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jayfye86 04-27-2012 12:43 AM

Building a Deck
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OK... not very experienced but I'm going to build a deck. I am moving my ac out of the way this week and I'm relatively close to submitting my plan to the BI. I plan to build an upper level now, with intentions of putting a stairway and lower level on later in the year or next spring. To allow for a stairwell in the right spot for privacy and the way my yard works out, the stairs will be on the right side of the picture. The far end of the deck will be roughly 12' off the ground. The dimensions of my house where the ledger boards will be are 7' on the left and 13' under the door. I am considering going 16' wide. If it simplifies the plan significantly, I can just stick with 13'. When I notch out for my stairs, that will only leave me with 16X9 for most of the deck. I think for the extra 4', it's probably worth an extra hole in the ground and post.

My questions are:
I know I need to go 40" deep for 6X6's. Does my board need to go that deep or can I rest my board on one of those concrete bases and only have the 6X6 near ground level?
My deck will be roughly 16X16. Does 6 posts seem right?
. If I do, will I have to put a post on the far end of my 16' ledger or can it hang free? I figure I'll need 2 posts near the outside end, then 2 roughly 7-8' from the back of the house, maybe even with the 'other' back of the house. The other 2 or 3, if necessary, would have to be at the end of the ledger I already spoke of, and underneath where the top of my stairs will end up.
_ _______16_______
A little sketchy, I know, what I'm trying to show here is the shape I'm going for and get some advice. The X's represent where I think posts should go. A-D are where maybe some should go. The dimensions are on there as you can see.
I am using composite decking and I plan to get plenty of use out of this thing so I want to make sure It's BUILT. I do not intend to save a couple bucks by compromising stability. Help me out fellas!!!

Just Bill 04-27-2012 06:27 AM

Concrete footers for your posts need to be 40", not the posts. Not a good idea to bury wood. That reduces the life considerably.

I don't see a dimension for the width, only the 16' for the depth. Assuming 2x12 for joists, I would set one beam at abot 7', the other at about 14". Each double beam should be supported at about every 4'. There will be a ledger board attaching it to the house??? My 16x20' deck/porch, has a beam at 8' and at the outer edge of the deck. The 6x6 posts go all the way up to form the roof support. There are other things to consider, like crossbracing and bridging to make the sturcture rigid.

Your building department will be quick to point out where your plan is good or bad.

There are lots of books on building decks at home and book stores. They have lots more information than can be supplied here.

Daniel Holzman 04-27-2012 08:25 AM

Your building inspector may have a copy of the International Residential Code (IRC) Prescriptive Residential Wood Deck Construction Guide. If not, you can get a copy on line. This guide tells you everything you need to know about deck design to code, including minimum joist, beam and post sizes, allowable connection details, how to build railings and staircases, bracing, and a lot more information. I don't know how you are developing your design now, but I strongly urge you to get a copy of this document before you get too far into the design, it is very helpful, and if you follow the rules, your building inspector will probably be happy.

joecaption 04-27-2012 10:34 AM

Make sure the deck is at least 4" below the door threshold, That dryer vent will need to be relocated most likly.
Make 100% sure you use flashing under the siding and out over the ledger board. (aluminum can not be used due to it can not be in contact with the pressure treated wood.)
Do not install the decking tight to the side of the house.

quincy 04-27-2012 10:54 AM


What is the purpose of the decking at least 4" below the door threshold, snow?
How far the decking should be away from the side of house?

Thanks in advance.

joecaption 04-27-2012 11:04 AM

So water can not get in under the threshold.
Look around on this site and any DIY site and you will see pictures of whole walls and subfloors rotted out from this one mistake.
We have to do at least 3, a year with this one problum.
I've seen one so bad it took out all the floors, bottom plates, bottom of the studs, rim joist, even the foundation plates were shot.
All in a 10 year old house.
We worked on that one house for 7 months fixing all the mistakes.
Some of the windows could be pulled out of the wall without pulling a single nail.
Vent for gas fireplace installed up side down (there was the words up stamped on the vent in capital letters THIS SIDE UP. Installed in direct contact with Cellotex sheathing that had the words FLAMABLE written right on it.

quincy 04-27-2012 11:28 AM


I have learned so much on this site/forum.

2nd question:
How far the decking should be away from the side of house?


joecaption 04-27-2012 11:48 AM

When I have to build a deck like yours I remove the siding, install Storm and Ice shield over the wall making sure it sits at least a few inches below the foundation.
Then I install my ledgers using a piece of 1 X 6 vinyl lumber sitting vertical that sits between the sheathing and the ledger to act as a shim so water can noot just sit on top of the ledger and rot it out.
Then I install vinly flashing It comes in a roll and can be bent to shape.
(there's several other flashing that will work)
It's bent sort of like the shape of a lazy Z so the top part is going to be at least 6" up under the siding and it goes out over the ledger.
I install the decking about 1/2" from the side of the house.
Once the decking in place I install a piece of 1 X vinyl lumber tight up under the threshold and the width of the threshold and sitting on the decking, held in place with Stainless steel trim head screws.
What that will do is fully support the threshold so it can not flew or twist and crack the caulking in the outside corners of the door, will keep water out, and will act to protect the siding from someone kicking something off of the shoe.
Add J moulding to the ends of the vinly lumber and reinstall the siding.

beachfront71 04-27-2012 12:09 PM

All cities are different but mine requires a structural engineer when a deck is over 60" off the ground.

That being said, we used 6x6 posts and they called for a 2'x2' hole 27" deep with rebar and a CB66 bracket to set the posts on. Google "simpson cb66" to see what I am talking about.

We have earthquakes so something similar may or may not be overkill

Just some food for thought

framer52 04-27-2012 12:12 PM


Originally Posted by beachfront71 (Post 908852)
All cities are different but mine requires a structural engineer when a deck is over 60" off the ground.

That being said, we used 6x6 posts and they called for a 2'x2' hole 27" deep with rebar and a CB66 bracket to set the posts on. Google "simpson cb66" to see what I am talking about.

We have earthquakes so something similar may or may not be overkill

Maybe this will surprise you, but most of the country do not operate like California.

quincy 04-27-2012 12:12 PM


I told you, so much to learn.

One more question (today) for you if you don't mind,
Decking height to door theshold and away from side of house, what if the house siding is brick veneer and door has cement piece at bottom?

Thanks in advance.

framer52 04-27-2012 12:15 PM

Unlike Joe, I prefer to make a deck free standing. That solves the flashing problem from the start.:thumbsup:

joecaption 04-27-2012 01:02 PM

Quincy you need to start a new post not hijacking someone elses for clearer ansewers.

Framer I agree with you 100% but a first time DIY building one? Did you see the other one the guy is trying to build on here with no diagonals, and thinks adding horizontal 2 X 4's is going to fix it?

quincy 04-27-2012 01:17 PM

Joe, will do.


GBrackins 04-27-2012 01:25 PM


Here is a link to the American Wood Council's Prescriptive Residential Wood Deck Construction Guide. It is based upon the 2009 International Residential Code.

Check with the local building official. Some jurisdiction provide their own guideline.

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