Using telephone pole for house beams 1

[jimtheengineer10]

I was contacted today by a guy who got his hands on some old utility poles that a town recently removed. He wants to install them as beams to support floor joists for a house. He wants to use some of them as piers (bury them 6' deep in the ground) and then run other utility poles on top for the beams. He would then run conventional 2x10 floor joists on top and build a 2x6 wood stud framed house.

The poles are 12" diameter at the start and taper down to 10". Does anyone know of any kind of load tables for something like this?

 

[SlideRuleEra]

Doubt you will find any load tables and if you do, the tables will not be for used poles. The basic calcs for poles as beams are not difficult... the assumptions to make the calcs need to be carefully selected. Are the poles pressure treated (say, creosote) or a rot resistant wood like cedar?

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[jimtheengineer10]

How would I determine if creosote was present?

 

[JAE]

Agree with SRE.

The design of these would be based on two things:
1. The actual grade and species of the poles (which you probably can't determine)
2. The condition of the poles - if they are "used" poles, how much deterioration/rot/etc. has occurred such that the capacity is somewhat reduced.

A close visual inspection of the poles might deal with item 2 above.

For item 1, if you can find the species/grade then NDS design criteria could be utilized.
But if you can't feel comfortable with a pure design check only, or if the local building official doesn't like it, you might have to do several load tests on them to establish some measure of true capacity.
This might involved temporarily supporting the poles as a beam and loading them progressively to various levels, checking for failure load.



Check out Eng-Tips Forum's Policies here:
faq731-376

 

[bridgebuster]

The wood will appear dark brown, even black. It's somewhat oily/greasy. If it were fresh you'd smell it. Most important: Creosote treated lumber is not for interior use.

 

[LittleInch]

Using them as "piers" or columns seems like a good idea.

Using them as beams doesn't.

apart from the issue over the taper, there will be a need / desire to cut notches out of the poles in order to increase the bearing area on top of the ones used as columns and also to set his 10 x 2 joists into, thus weakening the poles.

Otherwise you risk excess bearing pressure on the small contact area between pole to pole and pole to joist.

Also we assume these are wood??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MotorCity]

May want to consider having them re-sawn to a square or rectangle section. Would make them easier to work with and eliminate or minimize creosote exposure.

 

[dik]

Utility poles are normally rated based on class... and generally have much higher bending strength than regular lumber. You might want to contact one of the utilities to see what information you can gather.

Also creosote is harmful in an interior environment. Did a report about a decade back on a log home that was so constructed. Had a bunch of research paper... I'll see if I can still dig it up.

Dik

 

[SlideRuleEra]

In North America, utility poles are covered by the North American Wood Pole Council (NAWPC). Preservatives, such as creosote or CCA, are not applied the same way as structural lumber. The preservative is forced in, under pressure (same as structural lumber), but then "drawn" back out (with vacuum). Because of this lower treatment requirement, utility poles are more subject to in-ground "rot". This is partially compensated for, as dik mentioned, by using high quality trees, when new.
Since the poles being considered are used, be selective about deciding which ones, if any, are direct buried.

Creosote is a proven cancer causing agent (carcinogen). Historically, I believe it may have been the very first "chemical" to be proved to cause cancer.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[thaidavid40]

Most mills will decline to resaw used timbers, for fear of breaking saw blades on hidden, embedded steel items. And they would almost certainly decline to do so if they were creosote treated. Most mills aren't equipped to handle the environmental requirements from the production of creosoted timbers.
Dave

Thaidavid

 

[oldestguy]

Another thing about creosote treatment. Usually it only is done for the part buried. So likely use of them as buried supports would not be a good idea unless you know tht part to be buried also was in use that way.

 

[BAretired]

All in all, it sounds like a bad idea.

BA

 

[dhengr]

Jimtheengineer10:
They better have paid him a lot to take those poles, because they are going to be more trouble than they are worth. You don’t know the species, the grade, etc. etc., so what are their material properties, let alone, are their design tables? You don’t know what the preservative is, so you have to tack that down too, to know how to handle these. No one wants to saw them for you, so nothing will be square, level or plumb. And, to make any of this happen will require a lot more work up front, so you have some level, square starting plane. Use them for landscaping, raised gardens, low retaining walls or terraces, edging, risers on a rustic steps or walkway, etc. In these latter uses, you can work around the difficulties, or live with them and at the same time appreciate their utility and beauty.

 

[JStephen]

I've seen plenty of what I assumed to be creosote on the above-ground portion of poles. I just assumed they treated them top to bottom.

A friend said her husband came up with a bunch of old telephone poles like that, and he sold them off to area farmers/ranchers for fencing purposes.

 

[SlideRuleEra]

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[wannabeSE]

For information about the species and preservative treatment on utility poles, look for a metal tag or brand on the pole. See

http://www.bki.cc/blog/15