Exterior House Painting ?

Hello,
Live in Mass.
Will be having the exterior of our house repainted. Latex paint.
a. Was wondering about how "absolutely" dry the horiz. Clapboards of the house must be after a rain before I allow the painter to put on the new paint.
Worried, of course, about adhesion to the old, existing paint that is on there now.
Does the fact that we will again be using Latex Paint make this a minor point,as the Clapboards can be somewhat "moist" still on their surface ?
Or, should/must they be absolutely dried out first ?
Would take several days, I imagine to achieve a really totally dry state,and I imagine the Painter would be putting a lot of pressure on saying "it's O.K. even if a little damp, etc."
Same question for the areas where the paint has peeled, and the new paint will be going over the bare wood Clapboards ?
b. Let me also ask this, please: Lots of paint peeling of existing paint. How is this handled, for new paint.
Does one just hope that the new paint is going over areas of old paint that still adheres to the clapboards, or is there some "treatment" to put on first, or...?
Scared about having the house prerssure washed first. Would this likely cause even additional peeling ?
Much thanks,really appreciate your help and comments, Bob
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On 04/17/2016 06:02 AM, Bob wrote:

<snip>
Though I'd not call my self an expert, my buddies and I worked our way through college by painting houses.
The peeling paint must be thoroughly scraped first. We used scrapers and coarse wire brushes.
Next, the bare areas were primed, then we'd make sure everything was dry.
Then we'd do the actual painting.
We generally painted on hot, sunny days and got good results.
It would not have occurred to us to paint unless the surface was completely dry.
We'd often go back to check even a year or two later...all looked good.
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On Sunday, April 17, 2016 at 7:02:55 AM UTC-4, Bob wrote:

They must be thoroughly dried out. The new paint needs to go into the surface. If it's dry, the excess moisture that's already there will prevent the paint from properly integrating itself into the surface and bonding. Latex paint is probably more tolerant, but read any paint can instructions and they say it has to be dry.

That depends on how wet it got, what the conditions after are and where exactly on the house you're painting. If it was raining in the morning on a warm sunny day, followed by low humidity and a breeze, you're probably OK to start the next day. If it was a soaking, driving rain, followed by 50F temps, cloudy, high humidity, then it may take a couple days. If it was after power washing it, then even longer is typical. You can get an idea by touching it, to some extent. Or there are moisture meters and a pro may have one. It's definitely not OK if it's a "little damp". It should feel dry to the touch for sure.

Prep is the most important part. First it should be power-washed, using a detergent made for the purpose that includes a mildewcide. I like Jomax. Then any loose paint areas must be scraped/sanded, etc. Then primed. For priming those areas, I like PeelBond, which is a very thick primer. It helps level the transition areas from bare wood to where there is paint, so even if it's not sanded perfectly, it will look much better, more uniform. On areas that are not as visible, eg high up gables, you can even use it with good results with just scraping, no sanding. Any areas that need to be caulked, filled, etc should be done.

The power-washing, scrapping, etc should have gotten rid of the paint that won't stick.

Yes, and that's what you want. Paint that can't stand up to the power-washing needs to come off. That's with the correct pressure, obviously. If you don't know what you're doing, you can easily damage the wood with too high a pressure, getting too close, etc. I'd wait about 4 days after power-washing to paint, assuming it's reasonable weather for those days. Usually that's not a problem, because there is prep work or the painter has other jobs, etc.

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Existing paint won't stay wet for long. Bare wood should be allowed to dry and then primed first, preferably with linseed oil primer, which should then dry for a couple of days.
Loose paint: Scraping needs to be done first, to look for and scrape off anything that's starting to peel.
Powerwashing can do some damage, but it's also a popular method. I wouldn't do it myself. If it needs washing I use TSP solution by hand, and bleach for mildew. Areas in the open generally don't need washing. (Or at least they didn't used to need it, before it became easy to point a powerwashing hose at the side of the house and blast away. :)
I wonder why you're so worried, though. It sounds like you haven't even hired a contractor yet, but you already distrust their competence. You're asking random people in a newsgroup to decide how your house should be painted. Maybe you just routinely distrust people? That's not going to be a good way to get along with the contractor -- second guessing how he does the work. You don't have to be a sucker, but you should try to find someone you trust and then just keep an eye on him without being a busybody.
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On Sunday, April 17, 2016 at 8:47:23 AM UTC-4, Mayayana wrote:

I disagree and I think you'll find almost every pro painter will too. Old paint oxidizes, what's there will come off with a good washing, leaving a better surface. It will also have dirt on it, even if you don't see it. Rub it with a white wet cloth and see what comes off.

I don't see anything wrong with asking questions, learning about the process. It's a good way to help prevent yourself from getting screwed.
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On 4/17/2016 7:02 AM, Bob wrote:

Did you hire a reputable painter or the kid down the street? A pro painter will have all the answers and do the job right. Pressure washing takes a bit of skill so you get rid of the dirt, loose paint, but you don't put gouges in the wood.
Latex paint is water based so a little moisture is not a big deal, but is should still be dry to the touch.
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