Installing a large sign

[hubbiida]

Hi,
I need to install a large sign next to the road in my front yard to advertise a business I have on the premesis. I am not sure, however, of exactly how to do this and to do it safely. The sign itself will be about 4' by 3'. It should have, I believe, two timber posts, probably 4x4". And I believe the holes for the posts should be 1/3 of the total pole height. That is, if the poles are a total of 12' in length the holes should be about 4' deep. What I don't know is, do I need to pour concrete around the base of the poles or can I get by with packed dirt?
Any advice would be greatly appreciated.
Andrew

 

[breezer]

concrete, dirt will move over time or when wet

 

[JohnD]

It sounds like a lot of work if you're using wooden posts which will go rotten and break off, in time.

Have you considered using a concrete or steel support below ground level, and bolting the wooden posts to these so they do not get damp?

 

[Symptoms]

Andrew - I was just about to say you'll need planning permission from your local council to erect this until I saw you are posting from Japan, so you may not need to do this there. Treated timber posts into concrete (bags of ready dry mix are the way to go - no back-breaking mixing!) will last at least 10 years before you might need to worry about rot. You could use galvanised steel post spikes into which you insert the posts or concrete spurs with the timber posts bolted on (as JohnD says). 4' in the ground seems a little excessive to me but we don't have typhoon winds. You can bury them shallow if you brace the main posts with timber struts (again into concrete) - this is the preferred method.

 

[Thermo]

4 feet is not excessive for something that will act as a sail and put a lot of loading on the posts and foundation. Any fence post should be 1/3 below ground. Definetly concrete in the post hole and timber posts will be fine.