Deck Ledgers and Cantilevered Floor Trusses

[Frank Woeste]

In this September Prof Deck Builder article, we will explain some of the technical obstacles facing a homeowner and deck contractor when considering the addition of a deck to a new or existing home with a floor system built with open-web floor trusses, with a particular focus on the structural problems that arise when attempting to fasten a deck ledger to cantilevered trusses. Comments are welcome and appreciated.

 

[Inspector Gift]

Structurally speaking, the article appears solid. But the first thing I noticed is the lack of flashing. In our wet region (4C) we require 2 layers of flashing: the 1st between the ledger and wall, and the 2nd over the top of the ledger. (See FEMA's Technical Fact Sheet No.23)

 

[wwhitney]

I enjoyed reading the article. One question it raised for me:

Would replacing the 2x4 ribbon board with a 2x10 or 2x12 band joist typically work? Does any authority publish a prescriptive detail for attaching such a band joist to the ends of floor trusses, and would that allow the use of the IRC prescriptive details for attaching a deck ledger?

Thanks,
Wayne

 

[Frank Woeste]

I enjoyed reading the article. One question it raised for me:

Would replacing the 2x4 ribbon board with a 2x10 or 2x12 band joist typically work? Does any authority publish a prescriptive detail for attaching such a band joist to the ends of floor trusses, and would that allow the use of the IRC prescriptive details for attaching a deck ledger?

Thanks,
Wayne

Wayne:
Thank you for the thoughtful questions. Regarding:

Would replacing the 2x4 ribbon board with a 2x10 or 2x12 band joist typically work?

It wouldn't for the same reasons the two 2x ribbon boards and 2x ribbon block doesn't work, being the 2x10 or 2x12 would not have wood-to-wood bearing as required by the IRC. If constructed, the ledger connection fasteners would pass through 2-inches of materials not supported below, effectively creating a two-inch gap in the ledger structural connection.
Regarding: "Does any authority publish a prescriptive detail for attaching such a band joist to the ends of floor trusses, and would that allow the use of the IRC prescriptive details for attaching a deck ledger?", I am not aware of such detail.

 

[Beniah Naylor]

Best I have found.

Good article, expands quite a bit on the one from SCBA.

Most people around here end up putting beam on two posts up near the house to take the load off of the cantilevered trusses, rather than hiring an engineer.