Threaded Inserts: Which ones are best? And why?

There is scattered info on the builders forum about these, but nothing concise. What threaded inserts do you use on what board and why?

This has become my preferred method


Here we go! Different schools of thought on this, and some decks (harder or softer wood) work a little better with various inserts.

I prefer to use the stainless ones though. EZ Lock inserts are a pretty nifty little system too. @mmanerjust got some of those and had some good luck with them.

I feel like a lot of different styles work, but the right size hole is paramount. I always recommend doing a test hole in some scrap wood that you have around that is (hopefully) close to the same density as the deck you are using, or at least relatively close.


As @Sender said, I had good luck with these, but don’t use them in a fiberglass deck (or fiberglass layers) without epoxy on the perimeter of the hole.


I have a moderate woodworking background and get pretty moody about this topic so I will only list information.

There are 2 main types of inserts used in our application:

Soft wood inserts

Hard wood inserts

Our decks flex and move. No mater what material they are made of. For this reason, I recommend soft wood. Trampa/composite decks might be the only exception but I have yet to test one of those decks. The loose teeth grab more without stripping.

Hard wood inserts are for hard stationary wood like cabinets or other furniture.

To further confuse things, most of the hardwood inserts have slots in them. There is constant debate whether this is:

  1. for installation with a tool and the slots should be surface side


  1. for cutting a thread (self tapping) and slots would be wood side

Both are correct! You need to know which one is which though.

You can differentiate these 2 by the depth of the slot and whether the slotted end is tapered like its meant to go in a hole.

Deeper slot and tapered edge = self tapping.

Shallow slot and square edge = insert with tool.

Some hard wood threaded inserts have self tapping barbs that will go on the bottom so I think that’s where a lot of confusion comes from (like drywall anchors). The slot on the thread is meant to be used with a specific manufacturer drill bit that will drive the insert without marring any surrounding wood. Most people just use a flathead screwdriver but make sure the head is NO WIDER than the insert itself. You can also use a hex head bolt that is meant to fit that specific thread pattern, tighten it into the insert, and then insert the insert/bolt combo into your hole and ratchet it tight.

Just a tip of general info that will serve anybody well: when picking a drill bit to fit a screw, the diameter of the drill bit should be equal to or barely smaller than the diameter of the screw’s shaft (if you stripped all the threads off)

As @Sender mentioned, epoxy the inserts in without getting any inside the insert


On that note, epoxy locking in inserts is good, but of course be careful to keep the epoxy off the inner threads! In order to help with this, just a smear of epoxy in the perimeter of the (properly sized) hole and let it reach the b stage cure so it is a little more tacky before placement. A small dab does a lot. If you put too much, you WILL get some in the threads.

If that happens, go to have a tap set on hand to open the threads back up. No harm, no foul.

If you don’t have a tap set, get the m2-m5 kit on Amazon. It is like $12, and really comes in handy for all sorts of stuff.


This is perfect. You guys are legends. Keep it coming.


These are pretty great too, just takes forever to get them.

  • EDIT: They also work with the E-Z lock tool linked above. I just ordered 40 for 5 bucks, they will get here about the time I start getting social security (yeah right, like there gonna be social security :slight_smile:).

Any insert hold well if you secure it in with some resin, glue would probably work as well


Damn I wish you ordered 100. I was paying way too much for those fuckers.


If you haven’t ordered from Ali in awhile they will give yo a $4 coupon which is essentially free shipping. Its better to make multiple orders of 40, if you order 100 it’ll take 3 months to get here, as it is it’ll take a month at least.


use these on my trampa. never had a problem. the slotted side goes in first and once the slots are in, i apply loctite red on the thread and screw hem all the way in. the correct drill bit is 4.5mm for the 3mm inserts.


Use the hard word type on a Trampa deck btw


I’ve used the hard wood and soft wood styles above myself. Have to say I preferred the soft wood ones. Just found them easier to work with. They’ve both held up well over time. I used wood glue to secure them instead of epoxy. For me this has worked out really well. First attempt was a disaster. Had to remove, fill and try again. @Psychotiller has a fantastic how-to on the other forum (not sure if it migrated here yet) on how to install the inserts deftly. Would highly recommend checking out if you’re about to do for the first time.


Even though they’re self tapping do you still drill a hole for them and then epoxy them in? Or do you just drill a small divot and screw them in from there?

Thanks for mentioning the bit size too, good info to know for these inserts.

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Gonna rudely jump on this answer haha.

Drill a pilot hole the size of the shaft of the insert (the part without threads). If you don’t have the exact size drill bit, go a size down. The idea is to get only the threads to cut into the wood and no wood get smashed or compressed.


Am I the only one who just used M5 wood inserts that bite into the wood so hard, that even without glue removal is impossible? :laughing:



I do drill a full hole the length of the insert and use a drill bit collar to make sure I don’t drill all the way through the deck. Just put the insert right next to your bit and find the place where your collar needs to be. If i remember correctly, the trampa 15 ply is about 10mm thick. my insert is 6mm long. I drilled in about 7/8mm and it worked beautifully.

Practice on a piece of wood first. I use loctite 648 btw. You can sort of see in this picture the point at which I apply the loctite. see the insert is halfway in.

There is actually 2 inserts on that screw. the top one is being used to push and screw he bottom one in and when the bottom once is flush with the deck, you just unscrew it and violla, insert inserted. Saw this on a @Psychotiller thread so just stole the idea blatantly :joy:


I use soft wood ones however i fined that if you apply to much torque they tend to crack at the top so. be careful with them.

I actually had a different experience with the ez-lok threaded inserts went with the recommended size and it cause the wood to bulge up and stripped 2 of them trying to get them in. I the drilled the hole to the next size up and it was a lot easier to screw them in. I also used a socket cap screw with a nut I between the insert and the screw head as I have seen the screw head get stuck to the insert.


Interesting! Were you using the hard or soft wood style?

The hex head on the soft wood version makes for a nice install. Gotta keep a decent amount of downward pressure too.