vinyl siding

[PSUengineer1]

Thank you for your consideration.

I have attached two photos for reference to my question.

I observed alage growth on the north-facing elevation of a house clad with vinyl siding. Relative moisture readings at inside of exterior walls read about 50%. No roof leaks, no fractures in siding, no leaking windows, etc. Siding was not removed for inspection of house wrap (if any). Interior drywall not cut for inspection of insulation. No metal flashing installed at bottom of vinyl siding but I do see what appears to be vinyl siding installed over existing siding with weep holes drilled in both. Does anyone agree with what I am seeing here? One of the photos is at base of a bump out and the other photo is at transistion of vinyl siding to parge-coated block wall.

Additional notes:
High humidity in basement, ground water intrusion in basement, inadequate ground slopes around house (drainage), etc.

Thanks,
jimjxs263

 

[hokie66]

Fungal growth of some sort. Fungus likes to grow on dirt, and doesn't like UV light. So the north side (assuming you are in the northern hemisphere) of a dusty house is ideal for fungal growth. Where I am, the fungus grows on the south side.

 

[dik]

50% is way too high... you have to find out why it is getting in... and why it can't get out...

Dik

 

[tony1851]

Where I am, the fungus grows on the south side.


So by a process of deduction, one might reasonably assume you live in the southern hemisphere???

 

[ToadJones]

Algae or mildew (fungus)?
It's got nothing to do with moisture behind the siding.
This is as common as the day is long.
Mildew grows on vinyl siding where it is shaded.

Those weep holes were not drilled in the siding, siding is produced that way.
Vinyl siding is not water proof by any means and it sweats with changes in temperature.

Spray some watered down bleach on it with a garden sprayer and hose it down.
The mildew will disappear almost instantly with the bleach...add some TSP to get the beach surface tension to break a little..makes it "wetter" and will coat the siding better....

Oh, then remember to do this every year because you'll never stop this from happening where you live.

 

[ToadJones]

the other thing that I never understand is what people interpret as "high humidity"....where I live, you'd play hell for 9 months of the year keeping the humidity in your house down below 50%.

The other three months, your skin is cracking.

 

[DRWeig]

Same in my location, Toad. We can do the 50% in summer, but man o man it's expensive.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[dik]

Sorry... read that as moisture content, and not relative humidity...

Dik

 

[hokie66]

tony1851,
Yes, Brisbane.

50% RH is good. We don't have either heating or air conditioning, so live through the full cycle.

 

[SteelPE]

I have vinyl siding on my house. I get the green stuff on the side of the house all the time that isn't exposed to the sun. I heard about this produce called "Wet and Forget" which was developed in Australia (I think) and brought to the US. I tried it on some of the areas where the green stuff was growing and it did seem to work. In all, I think it lasted about 1 year before the green stuff stared to grow back. You might want to look into that.

 

[hokie66]

The "green stuff" will always grow back. It grows on the dirt, not on the vinyl. Dishwashing detergent or sugar soap and water are probably better solutions than bleach.