double deck porch advice

[farmerpsv]

Hey friends,
i've gotta say that tractorbynet is the greatest site on the web. there is more knowledge here than most college campi ( which may not be saying much /forums/images/graemlins/shocked.gif). anyway y'all are a great bunch, always get help and enjoy reading all the posts. now, to the current project...
am building a house and want to attach a double deck wrap around porch but don't know the size lumber to use. the house is a double A victorian (two side by side 14' sections offset two feet). the porch will stand 8' from one section and 10' from the other. the side portion will stand out 8'. the total front portions will be 36' wide and the side portion will extend about 14'. i want to be able to have the hot tub on the top porch, in the corner, so i imagine this thing will need girth. my questions would be:
1. what size ledgers to use?
2. what size joists?.
3. 6x6 posts adequate? spacing?
4. buried posts or concrete footing? (distance to upper deck is 14'from ground)
5. what to do with the corner when i run out of ledger, will a doulble joist resting on a post suffice to run floor joists off of?
and any other advice you may have for a died in the wool do it yourselfer.
thanks,
paul

 

[bczoom]

Paul,

Check out my posts in this thread

Are the pics I posted similar to what you're considering?

Brian

 

[PBinWA]

Check out this site

The Journal of Light Construction

http://www.jlconline.com

They have articles from back issues that give a lot of good advice and have done a fair amount of coverage on deck building in the last two years.

 

[EddieWalker]

As much as I hate doing it, in your case, I think you should pay for an engineer to design it for you. The span you mention and the unknown weight of the hot tub plus the type of soil you have add up to some variables that nobody should be guessing on.

For example. What is your frostline, or how deep do your footings need to be? What size hot tub will you put in? 1,000 gallons will be 7,000 pounds. That's a HUGE issue, especially when your tying it into an existing structure AND putting it on the second level.

I would also be extremely hesitent on listening to anybody's advice on how to do it who doesn't have the qualifications and is willing to put it in writing.

Once you know for sure what it will take, then it should be a fairly simple project that you will enjoy doing.

Eddie

 

[beenthere]

Putting a 'ledger' on a house is
1) critical from a structural standpoint, as normal house construction isn't engineered for the forces of a deck.

2) critical from allowing water to penetrate the walls, and behind the ledger, promoting decay problems that haunt one later on.

Free standing would be my choice, as much as possible.

A construction certified engineer would be my suggestion as well.

 

[farmerpsv]

thanks everyone for the input and links. sounds like an engineer might be in order. was figuring on z flashing the ledger and attaching with 2 lag bolts every 24". still, would be worth the cost of being safe. 7000lb is alot of weight, and that's without wet bodies /forums/images/graemlins/smile.gif
thanks again
paul

 

[beenthere]

Call the wood dept at VPI in Blacksburg.

Brooks Forest Products Center
(540) 231-7134

They will have some wood engineers who should be able to give you some good pointers, I would think.

 

[gates]

Are you going to get a permit? If so , draw the plan the way you are considering building it and submit the plans for review. The plans reviewer should make necessary changes, required by code, with in reason. They will not design the project. If no permit I definetely agree with others, hire a structural engineer! Information obtained on this forum may be area dependent, this is something else to consider. Building code is not universal, ie. depth of footers.

 

[dmccarty]

</font><font color="blue" class="small">( ... attaching with 2 lag bolts every 24". )</font>

I am pretty sure that using lag bolts was a no no on the ledger board. JLC's article was pretty in depth on this subject. I think the recommendation, depends on load of course, was BOLTS and washers, not lag bolts, every six inches or some very close distance.

You should be able to access the JLC articles without being a member. You will see a summary of the article. If you are doing any sort of construction, barns, decks, plumbing, tiling, etc around the house I highly recommend the magazine and the website. If you pay for access to the website they have their magazine articles going back for years. They have a mechanism to keep a library of their articles on the website. JLConline is a great reference.

Later,
Dan

 

[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