Ledger Board Overlapping Siding Below It

My contractor installed my ledger board with about a 1/4" to 1/2" overlap on the bottom edge over the HardiePlank siding. They said this was intentional so that water wouldn't get behind the siding underneath the ledger.

This has cause a slight tilt to the ledger board and they said to cut the end of the joists at a matching angle.

Is this right?




Editor's Comments

This is a great question and a perennial topic. It is a bit unusual for a builder to just lap the lower edge of the ledger board over the next course of siding. It is not really common practice.

Now that is not to say it is completely wrong. If done the right way it might perform fine over the years if the top of the ledger is flashed properly and the flashing reaches well up under the upper courses of siding. But let's examine this a bit further.

Lapping Over Siding

Installing a ledger against the side of the house at an angle so that the lower edge sits over the next course of siding conjures up all kinds of images and potential problems.

Normally the ledger should be fastened flat against the house or spaced using spacers. Either way, it is oriented flat against the wall of the house for maximum security. It the ledger is tilted is there anything filling the gap? There should be a solid path of contact.

Are the joists therefore cut at an angle to mate with the tilted ledger? You see there are other problems that arise when you build this way.

Water Flow Over The Ledger Board

It is true that water would flow over the ledger and onto the siding and not go back up. But there should not be any water trickling down the ledger board to begin with. There ideally should be flashing against the house, then the ledger board and then another upper layer of flashing covering the top of the ledger.

You are protected two ways from water damage.

An Example Of Double Flashing A Ledger

You might wish to read this article where we removed siding and located the rim joist and double flashed. This was a lot of work but well done.

A Refresher On The Principles Of Ledger Board Connection Techniques

And then just to get you fully up to speed on this issue, you will appreciate reading this article that covers the various methods of connecting ledgers so they stay dry and strong forever.

So in summary, I would say you should take a closer look at what your builder has done just to be sure it is right. Why not get a second opinion from another respected builder just to be sure?

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