# Exposed Glu-lam Beam



## T-Bird (Dec 11, 2020)

When a glu-lam beam is exposed without a roof or an eave covering is metal flashing an acceptable method of providing protection?


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## steveray (Dec 11, 2020)

https://www.anthonyforest.com/assets/pdf/apa/glulam/Tech_Note_Preservative_Treatment.pdf
		


Ask the manufacturer...


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## ICE (Dec 11, 2020)

LVL exposed to weather - Wood design and engineering - Eng-Tips
					

I recently saw a laminated veneer lumber beam being used in an outdoor application (header on a deck). This made my engineer sense tingle, because I'm pretty su




					www.eng-tips.com


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## Mark K (Dec 11, 2020)

glu-laminated timber is different from  LVL

Glued-laminated timbers can be used in wet regions but they need to comply with special fabrication requirements.

Reference IRC R317.1.5 and IBC Sections 2304.12.2.4 and 2304.12.2.3

The concern has  to do with moisture/rain accumulating on top of the wood which penetrates to the interior of the member through the small cracks that are natural in wood.  The member then rots out from the interior.  This is an issue where there is no difference between residential or non residential occupancies.  There is little  difference between sawn and glued-laminated members.

On one building I inspected I observed mushrooms growing on top of an exposed glued-laminated member.

When lumber is treated the penetration of the treatment is limited to 1 to 1.5 inches which means that the interior of the member is untreated and will rot out from the interior if moisture gets in from cracks on top of the member.  Theoretically you could overcome this by treating each lamination before laminating the member but this is not commercially available for several reasons.

The laminating industry recommends that members not protected from an overhang has metal flashing installed on the top of the member.  The engineer designing the glued-laminated member should have access to these recommendations.  This flashing is installed with a gap between the wood member and the flashing thus providing for venting of moisture on top of the member.


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## Rick18071 (Dec 14, 2020)

R317.1.5 Exposed glued-laminated timbers. The portions
of glued-laminated timbers that form the structural
supports of a building or other structure and are exposed to
weather and not properly protected by a roof, eave or* similar
covering* shall be pressure treated with preservative, or
be manufactured from naturally durable or preservativetreated
wood.


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## fatboy (Dec 14, 2020)

I agree with steveray.......I'm sure the manufacturer has specs that are code compliant, start there!


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## mtlogcabin (Dec 14, 2020)

A deck with a composite decking with no flashing/protection for the top of the glu-lam


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## steveray (Dec 14, 2020)

Is that a beam failure? Looks like something else by the joist hangers being intact....


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## mtlogcabin (Dec 14, 2020)

No it was a failure in how it was constructed 10 years earlier and about 75 people dancing on the deck. I just provided the photo to show how they will rot from the top down and inside first


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## steveray (Dec 14, 2020)

Thanks MT!


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## ADAguy (Dec 14, 2020)

Good stuff!! thank you.


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## mtlogcabin (Dec 14, 2020)

One of many products out there





						Deck Joist Tape™ | Protecto Wrap
					






					protectowrap.com


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