Hello all-
First post so please be patient. I am building a deck and am wondering if anyone has tried building their own girder beam. I have an existing deck with cedar 2×4 decking in ok shape. Thought it would be great if I could glue and nail the 2x together to creat a beam that could replace the requried 4×8. Any thoughts?
Thanks
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Replies
Welcome to BT from another new guy.
If you wanted to glue two 2x8's I'd say ok, but flirting w/ 4 or 5 2x4's laying flat???? Too much riding on the glue holding and w/ recycled timber to boot.
Save yourself the worry.... spring for the 4x8 or at least 2 2x8's, and go w/ PT.
go with the 4x8, the thing with glulams is that they are glued under extreme pressure, and you cannot make them at home. Also, you said REQUIRED 4x8, that means you have to use a 4x8 anyway, so the question is irrelevant. I hope this helped.
Chance
Sure you can. PL PREMIUM GLUE, not Liquid nails. Drizzel it in a zig zag pattern outta the tube on one surface of the 2x8 ( wide face) and slap on the next one.
Arrange to have a zigzag pattern of fastners ( DOUBLE HOTDIPPED GALV, Or Stainless Steel Screws) and place them from both sides.
Beig as you have two independant "beams" there is no weakness from say a large knot in a single 4x8...so the double is stronger. In theory.
I'd certainly use PT for the girder, cedar is not near as structually strong.
Spheramid Enterprises Architectural Woodworks
HOW ABOUT THAT REZ GUY? UH HUH? ...He ain't Silesien I bet....wimp
>> I am building a deck and am wondering if anyone has tried building their own girder beam << Using 2x8s, 2x10s, etc, to build beams in this part of the country is done every day - all day - that's all we do, unless you truly need an engineered beam. 4x8s are rare here. On the other hand let's not call it a glue-lam. Let's call it a built up girder or built-up beam. No need to glue it unless you really want, but if you take the trouble, use polyurethane glue as Sphere said. The PT 2 bys are normally just nailed up real well with hot dipped galvanized nails. If you think a thickness of 3" (two 2by?) isn't enough, go with a 3 ply beam; 4.5".
I think there is some confusion here on what it is you are proposing doing. I'm guessing this by looking at the answers you're getting.
Are you talking about laminating 2x4's "on the flat" to build up a glu-lam?
Or are you talking about making a 'built up beam' out of 2x8 or 2x10. By that I mean using a pair of larger 2X pieces and glueing and nailing them together like a header? To be installed on edge, of course.
You can't do the former, but the latter is done everyday all over the country.
Bryan:
Your right - my bad - We rarely see glulams areound here - only for exposed beams like maybe in a church... Also, I guess I would never in a million think of using something like that on a deck... I was thinking he ment LVL, or something...
Are you talking about laminating 2x4's "on the flat" to build up a glu-lam?
I hope I am wrong, but that was the impression I got from his post since he only mentioned 2x4's.
I'm a little confused. You have an existing deck, and you're building a deck. So are you proposing to take the old deck apart and reuse the materials?
Why did you say that you need a 4x8? Just curious. If you have the room, use two 2x10's nailed together. But don't use cedar for the beams, use pine.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Why use pine? The initial strength of the pine is slightly better than cedar, but after it rots in three years, it will be far less.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
1. Use pressure treated material.
2. Design it so that it sheds water and does not rot.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
2 2X8s joined together is better than a single 4x8.
Difficult to find large timbers that are straight anyways, particularly for pressure treated.
Just be sure to cover the top of the beam with something to keep the water out of the seam. That is a big failure point on the rotten decks I have removed. You can use feltpaper, sticky membrane, or metal flashing. I prefer sticky membrane because it stays put, and seals around the fasteners.
Thanks everyone. I was wondering about laying 2x4's horizontal but sounds like everyone thinks this is an awful idea. When using 2 - 2x8's is there any difficulty in securing them to the post with galvanized connectors? I was planning on using a simpson product.
Gluing up a stack of 2x4's *might* produce a beam equivalent to solid sawn lumber, *but*:
1. The glue you use has to be at least as strong as the natural lignin that holds wood together.
2. You have to get complete coverage of all surfaces without voids.
3. The glue can't be a kind that will dissolve out if it gets wet, or turn brittle if it gets dry.
4. The 2x4's need to run the full length of the beam, except maybe the middle ones where you have neither tension nor compression.
5. If you build this non-standard beam, you're liable forever if anything goes wrong with it.
Bottom line, it can be done, but it shouldn't be done.
-- J.S.
Excellent.. i was conjuring a method I have used, and you are 100% on track.
I made the main carriages for an arched bridge in NC..not real big, but needed an positive camber.
Planed all the stock ( red wood in this case) and slathered the Gorilla to it..clamped to a few blocks in a jig ( stakes in the ground), and went away for a few days.
Powerplaner, beltsander and bridge..in that order. Spheramid Enterprises Architectural Woodworks
HOW ABOUT THAT REZ GUY? UH HUH? ...He ain't Silesien I bet....wimp
The other glue requirement would be that it does not allow "creep"
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
That's true too. Horizontal shear is what the glue would have to resist.
Going to all that care and effort doesn't make sense when you can buy the equivalent or better stick of solid wood for maybe $30 - 50.
-- J.S.
No problem securing them to the the posts.... you have many options through Simpson:
http://www.strongtie.com/products/connectors/AC-LPC-LCE.html
or
http://www.strongtie.com/products/connectors/BC.html