glulam beams

[barney55731]

I need to come up with a design for glulam beams, utilizing pressure treated wood, used to support a boat-house. The beams must be constructed in place and will spend their life half-in and half-out of fresh, clear water in Northern Minnesota. My thought is to use 2X? lumber, on edge, with staggered lengths and widths, glued and screwed together. By placing the lumber on edge I believe that the glue will not be as important, although, the glue must still be waterproof. The 10"x18"x35' beams that are currently in place were salvaged from an old iron ore mine in the 60's. The beams have rotted on the ends.

The boathouse is owned by my family and with the current building restrictions, it would be best to build in-place. I don't know what glue to use or what type of pressure treated wood. The old pressure treated wood did not have slashes cut in for preserving. That is the type that I believe would work best. I live in California so I do not have access to Minnesota companies. My specialty is in highway-heavy construction and not wood design.

Any help would be appreciated.

 

[DaveVikingPE]

Why do you want to use glulam? Fabricating a glulam product requires specialized manufacturing equipment.

You could fabricate a large enough beam from 2x12's. There's an interesting company called Northstar in Georgia that's got a process for coating pressure-treated wood with vinyl (

http://www.endurancecsp.com)

you might want to look into.

 

[boo1]

Barney, why glue? SST fasteners (bolts) could be used. Remember also to include the wet service stress reducton factor.

Consider using three inch stock and 2.0 CCA treated wood. Companies dealing in bulkheads and docks should be able to supply it.

 

[Trussdoc]

I believe that Parallam, or something similar, is still available with Wolmanized wood treatment. You may save yourself some work by buying the beams as one large chunk.

The incising that you mention is used for some lumber species that do not readily accept pressure treatment, and it does reduce the strength of the lumber. Southern Yellow Pine does not require incising.

 

[boo1]

Trussdoc has a good idea, a quick email/call to a few companies could save you time!

 

[Glueguy]

Do not use Titebond or the equivalent. The aliphatics have horrible resistance to water. Even the Super Titebond was not designed for submersion. Use a structural urethane (used commonly in RV mfg to bond sidewalls to aluminum studs. Cure time is approx. 4 hours. Will be impervious to the water.


I hope I've helped,


John Schrock

http://www.glubie.com