Cleaning siding

firsthomegal

There are a lot of products and home recipes for cleaning exterior painted wood siding prior to repainting. What do experienced painters recommend for cleaning off the chalking and dirt? TSP? Sodium carbonate (main ingredient in a product at Home Depot)? A home brew?

Also, can you damage your siding using a power washer? Is there anything I should be cautious of?

RAD Systems

TSP or TSP substitute (which is sodium metasilicate) are both good cleaners for paint prep. If your wood is exposed it should be neutralized with an acidc based deck cleaner (look for something that contains oxalic or citric acid.

You can use a pressure washer but its not neccesary unless you have flaking paint. Always keep your pressue under 800 psi (done with the right nozles) and you will be fine.

slickshift

You can destroy wood siding rather quickly if you are not careful with the PWer

firsthomegal

Can you recognize the damage when it is happening? Or does it just show up later?

Is the problem with damage only with exposed wood or can you also damage the old paint surface, affecting the end quality of the new paint job?

RAD Systems

The damage will be evidenced in a couple of ways.

If you use pressure that is too high you will damage the wood. You will see splintering etc.

The other is a bit more insidious. You can drive water under the siding and wet the substrate. This can result in expensive mold remediation down the line.

If your goal is just removing paint oxidation (no flaking) then let your chemical do the work. Use a garden hose to rinse. Watch your plants and glass. TSP can etch. You should also use bleach in your house wash mixture.

firsthomegal

There is only one side of the house that has a fair amount of flaking, the exposed south side.

Does the TSP substitute also etch?

The sprayer I bought is 1550 psi. The wand has two settings, "high pressure fan" and "jet stream." I assume that "jet stream" is unwise. However, a previous post recommended no more than 800 psi. Should I return the sprayer? Is this too much risk for someone new to this type of project? I can't afford a more expensive sprayer, so I would need to scrub and scrape the house by hand (it's not a huge house, but still a good sized job for one person).

RAD Systems

That machine will be similar to using a water pic to wash a sink full of dishes (in terms of production rate). I would return the machine and use the money to rent a decent machine with higher flow. A machine that outputs 4 gpm per minute can be had for $65 per day. When you rent the machine ask for larger orifice nozzles to drop the pressure leaving the gun.