Cutting the web

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#1

Originally Posted By: apolillo
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Fellow Inspectors,


This ductwork was installed through the web. It seem to exceed the recommended specs. Any comments?


![](upload://xEz89vHTzlqm1TSde1Aw756rUsz.jpeg)

Anatol

#2

Originally Posted By: jhagarty
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http://www.trusjoist.com/PDFFiles/2025.pdf


http://www.trusjoist.com/PDFFiles/2035.pdf#search='tji%20Installation%20holes'

What is the size of the duct?

Are they any other cutouts within the span of the webbing?

--
Joseph Hagarty

HouseMaster / Main Line, PA
joseph.hagarty@housemaster.com
www.householdinspector.com

Phone: 610-399-9864
Fax : 610-399-9865

HouseMaster. Home inspections. Done right.

#3

Originally Posted By: apolillo
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Duct size aprox. 8"x12"


No other cut outs in use. Here is another shot which shows the Flange cut on another I-joist.


![](upload://oRjRnCPtmnD8kDLeObsQkax7UNY.jpeg)

Anatol

#4

Originally Posted By: ccoombs
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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.

Good find and good luck!

--
Curtis

#5

Originally Posted By: dspencer
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The specs are on page 11 in above link… Seems to me that the elec should not be ran with the duct work. The city inspectors here wouldn’t allow this.

#6

Originally Posted By: R. Michael Gray, P.E.
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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."

Hope this is of some help.

R. Michael Gray, PE
Professional Structural Engineer
webmaster: www.houston-slab-foundations.info

#7

Originally Posted By: apolillo
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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.


Anatol

#8

Originally Posted By: mtimpani
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I think the code check series answers this…

–
Thank you, MarkTimpani


www.pridepropertyinspections.com
#9

Originally Posted By: dhadler
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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 ![icon_question.gif](upload://t2zemjDOQRADd4xSC3xOot86t0m.gif)

--
Darrell Hadler
Five Star Home Inspections
Medicine Hat, Alberta CANADA

#10

Originally Posted By: dspencer
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Perhaps someone should invite an I-Joist rep into this post? Take care of everyone’s concerns.

#11

Originally Posted By: R. Michael Gray, P.E.
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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.


R. MIchael Gray, PE
Professional Structural Engineer
webmaster: www.houston-slab-foundations.info

#12

Originally Posted By: dhadler
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icon_eek.gif icon_eek.gif icon_eek.gif I’m missing the forest cause of all the trees

–
Darrell Hadler


Five Star Home Inspections


Medicine Hat, Alberta CANADA

#13

Originally Posted By: dvalley
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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.

--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

#14

Originally Posted By: lkage
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Good info here.


Thanks everyone. ![icon_biggrin.gif](upload://iKNGSw3qcRIEmXySa8gItY6Gczg.gif)

--
"I have never met a man so ignorant that I couldn't learn something from him."
Galileo Galilei

#15

Originally Posted By: dhadler
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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

#16

Originally Posted By: dvalley
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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.

--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

#17

Originally Posted By: dhadler
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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 icon_eek.gif icon_eek.gif icon_eek.gif

–
Darrell Hadler


Five Star Home Inspections


Medicine Hat, Alberta CANADA

#18

Originally Posted By: dvalley
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So what you are looking for is a 1/8" of web on the top & bottom of the HVAC... Your pic definitely has the allowance.

--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."