Why does Hardiplank siding 'sweat' ? 3

[swthwdy]

All homes in our neighborhood have horizontal Hardiplank siding on the second floor. Why does this siding 'sweat' and produce a vertical green algae that has to be pressure washed every year, even on the West sides where the summer sun hits all day long. Does this have something to do with the moisture barrier paper, or lack thereof?

 

[RAS04]

Have you contacted the company? If the product is still under warranty, I would get them involved first.

 

[swthwdy]

Thank you for your reply. Yes, I have contacted Hardiplank, however, no answer back as yet. Somehow I feel I will be surprised if I do receive an answer. The more houses I view I am beginning to think that Hardiplank of the past 6-8 years of age may have a moisture problem of some kind. Our Structural Engineer has noted that our Hardiplank is not correctly installed, therefore, no warranty would be in effect anyway.

 

[sda97]

Even vinyl and aluminum siding will develop algae. I have aluminum siding and depending on the humidity, I have to wash off my siding almost every year. Usually this occcurs on the north side of the house. Are your walls properly insulated? It sounds as if exterior moisture is condensing on the siding. What was the problem with the siding installation? Perhaps a paint with a Mildecide would help.

 

[losthenfound]

This sounds like moisture that just may be eminating from the inside of the home. Some homes do have undue amounts of moisture and the pressure during the winter months is tremendous, especially with new window technology, etc. External vapor barriers, many times act to inhibit this moisture from escaping and it can freeze beneath the siding. The moisture begins to move outward in the warm months and onto the outside of the building. The algea is usually present on most homes in a given area. Also, if you tear off siding on a few homes in a given area, you just may find high moisture and rot beneath many of the same homes in a given area. High water table may be an explanation, and so could lack of vapor barrier beneath the slab in basement or crawlspace (especially on ranch homes). Check your heater for humidifier, etc. ALso, sometimes the moisture can be rising up from the ground during certain times of the season. Schrubs hold ground moisture and release it when the sun heats up - to feed the algea.......Some ideas

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[haynewp]

Our house and the other ones in our neighborhood have the same problem with Hardiplank. I thought is was mold.

 

[casseopeia]

I would look at this from a different angle. You will always have moisture and algae present to varying degrees outside.

I think there is a possibility that the painter did not prepare the siding properly, such as removing algae by powerwashing with diluted bleach, or using an inappropriate, non-approved product.

Algae, mildew and mold typically prefer higher oganic content (like linseed oil). They do not like 100% acrylic paints. They grow better on flat-painted surfaces than on gloss. If your area allows mildewcide in the paint, it should be there.

I would remove a section of siding and have it examined by a paint consultant. If the algae originated below the shop primer, it may be Hardiplnak's problem. On top of the shop primer, it would most likely be the painter.

Also, powerwashing every year will prematurely wear the paint surface, exacerbating the problem with the algae growth.

 

[danace99]

Hmm. This is bad news for me. I just bought 4 squares of Hardiplank for the north side of my house because the old siding (hardboard) developed moisture problems. James Hardi Co. recommends 100% acrylic paint in their tech paper, but I already have latex paint for the whole house. I called their tech phone number and the person said latex would be OK but I don't think he gave it much thought. Acrylic is often used as concrete floor paint so it makes sense since Hardiplank is cementitious. I guess I will have to research this some more before I start installing.