Reseal,Patch,Coat,orReplace:SortingOutWhatYourRVRoofActuallyNeeds

Ask three people what your RV roof needs and you may get three different jobs. One says reseal it. One says coat it. One says the whole thing should be replaced. They might all be looking at the same roof, and they are not necessarily wrong. They may simply be answering different questions.

These are four distinct jobs with very different costs, and the right one depends on a few observable things. Here is how to sort them.

Start with one question: is the decking sound?

Everything else depends on this. Walk or press across the roof, where it is safe to do so, and feel for soft, spongy, or flexing areas between the rafters, especially around fixtures and along the edges. Look for dished spots that hold water.

If the deck is firm everywhere, you are in maintenance territory: reseal, patch, or coat. If it is soft anywhere, water has reached the wood, and the roof has moved into structural repair, no matter how good the surface looks.

Reseal: when the sealant is the problem

This is the most common need and the least expensive. The membrane is intact and the decking is firm, but the lap sealant around fixtures, screw heads, edge moldings, and cap seams has cracked, shrunk, or lifted.

Sound, well-bonded lap sealant can take a fresh layer, and self-leveling sealant flows into small cracks as it goes on. Sealant that is lifting, separated from the roof, or cracked all the way through comes off first, and so does any silicone, because other sealants will not bond to it. Fixtures that still leak after resealing usually need the butyl tape underneath them replaced, which is a bigger job than a bead on top.

Patch: when the membrane has a hole

Tears and punctures from branches, hail, or dropped tools are very repairable on membrane roofs. Dicor says a properly applied patch should last for the life of the membrane. The work is mostly preparation: the area around the damage has to be cleaned of chalk and dirt so the patch bonds to the membrane itself. Peel-and-stick membrane patches and roof tapes like EternaBond are the usual materials.

A patch is the right answer for localized damage on an otherwise healthy roof. It is not the answer for a membrane that is failing broadly.

Coat: when the membrane is sound but tired

A coating makes sense when the membrane is intact and bonded, the decking is firm, but the surface is weathered, chalky, or aging. It adds UV protection, stops chalk streaking, and extends the life of a roof that is fundamentally fine.

It has to be the coating system made for that roof type, the sealant work has to be done and cured first, and it is not a substitute for any of the other three jobs. A coating over failed sealant still leaks, and a coating over soft decking seals the moisture in.

Resealing, patching, and coating all assume the roof underneath is sound. Replacement is what you do when it is not.

Replace: when the roof itself has failed

Replacement is warranted when the problem is the roof structure or the membrane as a whole rather than the seals around it.

• Soft decking in more than an isolated spot, from water that has been getting in over time.
• Membrane swelling or loose areas across large parts of the roof. Dicor identifies these as signs of petroleum damage, which does not reverse.
• A membrane that has separated from the deck broadly, or that is torn and degraded in many places.
• Damage around the edges extensive enough that the membrane can no longer terminate properly under the moldings.

Dicor is unambiguous about one thing: whenever a roof is replaced, new decking goes down too, because the membrane adhesive needs a porous substrate to bond to. That is a large part of why a replacement costs far more than any maintenance job. It is a structural job that involves removing every fixture on the roof, and it is best done by a shop set up for it.

The finding that changes everything: delamination

If the sidewalls show waves, ripples, or bulges when you sight along them, water has been getting into the walls long enough to separate the outer skin from its backing. That is delamination, and it is a structural repair to the wall, separate from anything on the roof.

Stopping the leak that caused it still matters, since it keeps the damage from spreading. But a reseal or a coating does nothing to repair a wall that has already delaminated, and anyone quoting a roof job should tell you plainly if they see it.

A simple way to sort your roof

• Firm deck, intact membrane, cracked or lifting sealant: reseal.
• Firm deck, a localized tear or puncture: patch, plus reseal anything else that needs it.
• Firm deck, intact but weathered membrane, sealant in good order: coat, after the sealant has cured.
• Soft deck, widespread membrane failure, or petroleum damage: replacement, at a shop that does structural roof work.
• Wavy sidewalls: a structural wall repair, separate from whatever the roof needs.

Most roofs we see sit in the first three lines, often more than one at once. The point of an inspection is to find out which, before anyone spends money on the wrong job. If someone quotes you a replacement on a roof with a firm deck and a sound membrane, ask them to show you why. If someone quotes a coating on a roof with soft spots, ask the same question.