Floor I joists

The truss web perhaps? :wink:

I believe that was taken for granted, of what the issue is.


No, trusses, as opposed to I joists, cannot be changed, only cut at the ends, and even then, there is restrictions as to how much you can cut.

I think you mean I-Joist and cutting the web of the I-Joist … :wink:

While it is possible to cut out a very substantial length of an I-Joist web and still have significant bending resistance, a large concentrated load directly over that cut section (transverse wall, water bed or fish tank leg, large appliance, etc) could cause excessive local bending of the top flange (essentially a flat 2x3 or 2x4) that could fail.

That is why I-Joist manufacturers usually limit square cut-outs to only a portion of the web that will fit in a circle, with a diameter of that circle the same as the web height/depth.

JMO & 2-nickels … :wink:

I-Joists TJI Web Cuts.jpg

Excuse me, I-Joists. Thanks.
And thanks for the table.

page 11 has the chart with allowable holes

pretty good engineering


For TJI I-Joists here is a pdf version of a real handy span/hole field card … :wink:

Keep in mind this is specific to the TJI TrussJoist products. So I prefer going to the more general APA guides I referenced, unless a specific manufacturer is known … but I think it’s beyond a typical home inspection to do that kind of research.

JMO & 2-nickels … :wink:

I agree whole heartedly.

Marcel :slight_smile: :slight_smile:

Table of allowable holes, pg. 11

2x hole diameter minimum required between holes. Looks marginal. Hole size OK.
What about no separation between wires?


E-mail them a request for their data, they sent me spec guides and installation instructions on everything they manufacture.

I use the pocket guide when I’m out in the field:

You can download all of the TJI documents from their website, but that info is manufacturer specific.

Bruce … I am curious to know what the outcome on this issue was.

Client did not return my call that I made to see what their decision was.
They did mention earlier that their friends had the same issue on their house.

I suspect the builder talked them out of it and they did not want to discuss it any more out of frustration. It was definitely wrong and out of spec.

I have started warning clients about the one-liners they will hear from builders.

Is anyone concerned about the elecrical wiring running UNDER these ducts? Seems to me that when the A/C kicks on, and expands these ducts, this would eventually wear through any sheathing on the wiring. Or not?

Rob I agree with you it is beyond the call of the inspector, recommend evaluation by PE or architect is correct.

I just realized that the picture did not show everything so…

The correct answer, based on the picture is number 3.
Sorry, it was not one of the choices.

Being Manufacturer specific in quality control and execution of the picture that does not show the whole picture, my answer is still #1. Sorry.

Marcel :slight_smile: :slight_smile:

Its easy to estimate with the eye and see that the distance between the holes is less than two times an hole diameter. Can anyone produce a manufacturer spec that allows less than 2X diameter?

Bruce hope you are doing alright.

Put your glasses on, if you want to eyeball something. ha. ha. ha.

The hole diameter is six inches and it is 12 " in between the holes.

Marcel :slight_smile: :slight_smile: :wink:

Where did these dimensions come from?

Those are not six inch dia. holes in my picture.

It is easy to do this: imagine making two holes the same size as those in between the existing holes. Will it fit? Nope it wont.

Hey Bruce;

From what I can see from the picture, these are ventilation ducts, and are usually 4" in diameter and once insulated with the sleeve, you need 6" to get them through a hole.
Since I am guessing that is what was used, the logic would tell me the the floor I-joist were 9and 1/2" in depth.

If that is the case and if you inspected this property, you should know what the depth is and therefore, if my conclusions are right, the distance between the holes would be within the standard parameter.
Which is based on a visual picture that usually deforms the actual.

Marcel :slight_smile: :slight_smile: