Replacing deck and re-using ledger board lag holes

I have an existing 8'w x 6w' deck that I am planning to replace with a 16x12.

The current deck has the ledger board at 16oc (2x8). To keep things simple I want to use 2x8s for joists/beam/ledger. That will require a joist spacing of 12oc.

Obviously I'd like to reuse the existing holes from the current ledger but that spacing will put several of the holes where the joist hanger will be.

Can I put a joist where the ledger lag bolt head is?

Thanks!



Editor's Comments:

One of the first things I would suggest is to refresh your memory by reading this important article on proper ledger board building techniques.

This is a unique situation that I have never been faced with. A number of thoughts arise and I will try to cover them off one by one. If there is another builder out there who has more recent experience, do participate.

Lag Screws Conflicting With Joists

Since some of the new joists at 12" o.c. will now land precisely over some of the original holes at the 16" o.c. pattern the head of the lag screw will conflict with the new joist.

Let's talk about the strength issue first and then ways of dealing with the lags conflicting with joists next.

Ledger Board Options

The ledger screw layout pattern for 2x material up to 16' long (length of ledger against house) is recommended to be 11" o.c. for each lag screw. This is "recommended" by the American Wood Council. However, this does not mean that 12" o.c. lag patterns will not be permitted and would not provide more than adequate strength.

I am merely quoting from the Design Code Acceptance prescriptive residential guide and they are going to always err on the side of extra caution.

So let's presume you are going to keep the 12" pattern and for sake of argument, the strength issue is not a problem. How then, to fix the problem of the odd lag screw conflicting with a joists?

Counter Bore Holes

One option might be to counter bore the ledger to a depth of about 1/4" and allow the lag screw head to sit below the joist contact surface of the ledger.

Counter Bore End Of Joist

You might also counter bore a 3/4" dia x 1/2" deep hole in the end of the joist where the lag will be.

Since all of these measures are atypical I would probably run this by your local inspector to make sure they are onside with this approach.

New Holes

Alternatively you could add some new lags off set from the 12" pattern where necessary. You did not want to do this but that would be your only other choice if the above ideas will not fly with your local building department.

Other builders reading this may have some relevant and recent experience with this. Please have your say and help our visitor out.

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