how to replace a roof seal trim on a motorhome ore campervan

Renewing campervan high roof trim seal

This was a job on my ‘to do’ list before I had even taken ownership of my 2007 Transit Leisuredrive campervan. It looked a mess and more of a concern were the bodywork rust marks between the trim and windscreen.

I have to say, Leisuredrives choice to finish the roof in this way was a mystery to me. The obvious problem is the ‘U’shape trim acts like a gutter collecting water from the forward sloping roof. The trim that Leisuredrive used has metal ribs that provides grip, unfortunately, fitted as it was these have now rusted. The original trim had been sealed on the underside with mastic to prevent water from being driven under the raised roof section. But, surprisingly the trim hadn’t been sealed along its topside to prevent water from entering it.

replacing a high roof motorhome campervan seal

Stripping a campervan roof seal

My intention was to remove the trim, clean up the bodywork and roof edge, then finish the joint with a SikkaFlex sealant rather than replacing with another seal. Unfortunately once the old trim had been removed I discovered I would need to trim it again rather than my preferred method of a sealant joint.

The first step was to carefully cut the mastic seal on the underside of the trim with a Stanley knife. Once cut, the trim can begin being removed. The trim had rotted so badly that it had to be removed in small pieces.

replacing a roof trim on a transit leisuredrive motorhome

Leisuredrive had obviously applied the trim to the roof section before fixing it to the campervan. Because of this the last two or three inches of trim will prove impossible to remove. I found the best solution for this is to cut away the front face of the trim leaving only the inner leaf of the trim which can’t be seen. When it comes to applying the new trim it will mean you can’t trim these last few inches. It turned out that in my case, this was an advantage. Originally the trim finished in the vans gutter which I think is a real design fault. The gutter would direct yet more rainwater directly into the open end of the trim.

replacing a high roof motorhome campervan seal
Roofline gutter directed water into the old trim

After removing the trim you’ll be able to see what you have to deal with. I had to remove an excess of sealant under the front lip of the roof so that the new trim would fit correctly. For this job I used a Stanley knife to cut it away from the bodywork and a decorators scraper clean it off. A good tip it to wrap handles and any unused parts of blade in insulating tape to prevent damaging your campervan bodywork.

replacing a motorhome roof seal

Keep rinsing the work area to remove debris and to see what you’re left with. I noticed another two problems at this point.

Problem 1:¬†The conversion company had cut the front edge of the raised roof so unevenly that sealing it with a mastic fillet as I had intended wasn’t an option. A replacement trim was needed purely to conceal the rough and uneven front roof-line.

replacing a ford transit leisuredrive motorhome high roof edge trim
Ragged & misshaped roof-line cut

Problem 2: For the life of me I can’t understand why but Leisuredrive had applied the trim, masked it and then sprayed the roof. This meant the last few inches on either side would need the old paint line rubbed down and blended in. Luckily the rest of the existing paint line was covered by the new trim. You can buy aerosol cans and brush applied touch ups online for most makes and models for small touch up jobs.

edging a fibreglass high roof on a motorhome
Original paint line gets covered by the new trim

The good news was that the bodywork between the windscreen and raised roof hadn’t began rusting. The rust marks were simply stains from the rusting ribs within the old trim. These are cleaned up easily with a cutting compound like Faracela G3 advanced. The ‘advanced’ version of ‘G3’ can be used by hand so is ideal for compounding small areas. At this point, whilst the trim is off it’s worth compounding the complete strip over the windscreen. Tape the edge of the roof-line as this is likely to be sharp.

What trim for your campervan roof?

Good news, there is a trim now available that doesn’t rely on metal ribbing for grip. These metal ribs have been the weak point of this trim but it needn’t be. Follow the fitting guide below and the metal inserts won’t cause you a problem. I chose to use the metal ribbed version as I wanted a white trim and at the time could only find the the metal free version in black.

Fitting a new roof edge trim to your campervan

Once you have your work area cleaned down and ready for the replacement trim it’s worth cutting a four inch strip of new trim and trying it along the length of the roofs edge. This will tell you if you’ve cleaned out enough of the bedding sealant from under the roof line so the trim can be applied without obstruction.

Is your roofline watertight?

When a raised roof top is installed it’s bedded down to the cab roof on sealant. Take a good look under your roofs front edge, use a torch, can you see any gaps in the sealant? You have two options at this point.

You can either apply a seal once your trim is applied or make sure your roof sealant is sound prior to the trim being fitted. The downside of sealing to your trim is you’ll need to cut and remove the sealant before you can replace the trim in the future.

If your sealant is watertight beneath the front edge of your roof you can apply the trim and just put a neat bead of sealant along it’s top edge rather than pump a tubes worth of sealant beneath it. This way you’ll save yourself the painstaking job of digging out a mass of cured sealant when it comes to renewing your trim.

Fitting the trim to your campervan

Measure your roof-line allowing for any curve. Cut a length of trim allowing a few inches over your roofs measurement. Make sure the end of trim you’re starting with has no metal ribs exposed.

Begin fitting by pushing the start of the new trim on to your roof edge close to the intended start point, then slide the trim to your start point with a few hard shoves. Whilst holding the trim at your start point begin tapping the length of trim on to the remaining roof edge working towards your end point. The best tool to do this with is a non-marking rubber/plastic mallet like window-fitters use. Alternatively the handle end of a hammer will do, use masking tape to cover the end so it doesn’t mark your paintwork.

As you approach the corner (end point) stop fitting the trim with approximately eight to ten inches to spare. Offer the remaining trim to the outside of the roof-line and put a pencil mark on the trim where it meets the end point. Cut your trim on this mark, if a metal rib is exposed cut the rib out. As you did with your start end, tap the last inch or two of trim on just short of your finishing point and then push it in to position whilst tapping the remaining trim on to the roof edge.

edging a fibreglass high roof on a motorhome

With the trim now in place you can push and pull the trim to even the line so it looks true along the entire length. You can also remove the trim ends to blend in paintwork and even remove the entire length if you need to make any alterations and then refit.

Finishing Up

Once any paintwork that been touched or blended is fully dry, add a neat bead of sealant to the top edge of the trim and each end.

Providing the silicone seals are maintained this trim, although not ideal, will last in excess of ten years. I have used it on my boat and even without sealant, they remain in A1 condition after nearly ten years in a saltwater environment. For the best seals and trims for your job take a look the selection from Seals Direct


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