Understanding Wood Joints | Ask This Old House

In this video, Ask This Old House general contractor Tom Silva teaches host Kevin O’Connor about the different wood joints, including their strengths and weaknesses.
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Kevin O’Connor meets general contractor Tom Silva in the shop for a lesson on wood joints. With several power tools and jigs on the table, Tom explains how joinery works and some of the most popular methods. He teaches Kevin everything from mitered and lapped joints to dowels, biscuits, floating tenons, and pocket hole joinery, with examples of each type to show how they work.
Different Types of Wood Joints
Butt Joints
Miter Joints
Half-lap Joints
Dado and Rabbet Joints
Box Joint
Mechanical Fasteners
Dowels
Floating Tenons
Biscuit Joints
Pocket Hole Joinery
Where to find it?
Tom explained how to identify different types of wood joinery and why they’re used in woodworking.
Half-lap joint-Formed by creating two rabbet cuts, which requires cutting half of the end of the board. DOMINO DF Q-Plus by Festool [www.festoolusa.com/]
Half-lap butt joint-Formed by creating one rabbet cut, as explained above, and then placing the other board into the opening created by the rabbet cut. Hoffman-PDS 32 [hoffmann-usa.com/]
Miter Joint-Formed by creating two, opposing, 45-degree angle cuts on the ends of the board and then bringing them together, creating a 90-degree angle. Cut created using a Zeta P2 made by Lamello [www.lamello.com/]
Floating tenon joint (aka biscuit joint)-Formed using a biscuit joiner, a specialty tool that drills mortises wide enough to accept biscuits or tenons that are pre-cut and connect two boards with mortises together. Cut created using biscuit joiner, Top 10 by Lamello [www.lamello.com/]
Box joint-Formed by creating a series of cuts on each end of the board that create a castle or finger-shaped look. Cut created using Kreg Jig® K5 [www.kregtool.com/home]
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From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. Ask This Old House helps you protect and preserve your greatest investment-your home.
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Understanding Wood Joints | Ask This Old House
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[@sweet_t_6]

Tommy & Kevin, top tier duo

[@timkendall5786]

I've been watching This Old House going all the way back to Bob Vila, I always learn something new. Thank you👍

[@sean8081a]

Love the half lap, easy, only uses a table saw and super strong.

[@akoznasovajusername]

I am following all of the instructions from This Old House while building my house.

[@BilliamNye1]

I enjoy watching. I remember being knee high to my great uncle and him and I doing woodworking projects and watching this old house and remembering this old house. I enjoy I can continue on learning even after he has passed. Thank you

[@angellas.1314]

Okay Tommy, now we need to know when to use which method! Great information as always! Thanks 🙏!

[@scottsatterthwaite4073]

Really? And how many of those special saws do you have? I have a pocket hole jig, a biscuit butter, and some drills. I can use dowels, pocket screws, or biscuits. The method I use depends more on what I happen to have handy. These days, I use pocket holes and glue on the majority of joints because its both convenient and very strong.

[@joshuahasson9687]

@@scottsatterthwaite4073 pocket screws are strong? That is not an accurate statement.

[@scottsatterthwaite4073]

@@joshuahasson9687 Yes it is. Properly screwed and glued, such a joint is very strong. The key is "properly".

[@angellas.1314]

@@scottsatterthwaite4073 Let’s see. I have a circ saw, miter saw, a few hand saws, pocket hole jig….and on the market for a router and possibly table saw. With the former few tools I already made a few cabinets so far. And I have many more projects planned. What’s your point?

[@scottsatterthwaite4073]

@@angellas.1314 You just made my point. Like most of us (including myself and I occasionally build custom cabinets for my clients) you have a fairly normal array of tools at your disposal. We have learned to use these tools to get the job done. The specialty saws that Tommy was demonstrating are not usually found in the DIYer's garage. Most of them are very expensive (the domino cutter is HUNDREDS of dollars). So, why not ask Tommy the best way to use the methods at our disposal to make the best joints possible? I'm not picking on Tommy. I just don't see the point of demonstrating jointing methods that the majority of us can't afford to explore.

[@karl_alan]

That biscuits type slot with the hardware was cool. Never seen something like that before. Also didn't know there was an automated dowel machine like that either. Always seen jigs you clamp to the project instead.

[@leozmaxwelljilliumz3360]

Cant remember which company makes it but it's called a "duo doweler" super handy, pretty expensive too.

[@hchris96]

I think the machine Tommy is showing is the Mafell DD40P. Depending on how much woodworking/joinery, you still might get ahead of the Festool Domino due to its proprietary tenon and dowels are much more common to buy or make. As of writing this, the Festool Domino is around $1000 and the Mafell Duo Dowel System is a little over $1350.

[@rickfromthecape3135]

Love Tommy! A real craftsman.

[@MasterHustler]

Tommy is a pros pro. Thank you for the knowledge.

[@Draugluin999]

Love the Tom Silva videos the other guys are great to 👍

[@MariuszChr]

I wish I had patience to use that awesome technics to do some nice furniture...

[@ProudZionist12]

Indirectly-related question: in an old house, when you re-paint previously-painted door casings, do you caulk the edges where the two side jambs meet the head jamb?

[@Off-Grid]

Always good info, have been watching for years

[@craigyarmulasr1845]

Another great video.

[@veenaymungal8736]

Great video guys, I now have a better understanding of wood joints... 👍👌👍

[@ming236]

Very good job !

[@karl_alan]

The biggest difference between the floating tenon and biscuits is the grain direction. In floating tenon, since the grain is perpendicular to the joint, it is super hard to break. The biscuits could be just about any direction, but more often than not, it's similar to the joint, so it helps more with alignment than strength.

[@SciPunk215]

Very thorough. The only thing missing was the spline.

[@japan5865]

Beautiful

[@alonzojohnson7955]

Tom 🎸

[@brucechan9140]

I didn't get the last part about pocket screws. Tom said that you cant use pocket screws if the width is greater than 6 inches. Moments later he also said that you can build cabinets that are 3 or 4 feets.

[@frankvucolo6249]

Probably referring to the fact that cabinet parts are usually made from plywood that doesn’t expand and contract across the grain like solid wood. Plywood is constructed with multiple layers, the grain of each layer runs opposite the other layer so it is very stable.

[@angellas.1314]

The thing with pocket holes is that they should be spaced correctly and it will hold any width. I’ve seen many professional carpenters use it effectively and they built cabinets, small and large.

[@mannyfresh8504]

Why can you build cabinets all day without worrying about expansion???? Is it because of the use of ply? Thanks for the information. Learning a lot as a newbie woodworker.

[@nnamerz]

Yes, I believe that is what he was implying. There's very little contraction/expansion with plywood due to each layer being perpendicular to the next layer.

[@mannyfresh8504]

@@nnamerz ok, thanks a lot for your response.

[@RogueCylon]

Weird you missed the most popular and historical joints - mortise and tenon, and dovetail.

[@mrkattm]

I wouldn't go as far as saying a master class but good info none the less.

[@kasbakgaming]

And if you want to know how to make the jigs and machines that make most of these joints easily, watch Matthias Wandel.

[@nnamerz]

He also did some great videos on testing the strength of pocket screw joints, lol

[@efox2001]

What is the name for the tool that drills two holes at once? I haven't seen that one before.

[@augustreil]

Did they mention dovetail and I missed it ?

[@Peter-.H]

No, he didn’t mention it. There are many different types of dovetail joints. I guess tommy didn’t have time to get into it. Cheers 🍻

[@timothyschriefer2822]

There was the guy not too long ago showing that end grain glue was actually stronger.

[@Davey768]

End grain glue surface is just as good as side surface.

[@forseti52]

Dove tail joint?

[@langrock74]

Similar to the box joint, but prettier and harder to make;-)

[@robohippy]

Tried the pocket screws and didn't like them. One of the 2 pieces being joined would 'climb' as I would screw them together, and one would end up higher than the other. Funny to see the Festool set up being called a tenon. Guess that works, but then the more common biscuit would be a tenon also. Missing are dove tail and spline joints. Guess the biscuit could be a spline. Oops, new product, biscuit cutter that will slide and make a full length dado..... Splines to match or contrast...

[@ddr526]

It’s an art form

[@drexlspivey96]

Forgot the best one, mortise and tenon joint

[@artvandelay1099]

Times like this, you miss Norm Abram. No offense fellas.

[@todd2456]

Draw = drawer Idear = Idea .... Remove the R when it's there and add an R where there isn't one. Got it.

[@donc-m4900]

Pak the ca at Havad Yad. I got idear wrong on a 6th grade spelling test because I 'sounded it out'

[@Pyth110]

Amazes me that TOH has existed forever and people like you still act like you're the first ones to ever make jokes about their accents. Please get new material.

[@todd2456]

@@Pyth110 Let's try this: They used to call them jumpolines until your mom got on one back in '83.

[@A6Legit]

Floating tenon: aka oval dowel

[@johnarnold6623]

Tommy, just so you know, if I hit the lottery I’m going to hire you to redo my house. However you want, you got a blank check. Your imagination will be the limit

[@Nebulous0_o]

Is that Mike Ditka?

[@Terminalbeats]

Tommy's worst enemy: the word "drawer"

[@CalebHensinger]

I'd have have to imagine wood joints would be quite the carcinogen... ;)

[@rayscdn07]

first!!

[@regularguy9264]

You know you will get called out on the biscuit joints: 1) Stronger due to glue surface area? No. 2) Perhaps a little if grain direction of the biscuits is perpendicular to the joint? A little. 3) Good for alignment? Absolutely.

[@Mekhanic1]

Biscuits add strength. Stop spreading bad information.

[@regularguy9264]

@@Mekhanic1 sorry, I should have supported my statement. You can check out this link to Stumpy Nubs, but you may also wish to check out the video he refers to near the end. There have been people who have strength tested different types of joints, and a butt joint with or without a biscuit tested out virtually identical. If you’re looking for strength, I would suggest dowels, dominos, or another type of joint such as a mortise and tenon for example. kzbin.info/www/bejne/eHfTY5psm7p1d6s

[@clearcut6818]

I just used the biscuit cutter today. I seriously doubt it's for joining boards. It's only use is to get even height

[@karl_alan]

@@Mekhanic1 Fine woodworking tested them too. Overall there's virtually no improvement from adding biscuits over the alignment angle and helping in general with getting the joint to stay together through the glue up while the glue dries.

[@langrock74]

Biscuits are good for alignment. They don’t add strength beyond what the glue already does. Matthias had a video on that.

[@ShadowzGSD]

endgrain glueing is good, it has been proven.

[@bettymaverick1098]

For most purposes most of these joints are overkill and more work than needed. Super strong joints for weak structures. Just saying.

[@rbnhd1976]

Thanks toh let's go brandon

[@augustreil]

Yup, Lets go Brandon !!

[@Pyth110]

TOH: wood joints You: hurr durr politics!! Can't have anything nice.

[@rbnhd1976]

@@Pyth110 hit the thumbs down and scroll on my friend I really don't care, it's my comment and you can cry if you want to

[@rbnhd1976]

@@Pyth110 foxtrot juliet bravo

[@anthonya.torchia396]

Let’s go Brandon!