Stripped Decking, New Membrane, Resealed Penetrations
Written by Structural Repair Lead, Structural and Frame Lead, OCRV Center. Reviewed by RV Systems Lead
In shortThe useful frame is the open roof, because it is the only proof of which decking bays were replaced. Layered sealant beads in the before plate mark a roof maintained by adding rather than removing.
What should roof replacement photographs include?
An open frame shot showing exactly which decking bays were removed, not just a before and after of the finished surface. This fifth wheel roof took forty six body hours at Yorba Linda, with the saturation boundary established by pin meter against a dry reference before cutting.
- A finished membrane looks identical over sound and soft decking
- Layered sealant beads trap water against the layer beneath
- Air conditioner gaskets take a compression set and need replacing
- The saturation boundary is measured, not estimated
- Unit
- Fifth wheel roofMembrane over lauan decking, fourteen model years old
- Labor
- 46 body hoursBody and paint department at $210 per hour
- Shop days
- 12
- Decking replaced
- Two baysBoundary set with a pin meter against a dry reference area
- Penetrations reset
- All of themIncluding the air conditioner flange gasket rather than a reseal over it
Last verified
A finished roof photographs the same whether the decking under it was replaced, patched or left alone. That is not a small problem; it is the reason roof work is the easiest place in this trade to charge for something and not do it. So the middle pair on this page is the one that matters, and it is the one a gallery normally leaves out.
The unit is a fourteen year old fifth wheel that arrived with a roof surface that had been maintained enthusiastically and incorrectly for most of a decade.
Counting sealant layers in the before frame
Look at the front seam and the vent flanges in plate 1.1. You can count at least three distinct sealant applications, each one laid over the last, with the outer layer cracked and lifting at its edges. This is the standard failure pattern on a roof that has been maintained by adding material rather than removing the old bead first.
The physics is unkind. Each new layer bonds to the aged surface of the previous one, which is already losing adhesion, and the joint between them becomes a channel. Water gets under the outer bead, travels along that channel and reaches the fastener or the flange edge the sealant was supposed to protect. From above the roof looks well cared for, which is the cruel part.
The open frame plate, and why it is the important one
In plate 2.1 the roof is open to bare framing with two decking bays cut out. The dark staining at the cut edges shows how far saturation had travelled, and the clean framing beyond it shows where it stopped. That boundary was not judged by eye. It was read with a pin meter on a grid and compared against a dry reference area at the rear of the same roof, then marked before any cutting.
This is the only frame in the set that proves anything about scope. Anybody can produce plate 1.2. Producing plate 2.1 means the roof genuinely came apart, and the specific bays visible in it are the specific bays on the invoice. Owners commissioning roof work should ask for this photograph as a condition, not as a favour, and any competent shop will already be taking it.
The air conditioner gasket, and the shortcut it invites
Plate 3.1 shows the roof air conditioner flange lifted, with the original gasket visibly compressed to a fraction of its intended thickness and a ring of old sealant that had pulled away from the roof surface. A gasket in that condition is no longer sealing; it is a spacer. The unit is being held down by its bolts and the water is being kept out, for a while, by whatever bead was last run around the outside.
The shortcut is obvious and extremely common: run more sealant around the flange rather than lifting the unit. Lifting means disconnecting the air conditioner, removing it from the opening, cleaning both faces and reseating on a new gasket, which is real labor. Sealing over a compression set costs fifteen minutes and fails in the next Santa Ana wind event with rain behind it.
What this set does not tell you
It does not show the fastener pattern under the new decking, and it does not show whether the membrane was adhered with full coverage or with a lighter application. Both matter and neither is visible once the surface is closed. What we do is photograph the adhesive coverage before the membrane goes down, and that frame is in the owner's file even though it is too dull to publish.
It also cannot tell you about the rest of the roof. Two bays were replaced and the remaining decking was read as sound, which is a measurement taken on a given day. A roof of this age will need attention again, and the honest framing is that this job restored the front two thirds and reset every penetration, not that the roof is now new.
Exhibit plates
Plate 1.1 and 1.2. Count the sealant layers in the first frame. Bead over bead over bead is a roof that has been maintained by adding rather than by removing, and each layer traps water against the one beneath it.
Membrane and two decking bays replaced. 46 body hours at $210 per hour across 12 shop days.
Plate 2.1 and 2.2. This pair is the whole point of the set. The dark boundary in the first frame is the actual extent of saturation, which no photograph of the closed roof could have shown, and it is the only evidence of which bays were replaced.
Two bays removed to sound framing. Boundary established with a pin meter against a dry reference.
Plate 3.1 and 3.2. Detail pair. A compressed air conditioner gasket is one of the most common roof entries and one of the least often replaced, because reseating the unit is more work than running another bead of sealant over the outside.
Gasket replaced and flange reseated rather than resealed over the existing compression set.
Appendix: questions and answers
- Should I insist on an open roof photograph before paying?
- Ask for it as part of the file, ideally at the point of authorization rather than at the end. Any shop doing the work properly has the photograph already, because the boundary has to be marked before cutting. A shop that cannot produce one has either not opened the roof or has not documented what it found.
- Does old sealant have to be fully removed rather than covered?
- Yes, back to the membrane or flange surface, which is tedious and is why it gets skipped. Fresh sealant bonds properly to a clean substrate and poorly to an aged bead. Every layer left in place is a future channel, and a roof with three layers on it has to be cleaned back before any new bead is worth applying.
- Is replacing only two decking bays a legitimate repair?
- When the rest reads dry against a reference, yes. Decking is fitted between rafters, so a bay is a natural unit of replacement with a supported edge on both sides. What is not legitimate is leaving a bay that reads wet because it sits at the edge of the opened area, which is why the boundary is measured rather than estimated.
- Can the roof be walked on normally after this kind of rebuild?
- On the rebuilt section, yes, since new decking over sound rafters is stiffer than what was there. Step over rafter lines where you can feel them anyway, and be careful near flange edges where the membrane turns up. If any part of the roof still feels springy after a partial rebuild, that area was outside the repaired zone and should be read again.
Open a file on this repair
Tell us the vehicle, what happened and whether a claim is open. We will tell you what the scope looks like and what it takes to get you back on the road.
Or call (949) 799-3387