Chemical/Paint Paint bubbling off wood beam DIY help

[OmCheeto]

Ha! We've currently got a "bubbling off" problem here in town, that makes your problem seem, um, kind of trivial.

[ref]

ps. Contact @phinds . He's knows wood.

 

[Wes Tausend]

As you can see from the image a vertical portion of my wall (a wood beam) has developed this vertical bubbling where the paint is being rejected. It spans from the ceiling to floor. First thing I thought of was water damage, but as I chip away at the paint and get to the wood it doesn't seem like there is obvious damage, but maybe it's further in the wood? Any other reasons this is happening? Do I simply keep chipping away, then slab a bit of spackle on the plaster and repaint?

Greg,

I have an argument, biased perhaps. Food for thought.

It takes a bit of thinking, but much of paint-peeling is likely due to the vapor pressure of water. It is quite powerful in it's effect, note the power of steam which is just a vapor, a rather hot vapor. A steam engine is a water vapor powered machine that depends on temperature differences. Certainly the applied heat is faster in such an engine, but cooler vapor pressure can easily slowly lift a weak-toothed paint at much lower temperature differences. That is why it often looks blistered. It doesn't naturally curl that way, it is ballooned by thermodynamics. If it just flakes off, it wasn't bent or ballooned because it didn't stick at all.

I'm not sure where you live, but in your case, if you are in California, it may have been quite wet (and warm) outside this year. Contrast that to the low, comfortable humidity you have tried to maintain within your home. Vapor pressure in buildings vs. outside is often described as the pressure between low and high humidity. Water likes cold. If high outside humidity migrated through your porous wooden beam from the warm outside, seeking cool, it would hit a barrier when it "bunched-up" (by partially condensing) right behind the AC-cooled difficult-to-penetrate-film of oil paint. That is because most oil paints naturally have a very low permeability rating (to water vapor). Low permeability means that the vapor can only most slowly migrate through a substance.

If, for some reason, the interior temperature rises (sunlight ect.), the water vapor cannot quickly "back-up", that is escape back through the wood beam, and a relentless vapor pressure develops. Note this method is quite successful in removing wall-paper. One soaks the wall, then quickly heats the paper with an iron. The heated moisture cannot all escape quickly enough through comparatively slow migration and expansion literally lifts the paper off the wall in a hurry. The same process sometimes lifts the paper off the wall in a slower manner without human help. Paper and paint don't always just fall off; they are often pushed.

Properly protecting homes is different in the north vs. the south. Wall cavities (including a solid beam, or 2x4) can accumulate moisture in two ways. In the south, warm outside humidity tries to permeate towards the AC cooled interior. In the north, the inside human-created humidity tries to permeate from the warm, moist interior to the cold, dry exterior. Somewhere in the middle may lie the Dew Point where wet forms. The secret to control is to apply a vapor barrier (usually translucent polyethylene sheet) to the warm side of the wall where the humidity is still dry (not condensed). In the south this is often right under the exterior siding, stucco or brick. In the north this barrier belongs directly under the plaster lath, or more commonly, drywall (ex: Sheetrock brand). Either way the humidity is not allowed to reach the cool core where the dew point resides. The reasoning is that all humidity is actually dry. When it cools and reaches the dew point, it becomes wet; ready to warm up, re-vaporize and lift a coating.

SOME TRIVIA:
As an example, prior to 1974 fuel was cheap and plentiful, many homes had little insulation and leaky doors and windows. At the same time most of the financing used to be provided by the Fed; FmHA (Farmers Home Administration) and FHA (Federal Housing Administration). Likely because of the close government relationship, homes became forcibly spec'd with much better sealed doors and windows.

The vapor problem then became pandemic in the northern climes after the 1974 oil crisis hit and homes were suddenly spec'd to be sealed better and more fuel efficient. Suddenly expensive home heat was retained -- but so was home moisture -- laundry, floor cleaning, cooking, bathing and plain old human respiration. I have read reports of humidity estimated to be a release of about one gallon of water per person per day, a huge quantity that no longer accidentally dissipated harmlessly outside. Excess humidity has since damaged ceilings, walls, windows and wall cavities with mold and rot. It has lifted exterior paint off the surface. But for the record, overall it is a good thing. Modern northern homes are starting to be built with whole-house air interchangers, a type of venting that retains heat while replacing stale, moist air. Indoor humidity is kept at more moderate, safer levels.

FYI, dry humidity is lighter than air. Composed of a single oxygen atom and two puny hydrogen atoms, the dry water molecule "weighs less", I believe rather is less dense per volume than O₂ or N₂ which composes 99% of our atmosphere. O₂ is usually found as a heavier bound pair and the same for N₂. Consequently the dry water molecule "floats to the top" -- rises -- after evaporating. Finally clouds form as the humidity cools, but not clouds of dry water. Clouds are actually small wet, water droplets that are still apparently still lighter (or as light) than ordinary air as long as they stay small. Fog, nearer the ground, is identical -- tiny wet droplets. When the droplets coagulate to drops, it rains. Or in the case of condensation inside a wall, the water often semi-dissolves some solids like plaster. If the wetted substance is heated the least, a dry vapor pressure is again formed out of wet water. Hot steam, cold steam, tepid vapor -- they are all dry by nature -- and powerful.

I once read that Egyptians drove a wood wedge in a crack in stone. When water was added, the wood expanded and the stone cracked. I have witnessed moist wooden Fink ceiling trusses lift a center wall up off the centerline of a house. The power of water.

I spent about 25 years self-employed as a subcontractor, usually plaster, drywall and paint. I was that guy that people blamed when it didn't go right. I spent a lot of time studying and explaining what really happened as best I could. This may post be long but it is by far the short story.

Wes
...

 

[Rive]

New update, it's not a beam, but a hallow wood encasement that encloses a radiator pipe. I still don't see any sign of water damage.

Temperature changes does the same as humidity changes. Wood contracts then expands, and the (far too old, thick and rigid) paint sandwich develops cracks, then peels off.

It is often enough to paint over, but at some point you will have to get rid of all the previous layers first.
Not as if the new layer won't develop cracks too, but at least it is not so visible if it is just one layer ---

 

[Wes Tausend]

Temperature changes does the same as humidity changes. Wood contracts then expands, and the (far too old, thick and rigid) paint sandwich develops cracks, then peels off.

It is often enough to paint over, but at some point you will have to get rid of all the previous layers first.
Not as if the new layer won't develop cracks too, but at least it is not so visible if it is just one layer ---

I can attest to the fact of temperature change problems you've mentioned also.

This type question may be particularly perused by homeowners searching for answers to fractures (cracks) and adhesion failures well into the future, so if no one minds, I'll add more info on moisture too because it goes hand-in-hand with temperature and climate. In a way this post may better fit under a landscaping and/or foundation thread prefix.

Regarding temperature, in some cases home developers in my area decided to try saving time or money by building soffits formed with only particle board to hide exposed ductwork, in some types of basements. Their plans were usually to have a company like mine use paper drywall tape to cover the joints and then finish directly over the wood product like what would be done over a wall/ceiling. There were two major downsides to this and I highly recommended against doing this. One downside is that paraffin wax is added to the oatmeal-like board mix during manufacture, possibly to semi-resist water. Consequently, the low adhesion of water-based mud compound (plaster) used to apply the tape, did not stick well to the wood because of the wax. The other downside is that these boards expand in all directions (since the fiber is random and the resin is a type of plastic) and apparently expand more than the paper tape (also wood fiber), a common characteristic of most plastics.

The installed paper tape seemed to pop off the wood surface after the first heating season similar to a flake. Since the tape didn't appear to blister, the loss of adhesion seems uniform, a shear. Still, there is also the very real possibility that humidity caused some pressure, driven from the hot core, presenting another case of moisture expansion lifting the weak, waxed, adhesive point; the plane of wood to compound. The paraffin itself can also have gassed or a multiple combination of volatiles ensued. Under the dry, protected temperate conditions where the paper tape works as intended, I have read it will hold about 25 pounds of tension per lineal inch of joint, still not much considering all the possible forces of defeat.

Further Comments:
FYI, plywood worked a little better, but I usually encouraged the use of proper framed gypsum sheet anyway. Gypsum (otherwise known as plaster of Paris) is the standard self-hardener for all interior plasters, with portland cement being preferred outdoors. The gypsum sheet is safer than wood products because it is fire resistant, unlike wood which is fuel. Also note that all the water used in mixing gypsum, is released when gypsum is heated to the boiling temperature (This boiling-off must be done to the raw mined product to prep it for consumer use). Then just like a kettle of water, the outer sheet surface can therefore get no hotter than about 212⁰ F (100⁰ C) even if a much hotter flame is right behind the inner surface... that is until it runs out of water. So this suspended transition state is true of a boiling kettle or gypsum wall. The resulting retarding effect then suppresses flashover, slows home and industrial fires and has made a world of difference in saving lives, especially when it was finally also applied to mobile homes. Gypsum should therefore always be applied behind wood decorated walls just to slow fire from blowing through the entire building, room-to-room. Gypsum is a dry built-in sprinkler system.

In my experience of a variety of home troubles, I have grown to believe a main culprit is the vague action of water molecules, hidden behaviors that are not so obvious. To give him credit, jim mcnamara had earlier mentioned (post #27) the migration problem and I mostly agree with him.

One other point to add: Tyvek is not really a general moisture barrier... it is a specific barrier to condensed, wet water... but not dry water vapor. This outer-house-wrap serves the identical purpose that GoreTex does, only for home "socks", not foot socks for people. The Tyvek resists water leaks that may occur around windows, doors and other breaches on the outside. Just as importantly it resists wind-pressure air movements that tend to make the walls breathe too much and defeat loose fill insulations. But any humidity that accidently gets past the low permeable interior moisture barrier (generally polyethylene sheet, Visqueen brand for example, NEVER Tyvek) can migrate outside through the Tyvek with ease and continue to dissipate without creating wall cavity moisture build-up. The Tyvek "perspires" the vapor away... just as Gore-Tex does for sweaty human feet. Yet like Gore-Tex, Tyvek keeps wet water out. The common trick of both is tiny perforations, big enough for single vapor molecules, too small for condensed water droplets.

Story:
Yesterday I watched an OR video in an adjacent room as my wife underwent cataract surgery. In the room was an attendent, an elderly (more elderly than me) lady who, when I responded to her questions on what types of work I have done, immediately mentioned she recently had developed a mysterious cracking problem with her home.

Since the lady mentioned it seemed random throughout her house and included interior walls, I suggested the home foundation was probably moving, which has given me many headaches over the years. Her eyes lit up and she then offered that, to repair the floor covering, her husband had already ground parts of the old basement floor back to level after it recently bulged.
Have any here ever wondered and thought about why their basement floor not only bulges (aha, the old blister effect) and occasionally even leaks water?
In her case there is a possibility that her newly installed sprinkler system is contributing to the issue. One has to understand the home history to know the likely cause.

After a foundation is dug, first the footings and later the concrete walls are poured. Any foundation must be at least four feet deep in cold country, hopefully below the frost line. Because there is a real fear of the yet unsupported open-top soft green walls caving in, the hurried landscaper oh-so gingerly pushes the clay back around the outside edge so that framers can conveniently work and add a sturdy flooring deck across the top... which then helps support the center top of the walls from caving in from soil pressure. Even then, sometimes an untimely rainstorm will be too much for the not-fully-cured cement..

Cave-in is a traumatic thing. Unfortunately, because of the cave-in fear and the hurry, the clay fill near the foundation is often never packed well, so it naturally settles later. If this flaw is not specifically corrected, it can become a major problem later. This scenario would mean that the newly established landscape "clay pan", the natural barrier to water which acts as the yard sub-drain system, now funnels water toward the foundation. Of course to compound this case, when the sandy, loamy topsoil is added, the dip near the foundation is often hurridly leveled with this more porous black soil -- not good. Problems from this arise during rainy seasons and sometimes from new sprinkler systems. The cure is to correct the entire base angle of drainfield away from the home. Hard work and quite pricy if not DIY.

BillTre hit the nail on the head in post #3. Water can be nefarious. As the climate changes, water tables also change over the years and homes nearly a century old can start moving because the clay layers that the foundation sits on, may slowly absorb water and swell. Unfortunately the lady I met is alone now and, if this condition is true, this type fix is to laboriously install drain tile near the footings and then install a sump pump in a collector... which can also be rather expensive if one cannot DIY.

Wes
...