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iowa
Exterior paint failure

We had the aluminum siding removed from our 100-year old house four years ago. We bought a reliable national brand paint. Almost immediately the paint started detaching from the wood. The paint store manager sent a specimen to their lab. The response was that maybe it was moisture. The paint has deteriorated further and we need to do something. Any suggestions on how we should proceed?

Jeanne
Re: Exterior paint failure

What kind of prep work was done before painting the house? Was it scra ped and primed? Do you know what kind of primer was used? Do you know what kind of paint was previously on the house (oil / latex)? Is the paint peeling everywhere or just in some areas? Was the old paint peeling under the siding?

If you could provide a little more info it would help. Paint can fail from moisture, but also from a poor or improper paint prep. I am not the paint expert, so after you answer the questions, one of the more experienced guys can help.

iowa
Re: Exterior paint failure

The paint under the siding was probably oilbase since the siding was installed in the 60s (my guess). There was some damage under the siding and some wood was replaced. With the siding removed the house was sc****d and primed, then painted with an exterior flat latex. After we noticed problems (a year or two later), we had the paint store send in a sample to analyze. Paint was coming off both on old wood and on wood on a new addition although less so. At that point we decided to have the loose paint removed, washed where necessary, sanded, primed, caulked and painted. We are having the same problem now. There is some laddering, but mostly it seems to be just paint peeling off the wo

After paying to have the house painted twice, would we be better off to have all of the siding replaced?

dj1
Re: Exterior paint failure

Question: After removing the aluminium siding, you had "wood". Do you know what kind of wood?

iowa
Re: Exterior paint failure
dj1 wrote:

Question: After removing the aluminium siding, you had "wood". Do you know what kind of wood?

No idea. There are two widths of wood separated by trim about 5 feet off the ground. The house is a story and a half, and built in 1910.

Mastercarpentry
Re: Exterior paint failure

There are a number of reasons the paint could be failing. The #1 cause is moisture, far and away the most common reason. Most latex paints do very poorly if what's underneath it gets wet (which isn't supposed to be happening so don't blame the paint). Most latex paints will not adhere to oil paint underneath them (which is why you must use the correct primer to switch from oil to latex- it sticks to both). Another cause is applying the top coat before the primer has completely cured- even though it looks and feels dry it may be uncured below the surface. The primer's instructions will tell you how long to wait. Cover it too soon and it will attempt to cure without an outlet for the gasses curing creates which prevent the top coat from bonding. A chalky surface will not provide a bond for primer or paint. Other contaminants like oil or certain pesticides also do this.

Without seeing it I can't say more, but from afar I'll bet on moisture behind the paint. If that is it, you've got to figure out how to keep the wood dryer. Only then will a repaint (including prep and the correct primer) do it's stuff for you. With proper prep, even without primer, I have almost never seen paint fail on wood unless it was really wet, but I've seen what was under the new paint fail frequently. That is why prepwork is critical. Great prep and cheap paint will outlast the best paint and improper prep. If you spend 2/3 of the time prepping and 1/3 painting you're probably prepping well. Much less and you're missing something and it might bite you back a few years down the road.

Phil

ordjen
Re: Exterior paint failure

I would agree that in the great majority of cases, moisture is involved when the peeling is to bare wood.

A hundred year old house would typically have virtually no insulation or vapor barrier. All the moisture that is generated within a household from laundry, showering, cooking and even breathing, tries to migrate to the exterior. In colder climates it condences or even freezes on the back side of the sheathing or siding. Come the warm months with the sun beating on that siding and that moisture wants out NOW! the result is peeling paint.

Oil paints were unfortuantely a very good vapor barrier on the wrong side of the wall. Especially after several coats over the years, it prfevented vapor from passing on through to the exterior. Modern acrylic paints are far more permeable and let the moisture pass on through without peeling, if good adhesion to the wood was gotten in the first place.

There is a scenario which can cause massive paint failure with peeling to bare wood which is not particularly moisture related: Oil paints dry hard, brittle and non-elastic. After many layers, it is especially brittle. With the advent of modern latex paints, people began to switch over to the water based acrylics. Acrylics have very good adhesion. Acrylics are also very elastic. When the sun beats on the acrylic paint, it begins to expand, the oil paint does not. The result is that the acrylic paint can break the bond of the oil paint right down to the bare wood.

A few yeas ago, there was an episode of TOH where I new type of paint stripper was used that used this phenominum. A clear resin was sprayed on the siding and allowed to dry overnight. The layer of stripper literally broke the bond of the old paint to where it could be zipped off with a sc****r. The stuff was non-toxic, sprayed on and then removed dry the next morning with the old paint.

In the case of the posters home which was covered with aluminum siding for 40 years, it might well be that oil paint was being painted over for the first time with acylic. The 60's were the dacade when acylics/latexes were starting to get a foot hold.

It is also possible that both "normal" moisture related peeling and paint stress related peeling are occurring simultaneously.

Getting down to bare wood is definitely the ideal. I would personally prime with a conventional oil exterior primer, and then finish coat with a a good 100% acrylic housepaint.

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