Clean Mildew Spots from a Deck
LESLIE: Mary in Virginia’s next and what’s going on with your deck?
MARY: Yeah, we’re having tremendous problems on our deck. Within the past year – we’ve had it on for a year and it just started developing these black spots on it.
MARY: Sort of like mildew spots.
MARY: We’re not quite sure how to get rid of them.
TOM: It’s not the fault of the decking. The composite decking will grow mildew or mold or can land on there. But what it sounds to me like what’s happening here is – are these very small spots?
MARY: They’re about the size of a baseball.
TOM: Of a baseball. OK. Because what I’m thinking is you may have something called artillery fungus, which gets into the air and lands and leaves these big black spots around.
LESLIE: Is that generally in areas where you have mulch or gardens? Doesn’t that come from that as well?
TOM: Yeah, and is this a very shady area, Mary?
MARY: No, actually the sunshine hits it every day, all day long.
TOM: Well, let’s see what we can get rid of whatever fungus is stuck there and growing. What I want you to do is to go out and buy a product called Jomax – J-o-m-a-x – which is a cleaner that you mix with bleach that, once you apply it, you let it sit. You want to let it sit for a good 15 or 20 minutes. Don’t let it dry on there. Keep it wet. And that’s going to kill all of the spores that are making this fungus grow. And then you can scrub it off with a stiff brush – you can use a floor brush – and then rinse it off with lots of water. But you have to use a bleach-based solution because if you don’t kill those spores, some stay behind and it will come back up.
It sounds to me like you’ve got some sort of an infestation there that just really likes your deck because it’s so nice and sunny there. That’ll get rid of it.
Mary, thanks so much for calling us at 1-888-MONEY-PIT.