Painting - Exterior paint has mildew

The exterior paint on my house is developing mildew, but I can't figure out why.

I had my house painted 5 years back. Two sides of the house are now mildewed and have peeling paint in a couple of places. A third side is starting to show mildew. The fourth looks as good as new.

The side of the house that is just starting to mildew gets sun all day long. The side that looks the best gets the least amount of sun. None of the other houses on my street have mildew.

Any ideas about where the mildew is coming from? I'll have the house washed and repainted, but is there something else I can do to prevent mildew?

Thanks.

Since you know you have a problem be sure to add extra mildewcide to paint. Mildew needs moisture and heat to grow. When dew settles on a house and doesn't dry up early because of trees or direction of sun that makes for good conditions of mildew. Another cause is lack of moisture barrier in the walls allowing moisture to seep through from the heated areas. I used to own a mobile home in Fla where mildew is always a problem. With good paint and mildewcide I had little problem on 3 sides. The north side was a big problem and needed to be washed every 6 months. hope this helps.

I'm not so sure its mildew. Could be a fungus instead. Mildew needs moisture, organic material (food), and lack of sunlight/air flow. The side with sun all day long should prohibit mildew. There is a fungus that attacks roofs and it is black - looks like black streaks on shingles. This could be a variation.
I don't know who to tell you to call for a visual inspection.

The peeling paint may be a clue. You might have a moisture problem - either a leaky roof or pipe.

I agree with other posts. Mildew could have been preexisting and painted over without removing it first. To be successful at controlling it you must make sure its completely gone before painting. Use a bleach solution or Jomax and then Tsp and power wash. Don't let the bleach dry up before removing it (with water). Add a mildewcide to the paint ( even if the manufacturer says it's there already). As pointed out mildew or fungus thrive in damp, poorly ventilated, and dark (no sun) conditions. If there is a lot of vegetation that can be cut back it will help.

The side that is the worst gets sun all day long. So either there is shrubbery that the poster neglected to mention, or its not mildew. I never heard of mildew growing in full sun, but I still learn something new everyday.

Thanks for your replies. There is a little shrubbery, and it has been there for years. There wasn't any pre-existing mildew that was painted over. This mildew is new.

Maybe it's a fungus, not mildew, as Bob said. Is there any way I can post photographs?

A lot of people use this. It is free and not half bad. Set up a free account then upload your pics and then post the urls here. You need to look around the site. It is pretty easy.

http://photobucket.com/

I see mildew on "the sunny side" of houses all the time
The spores get blown by the wind from the damp shrubs or trees
You don't see the spores sitting there
A little morning dew (I'm on the corner of river and ocean here...a lot of morning dew) and then some nice warm sun and pow
Well OK, it needs a food source too, but the pollen from the bushes/trees usually take care of that

Actually moisture, warmth, oxygen, and a food source is all mildew needs
The direct sun doesn't kill mildew, often it just dries up the moisture before the mildew uses it
Hence we don't often see mildew on the sunny side of a house
Except around here
In the "Land of Rust and Mildew"

Oh and it must be killed before painting it
Killed dead and removed
Then you can wash it and paint it