How deep to sink footings?

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Old 05-06-03, 07:03 AM
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How deep to sink footings?

Not sure if this is the right forum for this question, but here goes:

I'm planning a swing set for the kids, patterned after one my Dad made for us when we were kids. The uprights will be steel pipe about 2" OD, installed straight up.

In construction is there a rule or guideline that says "for X feet of upright above ground, sink the footing Y feet deep and use Z cubic feet of cement"? Is the above ground weight of the fixture a consideration? Naturally I want to do this right since the kids will be playing on it, and their safety is my biggest concern.

Thanks- any thoughts and comments, steering in the right direction, etc. appreciated.
 
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Old 05-07-03, 03:53 PM
Portable Welder
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You came to the right place,
I just did the same thing for my kids, I made mine out of 5"x 5"x 3/16" sq. tube with three uprights to accomadate 4 swings and the horizontal bar 14' tall.
Ya, mine is maybe a little tall but everyone loves it, I kinda made it for myself also.
As for using 2" pipe that measures 2.375 or 2-3/8" might be a little on the light side, if you were building the traditional A frame style that size would be perfect but since you going to be straight up you have different load factors, A major factor is how tall is your cross bar going to be will determine the size of your upright. The 2" pipe which is 2-3/8" O.D. is standard for the cross bar to hold 2 swings. and lets say you want your cross beam at 10' you will have no problems if you use 3" pipe which is 3.5 O.D. for your uprights, as far as your footings I went down 42" and went over sized on my hole, I used 2 yards of concrete for three holes. but in your case depending on where you live because of the frost heaving the posts out of the ground I would suggest you go at least 36"deep with a 12" dia hole. Dont forget to factor in how far the swing is away from the post. The higher you go the farther you want to be away from the post. with my cross bar at 14' I kept the chain 24" away from the post and an 18" gap from chain to chain. So my clear opening between posts is 108", Like I said if you r not going to be 14" tall you can have your swings closer together. If you have any more questins dont hesitate to ask, Good luck.
 
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Old 05-12-03, 07:21 AM
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Thanks, Portable Welder

Originally posted by Portable Welder
As for using 2" pipe that measures 2.375 or 2-3/8" might be a little on the light side
Thanks, PW, for your post. You're right- sorry, I left important information out of my description. Looking left to right, the uprights will be ladders with both legs buried and concreted in- deep, as you suggest. Monkey bars across the top, connecting to another upright ladder and raised platform with additional uprights and deep footers on the right. That should be plenty of lateral stability.
 
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Old 06-03-03, 09:06 PM
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Yes, there is a guide line that you can use. Engineers will recite the well known guide line of 25% underground, 75% above ground.

This works for fence post, basket ball posts, and many projects large and small. If you want to vary from that guideline, feel free to do so. Aside from that, experience will teach you that the 25/75 rule is a good one. Personally, a 20/80 rule is more economical for some home projects without sacrificing safety.

As to how much concrete to use, I am not aware of any guidelines, but I am sure there are plenty of standard practices for different types of projects. It could depend on the compactness of the soil, the expected load forces, etc.

I think 2" pipe is far too undersized for any length over 4'. You might want to consider 4" pipe.
 
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Old 06-05-03, 02:48 PM
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Thanks, Lugnut

I used to have a book called something like 'The Practical Engineer's Handbook' that listed all sorts of formulas, conversions, and such, as well as recommendations for just this kind of thing. Wish I knew where that thing was, now!
 
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