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-   -   Question about Supporting My Deck. . . (http://www.diychatroom.com/f19/question-about-supporting-my-deck-45299/)

bochamps 05-26-2009 02:27 PM

Question about Supporting My Deck. . .
 
4 Attachment(s)
Brand new house built last year. Planning on building a deck in the back yard. Started by attaching the ledger to the band of the house, like all of the books say to do.

After attaching the ledger, the building inspector mentioned that it is approved, but he suggested adding additional support under the bay window.

The bay window is well supported, the floor joists in the house extend all the way through. I also re-enforced the house band by L bracketing it to the floor joists in the basement.

To add additional support for lateral load, I was thinking of either:

1) Installing a post under each end of the bay. Attach the post directly to the ledger.

2) Installing a Post and Beam parallel to the ledger, about 6 inches out. This would handle the lateral load and the ledger would merely be holding the deck against the house.

3) Fabricating steel brackets to go at a 45 degree angle. They would attach to the ledger and down 45 degrees to the foundation.

4) Attaching 1/2" x 5" lag bolts through the ledger and into the floor joists. This would of course be the easiest option, but probably the least effective.

I know that a complete free standing deck is another option, but would like to use the ledger that I spent so much time on. Any suggestions would be greatly appreciated.

I've attached some pics to show what I'm talking about.

It's funny, I took a walk around the neighborhood and noticed a half dozen houses where they simply attached the ledger like I did. No additional support. No sagging is evident, but the houses are all 5 years old or newer. I'd like to err on the side of caution.

sendres 05-26-2009 02:57 PM

How big a deck are you building and what will be the support on the other end. If you Canter lever out over a support beam at the other end you reduce the load at the house. I'd likely go with Option 4. Depending on the load you end up adding to the bay joists it may cause a slight deflection and you may see some small cracking in your drywall when finished but thats easily fixed and should only be a one time unless the "live" load is exsesive.

If the deck size loading dictates added support I'd likely go with option one and then frame in the space under the bay for storage.

bochamps 05-26-2009 03:18 PM

Beam will sit 12' from the house (10' from the outer edge of the bay). Will Cantilever an additional 40" past the beam.

Total size of deck will be 23 feet along the ledger. 15' 4" from the house.

Gary in WA 05-26-2009 03:53 PM

I would put a beam 30" from the brick face, the whole length. Below, there would be a post at the door, at the center(roughly) of the bay, and at the end of the house, near the downspout. The trim belly board you are attaching to is not structural. It's good you through bolted that way, yet the rim of cant. to joists is weak with one lag on each. Most codes now require a beam near a cant., as the deck will pull the rim framing and trim right off from the joists. Good the Inspector caught this. Option #2 is best.

Be safe, G

Scuba_Dave 05-26-2009 05:06 PM

As Gbar said - beam is the best way to go
Especially with the height off the ground
The fact that others did it wrong doesn't mean you should (unless code just changed recently)

40" canti-lever is pretty big
Did the Inspector review & approve the plans?

Where are you located? Snow area?

bochamps 05-26-2009 10:44 PM

Quote:

Originally Posted by Scuba_Dave (Post 278834)
As Gbar said - beam is the best way to go
Especially with the height off the ground
The fact that others did it wrong doesn't mean you should (unless code just changed recently)

40" canti-lever is pretty big
Did the Inspector review & approve the plans?

Where are you located? Snow area?

Approved up to 53" cantilever, which I thought was large.

Settled on 40". This will allow me to add stairs later off the cantilever toward the sunroom.

Located in PA, so we definately get our share of snow.

Gary in WA 05-27-2009 05:36 PM

The cantilever is on the opposite side from house. As in this example from Palmer: Page 3----

http://www.palmertwp.com/code_docs/deck_details.pdf

It always attaches to the house with a mechanical connection to prevent uplift there. Always minimum 2/1 ratio, in length.

Dave, check out the 72" cantilever! Be safe, G

Scuba_Dave 05-27-2009 06:09 PM

Wow, 6' cantilever, & here I'm worried about a 24" cantilever for a bay window (sort of) that will be supported on one end by the garage. I thought steel might be needed over 4'

Need to start a thread on that project

Knucklez 05-28-2009 07:02 PM

come on.. 2x12's spaced 16 OC with a canteliver of 6' ?

did you get that in writing? think of a lookout area of the deck with a fantastic view of the forest. then.. during the quiet evening house party someone notices baby deer eating grass at the edge of the property.

.. so the people put down their drinks and quietly sneak out of the house .. tip-toeing across your beautifully build deck which doesn't squeak. the deer are not startled.

you motion for others in the house to come out in join you.. peering out over the edge of the deck.

::shhh:: don't startle them..

the last person (a little drunk) staggers out to take a pee (he thinks this is what you're all doing at the edge of the deck) and just as he whips it out, someone yells EEW.. GROSS!!

and then the 6' canteliver, with 8 adults at ONE end snaps

KAAA-- SMASH!!!

and people yell "OH MY BACK"

AND THE LAWYER YELL "CHA-CHING!"

:yes:
Knucklez

Scuba_Dave 05-28-2009 07:50 PM

I doubt 2x12's 16" OC are going to snap from 8 adults
Even if they weigh 300 lbs each
Look up the properties of 2x12's

sendres 05-29-2009 04:02 PM

In that situation I'd be more concerned with the up lift at the other end. Especially with joist hangers and only a hand ful of screws.

All of sudden tiny walks out of the huse just as the screws give was and he receives free flight into the neighbors pool while the deck flip on top of your guests.:huh:

Aggie67 05-29-2009 04:59 PM

I have a question for the OP (bochamps), and I could be looking at this wrong.

In your first photo, are we looking along the joists towards the bay window bumpout? And is that the sill plate blocking directly ahead, and sill plate along the foundation at the bottom of the photo? And you've installed angle brackets between the joists and sill plate blocking?

If so, is there another nut and washer at the rim joist, and for some reason you extended the rod all the way through the sill plate blocking and stuck a nut and bolt there?

If not, and there's not a nut and washer directly behind the rim joist opposite the ledger, then is this what you have (starting outside):

nut | ledger | flashing | rim joist | void | sill blocking | nut

The reason I ask is that it's not good practice to sandwich in a void in there. Also, is the ledger flashing hidden from view in the photos?

bochamps 05-30-2009 07:57 PM

Quote:

Originally Posted by Aggie67 (Post 280250)
I have a question for the OP (bochamps), and I could be looking at this wrong.

In your first photo, are we looking along the joists towards the bay window bumpout? And is that the sill plate blocking directly ahead, and sill plate along the foundation at the bottom of the photo? And you've installed angle brackets between the joists and sill plate blocking?

If so, is there another nut and washer at the rim joist, and for some reason you extended the rod all the way through the sill plate blocking and stuck a nut and bolt there?

If not, and there's not a nut and washer directly behind the rim joist opposite the ledger, then is this what you have (starting outside):

nut | ledger | flashing | rim joist | void | sill blocking | nut

The reason I ask is that it's not good practice to sandwich in a void in there. Also, is the ledger flashing hidden from view in the photos?


Want to thank all for their helpful input. To answer some of your questions:

1) The angled sections of the bay do have a void. This is why I installed long threaded rod. I figured a through bolt connection through the void was better than simply lagging in bolts. I did speak with a structural engineer in PA and he suggested adding 1/2" by 8" lags into the ledger and all the way into the house floor joists.

As an overkill to the situation, I'm also going to pour piers under the bay. I'll install 4x4 posts underneath, attach them to the bay ledger, then frame around that. I'll be left with a nice storage area under the bay window for gardening supplies, etc.

2) I did install flashing over the ledger where there was vinyl siding. But the bay window has a finished fascia material covering it. Would I need flashing there? Wouldn't a quality caulking material suffice between the ledger and bay material. I installed caulking, but could add flashing. However there wouldn't be anything to tuck it under.


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