# Why Both Glue And Screw?



## TwoRails (Jan 23, 2016)

I’ve seen photos in magazines, and YouTube videos showing that a glue joint when put thru torture tests, the wood always breaks and not the glue joint. I’ve seen examples in a press, folks jumping on the joint, being run over by a pickup, etc.

So why bother using both glue and screws? Yes, I get it that a few well placed screws are your clamping. But watching a ton of YouTube videos, I see a lot of folks glue something up but then they put a ‘gazillion’ screws along the joint as well. A while ago I saw someone with a board glued to another at a right angle that was at least 2’ long. And then they put in screws about every 2 inches along the joint…

Isn’t that overkill?

What’s your theory/workflow when using both screws and glue?


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## tvman44 (Dec 8, 2011)

Just MHO but the screws add a little strength to the joint as well as providing the clamping.


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## m.n.j.chell (May 12, 2016)

If you're using plywood, then I believe you need the screws. 
I posted this link on a thread about glue tests. The main thing I got out of it is, plywood glue is weaker than anything you'll use on the joint.






The screws are necessary to keep the plywood, itself, from separating.


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## Steve Neul (Sep 2, 2011)

A lot depends on the material and what you are building but for the most part the screws just pull the parts together better enabling the glue to work correctly. A lot of times if you have enough clamps screws are not necessary. The exception would be end grain joints like the corner blocks holding a chair together. On that application screws are very much necessary.


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## TimPa (Jan 27, 2010)

if there is a wood to wood joint, the glue will be the #1 fastener. however, there are other factors: long grain to long grain - glue and clamps is all that is necessary. ANY other joint, such as long grain to end grain, or other types of wood products - the glue may not hold because of expansion and contraction, atmosphere (indoor/outdoor). so mechanical fasteners are used as a second bonding method.


but with care, I have successfully glued edge to edge of 1/4" plywood, and end grain to end grain hardwoods. clean cuts, good glue and clamping. I would suspect they would not survive long in a press test.


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## Brian T. (Dec 19, 2012)

I use screws & lag bolts in a dry joint with damp/wet wood, fully expecting everything to shrink in my Frankenfurniture. I was right.
The legs are a bit wobbly, tighten the screws. Maybe this coming winter, I'll drill out the screw holes at 3/8" and peg and glue the joints.
Its a carving bench 12" x 48", built entirely out of 4x4 western red cedar (crappy small-log stuff, far harder than the fancy deck & furniture grades.) Easy shopping when the mills are side by side and 20 minutes from the house.
A decade ago, I built myself a simple bedside table. Dimension lumber, nothing fancy. Glue, dowel pegs and clamps. Clock radio, some books, that's it for load. It will last forever.

No, I have no idea why builders use both glue and screws, especially if the unit takes little load.


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## TwoRails (Jan 23, 2016)

Lots of good reading above. Thanks for the posts, they are very informative. I enjoyed the glue test link, too.

Thanks folks!


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## rubberduck (Jun 24, 2014)

Belt and braces


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## TwoRails (Jan 23, 2016)

Hi Everyone,

While 'surfing' woodworking videos, I found a glue test that was pretty interesting:


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## VIFmike (Jul 21, 2012)

I use screws and glue on table braces. Don't have to clamp the braces down and I can go ahead with sanding the next grit. I put these on with the table bottom sanded to 60 grit and the brace also at 60 grit. I use a small loop of glue around the perimeter. Just enough away from the edge so none squeezes out.


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