Safest Way to Connect 1/2" Plywood Joints

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Forum topic by wilschroter posted 12-14-2019 11:29 AM 10527 views 0 times favorited 10 replies Add to Favorites Watch
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181 posts in 1859 days

12-14-2019 11:29 AM

I’m building a cabinet and this one section requires me to screw directly into a 1/2” plywood joint. I know that I’m mostly safe pre-drilling a hole that’s hopefully straight but was curious what you guys recommend in this scenario to connect a clean 1/2” joint.

This seam runs about 7 feet in length so I need a lot of fasteners to finish it.

Should I be concerned about drilling directly into the side of plywood? It feels like I might be missing something. Pocket holes into just 1/2” of material feels like I wouldn’t get enough purchase.

10 replies so far

View Redoak49's profile


5466 posts in 3323 days

#1 posted 12-14-2019 11:54 AM

You can use micro Kreg job and screws.

Joining two sheets of 1/2” ply is not easy as easy to split the wood.

View Lazyman's profile (online now)


8802 posts in 2722 days

#2 posted 12-14-2019 01:36 PM

As long as you drill pilot holes there not a problem with splitting using screws into the edge of plywood, though if there is a lot of weight on it, there is a slight chance that it could split. A rabbet or dado/groove will make it much stronger and you could get away with just glue or at least fewer screws to cover up. In fact with a groove and glue, the screws are mostly for clamping pressure while the glue dries. Using pocket screws with the groove may make it so that you don’t have any screws to hide.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Jared_S's profile


489 posts in 1294 days

#3 posted 12-14-2019 02:22 PM

pocket holes or the spax mdf/particle board screws wont split it. Otherwise just pre-drill

View GR8HUNTER's profile (online now)


9314 posts in 2047 days

#4 posted 12-14-2019 02:40 PM

dado ,glue .and pin it done clean professional :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN :<))

View MPython's profile


402 posts in 1147 days

#5 posted 12-14-2019 02:47 PM

This ^^^. The glue will strengthen the joint considerably and there screws or brads will clamp it while the glue dries. I would use brads. They don’t split the plywood as bad as screws, and they’re plenty strong for this. you could also use a lock miter joint. Lots of people don’t like messing with the setup, but it’s perfect for this kind of thing. I built all my shop drawers with 1/2” BB plywood using lock miters. They are very strong.

View BuckeyeDennis's profile


115 posts in 1033 days

#6 posted 12-14-2019 03:07 PM

I like using a rabbet & dado joint (aka “tongue & dado” and “locking rabbet”) for casework.

They’re easy to make, self-aligning, and quite strong. In plywood, about half of the glue surface is long-grain to long-grain, giving a good bond. More info and instructions can be found here.

-- Dennis 'We are all faced with a series of great opportunities, brilliantly disguised as impossible situations.' Charles Swindoll

View LeeRoyMan's profile


2379 posts in 1061 days

#7 posted 12-14-2019 03:11 PM

Good plywood is no problem to screw into. predrill and screw.
I wouldn’t use anything bigger than a #6×1 1/4 screw.

Yes a dado or a rabbet, since the picture shows it on the end, would be better. Glue of course.

Knowing what you’re making and how strong it needs to be would be more helpful in getting you strong enough or not strong enough answers. Pin holes compared to screw holes, painted or stained?

View Axis39's profile


581 posts in 931 days

#8 posted 12-14-2019 05:35 PM

I like the rabbet and dado method most.

But, I’ve used pocket hole screws in 1/2” plywood a hundred times, at least. Never had it fail. (I do always use glue as well when building cabinets anyways)

I also own one of the mini biscuit joiners that Ryobi used to make. It has come in handy many, many times for things like this as well. I used it for a number of years before Kreg hit the market.

Also, I’ve done hundreds of glued and screwed butt joints that have held up as well. But, as mentioned, I always pre-drill and countersink.

-- John F. SoCal transplant, chewer uppper of good wood

View Phil32's profile


1636 posts in 1238 days

#9 posted 12-15-2019 06:25 PM

Most of the replies have only considered the joint itself. What are the likely loads on the joint? In your photo, the vertical panel appears to be an upright end panel, which means the loads on the joint would be sheer forces (crossways of the fasteners). Will there be “rocking” forces that need to be reduced by bracing or back panel? Think beyond the one joint.

-- You know, this site doesn't require woodworking skills, but you should know how to write.

View timmib's profile


14 posts in 2099 days

#10 posted 12-15-2019 08:10 PM

I have used a ‘glue joint’ approach to situations like this. Find millwork that fits your situation for the joint. I often use 1/2” x 3/4” pieces, though you can rip board to meet your specs. The glue joint piece is drilled to match the screw size you’re using so as not to split the piece. Apply glue to the joint piece, attach it to one board and the to the other. Provide a strong joint and a square one.

-- Kim, Chillicothe, MO

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