The LAG BOLT "Thread"

[srmofo]

I've moved away from lags and towards structural screws. I really like grk fasteners. I still pre-drill the holes but I have never had one break. They are more expensive so I try to stock up when Menara has those bag sales. Home Depot sells them and will honor the bag sale

 

[theoldwizard1]

I've moved away from lags and towards structural screws. I really like grk fasteners. I still pre-drill the holes but I have never had one break.

I thought the big advantage of most structural screws was no pre-drill !

Then why do you like them ?

 

[TOOL FANATIK]

Like some of the others, I like the SPAX screws over lag bolts these days. They come in some really heavy duty sizes, but they are not cheap.

As far as lag bolts for ledger boards are concerned some municipalities will not longer allow deck ledger boards to be attached only to the rim joists. They have seen newer houses with the rim joists being pulled loose due to decks. My brother has a 1999 house and he had to put in special hardware that bolts to the joists themselves for his deck. I will probably do the same thing if I ever build a replacement deck at my house.

Yea I think these municipalities are some of the earthquake zones San Francisco and such. I've seen these connections and they are awesome, comprising of a threaded rod that has a pair of connectors on either end wich get nailed to to home floor joists and the deck joists. One of these connectors on each end alone should help with lateral loads. I LOVE the idea of (with new construction) sisterjng the home's floor joists to the deck joists, with a good 4 foot overlap, with good ol thru bolts, washers and lock washers keeping the joists married. In this case the first place of failure would be the floor joists to rim joists connections (for lateral loads) ...I may have gone off topic a bit

 

[bob15]

I LOVE the idea of (with new construction) sisterjng the home's floor joists to the deck joists, with a good 4 foot overlap, with good ol thru bolts, washers and lock washers keeping the joists married. In this case the first place of failure would be the floor joists to rim joists connections (for lateral loads) ...I may have gone off topic a bit

Don't need lock washers.....there isn't any vibration to loosen them up and nothing to crush them against for the lock washers to actually work correctly.

If you are really concerned with the nuts loosening.....skip the lock washers and use lock nuts. Again, not really needed.

 

[TOOL FANATIK]

Don't need lock washers.....there isn't any vibration to loosen them up and nothing to crush them against for the lock washers to actually work correctly.

If you are really concerned with the nuts loosening.....skip the lock washers and use lock nuts. Again, not really needed.

You'd be surprised. Deck members expanding and contracting, line dancing on a pretty fall day with the little guys playing wrestlemania, plenty of vibrations there.

 

[srmofo]

I thought the big advantage of most structural screws was no pre-drill !

Then why do you like them ?

I'm not driving hundreds of these things and I don't believe the marketing. Just because you can skip the pre-drilling, doesn't mean you should. The cell structure of the wood hasnt changed. I think splitting is still a concern especially near the end of the board

Additionally it is a lot easier on the batteries to drive a 6" long X 5/16 screw when the hole is started. I don't make it the full depth of the screw, but every little bit helps.

I like them because they don't break off, most are coated, I don't have to fool around with washers, torx engagement, and they come in longer sizes at a smaller diameter.

 

[TOOL FANATIK]

Re: The LAG BOLT "Thread"

I'm not driving hundreds of these things and I don't believe the marketing. Just because you can skip the pre-drilling, doesn't mean you should. The cell structure of the wood hasnt changed. I think splitting is still a concern especially near the end of the board

Additionally it is a lot easier on the batteries to drive a 6" long X 5/16 screw when the hole is started. I don't make it the full depth of the screw, but every little bit helps.

I like them because they don't break off, most are coated, I don't have to fool around with washers, torx engagement, and they come in longer sizes at a smaller diameter.

I like hex engagement over torx engagement

Some of the torx fasteners the female torx pattern isn't deep enough. Then again, some hex head walls aren't tall enough.

 

[reader2580]

Yea I think these municipalities are some of the earthquake zones San Francisco and such. I've seen these connections and they are awesome, comprising of a threaded rod that has a pair of connectors on either end wich get nailed to to home floor joists and the deck joists. One of these connectors on each end alone should help with lateral loads. I LOVE the idea of (with new construction) sisterjng the home's floor joists to the deck joists, with a good 4 foot overlap, with good ol thru bolts, washers and lock washers keeping the joists married. In this case the first place of failure would be the floor joists to rim joists connections (for lateral loads) ...I may have gone off topic a bit

This is actually in Minnesota. I think sistering deck joists onto the house joists is overkill. I have a small bay in my house built that way, but it is only two or three feet out from the house and has no other support.

 

[TOOL FANATIK]

This is actually in Minnesota. I think sistering deck joists onto the house joists is overkill. I have a small bay in my house built that way, but it is only two or three feet out from the house and has no other support.

It is overkill, and that's how I like it. In your case if it's cantilevered then it's SOP and necessary

 

[Dennis Leigh Henry]

Are those 4 points?

Yes.. the reason I immediately went out and purchased 8pt sockets!

To the others: I'm also getting my share of structural screws, purchase a box or two when I can. I still find uses for the "sunk" investment in the old fashioned lag screws too.

Dennis

 

[OJ Bartley]

Interesting thread, I'm glad I caught it. I'm about to put some shelves up in the garage, and I did look at the new fancy screws that Home Depot carried when I was just planning. I ended up getting traditional lags because I wasn't sure if the lack of threads all the way up would allow some movement between the pieces, but it seems like I was wrong. I'll check them out again.

Sent from my HTC One using Tapatalk 4

 

[wotan]

Bringing this thread back from the dead. I'm building a workbench and using 2.5" spax screws with an impact driver. They drive easily and don't require predrilling but they are not "sucking together" 2x4s. They seem to just countersink themselves more and more without creating a tight connection. Is my impact to blame for this?

 

[csp]

Are they threaded for the entire length of the screw? Guessing they are.

They should be like the one in the middle of this photo with the threads grabbing one board and the head grabbing the other, pulling them together.

 

[-Brent-]

The only time I have ever snapped the head off is when I was stuck without the proper drill bit size, and knew the hole was too small... but tried to 'driver-her-home' anyway...

This is exactly right.

There are charts out there for pilot hole sizes. Here's an example.

I know this is an older thread but I thought the link could be of some help.

 

[APEowner]

Bringing this thread back from the dead. I'm building a workbench and using 2.5" spax screws with an impact driver. They drive easily and don't require predrilling but they are not "sucking together" 2x4s. They seem to just countersink themselves more and more without creating a tight connection. Is my impact to blame for this?

It sounds like you're not using the correct screw for the job. As CSP suggested the threaded portion may be too long. You can either get the correct screws, drill a clearance hole in the board you're screwing through or clamp the boards before screwing.

 

[theoldwizard1]

Never screw (or nail) into end grain. It will not hold long term. If you need to connect to end grain, temporarily crew the joint. Drill a 3/8-3/4" hole through the piece you want to connect and 2-4" into the end grain. Clear the chips. Put some wood glue in the hole and on appropriately sized hardwood dowel. To attach a 2x4 you really need two 1/2" dowels. Pound into hole and cut off flush. Remove temporary screws after 12 hours.

Through bolts with washers and nylon lock nuts are always better if you can use them.

In the OP case, try making the hole on the piece you are going through a bit larger.

 

[matt_i]

My free advice. Go to Home D. Get GRK-RSS screws and a T30 bit for your impact driver. SPF cannot resist. Even driven into end grain, a 5/16" x 5" screw will pull the twist & gap out of a 2x8 without stripping. Over and over. If you don't like the raised head, drive it deeper, it has enough grip to self-countersink the big washer head (except maybe not into a hard knot)

 

[wotan]

Are they threaded for the entire length of the screw? Guessing they are.

You are correct. Thank you.

 

[KenC]

googled 'lag bolt hole size', got lots of hits. here's one:http://www.portlandbolt.com/technical/lag-bolt-pilot-hole-diameters/