Why Paint Fails at the Bottom of the Board on a Pasadena Craftsman

Published September 1, 2026

Stand a few feet from the front of an older Pasadena bungalow and look at the bottom inch of the siding rather than the wall as a whole. On most houses that have not been touched in eight or ten years, that is where the story is. The field of the wall will be chalky but intact. The bottom edge of the boards, or the butt line of the shingle courses, will be cracked across the grain, cupped, lifting, or simply bare. That pattern is not random and it is not a bad batch of paint.

Paint Fails Where Water Sits and Wood Drinks

Wood absorbs moisture along the grain far faster than across it. A sawn end, or the exposed lower edge of a board, is effectively a bundle of open straws. Water reaches it two ways, running down the face of the wall in a rain and wicking up from anything wet below, and once it is in, it moves along the fibre and away from the surface where it could evaporate quickly.

Now put a coating over that. Paint is not a vapour barrier but it is a restriction, and the restriction is on the outside face where the sun is. Moisture that has entered through the unprotected edge has to travel back to a face to leave. When it cannot, it builds up under the film, adhesion goes, and the coating lets go from the substrate rather than from itself. Then the exposed wood weathers, the next rain gets in further, and the failure widens along the edge in both directions.

This is why the pattern is so consistent. The paint does not fail in the middle of the wall because the middle of the wall is flat grain with a coating over it and no direct route in.

The Five Places to Check on Your Own House

You do not need a contractor to find these. Take a small screwdriver and go round the outside on a dry day.

The butts of the shingle courses, if you have a shingle wall. Check the north and east elevations first, because those dry slowest after a rain, and check low, within reach of splash off a walkway or a planting bed.

The bottom lip of lap siding, particularly the lowest three or four courses, and specifically anywhere near a downspout that puts water out too close to the wall.

The exposed rafter tails. On a Craftsman with the classic deep overhang, those tails project out beyond the roof line into full afternoon sun with nothing above them. They are the most exposed piece of wood on the entire house and they are usually the first to go soft. Owners assume the overhang protects them. The overhang protects the wall, not the tail.

Window sills and the lower rail of the sash. If the glazing putty has cracked and fallen out anywhere on the lower half of a sash, water has been running down inside the joint for as long as that has been true.

The bottom of door casings and porch column bases, where trim meets a deck or a step that stays damp.

How to Test It Properly

Hold the screwdriver at a shallow angle, not perpendicular, and push with light pressure. Sound old growth redwood or cedar will stop the tip almost immediately and you will feel it refuse. Compromised wood accepts the tip a quarter inch or more without much argument and frequently brings back damp, stringy fibre.

Do this at every location that looks suspect rather than testing one spot and generalising. Rot is stubbornly local. It is entirely normal to find one rafter tail gone to punk while the next one along, four feet away, is perfect. The difference is usually a gutter joint, a tree that shades one bay, or a sprinkler that reaches one corner of the house and not the other.

Mark what fails with a pencil. Count it. That number is the single most useful thing you can hand a painter, because it turns a vague repair allowance into a line item.

What This Means for a Quote

An exterior on an old wood house should be priced in two halves that are kept visibly separate.

The coating half is predictable. Somebody measures the elevations, counts the openings, decides on the prep level, and quotes it. Reasonable painters land within a fairly narrow band of each other on that number, because the labour is knowable.

The repair half is not predictable from the street, which is exactly why it should be quoted from an actual inspection with an actual board count rather than as a percentage of the paint price. A repair allowance expressed as a share of the total is a placeholder, and placeholders get revised upward once the scaffold is up and you have no leverage.

If two quotes are far apart on an old house, this is almost always where the difference lives. One of them has looked at the wood and one has not.

Why Coating Over Bad Wood Is Worse Than Doing Nothing

It buys about three years and it costs you the material.

A soft board that is left open will keep weathering, which is bad, but it will also keep drying between rains. Seal that same board under two coats of a good acrylic and you have slowed its ability to dry while doing nothing about the water still getting in through the unprotected end. Decay organisms need moisture and they get a more stable supply of it. We regularly pull boards during a second repaint cycle that were merely soft at the last one and are now gone entirely, and the paint on the face of them is still in decent condition, which is the whole irony of it.

On old growth redwood and cedar this matters more than it would on modern stock. The siding on a house built between roughly 1905 and 1930 is tight grained, stable and naturally rot resistant in the field, and it is materially better than anything you can buy now at any price. Saving it is worth real effort. Replacing a whole wall because nobody dealt with the bottom edges is a genuine loss, not just an expense.

Sequence, Written Out

There is nothing clever about the order. There is only the fact that people skip parts of it.

Repair first. Cut back to sound wood, splice or piece in matched stock, and prime the cut ends on every face before installation, while you can still reach all of them. End grain primed on the ground stays sound for decades. End grain primed after it is nailed up, when one face is buried, does not.

Wash and scrape second. Take failed film back to a bonded edge and feather the transition so it does not telegraph through the topcoat. On a house that predates 1978, and most of this housing stock does, the old coats contain lead and that prep has to be done lead safe. Containment below the work area, wet methods where practical, no dry power sanding without extraction, and a clean up at the end of every day rather than the end of the job.

Prime third, per surface rather than per house. Bare cedar and redwood need a stain blocking primer or the tannin will bleed through a light topcoat and ghost brown over your new repairs about a month after you pay. A chalky old surface needs a bonding primer. Stucco needs a masonry primer. These are not interchangeable products and buying the cheapest one is a false economy that shows up as a callback.

Caulk fourth, and only the joints that should be closed. Trim to siding, casing to jamb, corner boards, vertical butt seams. Never the bottom edge of a lap board, never the underside of a shingle butt, never the bottom of a sill. Those are drainage paths. A painter who caulks them has turned a wall that dries into a wall that holds water, and that single well meaning mistake has ruined more old siding than neglect ever did.

Then colour. Two coats over any colour change, because one will not build the film thickness the coverage rate on the can assumes and it will fail early and unevenly.

The Local Part

Three things about this city shape the work. The summers are hot, dry and hard on ultraviolet exposure, so south and west elevations chalk and fail years ahead of the north side of the same house. It is common and entirely defensible to restore two bad elevations properly now and leave the other two for a later cycle rather than spending evenly across a house that is not wearing evenly.

The Santa Ana winds coming down off the San Gabriels drive grit into any joint that has already started to open, which accelerates a small caulk failure into a real one.

And surface temperature, not air temperature, governs when we can work. A west wall in late summer can be well past the maximum application temperature printed on the can while the thermometer on the porch reads pleasant. Paint applied to a hot wall flashes off before it can level or properly wet the surface. So we follow the shade around the house through the day, which looks inefficient and is not.

If You Only Do One Thing

Go and check your rafter tails. They are the most exposed wood on a Craftsman house, they are the cheapest thing on this list to fix while they are still fixable, and nobody looks at them until the painter is already on site with a quote written for something else.

Call (626) 243-2387 if you want a second opinion with a screwdriver in it.