Exterior Treatment for GluLam?

[Woodbender]

Yes I know this is sacrilege to post a question on Glulams here.  but I figured you guys haven't thrown me out yet so here goes...

Working on a project which will basically be 100% out in the elements.  Looking at various materials and treatments but glulam timbers (is that a contradiction?) have repeatedly come up.

They're stable and don't warp perceptively and can be ordered to length if needed.  My big concern is how can glulams exposed to the elements be protected?  The manufacturer states that the glue is a waterproof glue so that is not my worry.

Oil based stain? 20 year paint?  (Latex? Oil Based?)

Thanks,
Bro Tim

[Jim_Rogers]

My first advice would be to talk this over with the manufacturer and see what they recommend...

As I don't have any experience with glulams I can't help you other than that....

Good luck with your project.

Jim

[logwalker]

Metal caps might be appropriate. They certainly need something if they are going to last a long time.

Joe

[Woodbender]

Okay - thanks gents.

[breederman]

Unalam uses alot of oil based stain on their stuff.

[iffy]

I used one for a deck support over a driveway. Wrapped it in 1 x cedar. Put the cap on first, then the sides, and caulked the top joints. Left the cap overhang the sides by a 1/4" or so. Capped the ends. Might have been overkill.

[Rooster]

Hey there,

Is there a chance we might be able to see a structural design for your build?...With this much experience and info available on this site, it might be worth your time and energy to let us help you think outside the box, and maybe come up with a solution that doesn't involve exposing glulams to the elements.


Go ahead, we won't bite!

Rooster

[ljmathias]

I used a 8"X14" glulam for the main beam in our house, letting it stick out the end about 1' but just under the gable overhang.  Wrapped it in 3/8" finish plywood, primed and painted it to match the trim and it looks almost as good as new after 10 years...  Prime and paint might be just as good though.

Lj

[Woodbender]

Thanks guys... Rooster the client done changed his mind on materials (again).  In fact due to a questionable partnership (on their end not mine) it might just fall through entirely.

Thanks again folks
tje

[jamesamd]

Ya got any Glue eating beetles,up Your way?

[knowslittle]

Just a suggestion.

Down here (Calif.) the old time sheet metal guys would always put tar paper between the beam end and the s.m., saying that the condensation would occur between the metal and the paper, keeping the beam drier, i.e. lasting longer.  And they never would allow caulk at the bottom of the transition betwenn the s.m. and wood, stating this would perhaps allow water to drain out if any were to actually infiltrate (rust?).

  Lately (last 15 years or so) have not seen this done, and when asked the installer had never heard of it.

  Of late, when the owner doesn't like the look of the s.m. caps, and when it can be painted, I've been sealing beam ends with epoxy, (ususally 3 coats) and it seems to be working well here and in the very wet state of Washington..

  Just a thought.

bob

[beenthere]

An exposed glulam beam is a mistake, if any long-term performance is of any interest. (IMO)

Species of the laminations would have some bearing on performance, as well as some type of preservative in the wood prior to lamination. The adhesives used would be another variable to control the short lifetime of a laminated beam.

Finally dawned on me that s.m. means sheet metal in the last post.