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Deck Piers, yet again

Here's an inspection I just did yesterday:

Framing -- Failed
1. Post for top landing must be supported by a footing
2. All Posts must be on a 1 inch high standoff brackets
3. Main beam boards can not be apart, must be nailed together every 16 inches Staggered
4. Deck is supported by cantilever is beyond code. Must be engineered
5. Bolts in ledger board must be spaced not more than 12 inches and staggered
6. Deck must be connected to house by at least two lateral load tension devices within 2 feet of each end of
ledger board or at least 4 Simpson DTT1Z deck tension ties with two of them within 2 feet of end of ledger board
complying with manufacture instructions
7. Joist hangers not installed per manufacturers instructions. Cannot use screws. 10d x 1 1/2 required for ledger
connections and 16d for joists
8. Top of stair stingers to have support directly underneath or provide Approved brackets
9. Open risers between treads on stairway cannot have a opening larger than 4 inches
10. All risers on stairway must be within 3/8” of each other. Risers cannot be higher than 8 1/4 inch
11. The siding is not properly flashed behind ledger.
12. Edge of siding where cut out for deck needs to have proper J channel
13. A light is required for the stairway
14. A electrical receptacle is required on the deck
 
I built many decks in the past and always made them self supporting. It always seemed a lot easier and cheaper do do. Did not have to deal with ledgers with their hardware, siding, and flashing. If I rented something to dig the piers it didn't cost more or take much more time to put a few more holes in the ground. With a finished ceiling you didn't know what kind of rim board there was, some older houses I did not trust the rim board if it had one. Some times the ledger board did not line up with the rim board especially if the wanted different levels. Did a lot of decks for trailers too. Now that I am an inspector I am always surprised that I don't see more self supporting decks at a houses.
 
Rick18071 said:
Here's an inspection I just did yesterday:

Framing -- Failed
1. Post for top landing must be supported by a footing
2. All Posts must be on a 1 inch high standoff brackets
3. Main beam boards can not be apart, must be nailed together every 16 inches Staggered
4. Deck is supported by cantilever is beyond code. Must be engineered
5. Bolts in ledger board must be spaced not more than 12 inches and staggered
6. Deck must be connected to house by at least two lateral load tension devices within 2 feet of each end of
ledger board or at least 4 Simpson DTT1Z deck tension ties with two of them within 2 feet of end of ledger board
complying with manufacture instructions
7. Joist hangers not installed per manufacturers instructions. Cannot use screws. 10d x 1 1/2 required for ledger
connections and 16d for joists
8. Top of stair stingers to have support directly underneath or provide Approved brackets
9. Open risers between treads on stairway cannot have a opening larger than 4 inches
10. All risers on stairway must be within 3/8” of each other. Risers cannot be higher than 8 1/4 inch
11. The siding is not properly flashed behind ledger.
12. Edge of siding where cut out for deck needs to have proper J channel
13. A light is required for the stairway
14. A electrical receptacle is required on the deck
Click to expand...

Your correction list looks the same as mine, must deal with same contractors.
 
Ty J. said:
Who forgot the dead load?
Click to expand...
Nobody technically did. The deck description of the OP was deck only, not including the roof LL or DL. I think his point was that a simple deck, if designed properly, cannot support the weight of a roof just being attached to it. And I agree.
 
Ty J. said:
I think what Jeff was getting towards is that most jurisdictions have variable soils and are unwilling to take the liability of determining or even approving a soil type without some documentation. Minimum documentation would be a soils analysis including a sieve analysis report (particle grain size analysis).
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Not sure why you need this. You have already figured out the loading for the beams and columns. I would think that one final "resident friendly" determination of soil bearing capacity on your part would be in order. Shot in the dark, best guess, or whatever but with that final tidbit of information, you can determine the pier size real quick and be done designing your residents deck or roofed over structure. I wish you luck in court with your friendly resident if he or his family is ever injured.
 
rktect 1 said:
Not sure why you need this. You have already figured out the loading for the beams and columns. I would think that one final "resident friendly" determination of soil bearing capacity on your part would be in order. Shot in the dark, best guess, or whatever but with that final tidbit of information, you can determine the pier size real quick and be done designing your residents deck or roofed over structure. I wish you luck in court with your friendly resident if he or his family is ever injured.
Click to expand...
How would a plans examiner know the soil capacity from the desk? A building inspector may be able to make the determination, but by that point the plans are reviewed and issued to the field. Does one provide footing sizes for each soil type? Sounds confusing at best.

And as for your bestowed luck in court, not sure as why we would need it. The methods outlined are all provided in the IRC already either directly or by reference. It would be an extremely brief case to show that the culpability lies with the AHJ; the AHJ who completed the review per the International Code. Contractor or self-performing owner would ultimately be responsible for their design and construction.
 
rktect 1 said:
Not sure why you need this. You have already figured out the loading for the beams and columns. I would think that one final "resident friendly" determination of soil bearing capacity on your part would be in order. Shot in the dark, best guess, or whatever but with that final tidbit of information, you can determine the pier size real quick and be done designing your residents deck or roofed over structure. I wish you luck in court with your friendly resident if he or his family is ever injured.
Click to expand...

I am a little confused by your post. In one part you are asking that the inspector/reviewer make the determination of soil bearing capacity (maybe I am wrong) and then you are wishing good luck in court if someone is injured. Please clarify your answer.

Inspectors and plans examiners are not designers. The liability is in poor judgement that is weak or lax. If an plans examiner or inspector approves an installation that made no reference to soil bearing capacity and is acting on their own determination to approve a design or installation, they are taking on the liability.
 
The building dept may know better than anyone what the soil is in a given area....Assume your typical (or whatever you want) and if the inspector sees differently in the field, then call it on inspection....
 
Keystone said:
Your correction list looks the same as mine, must deal with same contractors.
Click to expand...

It's not the contractors, it's the home owners (and his neighbor in this case) that build it. And when the plans were reviewed it did not indicate any cantilever.

I don't design the deck or pier size. I just attach the pier table in the AWC Prescriptive Residential Wood Deck Construction Guide footing table along with a list of other requirements to the plans. If they think the piers should be smaller they need to prove the soil bearing capacity to me.

When I plan review a deck I mostly just check the spans and will call the owner/contractor to suggest changes to comply and then red ink the changes. Then I attach my list to it. I will share my list here and I am open to suggestions for changes.

2015 IRC Residential Deck Requirements

1. For free download on how to build a deck to comply with code search on line for:

AWC-DCA62015-DeckGuide-1804.pdf


2. Decks are to be attached to piers/footings which are required to be at least 42” deep and is to comply with footing table at the end of these requirements. Stair stringers are to be supported and attached to at least 4” thick concrete pad. Posts are to be on stand-off brackets 1” above grade or concrete or on concrete piers that are at least 6” above grade. Otherwise posts that are on or in the ground or concrete are to be “ground contact type” (proof is required).


3. Decks cannot be supported from cantilevers on the building. Decks can be self-supporting without support from the building


4. Decks are required to be built out of preservative-treated or naturally durable wood.


5. Ledger connection to band joist bolt spacing is to comply with IRC Table R502.2.2.1 or by the following: ½” bolts with nuts and washers or lags with washers or FastenMaster LedgerLok Screws; staggered, 2” from the top and bottom edge, 2 to 5 inches from ledger board(s) ends, tip of lag bolts shall fully extend beyond inside face of band joist. Space fasteners by the following chart. Joist spans are from ledger to supporting beam:

Joist Span 6’ 8’ 10’ 12’ 14’ 16’ 18’

Bolt Spacing 36” 36” 34” 29” 24” 21” 19”

Lag spacing 30” 23” 18” 15” 13” 11” 10”

LedgerLok 12” 9” 7” 6” 5” Not Used


6. Each deck is required to connect to house by at least 2 lateral load tension devices within 2’ of end of ledger board or at least 4 Simpson DTT1Z deck tension ties with 2 within 2’ of end of ledger board, both complying with manufactures instructions.


7. Flashing shall be installed properly under siding and over ledger to keep rain from getting between ledger board and house exterior wood (plywood/USB sheeting or framing)


8. Boards making up beams are required to be fastened together every 16” staggered. Beams cannot be supported by ledgers. Beams are to be directly on top of posts, not attached to side of posts or use brackets that are tested for this.


9. Beams and joists can only cantilever up to ¼ of the actual beam or joist span.


10. Tops of guards (railings) are to be at least 36” above the floor or 34” above stair tread nosing where the deck floor, ramps, landings and stairs are more than 30” above a floor or grade.


11. Graspable handrails are required on at least one side of a stair flight from top riser to bottom tread nosing with 4 or more risers. 2x 4’s and 2x 6’s, etc. are not graspable. If handrails are attached to side of guard (railing), return the hand rail to the guard so there is no space between the guard (railing) and ends of the handrail.

12. Guards and handrails are required to withstand a concentrated 200 pound load applied in any direction at any point on the top by attachment bottom of guard posts to joists and band beam. Railing posts cannot be supported to ban beam only. Do not notch railing posts.


13. Openings in guards cannot permit passage of a 4” (4-3/8 on stairway) diameter sphere. Opening between bottom of stairway guard and steps cannot permit a passage of a 6” diameter sphere.


14. Maximum stair riser height is 8 ¼”. There may be no more than a 3/8” variation in riser heights within a flight of stairs. This includes highest stair tread to deck floor and bottom stair to ground or floor. Openings in stair riser cannot permit passage of a 4” diameter sphere. Minimum tread depth is 9”


15. Top of stairway stringers are to be anchored to deck with metal connectors or supported underneath, not just by nails or screws. Stairway cannot be supported by deck cantilever.


16. An electrical receptacle is required within the perimeter of the deck.


17. Stairways are required to have a light at least near the top landing.




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rktect 1 said:
Not sure why you need this. You have already figured out the loading for the beams and columns. I would think that one final "resident friendly" determination of soil bearing capacity on your part would be in order. Shot in the dark, best guess, or whatever but with that final tidbit of information, you can determine the pier size real quick and be done designing your residents deck or roofed over structure. I wish you luck in court with your friendly resident if he or his family is ever injured.
Click to expand...

There was a case here in Canada where a building inspection department was held partially liable (joint and several) for the settlement of the foundation of a building. The building was constructed in an area that was known to have poor soils. Rather than rely on a geotechincal report of the soils, the building inspection department stamped the plans with a disclaimer stating that soils had not been reviewed for proper bearing capacity. The judge ruled that the building inspection department owed a duty of care to investigate the soils as it was known to be an issue in that area. So, the question is: if the quality of the soils is not known to be poor, can the building inspection department be held liable if it does not investigate the quality of the soils?
 
Rick,

I had a little heartburn with #16 GFCI recently went to do the framing inspection on a deck job and the homeowner was removing a double window and installing a patio door with out my knowledge.

I think I know your answer, would you require the GFCI and exterior light, there's only two stair steps from deck to grade on that end of the deck?
 
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