“It’s All the Painter’s Fault”
/What actually went wrong when this cedar siding was painted?
When paint fails prematurely, the first reaction is almost always the same:
“The painter did a bad job.”
That assumption is understandable. Paint is visible. Failure is visible. The person who applied it becomes the obvious culprit.
But in many cases, especially on older homes with cedar siding, the real problem has very little to do with workmanship. It has far more to do with building science, and with a wall system that was never meant to behave the way paint demands it behave.
In this case, the painter didn’t commit malpractice. He followed advice that is widely accepted in the industry. The real issue is that the advice itself was incomplete.
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Cedar is not just “another surface”
Cedar isn’t drywall. It isn’t fiber cement. It isn’t PVC trim. It’s a hygroscopic material, meaning it naturally absorbs and releases moisture depending on conditions.
In simpler terms, cedar gets wet sometimes, and that’s normal.
Most older cedar homes were built in an era when walls were relatively simple. They did not rely on tight air barriers, vapor retarders, or elaborate drainage layers. Instead, they relied on materials that could safely tolerate moisture and dry when conditions allowed.
Cedar was intentionally chosen because it could do exactly that.
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What changes when you paint older, previously unpainted cedar
Paint forms a film.
A film slows drying.
That isn’t inherently bad, but it becomes a problem when only one side of a system is changed.
It’s important to distinguish paint from penetrating stains and oils. Paint forms a continuous surface layer that restricts drying. Traditional exterior stains and oils soak into the wood and leave it vapor open, meaning moisture can still move in and out of the material.
On older homes, cedar siding is almost never sealed on all sides. The back of the boards, the cut ends, and the edges are typically raw wood. Moisture can still enter the siding from behind or through those unsealed areas, but once a film-forming finish like paint is applied to the exterior face, it cannot leave as easily.
Think of it like placing a sponge on a wet dish and covering only the top of the sponge with plastic wrap.
Water can still be absorbed from below. That absorption is called hygric loading, and by itself it’s not a problem. All porous building materials take on moisture at times.
What matters is what happens next.
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Hygric loading vs. hygric redistribution
Cedar is unusually tolerant of moisture because of how it evolved. As a living tree, cedar developed natural chemical compounds, often called extractives, that protect it from fungi and insects in consistently damp forest environments. These compounds are what give cedar its characteristic smell and its natural resistance to decay.
Just as important, cedar’s cellular structure allows it to absorb moisture, spread it out, and then release it again as conditions change. In nature, that ability helped the tree survive repeated wetting and drying cycles without breaking down quickly.
In building science, that movement of moisture within a material is called hygric redistribution.
If we go back to the sponge analogy, a sponge without plastic wrap doesn’t just absorb water. It also acts as a wick, pulling moisture away from the wet surface and promoting evaporation. In other words, it helps itself dry.
Cedar finished with penetrating stains or oils behaves the same way. It can take on moisture, redistribute it, and then release it.
When cedar is painted, hygric loading still occurs, but redistribution and drying are restricted. Moisture enters more easily than it exits. The wood stays wet longer, not because it got wetter, but because it can’t dry as efficiently.
The issue isn’t moisture itself.
It’s the loss of the material’s ability to dry.
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Why paint failure is an early warning, not the root problem
When paint peels or flakes on cedar, it’s tempting to blame cedar’s natural oils, wood movement, or the wrong primer.
Those factors matter, but they are secondary.
Paint usually fails because the wood underneath is spending too much time wet.
As moisture cycles increase, the surface fibers of the cedar weaken. Adhesion drops. The paint film releases. In some cases, the wood itself begins to degrade faster than it would have if left vapor open.
Paint isn’t failing despite moisture.
It’s failing because it changed how moisture behaves in the wall.
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Why “just use a stronger primer” doesn’t solve the problem
This is where paint manufacturers and paint reps often enter the conversation.
The advice is familiar:
“Sure, you can paint that. You just need the right prep and a high-bond primer.”
That advice isn’t dishonest, but it is product-focused, not system-focused.
Primers improve adhesion. They do not change how moisture moves through a wall.
If the wall assembly is still accumulating moisture, stronger adhesion simply delays visible failure. It doesn’t make the siding drier. It doesn’t restore the original behavior of the material.
This same logic is often used to justify painting brick or masonry. The coating may stick, but sticking is not the same as long-term compatibility.
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A note on workmanship
In this case, the overall workmanship was solid. Surface preparation was reasonable. Application was consistent.
There was one detail worth noting: the underside of trim and window sills was caulked. While well-intended, this further reduced drying potential at locations already prone to moisture accumulation.
That wasn’t sloppy work. It was a lack of building-science context.
And that distinction matters.
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When painting cedar does make sense
Painting cedar can perform acceptably when the entire wall system is designed for it.
This typically applies to newer construction, where cedar is often selected for appearance rather than moisture tolerance. These homes are more likely to include factory-primed cedar, boards sealed on all sides, and modern rainscreen assemblies.
A rainscreen is a small air gap between the siding and the wall behind it. That gap allows water to drain and air to circulate so materials can dry.
These conditions are uncommon in older cedar homes, because cedar was originally chosen specifically to manage moisture without those additional layers.
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The more durable alternatives for older cedar homes
For older homes with previously unpainted cedar, finishes that work with the material consistently outperform those that fight it.
Penetrating stains and oils allow cedar to remain vapor open while providing UV protection and color control. They weather gradually instead of failing abruptly.
When cedar has already been painted and is failing, the only true reset is to remove the paint and return the siding to a breathable finish. That approach costs more upfront, but it restores the behavior that made cedar durable in the first place.
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The real takeaway
This wasn’t a story about bad workmanship. It was a story about good work applied to the wrong system.
Paint failures like this are often architectural and hygrothermal problems, not painting problems.
Understanding how materials manage moisture over time leads to better decisions, fewer failures, and longer-lasting homes.
The failure wasn’t caused by poor workmanship. It was caused by a system that was never meant to be painted.
Situations like this are often less about execution and more about clarity at the outset. Before any work begins, a brief consultative review can help identify which approaches are compatible with an existing building assembly, establish a technically appropriate scope of work, and give a homeowner the language needed to solicit bids that align with long-term performance rather than short-term appearance. While I am a general contractor, I also work in a consulting and inspection capacity, and those roles don’t need to overlap. In many cases, the most effective contribution is simply helping define the right problem before well-executed work is applied to the wrong system.
Good stewardship isn’t about doing more work, but about making choices that respect how a building was meant to function over time.
