Fort for granddaughter, treated vs white wood

[iublue]

Not really woodworking but I thought I would ask here anyway.

I am going to build a fort for the granddaughter. You know, the regular tower, swings, slide and climbing wall. I would assume that the standard is to use treated but why wouldn't white wood (untreated) work just as well?

She is five. I would seriously doubt that she would use it past the age of twelve IF that long. That is only seven years. Untreated would last that long and longer. Beyond that, I don't really care. Besides, I have a concern about the toxicity of the chemicals used to treat wood. I was thinking that the only place I would use treated would be the posts, since they are in contact with the ground.

Has anyone used white wood to build outside, a fort or otherwise? If yes, would you do it again? Any shortcomings?

All input will be appreciated.

[Admiral]

If you keep it painted, it will last. Assuming pine. Why not cypress, or cedar?

[JR1]

For what you want to do untreated wood with a finish would be fine. If you apply a quality finish like gf 450 and were willing to touch up every ~3 years pretty much anything would work. You would need to put down concrete to keep it off the ground and provide good drainage. Insects may be an issue in some areas, but most places even quality pine would work. Using durable woods :
White oak,
Cypress,
locust,
Osage orange, would improve the appearance and resistance to wear and tear. Don't even think about Ipe, it's toxic. SW A100 would also work and be less cost but would require more frequent touch up.

[Matthew Williams]

The key is rot resistant wood off ground properly treated. I have had hem-fir rot completely out in 3 years painted when used as a sand box. I used good dark Doug fir, dried and stained on my elevated deck and three of the 40 boards completely rotted in 8 years. I would used treated for anything touching the ground and then rot resistant species painted for the rest.

[Steve N]

lil

Ground contact will allow moisture in the ground to wick through the painted endgrain of the non resistant wood, and 1 to 4 years would be all you could reasonably expect to get from it, Treated you can get ground contact rated and 40 years later it is still whole. BTW if you want painted, you can paint treated, or stain it.

[Robert Adams]

Had a neighbor that built stuff like that for his kids. Whatever you do don't over do it. You will only have it in the yard a couple years before you will be tearing it down. So pine is just fine. Paint it or treat it.

[srv52761]

Any wood will "weather" if left outside "unfinished", including treated lumber. The chemicals in treated lumber will help retard rot and insect nfestation, but the natural changes from varying sunlight and humidity will still occur. So you are going to end up finishing the wood in some fashion anyway to slow down splintering and other things that would degrade the use of the structure as a safe plaything (maybe not if done in cypress or redwood; I have not made one out of those materials before.)

If that is the case, then you can mitigate the migration and release of any chemicals in the treated wood by using a coat or two of a good quality oil based preservative.

Our town has two Leathers CCA pressure treated playgrounds, installed in the mid-90's.
One school had a conscientious program of sealing the wood about every two years.
The other school did not.

As a project for science fair a couple of students took soil samples in 2004 and had them analyzed by the Unversity of Iowa.
While neither sample came back above safety concern levels (can't remember what that number was), I remember the sealed playground was statistically no different than virgin soil but the unsealed one was significantly different.
As an aside, the school of the unsealed playground has decided their playground has deteriorated to the point it must be demolished.. Over a $100,000 when it was built.

The chemicals they use now are safer than before and I would think the kids would be perfectly safe from any chemicals if the wood was sealed. Additionally, the sealer would improve the feel of the wood and cut down splinters.

I have spearheaded six school playground installations and helped on a couple of others. As you are really concerned about the kids' safety, I recommend dowloading a copy of the Consumer Product Safety Code for Playgrounds. The dangers from chemical leaching pales in comparison to a poorly designed play structure.
*Do not forego addressing the safety surface. It is a foregone conclusion they will fall. It is up to you now to determine the degree of injury they will sustain then. Remember, soil, after a few weeks of no rain is not much softer than concrete. There will be some that say, "I grew up with no problem. And I used just plain grass on my kids's play structure."
Yeah, well... this is your granddaughter. You have to decide for her yourself.

[ianab]

A lot depends on your climate.

Locally it rains a LOT. Untreated pine in ground contact would be growing mushrooms in 12 months. In a dryer climate, it's no where near as bad.

Go with treated or naturally durable wood, then you KNOW it's going to make 10+ years. Longer if it's looked after by regular painting or oiling.

[Bibliophile 13]

Where I am, untreated construction pine will only last a couple years outdoors because of the rain and humidity. Painted, it might last a year longer if it's anywhere near the ground. But if it's painted and well up off the ground (say a foot or more) then it will last a good, long time.

In your area, you could probably expect untreated, unpainted wood to last a few years, but I like my work to last as long as possible. I'd either paint the untreated wood or use treated wood. In either case, put it up on blocks to minimized ground contact.

[brianwelch]

I would shy away from cedar or redwood due to the possibility of splinters and resultant festering...