Talk to the friend who is printing this. Though a roadside banner will not need to be as high resolution as say, a detailed map.

You haven't said what is going on the sign. Is it vector text and vector artwork or photographs of artwork?

Hi Tom,

One thing worth remembering with a project like this is that a banner 3m x 6m won't be looked at from half a metre away, like, say a business card or leaflet. People will see it from a fair distance away so the resolution won't need to be that high. 72 dpi should be quite adequate. Ideally you would produce the file using a vector programme like Illustrator or Corel Draw. Then resolution isn't an issue at all because they can be printed at any size. You would then supply files in .eps or .pdf format.

Well I only got given the job a a couple of hours ago and I sat down with him in his office/work space (This guy sells some paintings for a million baht), and I got some essential info.

It is going to contain text of Thai and English, 2-4 photographs of the different areas. So I still have't worked out the actual design as I have not yet sat down with ai or ps open. I need to take the photographs as well soon.

Do you think 600dpi would be an ok resolution for this or is that not what you guys would use?

If you are unfamiliar with a print process, talk directly to the printer or download their submissions specs.

For an outdoor banner meant to be viewed while driving by?
35ppi at final size. You could probably do 25ppi.
If meant to be read by a walking public with a viewing distance of 10' or more then 50ppi at final size. I wouldn't bother with higher than that on an outdoor banner.
600?
We don't even go that high on exhibit quality prints (though exceptions have existed).

How did you determine the bleed needed to be 4"? That would be something the printer who is finishing the banner would tell you. For a banner hung by grommets, 2" on a side is a lot. If you mean 4" on a side, you are paying for all that extra square footage.

Talk to the guy printing and finishing the banner.
Besides bleed, you also need to find out what he would like as resolution, what color space your images should be in (some like RGB rather than CMYK) and what layout program you should be using. You also need to find out the preferred scale. Since your artboard size is limited you will need to work in scale. Remember as you scale down, you need to multiply your placed image resolution by the same factor to account for enlargement.
Assuming you aren't making this entirely in Photoshop. If you are, you need to talk to your printer about color correction.
Get a proof.

One final thing, I take it you aren't in the US. Still, you may want to find out if there are any local ordinances on attaching banners to buildings and find out if there are any sign sizing laws you need to be following. To do something like this in the City of Boston would require half a handful of permits.

Thank you very much for the information, I am going to meet the client in a couple of hours and so will discuss this situation.

The bleed literally came from him himself, the client. I explained about how he wants to attatch this banner to it's metal fixing and I mentioned a bleed, he said that it would wrap around about 4inches all the way around. I will attach an image of the metal structure that it is going to be put on to.

Are you going to use bungie cords to keep it on there?
3 to 4" of bleed would make sense.

They have had a banner made before a long time ago so they know how to attach it and I guess they know 4 inches works for their method, I have not asked. I did get the printers number though so I shall contact them in them tomorrow.

As for now I have the most difficult and tedius job to do, I have three projects running at once and I have until Friday evening to finish this up (not the job in the OP). I have to go around a 27 hold golfcourse image from google earth and create paths, then copy and paste every bunker into the bunker paths tab, every fareway into the farway path tab etc for the entire thing. This is going to take some time -____-

I play golf and would love tracing a gold course! I used to run a sign and banner company. Design it so that no important information is close to the edges. Allow 100m bleed if it has to be wrapped. I'd suggest working at a scale of 1:10 and set your res at 720 dpi or else450dpi. That way it'll end up at 72 or 45 dpi. The printing process is also just as important.

H

Ahem. 100m? I think you meant to type 100 cm

100m, just to be on the safe side!

Probably want a safety of about 2" on the face too for a 6m long banner.

100m?? As in, 100 meters? 328 feet? 3936 inches??

I think he was being facetious

Why you gotta use big words like that.....