CHINOOK BAYSIDE – Roof Seal and Skylight Maintenance

by

Roof Seal and Skylight Maintenance for CHINOOK BAYSIDE

The Chinook Bayside’s roof is a layered system combining the Ford Transit 350’s factory steel roof with composite RV additions, and every penetration point — the MaxxAir fan housing, skylight frame, and Fiamma F45s awning mount brackets — is a potential leak path. Chinook’s revival production quality is solid, but the self-leveling sealant around roof penetrations is consumable and should be inspected every six months, not just annually. The Ford Transit also has a factory drip-rail seam tape running the full length of both sides of the roof that degrades independently of any RV-applied sealant — most owners don’t know it exists until water is already running down the interior wall. Budget a full day for this job; done right, it protects your investment for two to three seasons before the next full inspection.

Required Parts

Step-by-Step Instructions

Step 1: Set Up Safely and Access the Roof

Park the Bayside on a level, firm surface with the ignition off and the parking brake set. The Transit 350’s roof sits approximately 9.5 feet off the ground with the RV composite additions, so a freestanding A-frame ladder rated for at least 300 lbs is mandatory — never lean a ladder against the Fiamma F45s awning rail or the awning’s plastic housing, as both will deform under load. Before climbing, retract the F45s fully and lock it using its travel strap. Bring all your tools up in a bucket or tool bag on a separate trip; carrying a caulking gun in one hand while climbing is how injuries happen. Wear soft-soled shoes to avoid tearing the roof membrane — no hard heels, no bare feet. Walk only on the structural ribs you can feel underfoot, and stay off the flat membrane spans between them. If your Bayside has the optional solar panels, treat the panel frames as walkable structure but never step on the glass. Work in the morning or on an overcast day; a sun-baked Transit roof reaches temperatures that will burn your hands and cause sealant to skin over before you can tool it properly.

Step 2: Inspect and Document Every Penetration Point

Start at the MaxxAir fan, which is typically centered toward the rear of the Bayside’s living area. Crouch down and look across the sealant bead at a low angle — this raking light technique reveals cracks, voids, and lifting edges that look fine when viewed straight down. The MaxxAir frame has four corners that are chronic failure points; the sealant there bridges two planes and flexes differently than the flat runs. Move forward to the skylight, which on the Bayside is typically a Jensen or similar frameless acrylic unit set into the composite roof section. Check the full perimeter bead, paying extra attention to the front edge where road air pressure creates a slight lifting force at highway speed. Next, inspect the Fiamma F45s mounting brackets — there are typically three bracket feet on the driver’s side roof rail, each through-bolted and bedded in sealant. Check each bolt collar for cracking. Finally, inspect any TV antenna, solar conduit grommets, or vent pipe collars your specific build includes. Photograph every penetration with your phone before touching anything so you have a baseline reference if a question arises mid-repair.

Step 3: Inspect the Ford Factory Drip-Rail Seam Tape

This step is skipped by most DIYers and even some shops, which is why it causes so many mysterious interior leaks. The Ford Transit 350 has a factory-applied seam tape running along the drip rail on both the driver and passenger sides — it seals the joint where the roof panel meets the upper body rail. On the Bayside, this tape runs underneath the Fiamma awning rail on the driver’s side, making it harder to see but no less important. Walk the full length of both rails and look for bubbling, lifting edges, or sections that have gone hard and brittle — the factory tape tends to fail in segments rather than all at once. Press it with your fingertip; it should feel slightly pliable, not glassy. If you see any lifting at the edges, that tape is admitting water behind the RV’s composite sidewall additions. Cracked or lifted sections need to be addressed in this session; they will not self-heal. Mark any bad sections with a strip of painter’s tape as a flag. Note that this Ford-sourced sealer is a different chemistry from Dicor lap sealant — removing and replacing it with EternaBond tape is actually a more durable long-term repair than trying to match the factory product.

Step 4: Remove Old and Failing Sealant

Use the plastic putty knife set exclusively for this work — metal scrapers will gouge the EPDM membrane and create new leak paths. Start at the MaxxAir fan and work methodically toward the skylight. Grip the putty knife at a shallow angle, about 15 degrees, and push rather than pry — the goal is to shear the old sealant away from the membrane surface without lifting the membrane itself. On the skylight perimeter, the sealant often bonds tenaciously to the acrylic frame edge; work slowly and keep the blade as flat as possible. Do not attempt to remove sealant that is still fully bonded and crack-free — if it’s adhered on all edges with no voids, leave it and apply a fresh bead on top when you reach that step. For the Fiamma bracket feet, remove only the sealant around the perimeter collar of each foot; do not disturb the bolt itself unless you suspect a leak directly at the fastener, which requires re-torquing and re-bedding as a separate task. On the drip-rail sections you flagged, remove the factory tape completely using the plastic putty knife plus controlled hand pressure — it will peel in strips once you get an edge started. Clean all debris off the roof before moving to the next step.

Step 5: Clean and Degrease the Entire Roof Surface

Pour a working amount of the Dicor rubber roof cleaner and degreaser into a bucket and apply it with a soft-bristle brush in sections, working front to back so dirty runoff doesn’t cross areas you’ve already cleaned. The Dicor cleaner is formulated specifically for EPDM and TPO membranes — do not substitute dish soap, solvent-based cleaners, or anything petroleum-derived, as these degrade the rubber. Scrub the membrane, the bare areas where you removed old sealant, and all penetration frames including the MaxxAir housing and skylight acrylic lip. Rinse thoroughly with clean water and let the roof dry completely — at least 30 to 45 minutes in warm weather, longer if the temperature is below 65°F. The roof must be fully dry before any sealant or tape touches it; moisture trapped under Dicor or EternaBond is the number one cause of premature re-failure. While the roof is drying, clean the drip-rail bare metal sections where you removed the factory tape with a dry cloth to remove any tape adhesive residue. If adhesive residue remains, a small amount of isopropyl alcohol on a rag will remove it without harming the metal. Let the alcohol flash off completely before proceeding.

Step 6: Apply EternaBond Tape to Drip Rail and Reseal All Penetrations

Start with the drip-rail repairs since they’re the most structurally demanding. Cut EternaBond RoofSeal tape sections slightly longer than each bare section you’re covering, peel back about three inches of the liner, and align the tape centered over the seam before committing. Once EternaBond touches a clean surface it bonds instantly, so alignment before contact is critical. Lay the tape down progressively, pulling the liner back as you press forward. Immediately work the full tape length with the J-roller using firm, overlapping passes — three full passes minimum. The J-roller isn’t optional here; it seats the microseal layer into every surface irregularity and doubles the tape’s actual bond strength versus hand pressure alone. For the MaxxAir fan, the skylight perimeter, and the Fiamma bracket feet, load the self-leveling Dicor lap sealant into the drip-free caulking gun. Cut the tube tip at a 45-degree angle to produce a bead about 3/8 inch wide. Apply in a continuous bead around each penetration’s full perimeter, overlapping your start point by at least two inches. Self-leveling Dicor flows into low spots on its own — do not tool it with your finger or a putty knife, just let it level for 10 minutes. Apply sealant to all four corners of the MaxxAir frame as a final targeted pass since corners cure slightly thinner than flat runs.

Step 7: Apply EPDM Primer and Roof Coating

If your Bayside’s membrane shows surface oxidation, chalking, or micro-cracking across the flat spans — not just at penetrations — a full roof coating extends membrane life significantly. Apply the Liquid Rubber EPDM/TPO primer first using the 3-inch roller kit, working in 4-foot-wide strips from the front of the roof to the rear. The primer is thin and penetrates quickly; one coat is sufficient, and it needs 30 to 60 minutes of dry time before the topcoat follows. Roll the EPDM rubber coating in the same direction, maintaining a wet edge to avoid lap marks. One gallon typically covers 50 to 75 square feet depending on membrane porosity — the Bayside’s composite roof section will absorb more than the bare Transit steel areas. Apply two coats minimum, allowing each coat to reach a tack-free state before applying the next. Do not coat over fresh Dicor sealant — the sealant needs 24 to 48 hours to cure before being topcoated, so plan this as a second-day task if you’ve applied new sealant beads. Keep the coating off the MaxxAir fan lid, skylight acrylic, and Fiamma mounting hardware. Once the final coat is dry, do a slow walk-over inspection, pressing lightly along all taped seams and sealant beads to confirm full adhesion before packing up and descending.

← Back to Top 20 Class B RV Models