Last year I installed a couple of Fiamma 28 RV roof hatches on my Ford Transit Camper Van. I bought these RV roof hatches in Australia but the instructions are mostly in another language and very basic . The recommended sealant is Sikalastomer-712 so I thought this must be an Italian name for Sikaflex because I can’t even find this product anywhere in Australia. I went to the hardware store and found some good quality Polyurethane Sikaflex sealant and installed the two RV Roof Hatches and did a lovely job I might add.
About a month later we had some heavy rain and Both Fiamma Roof Hatches hatches leaked, luckily I noticed before any damage was done. I took out the screws that hold the two halves of the vent together and the top half lifted straight off, the Sikaflex hadn’t stuck to the vent at all. I used a sharp knife to remove the Sikaflex from the vans roof and went back to my Fiamma instructions sheet to see what I did wrong.
After some research i found that Sikalastomer-712 isn’t the Italian name for Sikaflex, Silly me. It’s actually a Sika product that is a type of Butyl Mastic or a Butyl rubber caulking compound, not Polyurethane or silicone like most Sika products are. When I search for Sikalastemer on the internet I find all these forums of people asking where they can buy it from for their Fiamma hatches,how funny is that? The problem is you can’t buy this product in the stores in Australia and the best I could do is find it on eBay in the UK and buy the time it’s shipped to Australia it would cost about $40.00 for a tube. I decided to buy a local brand brand of Butyl Mastic made by Selleys, Bostik also make a Mastic called Z Bond.
When you look at the sealing surface of a Fiamma 28 RV roof hatch you’ll notice that the surface area for sealant is narrow and it has a 12 mm groove all the way around the perimeter , it doesn’t even look like it was made for sealant. I had recently installed an RV window in the side of the van and the instructions called for the use of some self adhesive closed cell foam sealing tape, and I still had half a roll left over . The dimensions of the tape are 12 mm wide by 6 mm thick, so I decided to run this self adhesive foam tape inside this 12 mm groove around the perimeter of the Fiamma roof hatch and where the two ends of the foam tape meet I added a dab of Butyl Mastic. The roof of the Ford Transit van has these raised ribs built into it that hold the hatch off the roof as much as 10 mm in some spots and I wanted the foam to compress a bit for a good seal so I doubled the foam tape thickness by adding another layer on top of the original strip of foam. This gives me about 12 mm thickness I also sealed where the two ends meet with Butyl Mastic. You can buy this foam in thicker sizes so you don’t have to double up but I already had this roll in stock so I used it. It has to be (closed cell) foam so water can’t pass through it.
I cleaned the vans roof with some wax and grease removing solvent, then I flipped the Fiamma hatch upside down so I could see the foam tape. Then I ran a generous bead of Butyl Mastic onto the surface of the tape that will be touching the vans roof , then I installed the vent and tightened up the screws that sandwich the two halves together. Once I was happy with the fit and the screws were tight I ran a bead of Butyl mastic around the perimeter of the hatch and smoothed out with my finger. So basically I’m using a combination of foam and sealant. I did both hatches this way a year ago and have had no leaks since, the van has even been through Cyclone Debbie with no leaks.
I think that Fiamma make great products and I’m happy with these vents now that I’ve figured out how to seal them. I’d like to add that this model has permanent venting which means that it still ventilates even when it’s closed, which is a requirement when you have LP Gas installed. This allows dangerous carbon monoxide gases to escape when you’re using the stove with the hatch closed. I hope this has been helpful to you, safe camping!