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RE: Cutting a Glulam Beam

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Title: RE: Cutting a Glulam Beam

Definitely!!  The different laminations in a glulam beam are chosen based on different grades, depending upon where they are located in the beam. 

The bottom one, two or maybe three will be better grade material to provide tensile strength.  The middle laminations are generally a lower grade (i.e. cheaper) material, while the top laminations are either "medium" grade or very good, depending on whether the beam is an "EX" grade designed for tension in the top fibres too.

If you cut off the bottom three laminations you will be using the middle laminations in tension and the beam will be MUCH lower in strength than a new 16.5 inch deep beam. 

BTW: if you put a post at mid-span, you are now placing the top laminations in tension too.  If the beam wasn't originally a grade "EX" then the bending moment capacity is MUCH  lower.  The tensile capacity of the top laminations in a standard beam is about 1/3 of that of the bottom laminations. 

Looks like a trip to the lumber store is in order...

-----Original Message-----
From: Shafat Qazi [mailto:seaint-ad(--nospam--at)seaint.org]
Sent: Tuesday, June 29, 1999 22:38
To: seaint(--nospam--at)seaint.org
Subject: Cutting a Glulam Beam


One of my clients wishes to install a garage door to his two car garage.
The header beam is too low and needs to be reduced in depth by about 4.5
inches. One of the solutions proposed by the client's contractor is to
remove the bottom three laminations and add a new post + pad  about
mid-span. The current Glulam beam is 21 inches deep. It works as a 16.5
inch beam for the reduced span.

Question: Is there a problem if he cuts 4.5 inches from the bottom of the
Glulam?