Painting guide
Before a Nashville Exterior Repaint, Should Old Caulk Be Replaced?
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Look at the joints on your house before anyone quotes the paint. They are where trim meets siding, around every window and door casing, at the points where two boards butt together, and at the corners. A bead of sealant runs along most of them, and it has a service life considerably shorter than the siding it sits between.
The question is whether the existing bead stays or comes out, and there is no single answer. There is a test.
Two ways caulk fails, and how to tell them apart
Run a fingernail along the bead and press the edge of a putty knife gently against it.
Adhesive failure. The bead has released from one side of the joint. You see a dark line down one edge where it has pulled away, and a knife slides into the gap without effort. The bead itself may still be flexible. It has simply stopped holding on.
Cohesive failure. The bead has split down its own middle, or it crumbles under the knife. The material has hardened and lost the ability to move, and it tore itself rather than releasing.
Sound. The bead is continuous, attached on both edges, and gives slightly under pressure rather than cracking.
Do this at ten or twelve joints around the house, not one. Beads fail by exposure, so a house can need joints replaced on one side and none on another.
Joints painted over more than once tend to look better than they are, because the film bridges the gap and hides it until it splits, which is why the worst joints on a well-maintained house are often the ones that look fine.
What happens when you paint over a failed joint
Paint is not a sealant, and this is the practical reason the joints get settled first and the paint second.
A film of paint bridging an open joint is a membrane a few thousandths of an inch thick spanning a gap that opens and closes with every temperature swing. It splits. When it splits it does so along the line of the joint, which is the most visible place on the wall for a crack to appear, and the split gives water a direct route into the gap behind it.
The result is a joint that is now open, hidden under a paint film, in a wall that looks recently painted. That is worse than the joint you started with, because nobody will look at it again for years.
Joints that should not be sealed at all
This is the part that turns a helpful weekend into a problem, and it is worth reading before buying a case of sealant.
Not every gap in a building is a defect. Some are drainage paths, designed to let water that gets behind cladding find its way back out. Seal them and the water has no exit, which means it stays in the wall.
The specifics depend on the cladding system, and the manufacturer of your siding publishes what should and should not be sealed on their product. As a general orientation: the bottom edges of many cladding systems, weep openings, and the lower edge of certain trim details are drainage features rather than gaps to close. Vertical joints, the perimeter of window and door casings, and the junctions between different materials are typically where sealant belongs.
If you cannot establish which is which on your house, that uncertainty is itself the finding. Sealing a drainage path is not reversible by painting over it.
With the joints that genuinely should be sealed, the test at the top of this page sorts them into three groups, and each one gets a different answer.
Leave it, replace it, or seal over it
Leave it. The bead is sound: continuous, attached, still flexible. Clean it and paint over it. Sound sealant takes paint and carries on doing its job.
Replace it. The bead shows adhesive or cohesive failure. It comes out completely rather than being topped up, because new material over failed material bonds to the failure. The joint is cleaned to sound edges, and new sealant goes in before painting.
Seal over it. This option is named here so it can be ruled out rather than reached for. Applying fresh sealant over an existing bead that is still attached but has surface cracking produces a thicker bead with a weak layer buried inside it. It looks finished on the day, and when it fails it fails at that buried layer rather than at the joint faces.
One thing can make all three answers wrong. If the joints are open because the wood around them has deteriorated rather than because the sealant aged, sealant is not the remedy, because new material bonded to soft wood pulls away with it. Press the boards on either side of a failed joint before deciding anything. If they give, the joint is a symptom and the carpentry comes first. Anything firmer than a thumb means a tool against a painted surface, and both that check and the condition attached to it on an older house belong to Peeling Paint or Wood Rot? What Nashville Homeowners Should Check.
Why the same joint fails twice
A joint that has been sealed, failed, resealed and failed again in the same place is not a product problem. It is a movement problem.
Sealants are rated for how much movement they can accommodate as a proportion of the joint width. A joint that moves more than the material can handle will tear, whatever the material is, and it will tear in the same place each time. The two usual reasons are that the joint is too narrow for the movement it experiences, or that two materials with different rates of expansion meet there.
What that changes for you: reaching for a better sealant is unlikely to solve it, and a second failure in the same place is information rather than bad luck. The joint may need to be cut wider, backed differently, or treated as a movement joint rather than a cosmetic one. That is a detailing question rather than a painting one, and it is worth raising before anyone opens a can, because the alternative is watching the crack come back through the new film.
For every joint that does simply need replacing, the work itself is straightforward and there is more of it than the wall suggests.
Cutting a bead out and putting one back
The work is straightforward and every stage of it is a place people cut a corner.
One thing gets settled before any of it on an older house. Cutting a bead out takes paint off the boards either side of the joint, and on a home built before 1978 that puts the lead-safe question in front of the work rather than alongside it: Painting a Pre-1978 Nashville Home: When EPA Lead-Safe Rules May Apply. It is answered before the knife comes out.
The old material comes out completely. Cutting it back and topping it up leaves the new bead attached to a failing layer, which is why the assessment matters: half a bead removed is worse than none.
The joint faces then have to be clean and dry. Dust from removal, old sealant residue and moisture all interfere with adhesion, and a joint sealed over any of them fails early in a way that looks like a product problem.
Deep joints need backing before sealant, so that the bead bonds to two faces rather than three. A bead bonded on three sides cannot stretch and it tears when the joint moves. This is the technical reason a joint that was simply filled tends to fail again.
None of that is difficult, and all of it takes longer than it looks on a wall with sixty joints. That is the argument for testing every joint rather than replacing every joint: the twelve that have actually failed are an afternoon, and all sixty because it seemed tidier is a different weekend.
When the joints get done
Everyone asks whether caulking happens before or after painting. It does happen before, and that is only half the answer, because joint work has a neighbor on each side.
It comes after washing, for a practical reason rather than a procedural one. You cannot assess a bead under a layer of dirt and biological growth, and a joint that looks continuous when it is grimy often turns out to have a dark line down one edge once the wall is clean.
It comes before painting, and the reason is not appearance. A sealed joint that is then painted carries a continuous film over the whole assembly, which shields the sealant from ultraviolet exposure and gives the wall a single surface. Painting first and sealing afterwards leaves every bead on the house exposed and visible as a line of unpainted material.
It also comes before priming, because cutting a failed bead out exposes joint faces that were not part of the wall you assessed, sometimes bare wood and sometimes end grain. What needs priming cannot be settled until the joints are done, which makes priming the next decision rather than this one: Nashville Exterior Repaints: When Is Spot Priming Enough?.
New sealant has to cure before anything goes over it, and how long that takes depends on the product, the temperature and the humidity. The product states its own figure, and it is worth respecting, because painting an uncured bead can affect both the sealant underneath and the film on top.
Source. Sherwin-Williams’ problem-solver article on caulk failure, opened 10 September 2026: https://www.sherwin-williams.com/painting-contractors/products/resources/SW-ARTICLE-PRO-CAULKFAILURE. It describes the failure as a loss of the caulk’s initial adhesion and flexibility, causing painted caulk to crack or pull away from the surfaces it was applied to, and it attributes that to lower-quality caulk, the wrong type of caulk for the application, surfaces not properly prepared or primed before caulking, and too thin a bead. Movement ratings, cure times and paintability for a specific sealant are on that product’s own label.