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Kid's play structure with green loblolly

Started by ytnok, November 25, 2006, 09:03:08 PM

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ytnok


Someone over at the gardenweb forum sent me your way, said this was the place to learn about building with timber.  Scrolling and searching through the site I see the tip was a good one.

I have a pile of 3-8inch timbers from thinning out the loblolly pine on my property and I want to use it to build a play structure for my kids.  Some of the wood has been down for a year, some I just cut two weeks ago. I'm going to use the 6-8 inch timbers for poles and anchor them with cement.  The smaller timbers will be ballasters and railings.  I plan to use dimensional lumber for the platforms and flooring.  I will notch the timbers where they attach to the dimensional lumber and everything will be held together with bolts.  Oh, and today I cut down some 3-5 inch sweet gums to use for the ladder.   

I stripped the two biggest loblloly timbers and was getting ready to put them in the ground when I noticed how moist they seemed (felled two weeks ago).  I know wood shrinks when it dries so before I sunk anything in concrete I wanted to know if there are some potentional problems of working with green timbrs that I can head off with proper preparation. 

Any suggestions or warnings are greatly appreciated.

beenthere

I don't think you want to sink pine into concrete or the ground unless it is treated against decay. And even then, I wouldn't put them in concrete. Tamped gravel would be better and just as solid.

Welcome to the forum. You are at the right place. Hope we can help.  :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Tom

neither of the woods you have chosen do well outside in the weather, let alone in ground contact.   Any of the Southern Yellow Pines will be attacked by termites and rot within days of being put in the ground, concrete or no concrete, unless pressure treated.  It will do a good job if air dried to 19% and then pressure treated to the 'ground contact' impregnation of whatever chemical is used.

It will do well under cover of roof if not treated as long as it remains dry.

Sweet Gum would be a poor choice for a ladder, in my opinion.  It will not withstand the out-of-doors.  It makes good interior panelling and cabinet wood, but succumbs to rot rather quickly when left out-of-doors.  

If you build outside with these woods, don't expect much longivity and please inspect them frequently to insure the safety of your children.

Welcome to the Forestry Forum.

ytnok

Thank you for the welcome.  There are quite a few topics here that interest me and the site works so much better than the gardenweb forum so I'm definitely a happy camper.

Regarding treatment, one of the books I got on building play structures said to treat timbers with tar, any thougts on this?  I have some stuff that the guy a the hardware store gave me because the can was rusting, it is for treating direct bury or submerged timbers, though it says the wood must be fully cured before use.  It seems like some pretty toxic stuff and I was thinking of just taking it in to our local toxic disposal site rather than exposing my kids or soil to it.

Regarding concrete, when I built my last fence I read on one of the home improvement websites that the concrete would act as a sealant and as long as there is drainage at the bottom of the hole and no water could get in betweeen the wood and the concrete, that this is a sound way to set untreated posts.  I'd never considered using all gravel but it would certainly drain well and it would be easier to use than concrete.

Regarding longevity, my dad built us a play structure out of untreated white woods and it was still solid ten years later when we sold the house.  I know treated lumber will last several decades but it seems to me that untreated lumber will outlast my kids' childhood.  Will paint increase the longevity of the wood?  I was thinking of using the sweetgum for the ladder because it is stiff but will it really rot that fast if it is suspended in the air? 

I certainly intend to keep this structure well maintained and I'm designing it so that worn pieces can be easily replaced.  I chose these woods only because they are convenient and I don't have a  fireplace  :)

Thanks for the advice. 

Furby


ytnok

Quote from: Furby on November 25, 2006, 10:55:00 PM
What part off the country are you in?

Eastcentral Alabama.  I know this is not as good as if I lived in a drier climate, but we grew up in Dallas and i swear that structure my dad built suffered only from the abuse us kids put on it. 

So what kind of rotting time are we talking about here?  A year?  Ten years? 

Posts the size of these pine timbers would cost me around $50.  Surely the pine will last long enough to be both useful and economical.  (or am I really just grasping at straws :-\)

Raphael

  There's been some discussion on products for treating your own wood on the Drying and Processing board that might be worth a read.

  I don't know loblolly but I gather it's not much better than EWP in ground so don't count on more than 5 years max and probably less, sapwood in the ground will degrade rapidly.  I'd design the structure so that no wood is buried then it can last indefinately given periodic treatment with a stain or preservative.  Good drainage is essential for buried posts, I've seen PT 4x4s rot off after 5 years set in concrete and untreated fully round red cedar stay stable over 20yrs when packed in gravel.
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

TW

This is not an answer to your question but just another method.

In my end of the world we sometimes burn the end of posts before we bury them. That does not prevent rot in the long run but the post will rot quite a bit slower. You just make a fire and burn the end up to about 6" above ground and then you set the posts. The surfase should be charred when you are ready. Then set them in rocks and gravel.

This method is not much used nowadays since pressure treated wood became availeable but I learned it from an old man and tested it and the post has already lasted twice as lond as a uncharred post would do. Though it is near the end of it's lifespan now.

Maybe it would last until yous childran have outgrown playing. I do not know if that works in Alabama climate though.

About tar.
I used pine tar and linseed oil on my wooden boat and it worked well except for that it was sticky all the time and rubbed off on everything. That is:good on a boat but not on a play structure. I used to have some old trousers I used in the boat. They soon became brown on the "stern" and on the knees.

There are several on this forum who were building long before I was born so listen more to them than to me.

ytnok


Great tips everyone.  I'll try treating the posts and set them in packed gravel in case they need to be changed out later.  I'll try charring the bottoms of the posts as well and I read somewhere about melting candle wax into the end of the post. 

I'll be checking back if anyone has more suggestions.  Thanks.

PineNut

My experience with untreated SYP in ground contact is about two weeks before the termites move into it in serious numbers. I have seen sheds made from SYP in which the structure was kept dry that were over 50 years old. I have also seen structures that were in ground contact with serious problems that were less than a year old.

You may be able to get a lifespan of a few years if you use treated lumber in ground contact and your own timber for above ground structure.   

Tom

A distance of 18" is common, between the ground and untreated wood, to combat termites.  They have difficulty building their tunnels in the open environment over that distance.   If block is used, they will come up inside of the block.   They will also come up inside of a post in the ground to find the structure above.

Read up on the chemical that you obtained from the hardware store.  It might not be as bad as you think, if properly used.  It's not as if your kids will be gnawing on the post.

Yes, paint will protect the wood.  It must be good paint and properly applied.

For paint to stick or stain to penetrate, the wood must be dry.  Plan on stacking it on stickers for at least a couple of months.

Consider tying the ladder rungs on with seine twine.  The nylon will stretch as your wrap it and remain very tight, even if the wood shrinks some.   Nails and screws will let in moisture and might promote rot in untreated wood.

This will become a fun project for you and your kids if you accept the possibility of high maintenance.

ytnok


The chemcial is copper naphthenate and I put several coats on before I set the first post today.  I set it in pea gravel and tamped the gravel as I set the post.  I'm thinking of forming a concrete collar at the base of the post/grade to provide negative slope.

I realized this project will need good maintenance, and I am planning to get my boys involved in the idea that things we make should be maintained. 

One thing I'm curious about: on another thread someone psoted concern for using green loblolly pine to construct a house, many people gave assurances that green loblolly pine is a good building material.  What is the fundamental difference between a home building project and my project?  Such that building a house is OK, but building a play stucture is a problem. 

I appreciate all y'all's help.

Mark

Furby

Ground contact!
If you were to pour concrete tiers and have them extend oh say, 18" above ground and then build on top of them, you would be much better off. ;)

Tom

Yes, Furby is right.  Loblolly is good building material.  There are two concerns.  ONe is the ground contact that Furby mentions and the other is building a house with green pine.  Green pine has the rigidity of half boiled spaghetti when it is first sawed.  After about 6 or 8 weeks, it begins to harden and will support weight much better.   All green woods are more flexible than they are when dried.  You also run the risk of twist and warp disrupting the shape of the structure.

Of the Southern Yellow Pines, Loblolly is the third best and used frequently.  Once sawed, Southern Yellow Pines are not distinguished one from the other by species.  They are all good building material.  You just have to understand what you are expecting the wood to do to perform to your specification.

TW

If yor climate is that harch, please stear away from my charring method. It works for temporary stuctures here but we do not have termites and the ground is more or less frozen from December to April.

TexasTimbers

ytnok,

welcome to the FF club!

I have quite a bit of experience with loblolly pine. Not as much as Tom and other long-time sawyers but still alot in the past 2 1/2 years. I have been cutting it mor ethan any other wood except ERC and I can tell you from experience that you are not going to be happy with it's performance outrside unless you fully accept the fact that even with maintanence it is going to rot. I have timbers lying outside that i did not get under cover that are already unusable. The rings even have seperated as if it had shake when I cut it but it did not. I have not even cut any lately unbtil I get more covers built, and the posts will be made of ERC not loblolly.
i love loblolly for interior and for TFing. it is one of the preferred woods of the planet for TFing in my view but not for exterior use.
Just thought I'd warn you too.  ;)

Being in Alabama i know you have plenty of Walnut - use it.  :D
The oil is all in Texas, but the dipsticks are in D.C.

ytnok

Quote from: Furby on November 26, 2006, 10:53:16 PM
Ground contact!
If you were to pour concrete tiers and have them extend oh say, 18" above ground and then build on top of them, you would be much better off. ;)

Hmmm, that gave me a thought.  I've seen forms for pouring concrete piers, for decks I think.  I could use those to get the pine up off the ground.  Can I sink the posts into the concrete as long as there is no ground contact whatsoever?  So the pier would extend say 24" above the ground with the post sunk into 18 inches of that concrete leaving a six inch solid concrete barrier between the pine and the ground. 

I know it sounds like I should just go out and buy the lumber for all the trouble I'm going through, but I'm really psyched about using timber cut from my small property for something.  Everyone else the housing development throws it away but so far I've mulched all the smaller pieces and have only the bigger pieces to use.  If I had a fireplace I'd burn it.  But it looks like good pole lumber just sitting there and I really want to use it.  So, thanks for listening to me and offering advice.


Tom

Concrete isn't all that good on wood.  I've been told that the lime eats it up, I don't know for sure.  Sticking the pole in concrete is like putting it in a bowl.  Water that gets in there, can't get out.

The building supply places sell a metal bracket that is made specifically for mounting posts on concrete.  They can be gotten in 4x4, 6x6 or 8x8 sizes.  You stick the base in the concrete before it sets and later you can put the post in it so that the post will stay dry.  They aren't large and I think you screw or nail the post into the bracket.  They are frequently used for deck building.

4woody

maby if you coat it with fondation coating?

TexasTimbers

Anythng you do that traps moisture will rot a post. Anytime you sink a post into the ground/concrete/even gravel to an extent it will trap moisture. The end grain of a post is going to wick moisture up into it like a, well, wick.
As has been mentioned, the best approach, unless there is a reason why you can't do it, is to use standoff post bases. Simpson makes about a dozen different models for every imaginable application.
The only way to keep a pine post from rotting in concrete is to use a Bois D' Arc  post in it's place . . . it will rot too eventually but it will take about a hundred years.  smiley_roller
The oil is all in Texas, but the dipsticks are in D.C.

Mooseherder

Please consider the end user. Concrete and children don't play well together. teeter_totter

TexasTimbers

Quote from: Mooseherder on November 27, 2006, 10:53:16 PM
Please consider the end user. Concrete and children don't play well together. teeter_totter

Now now brown cow, let's not be over-protective of our precious little babies! Geez isn't this the epitomy of hypocritical. When my kids were in the learning to walk stage you could NOT find a corner in the house that wasn't duct-taped with plastic bubble wrap. I never did buy them 4 wheelers against intense pressure from even their friends' parents! It is still all the rave here and there is a huge 4 wheeler camp that they all frequent most every weekend. I still get haranged by my kids from time to ttime to get some for them. The answer is always something like "Nope. Buy your own if you want one I am not going to give you a weapon to hurt yourself with." Two kids that I can think of have permanent injuries; one of them is a paraplegic and one was killed about 5 years ago on one.
My daughter took a trip in an ambulance friday because she was driving her frineds, with her friend on the back who was supposed to be grounded from using the thing. They wrecked and of course had on ZERO helmets. Stooooopid. Groouunnded!
At the hospital, after we knew all necks/backs etc. were not cracked or damaged my daughters' friends dad, who is a deputy in the neighboring county was in the hallway trying to talk the State Trooper from issuing citations to my daughter for Excessive Speed and Driving Unlawfully on a County Road . . . I don't know how much headway he was making if any, but I said "No sir! You better write those tickets to her!" Larry looked at me like I had two heads and so did the Trooper. I told him later I didn't want my daughter thinking she could go through life reaking the law and daddy bailing her out.
Anyway, I say don't worry about the concrete too much Moose. Teach the kids that it is there and to respect it. Pick your battles - there are bigger fish to fry.  ::)

just my 2 coppers . . .
The oil is all in Texas, but the dipsticks are in D.C.

Raphael

I agree with kevjay, but it's also a good idea to radius off the exposed concrete corners.
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Furby

Yup, wood and concrete can be about even when it comes to kids.
Steel is in that same ballpark. ;)
Got a scar from some steel playground equipment when I was little.

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