wood beam repair 2

[RPB2]

I have a wood beam that, due to a large knot located at the bottom of the beam, has developed a vertical crack. Has anyone used an adhesive or epoxy product to strengthen a wood beam?

 

[Sawbux]

I assume from your description that this is a solid sawn beam?

There is no way to repair the tension side failure with epoxy alone. The easiest method is to sister a new beam along side or along both sides of the beam to provide the neeed load capacity.

Epoxy or adhesive repairs are too technical,complex and expensive unless there are other compelling reasons to conceal the repair or there is a lack of room to do it any other way.

Is this a "stand-alone" beam holding up a larger area or a "joist" hwere there are many parallel beams? If it is stand-alone and supports a large area, get a shore under it right away!

 

[BAretired]

I agree with Sawbux. Epoxy alone will not do the job.

BA

 

[RPB2]

Thanks for your input--you confirmed my own suspicions. The beam is a member in a panelized roof system. Since it was initially built, someone realized that the members were overstressed and added new members in between the existing members. However, the existing member still carries the reduced tributary load. Since 2" of the bottom of beam is expressed below the finish ceiling and remains visible, sistering or straps are not viable options. any suggestions?

 

[LonnieP]

Sounds like a panelized warehouse roof. I suggest using epoxy glue to add a 4x select struct lamination to the bottom of the existing purlin. Pre-drill the 4x lamination for 1/4" Simpson screws spaced at 2'-0" oc. Be prepared to shore the lamination at mid-span to take out some of the existing deflection. Once you mix the epoxy you'll only have about 1/2 hour before it sets, so collect everything needed and work fast. The simpson screws are installed after the glued lamination is in place and shored. Full glue cure takes 24 hours, then the shore can be removed.

LonnieP

 

[Sawbux]

Not sure that we have the full picture yet.

Is it a laminated beam or a solid sawn one? In panelized systems there are usually solid sawn 2x4 or 6's at 24" o.c. (sub-purlins) spanning 8 ft. between solid sawn or laminated purlins that can span 16ft to 40ft.

The type of member and location of the defect are important!

 

[nuche1973]

Try 1/4" A-36 steel plate on both sides, thru-bolted with 5/8" diameter screws. Shore the beam at the trouble spot to take out the deflection. Make the plate 1/3 your span length and same depth of your beam. Space the bolts at 12" o.c. Its over kill but there would be no question about the plate's ability to support the loads involved, since the wood will fail before the steel.

There are days when I wake up feeling like the dumbest man on the planet, then there are days when I confirm it.