There is a 2 fold reason for delamination. The first part is that water gets into the wall. The second part is that the exterior fiberglass panel had a luan (wood) backing. Since there was wood involved, once the wood got wet, it rotted and came apart. The new construction glues the fiberglass directly to the frame. Even if water gets in, the wall stays glued to the frame, hence no delamination. BUT the real problem of delamination is water damage, which still can occur. If water gets into the wall, the wall frame will rust, the insulation gets soaked, and mildew grows. So all the secondary damage that occurs with delamination can still occur in the newer type construction. Your real hope is that modern glues are much better than they used to be, so you are less likely to get water in in the first place.
The fronts and the rear walls on most trailers are just hung fiberglass sheets, with the rear wall usually having wood studs.
Most sidewalls are laminated walls, not really vacuum bonded as most people think, but each layer sprayed with glue, then run through pinch rollers to seal. That's why you can look down the sides and see lines and waves as the rollers squeeze there way through.
Don't let them kid you, if it is a bubble, it is delamination. The hung walls do move twist and wave in different temps, but a bubble is still a bubble.
Filon is a thin sheet of Fiberglass material glue bonded onto a very thin sheen of Luan plywood. Once water gets on the Filon backer board, it swells up, the Filon delaminates from the glue and you get the bubble or rippled exterior.
What To Look For The first evidence of a delamination problem is bubbles (or blisters) forming on the sidewalls as the luan plywood under the outer fiberglass layer breaks down, allowing it to pull away from the wall structure.
Delamination is generally caused by moisture infiltrating the wall and destroying the integrity of the luan plywood.
Flexing in the wall structure can also lead to the adhesive failing or cracks developing. Cracks are another similar issue that will rapidly send the value of your investment plummeting.
Buyer Beware: If You Spot Delamination Or Cracks. Over the years, I’ve seen many RVs that have delamination issues that just continue to get worse.
This should be a huge red flag if you’re shopping for a used RV of any make or model.
If you detect any area where you feel the fiberglass has pulled away from the inner structure, just pass that RV by.
In some instances structural integrity of the whole RV has been compromised. The wall skin supplies some of the strength of the entire wall. Picture it like your house without the outer skin being attached to the studs. The house would be weakened to the point of collapse.
The cost of replacing a sidewall would likely surpass the total value of the entire RV. As the delamination gets worse — and it will — the value of your investment will slide downhill rapidly.
The rule of thumb generally says that minor water damage can be fixed and large scale water damage is more likely to cost more than the RV in some cases.
Understanding Water Damage - Wood Rot, Mold & Delamination Water Damage
Water intrusion, if not stopped, can cause wood rot damage to your RV’s roof decking and trusses; exterior fiberglass walls backed with plywood; slide out floor and walls; and interior floor decking.
Water can also cause the exterior fiberglass (filon) to delaminate from the wood (luan), and electrical
issues resulting from wire connection corrosion.
Water can cause mold & spores to grow. Mold - is a fungus with its own unique “living style”.
Mold needs 4 ingredients to grow: Food: Extracts carbon from the substrate it lives on, wood or plastic made from petroleum products.
Humidity: Comes from high moisture levels in surface layers of above the listed materials.
Oxygen: From air.
Temperatures: Mold likes moderate temperatures as we do. When mold grows toxic compounds are produced and millions of spores are released. These particles are airborne and can cause serious damage to humans!