So the family home's Deck is going to dry Rot. Needs replaced. I was quoted as high as 20,000 dollars! Even the more reasonable quotes are too high for the budget. My nephew and I will have to do this ourselves. If there was no deck there we'd probably not have the skills but I have rebuilt smaller decks by copying what was already there and am ok at that so stop me if I am wrong or can I do this with this project?

I plan to re build the same support beam structure only with w solid beam not the two pieces you see here in the photo and install it into the existing deck inside the original as I plan a smaller deck to cut some costs and we never needed this large a deck anyway. Once the new support beam in in I plan to dismantle the deck floor and then install the new cross boards one at a time then lay the new 16 foot wide deck in and hope it will work. My only worry is the new support structure not settling for some time and then maybe sinking in and leaving no support and a sag develops. Can anyone tell me the pitfalls I am missing before I get started?

I've done two major deck projects, thinking about a third (I'm stupid). Saved a ton of money.

I think you're fine to put a 4x8 or whatever size that would be to replace the two pieces. I would consider stripping the decking first to reduce the weight while you monkey with that. And obviously you need to securely the support the deck while you are working under it.

Re sag, you can get adjustable pier block brackets, that way you can compensate for any settling.

Two more pieces of advice:

1) don't assume every other board isn't rotten either - check EVERYTHING. In my case, I replaced a couple rotted joists and one header, only to find accidentally at the last minute that the 4x8 had rotted inside (ants?) and needed to be replaced too. Attack everything and poke it hard with a screwdriver the whole way along.

2) Look REAL closely and measure your joist spacing. I was installing Trex which requires 16" OC for residential in 5/4" thick, and after I went to all the work repairing the frame, I realize the deck had been built 19" OC and I had to SHIFT every single joist, as well as adding two.

As mentioned. Remove as much weight as possible. Use temporary supports to hold up the deck as you replace the beam (4x10) and posts (4x6). Use the same connection on the ground if it’s stable or replace with adj CB44 bracket.

Install the knee braces similar to how they are shown, I’d use a 4x4 at a 45 degree angle for the lost to beam and a 2x4 will work on the post to joist.

Replace joists as needed and use joist tape on the top of all joists. Then, re-deck/handrail etc.

First we're going to need an environmental assesment. Find out if that bird's nest belongs to an endangered species, survey for pocket gophers, and *oh* I think I see water in the background so that means you're in a wetland...

Kidding, tear the fucker out and start over. It looks like the last joist was added at some point to make the deck wider maybe?

Pull up the first deck board next to the house and check the condition of the ledger. You want to make sure all the flashing is good and the house itself doesn't have any rot

If you dig down 18"+- into undisturbed soil and pour a concrete "sonotube/pier/footing/whatever you want to call it" and then build on top of that you shouldnt have any settling issues.

Simpson post base bolted into the footing. Rotohammer a hole and use a Simpson titen-HD concrete anchor with a impact wrench to secure it to the footing. Or wet set a concrete J-bolt if you are confident in your layout abilities to get it where you want it.





As far as rebuilding it, the easier course of action would be to remove all the decking and inspect the joists before you replace the beam. Once you're done with the framing, replace the decking. Start at the door and work your way out - I redid my parents deck 25+ years ago (very similar design to yours) and started off at the exterior most part of the wall and had to do some weird cuts as I worked back to the inset sliding door. It always looked weird, but I had no clue wtf I was doing when I repaired their deck.

Might as well add a roof to the bottom of the deck to create dry storage underneath while you have it torn apart
https://www.familyhandyman.com/project/under-deck-roof/

+1 on the joist tape -- will protect the joists and keeps the deck quieter as you walk on it

The sub floor borads that connect to the home are all in good shape but no worries we gonna replace EVERYTHING. Thanks for the advice.

Good call

Untreated wood in an exterior application is a bad idea

The 'overengineer it' in me is asking why there's not 4 supports, instead of just 2. That would take load off the ledger board and add add'l rigidity/loadbearing support.

Most deck failures that I've seen have been from overloading, and consequently, failure of the ledger board.

Seems that adding a small concrete footer with 4x4 support close to the house would be a small price to pay for redundancy.

If I start messing with concrete I might as well build a 4 sided concrete wall as the support structure then add gun ports and turn it into a bunker LOL

I fail to see the problem.

Yep, I agree. That just sounds like a solid plan to me.

From the photo, it appears that the deck is just nailed to the side of the house. If the deck were built today, in most jurisdictions I built in (King & Thurston county) it would be required to be lag bolted to the house. There was a rash of incidents years back of overloaded decks tearing lose and spilling unsuspecting drunkards to their demise that seemed possibly involving a legislator or family member.

Just sayin'. Good luck with the project.