Stage ("deck") footings question

[daniel lane]

Hi, all -

I've been asked to build a stage outside my kids' preschool...basically, a small deck (~60 sq.ft.) as close to the ground as possible. I'm trying to figure out the best way to do the footings, considering cost, ease of installation, etc.

I'm leaning heavily toward just digging down 12" [conveniently the frost depth here in LV] and pouring a footing and embedding a post anchor in each, but we're hoping to do this over a weekend and I'm concerned about time for the footings to set. I've seen some designs using the prefab footings and am wondering about using these. My hope is to use 4x6 beams and have them within 1/2" of the ground to avoid the need for stairs up to the stage, so I would have to dig down to set the prefabs in order to get the stage down low. Does this make any sense? Any recommendations?

Edit: Another question I forgot to ask. Since this is at a preschool, I've been asked to NOT use PT lumber. However, I am concerned with the beams and joists being so close to (but not touching) the ground, and the fact there is a sprinkler system in the area. Any ideas to get around this? Should I varnish the beams and joists before installation? This is in Las Vegas, so I'm not too concerned, but I'd prefer they not have to replace the whole thing within 5 years. (If it'll go 10, it's so small it's probably worth just accepting replacement at that time.) The plan is to use 5/4 cedar decking and to coat it with a protectant TBD.


Thanks,

daniel

[Rod Sheridan]

Daniel, my suggestion is that since this is a public area project, you consult an engineer familiar with building requirements for schools and areas used by young children.

Also make sure you have suitable amount of liability insurance, and apply for a building permit.

regards, Rod.

[Lee Schierer]

I think you'll find that the new treated lumber is far more friendly chemically than the older treated wood was that raised concerns about health. If the beams aren't where the children can get to them, I wouldn't see an issue. However, YMMV with unwarranted paranoia.

I agree with Rod, be sure to get a building permit and all inspections and have the plans and construction approved/reviewed by an engineer or at least the city inspector.

[James Tibbetts]

Ditto the advise on permits, inspection, liability issues etc

Quick crete has a post setting concrete mix that will set in less than an hour.
I am a great fan of Thompson's water seal. When I built my vacation property in WVA all of the floor; joists, sub-floor, underlayment, had 2 coats of Thompson's applied. (long story why). During the last flood we had, the entire floor structure was under 5' of water for about 3 days. After we cleaned up I was stunned that the floor system was and still is as flat as the proverbial board. As far as I'm concerned the Thompson's saved the house.

[daniel lane]

Thanks, guys. I have already talked to the school's owner about permitting/etc., what I'm trying to do is get plans sketched up to take to the city. My concern is less whether the city will accept one style of footings over the other, but rather if there's a benefit with digging down to set prefabs. Since James mentioned a post-setting quickrete, I think I'll just stick to poured footings, since I'd have to dig anyway. Regarding the PT, I may suggest it for the beams and joists, but not sure if they will accept even that slight use. If not, I think I'll just use Thompson's or an equivalent. Since we will have two full days, I'll set footings and get the beams and joists installed the first day, then coat everything and leave it to dry. The next day, we'll do the decking.

Edit: Oh yeah! I just remembered I did some work with my daughter's school back in CA. I set PT posts, then covered them with vinyl post sleeves embedded 1/4" into the concrete and screwed a cap over the top. No chance for PT/kid contact. (That project was not a deck, just a post to mount something to inside the play area.) I'll sketch up something that uses that and fascia to cover PT and see if that will work with the owner.


Thanks again,

daniel

[Art Mann]

Consumer Reports research several years ago showed that Thompson's Water Seal had no effect on preserving wood exposed to the weather.

[Matt Meiser]

Fortunately Vegas has very little weather

[Dennis McDonaugh]

What about just putting it on grade using these? Just sit the joists on top of them.

http://www.homedepot.com/p/Titan-Blo...1523/204840962

[Peter Quinn]

As closet to the ground as possible? How about on the ground. I think the whole thing is being over thought. Level the area, add crushed stone for drainage, essentially make a large pallet/grade beam system out of trek or similar.....leave it on the ground. Drive a few auger connecters into the soil to keep if from moving...done. Make it 4"-5" tall. Footings? For a preschool stage...in the desert? No sir-i Bob. KISS. When mine were preschoolers they could trip over any height greater than their own feet, and some parents will want to blame you when their kid trips over the stage you built and does a face plant, so make sure there is no liability to you. Honest, I'd skip the footings, skip the framing, make it all out of composite like a large pallet with decking boards on top, let it float, use those play set anchors to keep it from drifting, one at each corner. Do you really have a frost heave situation in LV? Even here in the the frozen Northeast this sort of construction would last easily 10 years before needing to be lifted, racked level and reset. Bugs don't like plastic.

As a side note,,,,take care what color decking you choose. Little feet, LV sun, composite holds and amplifies heat in dark colors.....

Or hire a soil engineer to test bearing conditions, and a mechanical engineer for structure, possibly an architect, rent an excavator, get an environmental study done to determine the feasibility of using treated wood. Wouldn't want to harm the southwest horned toad with ACQ leaching out from all that rain in LV. Yup, with the right amount of talent this could become a $7000/SF deck! I'm thinking 2 guys.....3 hours....you're packing the tools. Seriously, these are 2-5yr olds, they weight 40# if well fed. They only need to be 4" from the ground to "feel" like they are on stage, and that only requires a couple of pallets. IN fact you could probably use pallets....

Did a little research...Average annual rainfall in Las Vegas..4.4". One really wet year apparently they got 4.7", but thats abnormal. We get that in an afternoon here. Average low temperature in January/February....34-39 degrees. So if it never freezes and it almost never rains...what are the footings for? I read the Nevada building code....the "Accepted" frost line for "Elevations below 5000 feet" is considered to be 12"....Las Vegas is at 2000' and the realistic frostline is non existent. If I build a deck here with improper footings it will heave, twist, buckle, and generally fail...but they sell small sheds that sit on skids on grade, and those just sort of roll with the punches.

[Ted Calver]

Will any kind of bad critters get under the deck?

[Mort Stevens]

How about on the ground. I think the whole thing is being over thought.

I agree... it's getting over-engineered!
Forget about footings... you're not building the Nashville Radio City Music Hall here! Do this; thick plastic to keep the grass/weeds from growing, then a 1-2" layer of gravel and put your treated floor joists right on top the gravel - the height above grade being determined by the size of he joists and build you deck on top of that. This way you need no city approvals or permits, because it's not a permanent structure, and can be built in a relatively short period of time.

[daniel lane]

As close to the ground as possible? How about on the ground. I think the whole thing is being over thought. Level the area, add crushed stone for drainage, essentially make a large pallet/grade beam system out of trek or similar.....leave it on the ground. Drive a few auger connecters into the soil to keep if from moving...done. Make it 4"-5" tall. Footings? For a preschool stage...in the desert? No sir-i Bob. KISS. When mine were preschoolers they could trip over any height greater than their own feet, and some parents will want to blame you when their kid trips over the stage you built and does a face plant, so make sure there is no liability to you. Honest, I'd skip the footings, skip the framing, make it all out of composite like a large pallet with decking boards on top, let it float, use those play set anchors to keep it from drifting, one at each corner. Do you really have a frost heave situation in LV? Even here in the the frozen Northeast this sort of construction would last easily 10 years before needing to be lifted, racked level and reset. Bugs don't like plastic.

As a side note,,,,take care what color decking you choose. Little feet, LV sun, composite holds and amplifies heat in dark colors.....

Peter, you've made some good points, and have thoughts similar to my own at first. The desire to keep it as close to the ground as possible is to avoid the need for any steps. Building it like a pallet is exactly what my plan is, except I was looking to anchor it per request. Something that I was pondering earlier today, though, was pounding rebar into the ground and sliding the beams over that. The decking would cover the rebar, and the rebar would keep it from sliding around. And the weight would keep most folks from lifting it. [The idea came from how I suggested they build a cheap above-ground planter for a pizza garden; two-by lumber on edge, half-lapped to have ends and sides overlapping, with a hole drilled through vertically the joint. Pound rebar through and you've got a dirt cheap, solid, but easily removable above-ground planter.]

As you've noted, there's no need to worry about frost heave/etc. here. My note above was just that my plan was "convenient" to meet requirements if inspected. I expect the whole thing is being over thought, but the owner is extremely shy about liability issues herself...she won't even consider installing monkey bars for the 3-5 YO playground. (My son complains about that all the time.) With your comments and my thoughts about rebar, I'm going to back up and reconsider the design. If I can build this as a temporary/floating structure and not permanent, I'd love to keep the city out of it. If nothing else, because the costs for such a small thing would be disproportionate!

BTW, as for composite decking, that looks to be more than twice the price of cedar around here and for something this small/cheap, the owner and I agreed that it's better to just plan to replace it later if need be. We want to use the money for a bunch of playground additions, so I'm in favor of cedar but a couple of other toys added. And as for heat, kids aren't allowed out to play out there without closed-toed shoes. It's a miracle I made it past age 5, given all the rules these days.

Will any kind of bad critters get under the deck?

Bunnies. Lots of bunnies in the area. But there's a fence around the property and the bunny holes will be fixed as part of this work. (The coyotes are further south, near where I live. Seriously, can't let the cat outside, at least one a week is eaten around here.)

Forget about footings... you're not building the Nashville Radio City Music Hall here! Do this; thick plastic to keep the grass/weeds from growing, then a 1-2" layer of gravel and put your treated floor joists right on top the gravel - the height above grade being determined by the size of he joists and build you deck on top of that. This way you need no city approvals or permits, because it's not a permanent structure, and can be built in a relatively short period of time.

Mort, thanks for the thought. With what Peter said and this and my rebar thought, I think I'll combine the three and put down fabric, gravel, and stage with rebar. And frankly, the rebar is mostly as a salve to the owner's concerns, but it will help keep the frame square while we put down the decking (probably on the diagonal). As an added thought, I'm trying to convince them to put in a gravel pit (sand is forbidden, since "animals use it as a potty") for play, maybe I can just put the deck in the pit. Hmmmmm......

Consumer Reports research several years ago showed that Thompson's Water Seal had no effect on preserving wood exposed to the weather.

I remember hearing about that, so I keep referring to "protectant TBD". Whatever we do, though, it's going to be cheap and easy to apply or it will never be done in the future! (I'm only a transient sucker - both kids are out of there by fall.)

Fortunately Vegas has very little weather

So, so true. My brother and BIL both live in NE, I gently mocked their sub-zero temps while we had to deal with (OMG!!!) as low as 35-40 at night. These days, we're at 55/75. But come out here in August and tell me that, Matt!

[daniel lane]

What about just putting it on grade using these? Just sit the joists on top of them.

http://www.homedepot.com/p/Titan-Blo...1523/204840962

Dennis, those are what I meant by prefab footings. But given their heights, I'd need to dig down to keep the stage as low as possible. Given other thoughts, I'm thinking I'll pass on footings altogether!


daniel

[Rich Engelhardt]

Did a little research...Average annual rainfall in Las Vegas..4.4". One really wet year apparently they got 4.7", but thats abnormal. We get that in an afternoon here

LV and the whole desert are subject to flash flooding.
They can get half that annual rainfall in an hour.
I've been in a rain storm in Vegas.
Nothing is built there to handle rain run off.
The strip flooded to knee depth within a min or two.
Things were ==><== this close to the cars getting carried away.

An hour later and there wasn't a clue any rain had fallen.

An unsecured deck could become a floating battering ram in an instant.

Here's a video of one:

https://www.youtube.com/watch?v=efSVpt-anMQ

[Dennis McDonaugh]

Dennis, those are what I meant by prefab footings. But given their heights, I'd need to dig down to keep the stage as low as possible. Given other thoughts, I'm thinking I'll pass on footings altogether!


daniel

Sitting on the ground is the simplest way to do it. My son's day care had something similar and it was only about 10" off the ground so it must have just been sitting on the gravel in the play yard.