double deck porch advice

[PBinWA]

The other big point to emphasise is that the new ACQ PT lumber is more corrosive so you need to make sure you are using the right flashing and hot dipped galvanized or stainless steel (preferred) hardware. Unfortunately, there isn't a lot of solid information on the subject.

I've heard that you can use copper flashing but that you have to be careful about the bolts used because a combination of the different metals along with the ACQ chemicals can cause accelerated corrosion.

The whole things a bit of a confusing mess for us lay people that just want to build (or in my case rebuild) a deck.

IMO - a fully detached deck is probably the safest and best for lowering your chances of water damage and ledger failure. The posts up against the side of the house may not be all that attractive.

I rebuilt my front deck last summer and just removed the ledger and went with a detached deck. My back deck is higher and has a basement door exit under it so I have to use a ledger for it.

In my books it's always best to over-engineer stuff. My building inspector neighbor commented that my front deck looked extremely over-engineered.

/forums/images/graemlins/grin.gif

(I took that as a compliment.)

 

[beenthere]

I didn't attach the deck to my house for another reason - the property tax assessment. Not attached to the house meant it wasn't assessed. The assessor looked hard and long for the attachment, but there was none. /forums/images/graemlins/grin.gif

Besides the bolts to bolt the ledger, make sure the house framing is constructed such that it will support the ledger bolted to it. Most houses just have a 2" rim board at the ends of the joists, which is not structurally designed for a ledger board and deck hanging on it.

 

[dmccarty]

paul,

FYI. There was a deck failure in Durham, NC this past weekend. 12 people where on the deck which was about 12 feet above grade. I think seven people went to the hospital with the most serious problems being broken bones. It was a mixture of adults and children celebrating Easter.

From the picture in the paper it appears that deck failed at the ledger board/house. The picture was taken facing the deck and you could see the the joists and the bottom of the deck. It was like some one opened the deck floor like a door. With the door facing down and hinged on the post side of the deck. I'm guessing that since it was supposed to be 12 feet tall the that deck was about 12 feet wide and maybe 12-15 feet long. In the photo firefighters are knocking down hanging parts of the deck that where just hanging. They might have torn down the cross members between the columns. I don't know why they would have done this but the cross members are not in the picture and there don't appear to be any laying on the ground. There where railings on the ground by no easily indentified cross members.

12 children and adults should not have caused the failure of the deck. If ALL 12 people weighed 200 pounds, the deck was 12x12, and they where evenly distributed, that is a load that is less than 20 pounds per square foot.....

Later,
Dan

 

[farmerpsv]

Dan,
i've read similar accounts, seems that ledger failure is the most common problem. PBinWA made a great point about the new treated lumber being more corrosive making stainless or galvinized fasteners important. long and short of it is everyone here seems to vote on an engineer for design, and i will do so. it will be awhile, but i'll let y'all know the results and attach a pic when it happens.
paul