Chris' Corner: Notching Or Cutting Holes In Engineered Floor Joists

Notching Or Cutting Holes In Engineered Floor Joists

Jay Markanich, a very knowledgeable home inspector working in the Virginia area wrote this blog.  Never attempt to notch an engineered joist without consultation of an engineer or someone who can calculate the strength of the joist post notching.

Looking for a home in Bolton, Orangeville, Wellington County or Caledon?  Call me, Chris Smith @ 1.866.936.3500 for information and assistance in finding the property perfect for you!

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A popular construction material these days are floor I-beams, sometimes called "Engineered Floor Joists."  You have seen them.  They are convenient and easy to use.  But there are strict guidelines for notching or cutting holes in engineered floor joists.

From the side they look like a steel I-beam.  There is a top and bottom section, with a vertical member in between.  They utilize a lot of glue, which is why the fire department does not like them if they get too hot.  The glue melts!

There are strict guidelines for their installation, necessarily.  They are strong when left intact, and not so strong if cut improperly.  Hence the guidelines. 

These guidelines are based on codes imposed by Mother Nature.  She is a very strict disciplinarian.

But she also enforces her codes with impunity.

Just look at her!  Impunity I tell you!  Impunity means "exemption from punishment or consequences."  Go ahead, try to punish Mother Nature for her code enforcement!

These guidelines have been developed by engineers after much testing and analysis.  The local building codes are based on these criteria.


This diagram shows those guidelines.

The Moment Critical Zone is the only area that notches or holes should be cut.

If holes are cut at the edges, you see, the beams can shear off!

If cut at the bottoms and on the sides, you remove the beam's ability to bear weight.

But all three pieces, working together, are very, very strong.

The physics works.  That pleases Mother Nature.

This photo shows cuts made in consecutive beams to accommodate a metal HVAC duct. 

The cut holes are dead center in the beams.

They are fine!

Both Mother Nature and the local codes are pleased.

But what happens when the local code is met, but Mother Nature might not like it?

On this new construction the builder's answer to my pre-drywall inspection comment was, "It meets code.  We are only required to make changes when we are not code compliant."

In this case I am not so sure!

This is the next joist beside a load-bearing wall.  This stud wall is directly under another load-bearing wall above.  It is the wall between the kitchen and dining room.

This I-beam will be holding a long granite counter top and cabinets.  That hole on the left was cut in the wrong spot and they simply moved over and cut another one.  Yes, the hole is within the "zone" for such cuts.  But a large section of the center of this beam has been removed!  Do you think that affects its strength?

You can see also plumbing pipes along the top and a gas line on the bottom.  What if Mother Nature impugns this arrangement?  It's to the local code!  Is it to her code?

Dead load is the weight of the materials introduced and put into a house.  In this case it would be granite and kitchen cabinets and ceramic tile flooring. 

How much "live load" (that's the load that will be introduced after the dead load like from kitchen stuff) will be put in those cabinets by the occupants of this house?  My answer -- "dunno." 

How much live load will Mother Nature allow before cracking this beam?  My answer -- "dunno."

When I suggested all this to the builder, the answer was NOT surprising.  "Dunno."

Did they shore up that I-beam before the drywall was installed?  NO.  Why?  "It meets code."

Alrighty then!

My recommendation:  people are not smarter than Mother Nature.  Physics works unless a countervailing force overcomes it.  But even though we have learned to control gravity, somewhat, gravity is STILL in control.  And I remain concerned about the gravity of this installation.




Jay Markanich Real Estate Inspections, LLC

Based in Bristow, serving all of Northern Virginia

Chris Smith CSSBB
          Sales Representative

Interested in Buying or Selling Real Estate?

  ph: 1.866.936.3500

Chay Realty Inc.,

Comment balloon 0 commentsChris Smith • August 26 2011 08:04AM