RV Sidewall Blistering & Delamination Repair Guide 2024

Bottom Line Up Front

Those 12-14 inch vertical blisters on your 2004 Itasca Sunova's right sidewall behind the awning arm are caused by water intrusion that has delaminated the fiberglass from the underlying substrate. Since they just appeared and you're on the road, your immediate priority is preventing further water entry and stopping the spread. The location behind the awning arm and near your shower area strongly suggests the water is coming from either a compromised roof rail seal or the shower skylight as you suspected. While you can temporarily stabilize these blisters, a proper repair will require cutting out the damaged section and rebuilding the wall structure - likely a $2,000-4,000 repair job that's best done when you're stationary.

Root Causes

The vertical orientation and location of your blisters tells a clear story about the water intrusion pattern. Water is most likely entering through a failed seal at the roof rail where your awning mounts, or through the shower skylight gasket, then running down inside the wall cavity. The fact that this area is behind your converted shower closet creates a perfect storm - limited ventilation, potential temperature variations, and possibly higher humidity levels even without active shower use.

In 2004 Itasca construction, the sidewalls typically consist of an outer fiberglass (FRP) layer bonded to a thin fiberglass backing, with foam core or wood framing behind it. When water gets between these layers, it breaks down the adhesive bond and creates the characteristic bubble or blister. The 3-4 inch width suggests the water has spread horizontally along the bond line, while the 12-14 inch vertical length shows how far the water has migrated downward.

Your awning arm mounting point is particularly vulnerable because it requires penetrations through the roof rail, and the constant mechanical stress from extending and retracting the awning can work sealants loose over time. After 20 years, the original butyl tape and sealants around these penetrations are likely compromised.

Before You Start

Since you're currently traveling, your first priority is damage control, not permanent repair. Gather these readily available supplies: clear packing tape, plastic sheeting or heavy garbage bags, duct tape, and if possible, some Dicor roof sealant or similar RV-specific sealant from any RV supply store. Take photos of the blisters from multiple angles and measure them carefully - delamination can spread quickly, and you'll want to monitor any changes.

Resist the urge to puncture or press on the blisters, even though they're probably squishy and tempting to poke. Puncturing them will only allow more water in and potentially create bigger problems. Instead, gently feel around the edges to determine the full extent of the delaminated area - it's likely larger than what's visibly bubbled.

Check your interior walls in the shower/closet area for any signs of water damage, soft spots, or discoloration. Look particularly around the shower skylight frame and along the ceiling where it meets the exterior wall. Also check for any structural compromise - if framing feels soft or unstable, or if the wall flexes excessively, this could be a safety concern requiring immediate professional evaluation. Also inspect the awning arm mounting hardware inside the wall cavity if accessible.

Plan to address this issue at your next extended stop. This isn't a roadside emergency repair, but it will get worse if left untreated, especially if you encounter rain. Document everything for insurance purposes, as this could potentially be a covered repair depending on your policy.

The Repair Process

Your immediate roadside stabilization involves preventing further water intrusion. Start by thoroughly cleaning and drying the area around the blisters and the suspected entry points above. Ensure surfaces are completely dry - allow several hours of drying time in direct sunlight if possible, and test with a moisture meter if available before proceeding. Apply a generous bead of RV sealant along the entire roof rail where your awning mounts, paying special attention to the area directly above your blisters. Don't forget to seal around the awning arm mounting brackets themselves.

For the blisters themselves, carefully apply clear packing tape over the entire affected area, extending several inches beyond the visible damage. This creates a temporary moisture barrier and helps prevent the delamination from spreading further. The tape won't fix anything, but it buys you time until you can get professional help.

If you can access the shower skylight, you can carefully remove the interior trim (noting the order and orientation of parts for reassembly) to inspect the gasket, but be aware that removing trim may damage existing seals that will need replacement. Only proceed if you're prepared to replace the seals. Look for cracking, shrinkage, or areas where the gasket has pulled away from the frame. Clean the area thoroughly and apply fresh sealant around the entire perimeter. Many RV skylights use a butyl tape gasket that can be supplemented with Dicor or similar sealant.

The proper permanent repair is extensive and not suitable for roadside DIY work. It involves cutting out the entire delaminated section, cleaning and treating any water-damaged framing, installing new backing material if needed, applying new fiberglass cloth and resin, fairing the surface smooth, priming, and painting to match. This typically takes 3-5 days and requires specialized tools, materials, and workspace. Professional repair costs typically range from $50-150 per square foot of delaminated area, so your 3-4 square foot area could run $1,500-3,500 including paint matching and blending.

Professional Help Needed

This repair definitely requires professional intervention at a qualified RV service center or fiberglass repair shop. The structural nature of sidewall delamination, combined with the need to identify and permanently fix the water intrusion source, makes this beyond typical DIY capabilities. Look for shops that specifically mention fiberglass repair and RV experience - auto body shops often don't understand RV construction methods.

When you reach your destination or next planned service stop, prioritize finding a shop that can address both the cosmetic repair and the root cause water intrusion. Many RV repair facilities can handle this type of work, but get quotes from shops that specifically mention experience with delamination repairs. Ask to see photos of previous similar repairs and get detailed written estimates that include identifying and fixing the water entry point.

Consider contacting your insurance company before authorizing any repairs. Some policies cover sudden water damage, though gradual deterioration is typically excluded. The fact that these blisters "just popped up" during your travels might work in your favor for coverage, especially if you can demonstrate that you've been maintaining your RV properly.

If professional repair isn't immediately available, you can continue traveling with your temporary stabilization, but monitor the blisters daily for any expansion. If they start growing rapidly or new ones appear, you'll need to find emergency service sooner rather than later. Keep the area as dry as possible and avoid parking in areas where water might pool against that sidewall.