House Painting - surface preparation

[Glenn9643]

I'm preparing to do the deed, and have several areas with peeling and flaking paint. Removing dirt dauber nests will be a bigger task than removing the bad paint. A manual scraper is out of the question for physical reasons.
I have a couple of pneumatic sanders and a decent compressor. One is a "jitterbug" sander, and the other is a 6" random orbital sander. I've used both for automotive body work in the past, but never for anything like this. I do like the thought of being able to use the sanders along with water if need be.
Before I drag out the compressor, hose, etc. and try this, I thought I'd see if others had and what the thoughts were on it.

 

[Melensdad]

Glenn I had my house painted 2 years ago, so I only watched it being done (I'm a chicken on a ladder and the back wall of the house is 3 stories tall). I also got to be friends with the painter. He told me not to wet the wood and one of the biggest things that he has seen cause problems is water on the wood before painting. Especially pressure washing. I'd stick with a heavy wire brush for the mud daubers, a medium wire brush and/or air sanders for paint flaking areas.

 

[Glenn9643]

I'm aware of the problems caused by pressure washers. I'll probably try using the Sthil backpack blower to eliminate dust and spiderwebs instead of water. I've got scaffolding lined up, and I don't think I'll need to go over two sets high. As for the wire brush, I've not been overly impressed with the brushes you can put on a side-grinder... too many pieces of wire flying about. After knocking the nest off with a froe I think medium sandpaper should get the remaining dirt off the building. I'm trying to find the method that requires the least amount of repetitive physical motion/exertion. I have some damaged nerves in my right arm and scraping with a scraper or using a brush for a little while is not good if it can be avoided.

 

[buckle97]

I also got to be friends with the painter.

I have a question for Bob's painter: How do I get rid of all the mildew without wetting the wood? I think (and my wife knows) I need to paint our house by the end of the summer. Living in south Mississippi, our white house gets plenty of mildew on it that has to be removed every year. I use a bleach/water solution and then wash it off with the hose. I assumed I would do this, then scrape the house, then prime and paint.
Glenn, I assume you have mildew problems in your area as well?
I have plenty of flaking paint, so I'm sure I will get plenty of experience with a wire brush.

Lawrence

 

[Melensdad]

I'd have to track him down at chuch one Sunday to ask the question, but I was referring to the fact that he said that often people pressure wash their house and then paint it a day or two later. Obviously rain gets a house wet, washing it does too. But pressure washing gets water into all sorts or cracks and crevices and into the wood grain itself. And if you are not careful, it damages the wood too.

His concern was that the wood must be properly dry to paint.

In your case, you probably want to scrub it down or pressure wash the mildew off, but you'd also need to make sure the water is completely evaporated before you paint. So pressure wash (at lower than maximum pressure) but then I would bet he would tell you to let it dry for a week or maybe 2 weeks before painting.

That is what I interpreted his point to be when he and I were talking about pressure washing houses. He simply doesn't do it.

BTW, there are paints and primers that kill mildew, you might want to look at some of those. KILZ is one of them that I know of.

 

[buckle97]

In your case, you probably want to scrub it down or pressure wash the mildew off, but you'd also need to make sure the water is completely evaporated before you paint.

Okay, I've got it now. The way my time has been limited lately, there's no way I would be able to start painting within two weeks of pressure washing . I think painting over the mildew would be just as bad as painting over semi wet wood. I will plan to kill the mildew and then spend a few weeks scraping before I apply any paint.

BTW, there are paints and primers that kill mildew, you might want to look at some of those. KILZ is one of them that I know of.

That's a good one Bob. Unfortunately in my area, there is no such thing as no mildew. The last time I painted my back porch I used Kilz Premium and then a mildew resistant paint. Turns out it helped; I think the mildew resisted for about three weeks longer than it did before I painted

 

[Glenn9643]

I just noticed you are in McComb Buckle; I have a house in New Hebron, northern part of Lawrence County, about 55 miles from you.
Yes, we have plenty of mildew, both here and the place in MS. It's my understanding that the flaking and peeling paint is caused by moisture in the wood, so I'm planning to clean out damaged caulk and redo all the caulking prior to washing to kill the mildew. For that I'll use Jomax or TSP mixed with bleach/water in a backpack sprayer and rinse with the hose. No pressure washer.

 

[buckle97]

I have a house in New Hebron, northern part of Lawrence County, about 55 miles from you.

Well then, we are practically neighbors .

 

[RoadKing]

I pushed a brush professionally for about twenty years. I'd like to comment on a few points.

1. water is not an enemy of latex paint. On real hot days 90 degrees + I would hose down a house before painting to help the paint adhere and soak in rather than dry from the outside from the heat. Although powerwashing does force water into the grain so I would not paint right after powerwashing also I would not powerwash with anything bu plain water.

2. I've found nothing that kills mildew better than bleach. Anyone who gets mildew or mold in their bathroom or shower area may I suggest painting with oil base paint as mold will not grow on oil base paint. It's a little more work but saves a lot of work down the road.

3. Spend some money on good brushes. I know of no tool that is more labor intensive than a paintbrush. A good brush will do a better job in much less time.

 

[buckle97]

Thanks for the great tips RoadKing .

 

[Glenn9643]

RoadKing,
I too appreciate the pointers. I'm aware that latex paint is "water-based" but didn't know about hosing down to help the paint adhere and soak in. Just about all of our days now will be 90 degrees +.
Is my understanding that the flaking and peeling paint is caused by moisture in the wood correct for latex paints? If not, what is the cause? I would do this job right and have it behind me for a few years.

 

[RoadKing]

RoadKing,
Is my understanding that the flaking and peeling paint is caused by moisture in the wood correct for latex paints? If not, what is the cause? I would do this job right and have it behind me for a few years.

I got this theory years ago from a troubleshooter for Benjamin Moore. He told me that peeling and flaking is a result of two things.
1. The actual weight of paint layers - multiple coatsweighing more than a previous coat can hold to the surface. Example: one too many coats hung on the same hook will cause it to pull out of the wall.

2. Paint like everything else shrinks and expands with heat & cold. When one layer is shrinking more than a previous coat, this puts stress one the early coat and may cause it to split & lift at a weak point.

I'm no scientist, but I have experience with this guy solving some paint & stain problems that were pretty unique so I would tend to take what he told me as true.

Here's an old recipe I still use for an exterior stain/preservative for bulkheads, trailer floors, sheds etc.
1 part boiled linseed oil + 2 parts paint thinner or kerosene + 1 part exterior oil base enamel your choice of color.
This makes a semi opaque stain that will take a lot weather and protect the wood.

 

[mtntopper]

Here's an old recipe I still use for an exterior stain/preservative for bulkheads, trailer floors, sheds etc.
1 part boiled linseed oil + 2 parts paint thinner or kerosene + 1 part exterior oil base enamel your choice of color.
This makes a semi opaque stain that will take a lot weather and protect the wood.

I have used the linseed and thinner on my wooden trailer decks for years. They do hold up very good in the weather. Tends to be a little slick for a few months and then it is okay. Never have added the oil base paint to the mix yet, might give it a try next time. Thanks for your input!!!