Hi dcole,

The black spots are most likely Mold / Mildew. I'll be the sides of the house w/the 'problem' are the North, and possibly part of the East side. The South and West sides are usually mold-free (assuming they both get lots of sun and fresh air.)

There are cheap cleaners in the Home Centers. They're like $5/gallon. BEFORE you buy, make sure you read the container to see if you can use it on your siding. (You didn't say what you have for siding.)

My best to ya and hope this helps.

Jay J -Moderator

PS: If the Home Center doesn't have a cleaner for your particular siding, stop at your local Paint Retail Store (found in the YELLOW PAGES under PAINT - RETAIL) for a cleaner ...

My husband wants to power wash, will that alone get ride of the mulch spores, or do special cleaners need to be added to attack this things?

Hi dcole,

Yes, you can certainly try to clean the wall w/o any type of cleaner. However, it won't kill the mold - It will simply wash off whatever the pressure washer can remove. If you use a cleaner that MIXES w/the water (when it's turned on), then you'll certainly kill the spores. You can lightly hand-wash the walls to kill the spores, then your husband can follow-up w/the washer to actually remove it. By you hand-killing and him power-washing, you are accomplishing the same thing as if you were to pre-mix the cleaner in w/the pressure washer's water. (Usually, the PWs come w/a dip-tube that you insert into a Cleaner. And as you use the PW, it 'draws' the Cleaner up to mix w/the water. And usually, you can manually set the 'mix ratio'.)

My best to ya and hope this helps.

Jay J -Moderator