Originally Posted By: ccoombs This post was automatically imported from our archived forum.
Although this would have caught my attention, I also know some conditions would allow for such holes. I would check the manufacture’s product information. Or even better would be to have the manufacture send out a field rep. The as built conditions can be very helpful.
I'm always concerned about over cutting any square hole. As well as the cutting of the bottom flange you showed.
If it doesn't work, you can always get an engineered fix. I don't know if the fix will allow for the duct work to remain within the web of the truss.
Originally Posted By: R. Michael Gray, P.E. This post was automatically imported from our archived forum.
I suspect that the I-beam is structurally okay at least as far as the hole is concerned. It is hard to tell from the photo for sure, but I do not see any structural issue with hole. This assumes it is not near a support and there are no other holes around it. The flange damage is another issue. Again I cannot not tell from the photo how much damage might be there. But, generally speaking, flanges cannot be compromised.
The following is from a technical book, Engineered Wood Products - A Guide for Specifiers, Designers and Users:
"Under no circumstances should holes or notches ever be cut in the flanges of a wood I-joist; do so may seriously compromise its strength. The webs of wood I-joists routinely contain regularly spaced circular knockouts for running utilities. Holes can be cut elsewhere in the web of an I-joist, however, their size and placement is limited by their location along the members length. Most wood I-joist manufacturers publish illustrated guides to assist electricians, plumbers and heating contractors in determining permissible hole size and placement."
Originally Posted By: apolillo This post was automatically imported from our archived forum.
Thanks for all of your responses.
I wrote up the cut flange as an issue. The ductwork seems to be within allowable limits for these beams. The house has been there for 16 years and the flooring above was not bouncy.
Originally Posted By: dhadler This post was automatically imported from our archived forum.
Michael Gray,
I ran into a similar thing a few weeks ago with those laminated floor joists. I called it out to the attention of the contractor or local building inspector as it was a newer home. I haven't heard anything back?
I know they have knockouts for 5" round heating ducts, but the one I saw someone had cut out the OSB portion from top to bottom minus about a 1/2 inch to run a couple ducts through. This was done for 4 joists in a row till the ductwork changed direction. Is that allowed? and if so what is left to give that joist any stability? I figured that vertical OSB gave those things about 80% of their strength. Situation was very much like the photos above.
That just doesn't make logistical sense to me....please help me understand how this can be 
-- Darrell Hadler
Five Star Home Inspections
Medicine Hat, Alberta CANADA
Originally Posted By: R. Michael Gray, P.E. This post was automatically imported from our archived forum.
The web carries shear load only which is a problem only at and near the ends. The flanges carry bending moment which is zero at the ends but larger everywhere else. That is why you cannot alter the flanges but you can remove web material as long as you follow the manufacturer’s rules. The knockouts are for convenience only; you can remove web material outside the knockouts.
Originally Posted By: dvalley This post was automatically imported from our archived forum.
1. Except for cutting to length, never cut, drill, or notch I-Joist flanges.
2. Holes may be located vertically anywhere in the web. Wherever possible, center holes in the web and always leave at least 1/8" of web at the top and bottom of the hole.
3. The sides of square holes shall not exceed three-fourths of the maximum round hole diameter permitted at that location. Do not over-cut the sides of square holes.
4. Where more than one hole is necessary, the distance between hole edges must be more than twice the diameter of the largest round hole or twice the size of the largest square hole. In addition, each hole must comply with the requirements of Table 3.
5. Do not cut any holes in the web within a distance of d/2 from the support centerline where d is the depth of the I-Joist, otherwise, a 1-1/2 inch hole can be cut in the web anywhere.
6. Exceptions will require that additional data be provided to the local building official.
Warning
NEVER drill, cut or notch the flange, or over-cut the web. Holes in webs should be cut with a sharp saw. For rectangular holes, avoid over-cutting the corners, as this can cause unnecessary stress concentrations. Slightly rounding the corners is recommended. Start the rectangular hole by drilling a 1"-diameter hole in each of the four corners and then make the cuts between the holes to minimize damage to the I-Joist.
Originally Posted By: dhadler This post was automatically imported from our archived forum.
Thanks David,
Good Explanation.
Just to be sure then....the photos above were definitely not allowed, Yes?
It only makes sense that most of the load capacity is gone once you cut out that much material.
-- Darrell Hadler
Five Star Home Inspections
Medicine Hat, Alberta CANADA
Originally Posted By: dvalley This post was automatically imported from our archived forum.
This install doesn't appear to be a serious problem if its not sagging. If it were my inspection, I'd throw a four foot level under the lower flange to make sure there's no sag or deflection.
Originally Posted By: dhadler This post was automatically imported from our archived forum.
Sorry David, I was taking for granted they only allowed for a 5 or 6 inch round knock-out hole for heating ducts. Has anyone seen larger knock-outs…I said knock-outs… not knockers
