I’ve got Hardieplank siding painted a dark blue. It’s about four years old. The side that gets the most sun has white bleeding out. In reading I understand it to be “effervescence” from the sun drying moisture and salt/minerals remaining.

The interwebs talk about washing with mild cleaner and a soft brush, or using a weak acid.

It’s becoming unsightly, and that is the biggest side of the house, unfortunately. Any advice from those with experience?

I have to wonder if the Hardiplank was damp when it was painted. I have a lot of that product on the west side of our house where the sun really beats on it, and never had any issue with what you are talking about. Ours is painted a dark red.

I’d call the Hardi mfg and get their recommendation. This issue is not uncommon with concrete materials. Companies like Sika make chemical products to eliminate the issue, but I don’t know if that would work on a painted surface. You could call a rep and find out.

We have Hardiplank on our house as well, been there over 15 years now and I have never heard of that happening before.

On the north side of the house we do get a green mold of sorts on some boards and I knock that down with a mixture of one part bleach to four parts water. Spray it on, let it sit for ten minutes and it literally wipes right off. Don't know if it would solve your problem but thought I would mention it.

If it's what I think you're describing it's efflorescence. It happens on brickwork. It'minerals being washed out of the brick or concrete and then the water evaporates and leaves it behind.

If this is what you're having there must be a source of moisture causing the leaching of minerals out of the Hardie plank. Maybe something isn't flashed correctly on that side of the house and moisture is getting behind the siding, or because of the sun hitting that side it's a condensation issue.

I think you should try to address the moisture first. I know Arc described a siding practice he used where he spaces the siding off the building wrap so it could breath. Probably a lot of work to do now, but otherwise you might be constantly cleaning it, and it could also damage the siding over time I would think.

Yeah, call Hardi directly..shouldn’t do that, you may have gotten a bad batch.

If they don’t or won’t cover it, then I’d wash it with nothing more than water and Dawn so it doesn’t damage the paint.

Our house has 3 sides in strong sunlight parts of the day, in Hardiplank for the better part of 10 years. No such issue observed. Painted a mild light tannish color.

If my experience is typical, the painting is not done by James Hardie, but by the local distributor when ordered. At least that is what I was told.

quote:

Originally posted by GaryBF:
If my experience is typical, the painting is not done by James Hardie, but by the local distributor when ordered. At least that is what I was told.

That's interesting. When I applied for my siding it was represented to me that it was factory painted by whatever method they used. We just picked out the color.

whoever did it I am pretty pleased. It looks as new now as it did 16 years ago.

Efflorescence... it's quite common with masonry veneers and stucco. But Hardie is cementitious also. It can be cleaned off with a pressure washer or with water/ vinegar solution.

Typically it happens if water is entering from the back side of the material so you need to check and make sure you're not getting water behind the siding.

Well, called the manufacturer and wasted about 15 minutes of my time. I was rather surprised about how unhelpful they were. A few days ago my son and I cleaned a bit of it per their recommendations. Zero change in the white stuff. Will be trying a vinegar solution later this week to see what happens.

I’ll post a couple pictures when I can. It’s on the sunny side of the house, with no real water ingress options due to the way the roof is. I think it’s just catching the sun during the hottest times of the day and whatever moisture was ever in there came out and needs to either be painted over or cleaned off if possible.

https://www.facebook.com/JamesHardieBP

Use Social Media to ask them, since the CS person wasn't helpful...

Post a picture asking if the product is supposed to wash out like this, see how they respond, move it up the chain from customer service rep to supervisor to manager to VP Sales...

From Jameshardy.com

Traditional and timeless. Sleek and strong. HardiePlank® lap siding is not just our best-selling product—it’s the most popular brand of siding in North America, protecting and beautifying more homes from coast to coast.

With that statement, they should back the product up....