Ledger, Bay Window, Chimney Framing Problem

by Eric
(Nashville, TN)

Framing Details Around Chimney Bump Out

Framing Details Around Chimney Bump Out

I have a few questions about framing according to the Prescriptive Residential Wood Deck Construction Guide based on the 2012 ICC standards for deck building.

I've reviewed the guide and have a few questions.

My Scenario

First, an explanation of my scenario. I have a preexisting deck that is 20x18 (20' along the house and 18' out). The deck is centered around double patio doors that is surrounded by a chimney bump out on one side and a cantilevered bay window on the other.

The chimney is faced with siding and has a brick foundation base up to the rim joist level (so where the original deck's ledger was attached). The cantilevered bay window has a ledger board attached to it. The infield joists are are butted to each of these structures.

On the chimney side, the joist was nailed to the ledger that was anchored to the chimney. On the bay window side, it was toe nailed into a trim piece, and supported by a post that was just resting on the ground (shoddy work if you ask me).

I was going to resurface this deck, and as I pulled boards off I discovered absolutely no flashing, and a ton of rot below the entry way, and below the bay window. I probably had a bunch along the chimney, but I had all the siding replaced last year.

I know this is wrong, and I'm looking for a solution that will allow me to keep the same foot print, but be sturdy.

My Original Plan

I hoped to do the proper framing presented in the 2012 ICC codes book, whereby you run a beam perpendicular supported by 2 2x8 joists. But I discovered a problem with getting the decking close enough to the bay window to lay decking and not be a hazard.

The bay window has somewhere in the ballpark of a 20° angle which make it impossible to frame perpendicularly around as shown in the Deck Construction Guide and have the decking supported properly.

My Second Plan

I thought about a partially free standing deck consisting of running an additional beam that will be composed of 2 2x10 boards set on posts at about 3-4 feet from the house. This beam would allow me to get a 2x8 joists at a max of 2 feet cantilever over the beam and will reach the bay window. I would then cut that the end at a proper angle to add a rim joist to install decking close enough.

I would then shore all this up with blocking from the end joist (which I'm still not sure about anchoring to the trim piece) all the way to the joists that are supported and anchored to a proper ledger under the entry way.

Is This A Good Idea

If this is all a good idea, I have a few concerns of my own. First, the footers for the posts for that beam that's a few feet away from the house.

I've read I need to dig deeper due to the earth possibly being disturbed, and I need to dig to the same level as the house foundation. Is this safe? And I live in TN, and plan to dig 36 inches for all my footers, will that be deep enough for those as well?

The second worry is about the framing around the chimney. Should I do the same free standing post and beam configuration I plan to do at the bay window?

Or can I attach the ledger like it was originally attached, mind you I would install proper flashing and all.

The third concern is how the infield joists are being anchored to the house. If I can't add a ledger to the chimney, I don't have a good place to anchor the end of the joist at the house. I can't extend the deck any further in the chimney direction because there is a gas line that protrudes out around the corner of the chimney at the bay window.

I'm also running into issue with how the original end joist was installed. It was toe nailed into a trim piece at the edge of the bay window. I could extend the deck outward and attach a small piece of ledger to the side of the house (there is only siding to remove next to the trim piece). But I also need to be careful not to extend the deck greater than the distance of my 20ft deck boards. I'm trying to avoid adding cuts in the layout, and currently the deck stands at 19'-7".

Move The Deck Sideways A Bit?

Would it be wise to move the footprint of the deck over by a foot or two so that it only sits at about halfway around the chimney, and so I can properly attach a ledger next to the bay window to help with structure?

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