Thor Ace Fiberglass Rear Cap: Repair and Maintenance Guide

Short Answer

Yes, the back wall of your Thor Ace 29.2 is fiberglass, and the movement you're feeling when pressing on it is definitely not normal - this is classic delamination. While Thor constructs their motorhomes with fiberglass exterior walls, the back wall should feel solid and not flex when pressed. The fact that your sides don't move but the back does confirms you have significant delamination issues that Camping World correctly identified as a serious problem affecting your RV's value and structural integrity.

Understanding the Problem

Thor Ace motorhomes use a laminated wall construction with an outer fiberglass skin bonded to an inner framework, typically with foam or wood substrate in between. When this bonding fails, it creates delamination - essentially the fiberglass skin separating from the underlying structure. This is exactly what you're experiencing on your 29.2's rear wall.

Delamination typically starts when moisture infiltrates the wall system through failed seals around windows, doors, or roof penetrations. Once water gets between the layers, it breaks down the adhesive bonds and can cause wood components to rot. The "spongy" feeling you get when pressing on delaminated areas occurs because the outer fiberglass skin is no longer firmly attached to the solid backing structure.

This problem is unfortunately common in Thor products from certain model years, particularly affecting rear walls where water intrusion from roof or upper wall seal failures tends to accumulate. The rear wall's vertical orientation and exposure to weather makes it especially vulnerable to moisture damage over time.

Camping World's assessment is accurate - delamination significantly reduces an RV's value and marketability. Most buyers and dealers view extensive delamination as a deal-breaker because repair costs often exceed the RV's remaining value, especially on older units.

What You'll Need

If you're considering tackling this repair yourself, understand that it's an extremely challenging project requiring specialized materials and significant time investment. Ensure adequate ventilation and wear a proper respirator when working with structural adhesives and solvents in enclosed RV spaces, as these materials are toxic and can cause serious health issues even with good ventilation. You'll need structural adhesives specifically designed for composite bonding or Sikaflex polyurethane sealants, along with injection equipment to work the adhesive into separated areas.

Essential tools include pneumatic or manual adhesive injection guns, drill bits for creating access holes, clamps or vacuum bagging systems to maintain pressure during curing, and extensive masking materials. You'll also need moisture meters to verify the wall is completely dry before attempting repairs, dehumidification equipment, and potentially a heat gun for proper adhesive curing.

Material costs alone typically run $300-800 depending on the affected area size, but the real challenge is the 40-80 hours of labor required for proper preparation, injection, and curing time. Most DIYers underestimate the complexity of achieving uniform adhesive distribution and maintaining proper pressure throughout the 24-48 hour curing process.

Additionally, you'll likely need exterior refinishing materials including gelcoat, primer, and paint systems to restore the wall's appearance after repair, adding another $200-400 to material costs.

How to Fix It

Delamination repair is possible but extremely labor-intensive and requires perfect execution to achieve lasting results. The process begins with identifying and fixing the root cause of moisture intrusion (failed seals, etc.), then thoroughly drying the affected wall section using dehumidifiers and potentially removing interior paneling to ensure complete moisture elimination - this alone can take several days to weeks depending on how saturated the wall has become.

The actual repair involves carefully drilling small access holes every 6-8 inches along the delaminated areas, then using specialized injection equipment to pump structural adhesive into the separated spaces. The key is achieving complete coverage without creating air pockets while maintaining consistent pressure across the entire repair area until the adhesive fully cures.

Professional repairs typically involve using pneumatic pressure systems and pressure injection methods to ensure proper bonding. The wall must remain under pressure for 24-48 hours while the adhesive cures, requiring extensive clamping or vacuum bagging systems that most DIYers don't possess.

After curing, you'll need to fill injection holes, sand the entire surface smooth, apply primer and base coats, then match the existing gelcoat or paint finish. Even with perfect adhesive work, achieving an invisible cosmetic repair requires considerable skill with fiberglass finishing techniques.

Leave It to the Experts

Given the extensive delamination on your Thor Ace 29.2's rear wall, professional repair is strongly recommended. Qualified RV body shops typically charge $3,000-8,000 for major delamination repairs, depending on the affected area size and accessibility. While expensive, professional shops have the specialized equipment, materials, and expertise needed for lasting repairs.

However, before investing in repairs, carefully consider your RV's overall condition and market value. If Camping World identified the delamination as significant enough to affect consignment, repair costs may exceed what you'll gain in resale value. Many owners in similar situations find it more economical to sell "as-is" to buyers specifically looking for project RVs.

If you do pursue professional repair, get detailed written estimates from multiple certified RV body shops, not general auto body shops. Ask for warranties on both materials and workmanship, and verify they'll match your RV's existing finish. Reputable shops will also address the root cause of moisture intrusion to prevent recurrence.

Alternatively, consider disclosure-based selling where you're upfront about the delamination and price accordingly. Many experienced RVers are comfortable purchasing units with known issues if the price reflects the needed repairs, and you'll avoid the uncertainty and expense of major structural work.