Exterior Mildew Removal

DONNA: My husband and I had put an addition on our home and we have a brand new roof. It’s only about two-and-a-half, three years old.

TOM: OK.

DONNA: And then there’s the existing side of the house where we’ve got a farmer’s porch where there’s been a considerable amount of mildew and mold buildup.

TOM: (overlapping voices) Yep.

LESLIE: (overlapping voices) So you’ve got a new roof and an old roof and they don’t look the same.

DONNA: Well, and they both have varying degrees of mold and mildew and we removed it once with Simple Green and lightly used a power washer but my husband was explaining if we continue to use the power washer, he’s afraid we’ll damage the architectural shingles.

TOM: Well, you could because you are driving some of the granules off but if you’re very careful about it and if you’re just using, say, the wide, gentle spray – the same one that you use, say, to wash your car – you’re probably OK.

But the secret here, Donna, is that you want to apply the mildewcide and you want to let it sit. So I would use a product like Jomax for example, that you put on the roof. Let it sit for a little while and then rinse it off because sometimes if you just try to blast off that mildew – that moss growth – that’s not really getting to sort of the root of the matter. You want to put the mildewcide on; it’s bleach-based. Let it really do its job and then rinse it off. Don’t blast it off; just rinse it off and then you’re more likely to have a situation where it’s going to stay clean for a while.

Now, a couple of other things that you can do – first of all, is this a very shady side of the house? Because, typically, that’s what causes a lot of moss growth.

DONNA: Yes, and that is what’s happening. It’s a, you know, developed neighborhood; beautiful trees but it’s in – we have a couple of very large trees …

TOM: OK, so if you can thin out the tree a little bit so that you let a little more light in – you don’t have to get rid of it; just thin it out – that will make a difference. And the other thing that you could do is you could take a strip of copper or nickel flashing material – the metal – and put it up near the top of the roof. And what’ll happen is as the rain strikes that and washes over the copper or the nickel, it will release some metal which acts as a mildicide and actually cleans the roof every time it rains.

DONNA: Oh, wow. That’s a great idea. Well, thank you very much.

TOM: There you go, Donna. Thanks so much for calling us at 888-MONEY-PIT.