# Cabinet Assembly with Prefinished Plywood



## Tom-G (Nov 11, 2012)

I'm building maple face frame cabinets with prefinished 3/4" plywood boxes. For the wall cabinets, the sides, top, and bottom are tongue and grooved into the face frame and will be glued. The sides have dados that the tops and bottoms fit into and will also be glued. The upper rear rail is tongue and grooved into the top and sides and will be glued. The bottom rear rail will attach the same way. 

I have the first cabinet dry assembled and am happy with the way all of the components fit together. The question I have is whether glue alone is sufficient or if mechanical fasteners are also needed. The concern is movement in the dado joints with changes in temperature and humidity over time. Could the wood glue (Titebond) in those dado joints crack and the joints loosen as the prefinished plywood moves with seasonal humidity changes? With the prefinished ply, the only bonding surface is the edge of bottoms and the tops into the bottom of each dado. The dados are 3/8" deep. 

Do I need to also screw or nail through the sides into the edges of the tops and bottoms? I originally was thinking the wood glue would be a permanent bond but now I'm second guessing this.


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## woodnthings (Jan 24, 2009)

*in my experience ...*

Years ago I made a whole kitchen from 1/2" Melamine. I hated that stuff, razor sharp and heavy in 4 X 8 sheets. I was in the basement of a rented house with no space to work. I don't know how I did it to this day.

I figured glue wouldn't stick to the Melamine, so I use Liquid Nails in the rabbets and dados and it worked pretty well. You might try an experiment with both Titebond, a glue, and Liquid nails, an adhesive, to see which has greater holding power on the prefinished ply. The Liquid nails went on using a caulking gun, which was more convenient than a glue brush or squeeze bottle, but you had to release the pressure before you got to the "finish line". :grin: That stuff is nasty, sticky.


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## Steve Neul (Sep 2, 2011)

A lot depends on how smooth the parts were cut and how well the dados fit. If the edges are smooth and the dados are relatively tight glue alone would hold together just fine. For the most part cabinets are nailed together to hold the parts together until the glue dries. The back of the cabinet you need to use an adhesive for non-porous surfaces though. A cabinet gets a great deal of strength from it's back so an adhesive should be used there too.


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## Terry Q (Jul 28, 2016)

If the cabinet sides aren't going to show, then why not put in some screws if it would ease your mind. 


Enjoy yourself, life is short


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## Tom-G (Nov 11, 2012)

All - thanks for the replies. 

The dados are a tight fit and very smooth. All edge cuts on the plywood are very smooth too. 

There are 16 cabinets and 5 of them have both sides exposed. Another 5 have one side that will be exposed or partially exposed, such as the wall cabinets on each side of the stove. 

I never thought about an adhesive, and didn't realize it should be use for the back. I think I'll use wood glue for the dado joints and adhesive for the rear rails (stretchers?). 

In addition to Liquid Nails, are there any other brands recommended? I don't want anything that has a thick consistency. Several years ago I used some "PL" (I don't recall the number) construction adhesive and it was very thick, as I recall it would be too thick for the tight fitting joints. 

Thanks again!


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## sancho57 (Oct 23, 2011)

I use screws 5 ea #8. 2 1/4 long per joint. The screws will be covered by mounding or counter top on the exposed sides


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## flyingvranch (May 9, 2017)

I used pocket hole screws to attach my face frames. I drilled them on the outside of the boxes in areas that were not exposed or seen. When the boxes are butted against each other or butted to a wall, the screws are hidden. I also assembled the face frames with pocket hole screws and glue. Strong as heck and this method is used by many professional cabinet builders.


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## Toolman50 (Mar 22, 2015)

You might be surprised to see how many factory made cabinets get hot glued together. 
I was very critical of hot glue until I tried to pull it apart. I was impressed with the strength of hot glue. 
I've used it on drawer bottoms where I cut a 1/4" dado for plywood that was actually some metric size smaller than 1/4". It solidified the drawer bottoms.


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## CabTiger (Aug 8, 2017)

flyingvranch said:


> I used pocket hole screws to attach my face frames. I drilled them on the outside of the boxes in areas that were not exposed or seen. When the boxes are butted against each other or butted to a wall, the screws are hidden. I also assembled the face frames with pocket hole screws and glue. Strong as heck and this method is used by many professional cabinet builders.


You're absolutely right. A tip for any future builds, when you have a cabinet butting to a wall, let your faceframe overhang your box by 1/4" on the wall side. That will help make sure that both the face and the opposite side of the cabinet flush against the adjacent walls. Either out of square walls or sheetrock mud buildup can make a perfect cabinet look terrible after install.


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## Tom-G (Nov 11, 2012)

Update: I spent the last few months cutting and milling all of the parts for every cabinet. All have been dry fitted and then disassembled. I just started applying dye & clear coat to the first couple of wall cabinets. I know, it’s taking a long time. I try to get some evening time once or twice a week and at least one day on the weekend to work on it. 

One of the things I did on the wall cabinets that have prefinished ply sides, was to glue a 1” wide strip of maple along the bottom edge. This allows me to dye/finish the exposed area under the wall cabinets to match the face frames. The glue line is positioned so that when I ran a 3/8” deep dado for the cabinet floor the glue line is within the dado. The net result is only the prefinished ply can be seen inside the cabinet and only the dyed / finished 3/4” exposed under the cabinet can be seen on the outside of the cab. However, now I have a glue line of 3/8” holding the maple strip on and supporting the cab floor. So I have decided that in addition to glue to put some screws in through the plywood area of the dado into the floors for piece of mind if they will be hidden when the cabinets are installed. 

The cabinet floors are also prefinished maple ply. I'm thinking flat headed screws, maybe 1 1/2” long which will provide 1 1/8” bite in to the cabinet floor.

Does this length sound reasonable? I know it’s shorter than mentioned above. 

Should I use coarse or fine thread screws?

Any recommend screws for this application or basically sheet rock screws? I did look at McFleely’s site and there is so much to select from it is confusing. 

Thanks. 
Tom


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## nywoodwizard (Oct 31, 2006)

1- 5/8" course construction screws should suffice if just going through the dado, (Going through full 3/4 I'd use 2" min). Pre-drill the proper size holes so the ply don't split and not too close to the ends, 2" min.


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## Tom-G (Nov 11, 2012)

nywoodwizard said:


> 1- 5/8" course construction screws should suffice if just going through the dado, (Going through full 3/4 I'd use 2" min). Pre-drill the proper size holes so the ply don't split and not too close to the ends, 2" min.



Thank you!


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