House Washing Mixture


Is that vinyl or aluminum siding?


It could be that your mix is not strong enough or it could be oxidation. Try a stronger mix see if that helps, then use an extension pole and do a light scrub. Ive had some dark areas i just need to scrub then rinse.

If that does not work, use a ladder to get up their and run your finger/hand across it and see if it chalks up. You may want to do this first before your scrub so if it is oxidation your dont make it worse.

Also the fascia board still look dirty, hit it with a 4%+ mix and it will clean up

And for the guys who dont know this is hardiplank siding. It cleans up similar to vinyl, but it takes a stronger mix to clean.


Hey Donte55

When you say 4% mix, whats that mean? Im confused about the mixes.


It is hardi plank siding. I’ll check for oxidation and let you know if a bleach rag cleans things up. Not sure if I can reach the boards under the roof. Ideas?


X jet and a 4 gpm+ machine.


Nailed it. Hardiplank has a coating that’s not quite paint, but not quite vinyl. Some other polymer? I can’t wrap my caveman brain around what it is exactly I just know I can clean it.

Ever see the PVC/wood composite trim boards? What a time to be alive. Lol


Hardiplank is just cement siding. It has whatever paint the builder or homeowner has applied to it. Nothin special.


It means the strength hitting the surface should be 4%. This also means direct apply and NOT downstreaming. You can direct apply with a pump up sprayer, 12V pump, Air diaphragm, booster pump, or gas driven (Comet/udor). These systems dont add extra water to the stream like downstream or xjeting does. What ever the strength is in the mix tank, is the strength that will hit the wall.

So if you start off with a 100 gall mix tank and are using 10%SH to get 4% you would add 60 gallons of water and 40 gallons of SH. In a ten gallon tank it would be 6 gallons of water to 4 gallons of SH.

Even though you do need to know about what your mixes are don’t let ratios overwhelm you. In my pump up i usually just pour some SH/Water and go to town. Need stronger i just add some more.


i use a pump up on the fascia board, with my pump up’s i can reach 2 story’s in no wind.
The other thing you can do is put some on a brush and scrub it.


Ok that makes sense. Its turning 10%SH into 4%SH. Thanks for explaining, very helpful. I was thinking along the lines of house mix, like 1 gallon SH to two gallons of water.


Good to know. That explains why it feels different to the touch though. Thanks!


So whats the best way to clean hardi plank…I just got a call to do a home in a newer developement. with hundreds of the same houses potentially. The paint is oxidized…from my experience with aluminum siding, its gonna suck…


best mixture I should say…


Just use your house wash mix and you will be ok.


What does is mean if it does chalk up on alumonum like garage doors?


yep, I do a lot of it down here. Treat it just like vinyl except I tend to go a little weaker on mix. If it’s some weird color do a test. Some SW paints react weird on it when you wash so do test someplace inconspicuous.


What do you use?

How effective is it ?

Is it literally apply, dwell and rinse?


Be careful because I’ve heard of contractors using cheap paint on new hardi plank siding and it can lighten with SH or pressure. I haven’t experienced it yet and it could just be a local problem by me.


What do you use then if not SH?


It’s my belief IBS has left the forum. He never said he didn’t use SH.