# Girder or Beam



## Uncle Bob (Nov 16, 2012)

What is the difference between a Girder and a Beam?


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## Mac (Nov 16, 2012)

A girder is a particular type or use of a beam.

I think.


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## fatboy (Nov 16, 2012)

*I have always thought of them as one and the same myself. *

*Definition of **GIRDER*

*:* a horizontal main structural member (as in a building or bridge) that supports vertical loads and that consists of a single piece or of more than one piece bound together

*Definition of **BEAM*

*:* a long piece of heavy often squared timber suitable for use in construction


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## mark handler (Nov 16, 2012)

Girders are collector beams.

Girders support beams.

Sometimes "Girders and beams" are mislabled as purlins.

purlin is a horizontal structural member in a roof.


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## Rio (Nov 16, 2012)

I've always thought of a girder as a big *** beam.  From the *Dictionary of Architecture and Construction*:  Girder- A large or principal beam of steel, reinforced concrete, or timber; used to support concentrated loads at isolated points along its length.


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## mark handler (Nov 16, 2012)

Rio said:
			
		

> I've always thought of a girder as a big *** beam.  From the *Dictionary of Architecture and Construction*:  Girder- A large or principal beam of steel, reinforced concrete, or timber; used to support concentrated loads at isolated points along its length.


Yes

Girders are collector beams.


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## tmurray (Nov 16, 2012)

Beam support a distributed load where girders can support point loads and distributed loads


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## brudgers (Nov 16, 2012)

mark handler said:
			
		

> Yes Girders are collector beams.


  Or collector trusses.   e.g. a girder truss.


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## fatboy (Nov 16, 2012)

Great, nice to know!


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## Uncle Bob (Nov 16, 2012)

On an Engineer's website I found these descriptions to differentiate between the two.

A Girder is a member that has other members tying into the side of it.

A Beam is a meember that has other members bearing on top of it.

I have always wondered about that when reading the Girder and Header (beam) spans in the Tables.

I have a lot of framers attempting to use double 2 X 10s and 12s to span garages/over long spans of living rooms etc., and use them for purlin brace supports in attics.


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## DRP (Nov 16, 2012)

A girder can have beams on it, think about a dropped basement girder (a type of beam) with lapped floor joists (joists are beams too!) on top of it. It is a type of beam that carries other beams or loads


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## mark handler (Nov 18, 2012)

brudgers said:
			
		

> Or collector trusses.   e.g. a girder truss.


The OP wanted a comparison of girders and beams, not what is a girder


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## brudgers (Nov 25, 2012)

A beam can't be a truss.

    A girder can.

  Irrespective of your assertions.


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## DRP (Nov 25, 2012)

Actually...


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## codeworks (Nov 26, 2012)

girder: a horizontal main structural member (as in a building or bridge) that supports vertical loads and that consists of a single piece or more than one piece bound together. from websters

daniel webster was a statesmen, noah webster was the wordsmith


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