house washing, need fast advice!

[ghouchu]

i've been pressure washing roughly a month--flat pavement and a few decks so far. i use a cold water devilbiss 3500,4gpm, with a honda 13hp engine. i've now been asked to do my first house, one story, wood(board and batten(sp?), not shingle), and roughly 2000 sq ft. it's for my brother's mother-in-law, a real stickler. her principal concern is that the paint not be damaged--the object is to remove mildew, not to prep the house for painting.

as i understand it, the basic approach is to wet down thoroughly the flora around the house so as to prevent damage from the chemicals; spray a portion or the house with your chemical--working from bottom to top(?); give your chemical time to do its job (15 minutes?) but not time to dry out (need to re-wet it?); rinse well with pressure washer, being careful to avoid excessive pressure; rinse down the flora again.

first, what chemicals are best? i noticed a reference to bleach and a TSP, but don't know what a TSP is. any recommendations for a good commercial cleaner, or a recipe for a home-made mixture will be greatly appreciated.

second, near as i can tell, the chemical applicator on my pw is not calibrated, so there is no way to determine what water-to- chemical ratio is being sprayed. i can't even find an indication of what mix results when the chemical applicator is wide open. suggestions?

third, what is the risk that the chemical will fade the paint on the house? if there is a risk, i assume it's a function of both the strength of the chemical and how long you leave the chemical on. is there a risk and how can i best minimize it?

fourth, what about the amount of pressure? i figure to use the 40 degree nozzle on my wand, start well back, and slowly move closer until i achieve sufficient pressure to rinse off the mildew that has been loosened by the chemical. in the spirit of better safe than sorry, i expect to rely on repeated application or the chemical, rather than high pressure, to remove the mildew completely(unless the risk of fading the paint is greater than the risk of removing the paint). that approach has worked for me on the two relatively small retaining walls i've done.

fifth, i don't have any idea about how long it will take me so i have no clue what to charge. any thoughts?

finally, should i give the job a miss and wait until i can find a do-it-yourself painter who wants his house prepped with a good pressure washing, so that the amount of paint i knock off won't matter, nor will fading, and i can get a feel for the dynamics of pressure washing a house?

thanks for your help!

 

[JR Wood]

TSP is tri sodium phosphate it is available at any hardware or walmart or almost anywhere.
My house wsh mixture is like this
in a 5 gallon pale
3.5 gallons bleach one cup liquid tide(surfactant)1 cup sodium hydroxide(wolman deckstrip) half gallon sodium metasilate(look in various cleaning agents I use zep concrete cleaner,it also contains surfactants)

your injector ratio is between 7:1 to 13:1
just get three 5 gallon pails and see how much it takes to empty a gallon container.
with this mixture you should be able to rinse without getting too close.

 

[P Austin]

Other things to keep in mind... Use a test area, one that is inconspicuous prior to washing the entire home. This will give you an Idea of what you are up againced, and if for some unfortunate reason you make a small mistake it doesn't stand out like a sore thumb.
We like to start on the most easiest part of the home so we have a feal for how much work,cleaner, elbo grease to use when the hardest part of the home comes up. On most homes, this is normaly on end or the other (less surface area). We take our time and pay attention to how long we wait for chems to work. I am sure others have meathods that differ, but for us this has worked out well.

Good luck

Paul Austin
KNP Wash it
designe2001@yahoo.com

 

[ghouchu]

thanks, guys. i'm real tempted to to wait for a paint prep to be my first house so i can get some feel for what pressure takes off paint, chemicals fading the paint and the like. would that be smart or wimpy?

richard

 

[JR Wood]

There is no time like the present.In this business you are learning something new all the time.
Just test the chemicals and pressure on whatever you are working on.Every job will have a little variation and you are constantly adjusting chemical strength and pressure.I do it without even thinking about it.

 

[Bill B]

My house wash (with mildew/aglae present) is 2 gal 12% hypochlorite, 1 cup Dawn per 5 gallons of mix. I like JR's metasilicate idea. I use TSP when preparing for painting. Others use it all the time, but I personally think it dulls glossy paint (good when getting ready to repaint, bad otherwise). Also agree that you need to jump in there and try. I like your low reisk strategy. I frankly wouldn't worry about the $'s. The next job you do will go much faster. Bill B @In 'N Out Cleaning