Drilling holes for wiring in laminate joist
Drilling holes for wiring in laminate joist
(OP)
Hi,
I need to drill holes in floor joists to rout wiring. I noticed that the builder (or electrician) of this house did not rout any existing wiring through a laminate joist which goes across halve of the basement. It almost looks like that he avoided going through the laminate joist. The beam in question consists of 2 "sistered" laminate 2" x 10" in a residential house.
Is there any rule that there should not be any holes drilled into laminated joists for electrical wiring?
I need to drill holes in floor joists to rout wiring. I noticed that the builder (or electrician) of this house did not rout any existing wiring through a laminate joist which goes across halve of the basement. It almost looks like that he avoided going through the laminate joist. The beam in question consists of 2 "sistered" laminate 2" x 10" in a residential house.
Is there any rule that there should not be any holes drilled into laminated joists for electrical wiring?






RE: Drilling holes for wiring in laminate joist
RE: Drilling holes for wiring in laminate joist
http://www.ilevel.com/literature/TJ-9000.pdf
for a catalog on a particular brand of joist - look at page 36 for allowable holes.
Also see attached image for a screen shot of that page.
RE: Drilling holes for wiring in laminate joist
This applies to the overall depth of the joist as well as the joist span. Too close to the end of the joist could affect the joist in shear, and too or high in the depth of joist will affect the moment. Moreover, there is a size limitation on the diameter of the hole that can be drilled, particularly with manufactured joists. Some joists have knockouts that can be used as opposed to drilling in the field.
If these are manufactured joists, check the catalog for more specific guidance, that if not followed to the letter, will invalicate any warranty on the joists.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Drilling holes for wiring in laminate joist
RE: Drilling holes for wiring in laminate joist
RE: Drilling holes for wiring in laminate joist
Depending on the loading conditions, load types, bearing locations, etc. all this can change. So follow the mfg or seek professional help.
RE: Drilling holes for wiring in laminate joist
RE: Drilling holes for wiring in laminate joist
Garth Dreger PE
AZ Phoenix area
RE: Drilling holes for wiring in laminate joist
1. Deflections
2. Connections
3. Bending
4. Shear
Despite shear being at the bottom of the list it does become critical in the design from time to time. Particularly when using a material such as hardwood which has a low characteristic shear strength when compared to it's bending strength.
RE: Drilling holes for wiring in laminate joist
I don't do tons of wood design, but I have never had a beam even close to not working in shear. I would think this is more of a problem with heavily loaded glulam girders, point loaded beams, etc..
Deflection usually controls in my experience, and with residential, the spacing of the beams is critical to get a good, serviceable floor. I have also never given drilling a 1" hole a second thought since I am not usually "cutting" it that close on my designs...