DIY Elevated Play fort -- plan and support questions

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Forum topic by mishmish posted 09-07-2012 05:56 PM 35551 views 0 times favorited 3 replies Add to Favorites Watch
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1 post in 2326 days

09-07-2012 05:56 PM

Hi everyone,
I found your site while googling my problem (there was a helpful thread responding to Dylan in Half Moon Bay).
My issue is similar, but i want to make sure I fully understand my options. (I have built some furniture—but never anything of this scale and safety implications)

I am planning on building an elevated play fort for my two sons, 5 & 2. The fort will be based on a combo of these two plans: and

However I’m not entirely comfortable with the stability of these plans and have questions about how to make it rock solid. The play house will be 4 feet high off the ground, probably 10×10. Would it be better to A) have a 4×4 not only at the 4 corners but also halfway between each, so at every 5 feet; or B) dig holes for the 4 corner posts and put them in concrete, say around 18” down. (we’re in florida so there’s no frostline per se)

Also, if I were to use cedar instead of pt wood, would that affect the stability any?

Thanks so much, I appreciate your help! I will start this once the intense humidity + mosquitoes die down in the next few weeks.

3 replies so far

View mnguy's profile


207 posts in 3637 days

#1 posted 09-07-2012 06:05 PM

A play fort – awesome!

I do not believe you need intermediate supports on a 10’x10’ deck, but you can find many resources for span tables for various framing lumber dimensions. You are essentially building a stand-alone deck. You may have options between using larger joists and 4 posts, or smaller joists and 8 posts. The span ratings for cedar joists may not be the same as those for PT pine, so be aware of that.

As for footing depth, check you local building code for decks, and follow it. You can’t go wrong.

View whitebeast88's profile


4128 posts in 2429 days

#2 posted 09-08-2012 01:04 AM

when i built my daughters two story club house which is around 12’ if memory serves i used 6-4×4’s concreted 24” in the ground.i put cross braces at each corner and doubled the floor doesn’t sway any and me and a friend was on the top floor building rails which we both are fairly large and we couldn’t get it to sway and held us just fine.the way i look at it it’s for my daughter and if its overkill to add 2 more post i’m fine with it.hope this helps.welcome to lumberjocks.

-- Marty.Athens,AL

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404 - Not Found

2544 posts in 3208 days

#3 posted 09-09-2012 11:26 AM

This job has never moved. The outside corners are PT 2×4’s butted together to make an L shape, then all the bracing/rails/floor joists are bolted or screwed to the inside of the L

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