I am building a home in DE.
EdSe
| Posted in Energy Efficiency and Durability on
Ground floor with pilings and two living levels above. Each level will have a deck both sides of home. I am employing 1×3 firing for rain screen. Should I bolt the ledger to the home between levels, flash and start again below the ledger or set the ledger board on firing and have rain screen continous?
Thank you,
Ed Serafin
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Replies
Ed,
There are many ways to do this. The best approach is to design your decks to have independent foundations that are not connected to the house foundation or to the walls in any way. That's the best way to avoid moisture entry problems.
If you bolt ledgers to the house, you have no choice but to carefully flash the ledgers. If the ledgers are on the exterior side of the furring strips, your chance of moisture damage is reduced.
Many such ledgers fail structurally, and a certain percentage of these failures result in deaths. Make sure that you understand code requirements for ledger bolting, and consult an engineer if you have any doubts.
Hammer and Hand has some flashing guidance for deck ledges in their best practices guide that you might find helpful if you're not able to go the fully independent foundation route Martin is advocating: http://hammerandhand.com/best-practices/manual/9-structure/9-1-deck-ledgers/
Edward,
There are a couple of requirements from the IRC that are worth knowing about, but being from Canada I'm not that familiar with it, so you should probably not take my word for this without looking them up yourself.
- Even a free-standing deck is required to be attached to the house for lateral support. I don't think a totally independent structure meets your code.
- There are lateral resistance connections required. The only approved ones I know of are Simpson connections that tie the joists to the ledger in several locations.
These may influence how and where you plan to attach and flash your ledger.
Brendan,
The one thing I would change in the Hammer and Hand detail is to place the hangers up 1", so the top of the deck joists sit that much above the top of the ledger creating a drainage plane. If they are flush, the first deck board creates a dam where water and debris will accumulate with no where to go.
I don't know about code, but in terms of structural engineering, it's possible to provide diagonal bracing such that there is no need to attach to the house at all.
BTW: 1x3 furring is far more twisted and far more likely to split than 1x4s.
If it's already installed, leave it, but if it's still in the planning stage you're likely to have less scrap and less labor if you specify 1x4s instead.
Free-standing decks (more than a couple of feet off the ground) have something of an apocryphal quality: There is a lot of talk about them in the abstract, but no-one seems able to show examples that have actually been successfully built.
I'm not sure that there is a real advantage to leaving a gap between the deck and building anyway. For practical reasons it has to be quite narrow, and is therefore inaccessible for maintenance and re-finishing.
Successfully attaching and flashing a ledger isn't that difficult. The ones that fail are invariably poorly built. For a detail with such enormous consequences, it's surprising how little thought has traditionally gone into them.
Malcolm, I have a newly completed example of that mythical beast 1" from my house. And I'll reinforce your suspicions that they don't exist in real life by claiming that none of the pictures I have of it show the ledgerless gap. I've started blogging about it at https://prettygoodretrofit.wordpress.com/category/deck/ where there are at least pictures showing a well braced frame, more than a few feet off the ground, which is consistent with a plan for a free standing deck even though I admit it falls short of proof.
(I had initially planned to blog about our project regularly, but found that I didn't have time to blog while also working on the project, but I hope gradually go back and fill in the story over the coming year or so.)
Charlie,
Nice deck! Should last for ages - but it fits within my caveat of being a couple of feet above grade. The OP has decks on two levels, meaning substantially larger bracing would be necessary, and when this bracing would have to occur in front of windows or doors below things get tricky.
Then there is the code. My knowledge of decks and your codes comes from this document:
http://www.awc.org/pdf/codes-standards/publications/dca/AWC-DCA62012-DeckGuide-1405.pdf
My reading is that you can pick up your vertical loads without attachment to the house, but the lateral ones do require attachment. Section 17 says "Attachment to House: Decks shall be positively anchored to the primary structure [R507.1]. The lateral connection required shall be permitted to be in accordance with Figure 22 or 23 for ledger and non- ledger decks."
Malcolm, I hadn't read the original question carefully enough and wasn't imagining something so tall. Thanks for noting that. Freestanding doesn't make sense for that situation.
As for code, I agree that it could be a problem. Our building inspectors had no objection, but I can't promise that would be the case for anyone else.
Charlie,
I know I post about building codes a lot, but in many of the discussions here the requirements for whatever assembly are being contemplated often seems to get missed. It really should be the starting point. The code is what you have to do. Anything else you add is what you would like to do.