# Repairing Lag Bolt Holes



## jlhaslip (Dec 31, 2009)

Long story behind this, but assume the lag bolts are 3/8 inch by 8 inches long going through a metal plate, a piece of 3/4 MDF, 2 layers of 2 by material into a metal top plate backed by plywood.
The lag bolts are to hold down a base shoe for glass "handrail" on a 26 inch tall steel stud wall which was raised by two thicknesses of 2 by material in order to reach the required height of 42 inches.

The procedure was to drill a 3/8 inch hole down to the metal plate, then a 3/16 inch pilot hole through the metal plate which would allow the lag bolt to bite the plate and the plywood.

Long story short, about 20 percent of the holes are failing to tighten the lag bolts. The causes are multiple. Operator error and drilled the holes too big and too deep. Used too powerful of an impact and spun out the hole. Angled the drill and the holes missed the metal. 



About 20 per cent of the holes are not grabbing the Lags properly, so what methods are available to improve the "bite" the lags have on these holes?

All suggestions greatly appreciated. Thanks.


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## Inner10 (Mar 12, 2009)

7/16" Lag bolt.


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## slowsol (Aug 27, 2005)

Epoxy


Sent from my iPhone using Tapatalk


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## Munanbak (Jan 19, 2011)

chopsticks


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## hdavis (Feb 14, 2012)

Inner10 said:


> 7/16" Lag bolt.


This, or perhaps 1/2" If it's already stripped out and the plate has to have good hold, it's about all you can do.


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## m1911 (Feb 24, 2009)

I'm assuming you can't go iinside the wall for nut and washer. 
How about something like this

https://www.amazon.com/gp/aw/d/B0051IAUZ6?pc_redir=T1


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## Tom M (Jan 3, 2007)

I was wondering if you could get to the other side. I carriage bolt from the underside and nut from the top would really clamp down.


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## colevalleytim (Mar 1, 2008)

Sounds like you made a mess of this. oversized holes, misaligned drilling? Ugh!

first the bolts sound like they are too long. Is the double 2x on the face or the edge? if it's on the edge, the lags will only work if you are dead center on one of the 2xs. 

If you can't use a bolt, nut & washer, then filling the holes with epoxy or dowel & epoxy are the only good solutions


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## hdavis (Feb 14, 2012)

The way I read this, the two pieces of metal are the ones that have to be held together, and the wood between them is just to pad out to get the right final height.


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## Leo G (May 12, 2005)

I can't imagine the inspector would allow a lag for this. I would assume a nut and bolt. Or you should have just threaded the steel.


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## kapena (Aug 20, 2004)

You almost have to go with a bigger lag on those 20% of the hole failures. There must be room if an impact was used. No final setting the heavier lag with the impact. Finish tightening by hand.
I'm wondering what gauge the metal plate with the 3/16" pilot hole is?


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## kapena (Aug 20, 2004)

I have used commercial grade trimmer line (.095) as filler in an over-sized hole.
You have to experiment to find out how many lengths are needed for a tight fit.
Some extra line has to be above the hole to keep it or them from being pushed into the hole as you start and drive the lag in. The extra length of line gets cut before the lag head seats. The right size of zip ties can do the job too.
It sounds Micky mouse, but you might be surprised how well it can hold if done properly.


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## Tom M (Jan 3, 2007)

I have trouble seeing how the thread of a lag has any value in the steel. As Leo pointed out an inspector wont like it either.

It needs thread and nut connection.


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## kapena (Aug 20, 2004)

jlhaslip said:


> Long story behind this, but assume the lag bolts are 3/8 inch by 8 inches long going through a metal plate, a piece of 3/4 MDF, 2 layers of 2 by material into a metal top plate backed by plywood.
> The lag bolts are to hold down a base shoe for glass "handrail" on a 26 inch tall steel stud wall which was raised by two thicknesses of 2 by material in order to reach the required height of 42 inches.
> 
> The procedure was to drill a 3/8 inch hole down to the metal plate, then a 3/16 inch pilot hole through the metal plate which would allow the lag bolt to bite the plate and the plywood.
> .................


I might be misunderstanding the glass "handrail" description, but if you subtract the existing 26" tall steel stud wall from the needed 42" required height of the finished railing, you are talking about only adding 16" of "handrail" height. 
The 8"x3/8"dia. lag bolts are described as being needed "to hold down a base shoe for the glass handrail", which should be adequate if we are talking only about a 16" high railing.
If all of the layers 2 by material etc have not already been solidly tied together before the base shoes are installed, then lags are not the way to go. Those talking about using threaded bolts instead would be correct.


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## madmax718 (Dec 7, 2012)

This sounds awful. mdf, lag bolts, just sounds really bad for longevity


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