Wood Timber Columns... Glulam or Parallam ?

[Loui1]

I've got a single story pitched roof with exposed structure. I'm thinking the ridge beam will be a gluelam member just for looks, supported by timber columns.....either glulam or parallam. How do I design Glulam columns? There doesnt seem to be any good design info about it. It seems like all I can find on timber column design is for parallams. Is it cost prohibitive to mix glulams and parallam members on a job? Any info or a point in the right direction would be great.

 

[DaveVikingPE]

Breyer's got an example of a glulam column design in the second ed. of Design of Wood Structures. I'm sure there are others.

 

[SlideRuleEra]

"Design of Glued Laminated Timber Columns" from the USDA Forest Products Lab

http://www.fpl.fs.fed.us/documnts/pdf1995/zahn95a.pdf

...or tables, such as this

http://www.rosboro.com/techref-glulam/allowableloads-columns10-03.pdf

...from suppliers such as

http://www.rosboro.com/glulamcolumns.asp

http://www.SlideRuleEra.net

 

[SperlingPE]

I worked for a company that did weather testing, normal rate and accelerated, on Parallam pieces. The testing was for the electric utility industry for using Parallam members as beams on power and distribution structures. If looks are important, I would go with a glulam column.

 

[RARWOOD]

If your members are exposed to the weather you probably want to consider using treated southern pine glulams. In general you would not want to mix glulams and parallams on the same job. As a designer if I was going to use glulam beams I would use glulam columns. Although I work for a glulam supplier, I would use all glulams to avoid mixing different materials.

However as a designer you may chose to mix the materials for a number of reasons. For example if you can complete your design with the information you have on parallam columns you may chose to do so.

Depending on who supplies the material you may see several options. One supplier might propose supplying all parallam while another supplier may want to supply all glulam.

If you specify parallam and a supplier wants to use glulam, require them to provide you with information that the glulam meets your design requirements.