Repairing bonded grp rear panel on a coach build. (1 Viewer)

[CaravanConvert]

Hi

The rear of my motor home is a bonded panel consisting of a thin GRP gel coated sheet on 35 mm solid insulation. I have unfortunately punctured the outer sheet in two places after reversing into an overhanging plastic gutter. The punctures are about 35mm long and 6mm wide showing the insulation panel underneath. I have seen a product called gelcoat filler and l would like to know if anyone has any experience in using this type of product for a diy repair. Any advice on this or in fact any alternative would be appreciated.

 

[EX51SSS]

 

[gus-lopez]

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[f6c]

Welcome aboard

 

[Diabalo]

I have used it in my sailing days, it does what it says on the tin for boats so see no reason why it wouldnt be ok on a motor home

 

[treetops1]

Caravan convert, There will be someone along soon to put you on to the best method. Enjoy lol

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[Minxy]

Welcome to the fun house!

It would probably help those who can advise you if you put a photo on of the actual damage.

 

[ambulancekidd]

 

[CaravanConvert]

Thanks Airwave.

Thanks for you input, and here is further information.

I would say that the thickness of the grp sheet is about 2mm (I understand delivered to the factory on a roll like lino) bonded onto rigid insulation which appears to be polystyrene. The pictures show the damage. For indication of scale the temporary protection is 50 mm wide gorilla tape.The joint moulding above the damage is about 25mm wide.

The surface gelcoat has been cracked but not separated from the grp and the damaged area has been pushed back into the insulation by about 3mm. A small area, about 40mm diameter around the damage has been pushed back slightly but has not suffered material surface damage.

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[funflair]

OK @CaravanConvert

The first thing to establish is the insulation in the wall as if it is Poly"styrene" any standard polyester product will actually melt the insulation as the polyesters is "styrene" based.

To repair you would ideally get some polyester resin into the damaged area first but only subject to the insulation issue, the resin would be thinner than a gelcoat based filler and would find its way into any delimitation and it would stabilise the area before filling.

If the damage area feels fairly firm still and if insulation is polystyrene you could still make a repair with a Gelcoat or gel coat filler but to get a finish back onto it you would need to paint it or use a final coat of gelcoat of the correct colour, and yes the gelcoat would need covering to exclude air while it cures to stop it being sticky, you should be able to tape a plastic film over the gelcoat as a cover and then it will peel off if you can get some rigid plastic sheet this would give you a good flat finish but test the release first with some gelcoat.

Martin

 

[funflair]

Its only a small damage area that would not need reinforcing on a bonded panel and you can't get behind to do it anyway without cutting away insulation so not worth doing in my opinion.

Martin

EDIT re the foam if its very white and soft and squidgy its polystyrene if it more cream/yellow and granular its more than likely a PU and OK with styrene based resin.

 

[CaravanConvert]

Thank you all for your kind welcome and the many comments. This is my first motorhome purchase new in July 2017 so you can understand my panic on hearing a dull crunch as I hit the gutter. I was gutted . I will now go away and prepare a shopping list for the items required for the repair and if you don’t mind I will list it on here just to make sure that I have understood the products required.

Special thanks to airwave and funflair for taking time in compiling such comprehensive replies.

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[SuperMike]

So all that has to be worth the £15 joining fee as your ability to post will stop soon. The load of reprobates on here are a fountain of motorhome knowledge, unless I want to talk about American RV’s then they go very quiet ‘cos they know nuffffink about those.

 

[CaravanConvert]

Thank you again airwave.

 

[phil1946]

Not what you want to hear but if, after your best efforts, the repair is not perfect it is amazing what a 'graphic' can hide.

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[CaravanConvert]

Not what you want to hear but if, after your best efforts, the repair is not perfect it is amazing what a 'graphic' can hide.

Following the comprehensive advise I am sure that a reasonable job can be achieved. However, the gelcoat white finish may not be a perfect match to my motorhome white finish. If, and only it is way out your suggestion may be valid. Thanks.

 

[hilldweller]

Whilst I applaud your methods it occurs to me that the repair would be so good it would stand out from the rest of the mass-produced finish.

I know a guy who spent all winter re-doing the gel coat on a glider using your methods. The finish had to be seen to be believed, "mirror" did not do it justice. It was a club glider too.

 

[funflair]

Following the comprehensive advise I am sure that a reasonable job can be achieved. However, the gelcoat white finish may not be a perfect match to my motorhome white finish. If, and only it is way out your suggestion may be valid. Thanks.

If you get the RAL no for the bodywork Gelcoat you could get a pigment with a spot on match, if it needs filling just a bit of colloidal silica in the Gel and make your own but I think straight Gel would most likely do it if you build it up.

Martin

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