FLOOR JOISTS & STUD WALLS IN CONVENTIONAL …

1 Notching & BoringGuidelinesIntended for use by residentialbuilders, this WWPA TIP Sheetserves as a guide to code-allowedsize and placement of cuts(notching and boring) in FLOOR -joistand stud-wall framing number of problems canoccur if cuts are made throughframing members to make roomfor plumbing or electrical runs,ductwork, or other mechanicalelements such as sound orsecurity a hole or notch iscut into a member, the structuralcapacity of the piece is weakenedand a portion of the load support-ed by the cut member must betransferred properly to other is best to design and frame aproject to accommodate mechan-ical systems from the outset.

2 Asnotching and boring should beavoided whenever possible; how-ever, unforeseen circumstancessometimes arise it is necessary to cut into aframing member, the followingdiagrams provide a guide fordoing so in the least comply with therequirements of the three majormodel building codes: Uniform(UBC), Standard (SBC), andNational (BOCA), and the CABOOne- & Two-Family JOISTSThe following references are toactual, not nominal dimensions.(See Figure 1:Placement of Cutsin FLOOR Joistsand Table 1:Maximum Sizes for Cuts in FloorJoists.)

3 Holes:Do not bore holes closerthan 2" from joist edges, normake them larger than 1/3 thedepth of the :Do not make notches inthe middle third of the span wherethe bending forces are should be no deeperthan 1/6 the depth of the at the end of the joistshould be no deeper than 1/4 thedepth. Limit the length of notchesto 1/3 of the joist s depth. When a NotchBecomes a RipCodes do not address themaximum allowable length of anotch; however, the 1991 NationalDesign Specification (NDS)doeslimit the maximum length of anotch to 1/3 the depth of is important to recognize thepoint at which a notch becomes arip, such as when FLOOR JOISTS atthe entry of a home are rippeddown to allow underlayment for atile wide dimension lumberlowers the grade of the material,and is unacceptable under allbuilding a sloped surface isnecessary, a non-structural mem-ber can be ripped to the desiredslope and fastened to the struc-tural member in a position abovethe top edge.

4 Do not rip thestructural WALLSWhen structural woodmembers are used vertically tocarry loads in compression, thesame engineering procedure isused for both studs and , differences betweenstuds and columns are recog-nized in the model building codesfor CONVENTIONAL light-frame resi-dential construction. The term column describesan individual major structuralmember subjected to axial com-pression loads, such as columnsin timber-frame or post-and-beamstructures. The term stud describes oneof the members in a wall assem-bly or wall system carrying axialcompression loads, such as 2x4studs in stud wall that includessheathing or wall board.

5 Thedifference between columnsand studs can be furtherdescribed in terms of thepotential consequences of function asindividual major structural mem-bers, consequently failure of acolumn is likely to result in par-tial collapse of a structure (orcomplete collapse in extremecases due to the dominoeffect). However, studs functionas members in a system. Dueto the system effects (loadsharing, partial compositeaction, redundancy, loaddistribution, etc.), studs aremuch less likely to fail and resultin a total collapse than or boring intocolumns is not recommendedand rarely acceptable; however,model codes establish guide-lines for allowable notching andboring into studs used in astud-wall 2 and 3 illustrate themaximum allowable notchingand boring of 2x4 studs underall model codes except allows a hole one thirdthe width of the stud in allcases.

6 Bored holes shall not belocated in the same crosssection of a stud as a cut additional information onframing (and common framingerrors), contact WWPA forreprints of the following articleswritten by Association field Guide to CommonFraming Errors (JLC-2) re-printed from Journal of LightConstruction: article focuses onmost commonly-encounteredjob-site errors. 6 Roof-FramingErrors (JLC-3) reprinted fromJournal of Light Construction:focuses on problems and solu-tions with trusses, rafters, collarNOTCHING & BORING GUIDE FORFLOOR JOISTS & STUD WALLS INCONVENTIONAL LIGHT-FRAME CONSTRUCTIONNOTCHING & BORING GUIDE ties and structural ridges.

7 4 Perfect Framing (B-1)reprinted from BuilderMagazine:discusses cantilevers,joist hangers, blocking, notchingand boring, cathedral ceilings, andover cutting tapers. 4 reprints are 75 centseach to cover postage Wood Products Association522 SW Fifth Avenue Suite 400 Portland, OR 97204-2122503/224-3930 Fax: 503/224-3934e-mail: site: , 2-97/15 MFig. 1: Placement of Cuts in FLOOR JoistsTable 1: Maximum Sizes for Cuts in FLOOR JoistsFig. 2: Notches in 2x4 StudsFig. 3: Bored Holes in 2x4 StudsD/6 1/3 of spanEffects of notches can be reduced byusing a gradual tapered notch insteadof a square-cornered = actual dimensionouter 1/3 of spanmax.

8 Length = D/3D/6 " min. from topand bottom of joistD/4 max. at endsNotching not permitted in middle 1/3 of " * allowedin exterior andbearing walls3-1/2"1-7/16" "40%* allowedin any non-bearing wall3-1/2"1-7/16"5/8" * allowedin any wall2-1/8"3-1/2"5/8" * allowed in any non-bearingwall or in bearingwalls with not morethan two succes-sive studs boredand doubledJoist Size Max. HoleMax Notch Depth Max. End Notch2x4nonenonenone2x61-1/2"7/8"1-3/8"2 x82-3/8"1-1/4"1-7/8"2x103"1-1/2"2-3/8"2x 123-3/4"1-7/8"2-7/8"*Figures 2 and 3 illustrate 25%, 40% and 60% notches or holes in 2x4s(.)

9 25 x 31/2" = .875 or 7/8"). These percentages apply to studs of any size.