1.
Exception:When the entire side of the wall with the notch
or cut is covered by wood structural panel sheathing.

R802.7 Cutting and notching. Structural roof members shall
not be cut, bored or notched in excess of the limitations speci-
fied in this section.
R802.7.1 Sawn lumber. Notches in solid lumber joists, raf-
ters and beams shall not exceed one-sixth of the depth of the
member, shall not be longer than one-third of the depth of the
member and shall not be located in the middle one-third of
the span. Notches at the ends of the member shall not exceed
one-fourth the depth of the member. The tension side of members 4 inches (102 mm) or greater in nominal thickness
shall not be notched except at the ends of the members. The
diameter of the holes bored or cut into members shall not ex-
ceed one-third the depth of the member. Holes shall not be
closer than 2 inches (51mm)to the top or bottom of the member-
, or to any other hole located in the member. Where the
member is also notched, the hole shall not be closer than 2
inches (51 mm) to the notch.
Exception: Notches on cantilevered portions of rafters
are permitted provided the dimension of the remaining
portion of the rafter is not less than 4-inch nominal (102
mm) and the length of the cantilever does not exceed 24
inches (610 mm).
R802.7.2 Engineered wood products. Cuts, notches and
holes bored in laminated veneer lumber, glue-laminated
members or I-joists are not permitted unless the effect of
such penetrations are specifically considered in the design of
the member.
R802.10.4 Alterations to trusses. Truss members shall not
be cut, notched, drilled, spliced or otherwise altered in any
way without the approval of a registered design professional.
Alterations resulting in the addition of load (e.g., HVAC
equipment, water heater) that exceeds the design load for the
truss shall not be permitted without verification that the truss
is capable of supporting such additional loading.

That said, the center of the joist (the vertical dimension) is the zone of least stress, hence is the place you want to drill holes if possible. Clearly it was possible here, just wasn't done. As viewed horizontally, the center of the span is the zone of greatest stress, hence the code regulation against notching the center third of the span. As I read it, you can bore a hole in the center third of the span, but no notching. Still, you should avoid drilling holes in the middle third of the span if possible, which is generally the case when performing wiring.

Aside from weakening the joist, a hole or notch introduces stress concentration at the hole, which tends to induce cracking. Once a crack starts in wood, it tends to spread due to tension, which is exactly what appears to have happened in this case. Plus you have three holes, which only makes the problem worse.

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