How to vent my attic?

Long story short, I bought a house built in 1949, bulldozed part of it and I'm working on rebuilding it.  My current problem on the long list of issues is that there is no roof overhang(no soffit).  I'm wanting to do a metal roof on the house but I'm trying to figure out how to adequately vent the attic.  My initial thought was just a gable vent on each end of the house would be perfect until I starting reading into it more.  This might still be my plan B if I don't come up with a better plan A.  The house had a considerable amount of mold issues that I'm working through so it seems like it is in fact a problem that needs addressed.  First thing is I should probably ask the roof guy what he recommends, unfortunately my wife spoke to him while I was at work so it wasn't something I thought of in time.  

The best solution I've found so far is a vent installed on the edge of the roof but it's not exactly cheap and I'm not sure if it would work with the metal roof.

Any ideas?

When we put the metal roof on my last house I just had the guys mount the electric attic fan on the back side. I'm most likely doing the same thing when it comes time to replace the roof here, except have them hook it up with a temperature and humidity switch.

Powered vent fans through the roof. They look like big mushrooms. 

My metal roof garage has a ridge vent.

FYI... Ridge vents don't really work without soffit vents, and gable vents and ridge vents don't play well together. 

In reply to SV reX :

That's what I've figured out after a couple hours of googling.  

I'm trying to figure out how to get more intake air down low so it can vent out through a ridge vent.

It is possible to do eave vents without soffit vents (which would work well with ridge vents)

JLC article on eave vents

It is also possible to add low gable vents or roof vents (but open area of ventilation may be limited)

Venting attic with low vents

Before you assume the low vents will work, do some math on the actual open ventilation area vs the actual ventilation area of the ridge vents. 
 

Those things may be smaller than you think. 

Another thing to consider... Vapor barrier paint on the ceilings. 
 

The moisture comes from inside the warm house. You probably have no vapor barrier at all in an older house. If you can prevent some of the moisture transfer, you may be able to help reduce the likelihood of mold. 
 

You are on the right track. 

If the soffit venting doesn't work, I'd suggest eliminating the ridge vent and putting gable vent fans in. Exhaust at one end, intake at the other. Create a cross flow. 

You have an existing problem that passive ventilation has not solved. You have done a good job identifying why. It may be time for an active ventilation system to combat the problem. 

Originally the house had one gable vent on the west end.  The east end of the house had a very poorly done addition that connected a detached cinder block garage to the rest of the house with no other venting in the attic.  So with only one vent there was just no air movement at all paired with a leaky roof at some point during it's 75 year life and it was the perfect conditions for a disaster.

Similiar situation in the crawl space, only one vent on the SW side.  We have since replaced the foundation on the west end of the house and poured a new foundation for the rebuild of what we tore down on the east end.  Now we have 7 crawl space vents.

The long end of the house runs East-West so I'm thinking the gable vents with possibly some fans can be a viable option. 

The entire house also doesnt have a drop of insulation anywhere.  The outside is getting Typar wrapped, 1" foam board, and then LP siding.  R15 batts in the walls(only 2x4 studs), and new windows. Also doing 12-13" of blown insulation in the attic to get to around R40.

In reply to Patientzero :

Sounds like you have a pretty good handle on it. I wish some of my construction folks understood ventilation as well as you do.