12 X 16 playhouse; 6' feet above ground

treehouse'11

I'm looking to build a 12'X16' playhouse 6-8' (feet) above grade. trying to get kids the treehouse (absent trees) with a space below I can enclose at later date for storage. free-standing, 200+' from any other structure.

Plan on using 6"x6" treated posts to build base as deck style frame with shed then stick built on top. shed will have 10' side walls with a gable roof peak; at +/- 15' so they'll be considerable wind resistance...

looking on guidance on best way to set the posts for base??? seems to be a good deal of debate between setting them in concrete vs on concrete pillars w-ties when discussing decks, but this seems to be more of a sheer strength/resistance issue

Daniel Holzman

Deck design is typically regulated by some sort of code, in my town we operate under the 2006 International Residential Code. There is really no debate about how to build decks in my town, the building inspector gives you a copy of the Prescriptive Residential Wood Deck Construction Guide, you follow it, he approves your plan, and approves your construction. Or you don't follow it, and either you get an engineer to design all of the aspects that do not follow the book, or you don't get a permit.

You may not need a permit for what you are building, and if you do, it may not follow deck design standards, but it would be a good idea to follow a standard design and construction procedure such as the Prescriptive Guide, unless you plan to either engineer the playhouse yourself, or get it engineered. A 12 ft x 16 ft playhouse is pretty big, and at that height above ground, you really should think carefully about construction practices. You asked specifically about setting the post bases, which is covered in glorious detail in the Prescriptive Guide. In the Guide, the size and depth of the required footing is specified (this is a concrete footing), and the means of attaching the post to the footing is specified (you need to use a galvanized steel standoff bracket, you are not allowed to bury the post in the concrete).

Now there are folks on here who probably think I am one level above or below being a communist for suggesting that you follow code, but even if there WERE NO CODE in your area, I would still suggest following the guidelines in the Prescriptive Guide, since it will give you a conservative design likely to last a long time, and will go a long ways towards minimizing the chances of someone falling off the deck or going through and getting hurt. Posts are just one of many design details covered in the Guidelines, which are free and can be found on the internet. Course your town may have different requirements, always good to check first with your building inspector.

concretemasonry

Your structure above ground level sees all the lateral loads. It must be able to resist the lateral loads because of the design.

The traditional, CHEAP, simplistic solution for lower structures is just embed the posts into concrete that is in natural soil that can have little resistance.

When you get well above grade, you need some sort of diagonal bracing between the posts and the floor system to to provide stability.

As Dan mentioned, a code is just the minimum standard and not really for the desired results in the real world.

What happens if there is a real wind that can blow it into Kansas and the Wizard of Oz because there is no enough anchorage for a playhouse of that size. - Do you and your neighbors have good insurance? A 12x16 playhouse is really a structure to be considered. My house got hit by a 8x10 wrinkled tin shed and caused a lot of damage.

Dick

abracaboom

I'd follow Daniel's advice.

DIYWorker

Daniel's got some sound advice here about following code, even if you don't have to. I'll just reiterate that since this will be designed for kids - put in the engineering and design to do right. This is one thing that if it went bad - it would be REAL bad.

When I built my kids playhouse, it was seriously over engineered - Code++! My wife was a bit freaked out by the price until I reiterated that I wanted it to be solid - even with all the crap they brought up there (and let me tell you, kids do things you would have never dreamed were possible.. or even rational)

Good Luck on the project!

joecaption

I built one that was 12 X 12 X 6' high with out any other building under it and it cost $997.00 just for the materials.
As often happens you lost me about building a shed under it. At 6' high how do you plan on installing a door. If you use PT deck boards for the roof on the shed there going to leak.
Nope read it again, still makes no since.