Deck Footings Question

[chrisrg]

Hi guys, I've been reading a bunch of posts here and I know how much you all love questions about decks, so I thought I'd throw out there for fun. I'm working on a deck/kids playhouse project. It's 14x8 total size, built on the side of a relatively steep slope. 6' off the ground at the bottom of the slope. I've been following the CDA6 guidelines, but the one thing that I'm second guessing myself about is my footings and the live load calculation. First I should mention that I live in Southern California and we don't have a frost line. My soil is mainly sandy clay. For my footings, I dug 28" diameter holes to approximately 36" depth. I drove rebar 2 feet into the hole bottom. I put 1 foot of concrete in the bottom and set 12" sonotubes in which are 36" in height so approx 1 foot of the sonotube is above ground. Holes were backfilled and compacted around the sonotubes. All of the concrete was poured at the same time, so it's one solid footing. 3 of the footings are supporting 6x6 posts. The 3 footings on the hill side have the beam sitting directly on the footing (no posts), attached with proper hardware. Beams are 4x6 hem-fir. Joists are 2x8x8, 16oc. Double rim joists. Joist hangers on both ends plus hurricane ties at both beam/joist junctions. I do know one item that I made a slight mistake on. The beams are 4x6 at 6'6" where they hit the post. I'm pretty sure that code says they can't be more than 6'. I thought they could be 7 ft. I'm going to be building a playhouse on top of this deck, approx 10x8 with roof, shingles etc. I have no idea what this house will weigh, but if it tops out at 2000 lbs I'd be very surprised. So if the dead and live loads combine to 3000 lbs / 112 sq ft of deck, that would equal 26.78 lbs /sq ft. All of the calculators have said it should be fine for 60 lb/ sqft, which means it should be able to handle 6720 lbs.By the way, my local codes require 18" deep footings x 18" square for the joist and beam spans I have. Even though I did round footings, I'm pretty sure I've well exceeded that requirement. I didn't pull permits for this project, not because I didn't think I could build it to code, but because this is the only location I could build this playhouse and it's closer to the property line than what's allowed. From everything I've mentioned here, does it sound like I've my footings properly to support the deck and structure I want to put on it? I think I'm ok, I'd just like to get a few expert opinions.

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[Msradell]

http://www.diychatroom.com/f19/raised-deck-kids-clubhouse-199343/

 

[jar546]

If your description is correct, you have 6 piers and if all of the loading of the piers are the same, at 6720 you have 1120 psf per pier so I don't think there is an issue at all except the fact that you intentionally did not pull a permit because you knew you were going to do something that is not allowed rather than going for a variance.

Welcome btw.

 

[chrisrg]

http://www.diychatroom.com/f19/raised-deck-kids-clubhouse-199343/

Yeah, not getting much response over there. Figured you guys probably new a heck of a lot more.

If your description is correct, you have 6 piers and if all of the loading of the piers are the same, at 6720 you have 1120 psf per pier so I don't think there is an issue at all except the fact that you intentionally did not pull a permit because you knew you were going to do something that is not allowed rather than going for a variance.Welcome btw.

Thanks. Appreciate it.

 

[jar546]

http://www.diychatroom.com/f19/raised-deck-kids-clubhouse-199343/

Interesting find. Looks like you answered questions about this project already. Could be a good subject here for everyone.

 

[mtlogcabin]

Playhouses under 200 sq ft are exempt from building permits under the IRC. Don't know about CA or your local jurisdiction. You could be wasting your money if you get caught. Are you sure you are in the setbacks?

 

[ICE]

The tributary area will be different for the piers.

The beams appear to be bearing on the bolts.

And those bolts, what size are they and what's the edge distance for the holes? Kinda long too...kids will be leaving skin at the playhouse. Are those carriage bolts?

The 36" deep footing is how far from daylight at the bottom? Next time, slope the concrete away from the hardware.

If I understand your description, you drove re-bar into the soil. Is that correct?

You are almost exempt from permit requirements but that six foot above grade changed it up for you.

In all the time that I have been doing this, I've inspected fewer than a dozen decks. People just don't bother with permits and unless it is over 30" above grade a permit isn't required.

 

[chrisrg]

Playhouses under 200 sq ft are exempt from building permits under the IRC. Don't know about CA or your local jurisdiction. You could be wasting your money if you get caught. Are you sure you are in the setbacks?

Yeah it's pretty close to the property line where it stands, so I'm sure I'm inside the setbacks. I'm friends with all surrounding neighbors and I'm fairly certina they couldn't care less, so I doubt I'm in jeopardy of them turning me in. Only one of the neighbors will actually be able to see the structure.

The tributary area will be different for the piers. The beams appear to be bearing on the bolts.

And those bolts, what size are they and what's the edge distance for the holes? Kinda long too...kids will be leaving skin at the playhouse. Are those carriage bolts?

The 36" deep footing is how far from daylight at the bottom? Next time, slope the concrete away from the hardware.

If I understand your description, you drove re-bar into the soil. Is that correct?

You are almost exempt from permit requirements but that six foot above grade changed it up for you.

In all the time that I have been doing this, I've inspected fewer than a dozen decks. People just don't bother with permits and unless it is over 30" above grade a permit isn't required.

Thanks for your response. To answer those questions. The beam is sitting on the standoff plates, not bearing on the bolts. It's just difficult to see with the angle in the photo. Those are 6" carriage bolts, which I've yet to cut off. There's a few others that need to be trimmed as well There won't be any kids leaving any skin at this playhouse, believe me.

The footings were 36" from daylight. They may have been closer to 40" on a couple of them. I did drive rebar 24-30" into the soil prior to putting in gravel and pouring concrete.

I knew the no permit thing would be a point of contention here, but I wanted to be straight up and not BS you guys. I think I'm well above minimum code requirements on the work I've done anyway, but I wanted the expert's (that's you guys), opinion.

 

[JCraver]

You would not enjoy the ticket when I caught you with it started without a permit. :wink: The playhouse itself may be under 200 sf and exempt, but the deck, even if it was flat on the ground, is not. You should go talk to your BO, be very apologetic, and ask him/her what you need to do to apply for a variance, and then a permit if the variance is granted. What if you had a neighbor on the uphill side from you do the same thing - only he did a crappy job and it fell down the hill onto your yard? What if your kids were over there playing with his kids, and his crappy deck/playhouse collapsed? Could be unpleasant...

Now that that's out of the way. :-D Code-wise you're mostly ok so far, and the loading will be fine. Without seeing the footings before you filled them there's no way to be sure, and I have a hard time taking people at their word when they've covered up work before I get there, but if they're poured as you describe they should be ok for where you are. The rebar driven in the ground wouldn't have passed here though - the rust will eat it from the bottom up and into your pier. In my area, with lots of rain and freeze/thaw, that'd be a big deal. I'd also check to be sure all your fasteners are galvanized or equivalent, because I can't tell from your pics. And I'd probably give you a little grief over the 45* cuts on your knee braces, unless you cut the ones that still need installed (perpendicular to your beam) a little better.