Ledger Board Flashing

I know deck ledger flashing is a critical component to protect the deck and house structure. However, I almost never find flashing installed during the deck inspection. I do call it out in the report, but the flashing issue will not be corrected in most cases. How often do you find flashing correctly installed and how do you address the missing flashing in the report?

If I don’t see it, I recommend it but I have no control over whether or not they take the advice.


Some installations need different details.

Thank you. I was looking for that PDF file. :smiley:


John, I find ledger flashing done correctly sometimes; It’s correct more often on higher end homes and less often on less expensive homes.

As inspectors serving different areas of North America we often find defects which are accepted locally because all the local contractors are used to doing it the same way- even if it’s wrong.

Best practices are the rule to go by. You should always recommend established, correct flashing practices instead of local practices unless there’s something obvious. Flashing is not rocket science. You’ll have many examples from credible sources to back you up.

I call it out.

Required, by Chicago code, but I have seen many code inspectors not call it out and tell me “it’s not really necessary” even though the code requires it.

I call it out, and if someone agrues, I show them the documentation.

If it’s not fixed, hey, at least I did my job.

Hope this helps;

Nice graphics Carl, and here is a picture of a field one.



Nice pic… am I correct that there are only screws fastening that ledger board? No bolts?

That is correct Jeffery, but they are not ordinary screws.

They are structural screws that are equivalent to lags.

See the data here. http://www.grkfasteners.com/en/RSS_1_2_information.htm

These structural screws are amazing. :):smiley:

For those that haven’t seen these, here is a good video:


Thanks Larry for the addemdum to the topic. I should have posted it, but assummed everyone would see it.

One has to use those to see how effective they are.
Here is a better photo of the screw being installed.

Hope this helps. :):smiley:

Nice graphic Nick.

If you look at the first pic of my post, the membrane flashing under the ledger board, is kept loose until the siding installation underneath is intalled.
Once the siding is up to the ledger on the underside, the course of siding before last is tucked under the membrane flashing that was installed behind the ledger. Then the last course of clapboard siding is installed.

So if water intrusion occurrs behind the ledger, it flows out onto the clapboard face of the subsequent layers of siding.

Hope this make sense, remember, I am French. :mrgreen::wink:

Marcel / Larry,

Thanks for the links. I hadn’t seen these yet. Now I will recognize them whenever I do.

Cool beans!!!


Does anyone else make these pr a similar product?

I called out the screws in a deck last week.
Most of the deck was lagged in just fine but the last 6 ft of the ledger were screwed in like this.