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Need some “engineering”–
Building a “pergola” across a client’s driveway. No permits needed. The span of the beam is 24′ clear, no live load, dead load consists of 22 8′ 2×6 redwood joists, with 2x2x24′ @ 6″o.c.
My question is–what beam would you use? It is going to be painted. I was thinking of a 6×16 glue-lam. What do you think?
Thanks, Syd Hawkins
Replies
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...Syd. i can't picture this.. where do the joists go ?
across TWO beams ? and then where do the 2x2's go...?
24' span is going to run the very grave risk of looking UGLYYYYYYY. it will appear low and flat no matter what you do..
think about going to a truss mfr. or a post and beam company and getting some arch into your span..
I saw something similar to what i think you're trying to do... they spent big bucks. and took it down 3 months later...
go figger..
at least get it drawn to scale, that'l simplify your
engineering question , too
*Mike--Yeah, that's what I was afraid of--looking like the deck of the USS Nimitz is attatched to the front of the house. Clients like the look of a similar construction down the road a piece.As far as particulars--the pergola is in front of their gaarage. The beam in question runs parallel to the garage wall. The joists bear on the beam and run back into a ledger board lagged into the garage door wall. The 2x2's then are run perpindicular to the joists, like purlins.Just wondering what kind of beam I'd need to hold the dead load without turning into a giant U in a couple of years.Thanks
*...Syd.....hope i didn't offend .... a picture is worth a thousand disapointed customers...
*Not at all--I always include some sort of shop drawing with my contract. I agree with you. I've worked with these clients before, and they seem to know what they like. It doesn't always match up with what I like, but as long as they're happy (and things don't fall apart).....
*Better check the additional loading imposed on the garage door wall. A lot of garage door headers are undersized to begin with. Hence the sag above the door. This happens most often with double wide doors. You'll be adding a substantial amount of weight to the load already being carried so proceed with caution.The drawing is a good idea. They may say they know what they like, but if they don't like it when it's done they might end up stiffing you. A scale sketch relating the new structure with the existing might help them see what they're getting into. Your call though.Eric
*hmmmm, tough call Syd....I built a clear span 24' deck above a double garage entrance a couple of years back. My reccomendation would be a minimum of a 4x12 Douglas fir beam(if availiable), and if you want to make extra sure...give it another 2x6 on either side to give a little extra stability...use waterproof adhesive between the layers. Overkill, yes, however...best to be safe. (this is off the cuff and obviously should not be taken as a structural engineers report, no liability is expressed or implied). I would also recommend paying close attention to the connection to the wall/ledger and using flashings to ensure long life. If you find these sizes are unavailiable you will have to go with an engineered beam. The supplier can size it for you(normally they employ engineers...you may want to add another 2" to their recomendations, and possibly cut some crown in it. (they do deflect) Good Luck,L
*Syd, Would a steel beam with a wrap be in the budget? Just another approach. Skip
*Thanks for the input--"Off the cuff" is what I need to hear. I think that every carpenter who's been around has a pretty good idea just by looking at a span what kind of header or beam will support the load. It is kind of nice to get some extra input, though.I was thinking of a 5 1/8 x 16 glu-lam, standard camber, architectural grade. I only need it to hold its own weight. (Sorry--steel won't work as this project is purely for asthetics.) But, now that you mention it, maybe a 4 x 12 or 6 x 12 would work......have to run some numbers on that one.As far as the garage door headers go, there are two 8'spans with triple 2x12 headers across both. Should be no problem there.