Deck design questions

[laurie71]

TL/DR version: planning deck ~10' x 15' + two 10' x 5' "wings" and need to pull permits; looking for information on code requirements and/or advice on construction. Plans below for 2x6 @ 16 OC framing set on concrete block pads on grade.

On to the details:

My wife wants a greenhouse and a little patio/deck put in. I bought a greenhouse and planned to place it next to an existing shed, with a concrete patio on the other side to the shed. However, I had a large Ash tree taken down in that location and the stump is too large to dig out without disrupting the shed. It's ground down to below grade, but I don't want to put the greenhouse over top of it and eventually have a sink-hole under it!

So the plan is to move the greenhouse over about 10' and build a floating wood deck in between and across the front of the two buildings. Since the deck is floating, I'll be able to move it to address any subsidence from the stump rotting away over the years. So the deck will be designed/built to sit on grade.

The deck needs to be as close to grade as possible (so it doesn't get in the way of entry to the buildings). I was planning to run 2x6 joists set on concrete block pads set on gravel for framing, decking over top of that.

I just found out my county permitting office wants me to pull both zoning and building permits for all this :-/ I didn't think they required either for a free-standing shed-type outbuilding or non-attached deck.

So, now I have to produce drawings and pull permits and I have no knowledge of what code requires on the deck. So, hoping for some education from the GJ!

I drew up a plan in SketchUp so my wife could see what she'd be getting and I could work out the deck framing details. The deck as shown is about 10' wide between the buildings and about 17' deep. The wife wants the back edge of the deck pulled forward a couple feet so she can plant a decorative bed along that edge between the buildings, so actual depth will end up being more like 15'.

So, my questions:

1. Is it acceptable by code to have joists resting on concrete pads, without support beams beneath?
2. is 2x6 treated adequate for the joists? or do I need to go larger?
3. what spacing would the supports need to be for the joists? (assuming my planned support system is ok, and based on joist sizing from question 2)

I want to picture-frame the decking, so the framing plan includes extra blocking to support that. Any additional comments/advice on the framing are also welcome.

Here's an overview of the project:



And this is my framing plan:



Joists and perimeter blocking spaced 16" OC; the extra joists for the picture framing are set one deck plank's width (5.5") in from the outside joist so, with a 1" overhang for the perimeter boards the inner joists are 1" back from the ends of the main deck boards. The cross blocking will fall on center with the deck planks. All intended to reduce the amount of framing that's exposed to water coming through the decking.

Thanks for any information or advice (including pointers to any resources to help me figure out code requirements). And yes, I know there may be local code variances I need to accommodate; I'll try and get as good a plan together as I can and submit it, and find out what those are at that time.

Laurie

 

[larry_g]

http://www.clackamas.us/building/documents/deckplans.pdf

Most counties in my area have a deck guideline like the above online. I would suggest you check with your county/city for requirements. Or show them the above and ask it it works for your area.

on edit; for your area http://www.daytonohio.gov/DocumentCenter/View/1587 Your just over the 200' area that requires a permit. Can you cut your design down a bit to get under the 200' permit exemption?

lg
no neat sig line

 

[laurie71]

Thanks for the link larry_g, that's much more detailed than what my county provides. All I could find on their website was this:

http://www.co.warren.oh.us/bldginsp/BuildingElectrical/BuildingElectricalSketches/DeckDetails.pdf

I'm not building a deck onto my house and don't want a permanent footer under it unless they insist (which will probably mean a total re-plan due to the tree stump :-/)

Laurie

 

[matt_i]

Seems like most of the codes for decks surround attaching the ledger board to the house. Obviously many fails of ledgers simply nailed on spurred this. I can't quote the exact codes but Simpson catalog will likely have a product line(s) to address this. I believe some localities require them to be thru-bolted with some diameter bolt at some spacing.

Also, good detailing for weatherproofing of this attachment is probably one of your best uses of time and money. Not sure what is below but you don't want to cause issues with the rest of the house caused by the deck attachment.

The other universal code seems to be exterior perimeter "fencing" with balusters on 4" centers maximum.

 

[laurie71]

As noted above, the deck will not be attached (or near) to the house, so no ledger board attachment to worry about. It also wont need railings as it will be less than 30" above ground (one code requirement called out in the mini-guide my building department puts out).

I think I need to call the permits office again and ask to talk to an inspector, not just the receptionist, explain exactly what I'm doing and see what he says.

Laurie

 

[MushCreek]

Free-standing and less than 30" above grade should make it a lot simpler. There is a Prescriptive Deck Code that you can find by googling, and it is eye-opening, to put it mildly. The attachment and guard rail requirements are something.

 

[laurie71]

Yeah; I've heard what I want to build described as a "patio deck" before, and always thought there were less compliance requirements for them. Called planning and zoning today and was asked to call back Monday morning between 8am and 9am and ask for the head inspector. Apparently that's the only time he's guaranteed to be available...

Laurie