RV Repair: fiberglass roof, polyurethane glue, gorilla glue

Question
QUESTION: We are comppletely replacing roof on our motorhome. We are planing to finish it with double layer fiberglass coating.We are still not completely shure how it will work, but we hawe idea because of the fiberglass decking.
Also we are going to exchange 3/4" to 1" blue foam insulation. Do you have any suggestions.  

Regards
Nenad and Brana

ANSWER: Nenad, First off I need to know what kind of motorhome you are redoing. If this is a class c why aren't you putting rubber on? Is there a reason you want to put fiberglass on top? And then are you using sheet fiberglass or doing it on your own? As for the insulation I say it is always better to go thicker where possible. If you want a better answer to this question please get more detailed and I will give you my best recommendation. Thanks, Bill

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QUESTION: We have Iatsca 26'by Winnebago 1988. Motorhome has low mileage and we would like to reroof it the best we can. The roof is weary damaged and needs to be replaced completely. I'm planing to put 1/8" ceiling panel first with 1" blue board insulation instead 3/4" and 1/4" plywood panel on top. All went openings will be framed and raced up for 1/4" to make better water protection. I am planing to put on top double fiber cloth with fiberglass resin. First coat is going to be thick fiberglass mat with unwaxed resin to prepare for second coat of fiberglass cloth and resin again. Right now I worry about the possible cracks on the joins between the two levels of the roof that it has and I needed to recreate again.Also when it is going to be driven I do not know how much it is going to vibrate and is it going to initiate cracking of the fiberglass on joints.
Can you please help me also with recommendation of the glue to use. I know that some companies using red glue for roof paneling (making sandwich. I was testing different tipes of glue and found that gorilla glue (polyurethane glue) is doing well too.What is better to use? The roof will be made on the floor in two pieces and they will be lifted to the motorhome, joined together and finished with fiberglass from scratch as I explained.
Thank you
Nenad


Answer
Nenad, It sounds to me like you are going through it the right way and testing everything. The red glue is about the best that I have found to use. I have never used the gorilla glue. I try to use what the OEMs' are using in belief that they have tested things pretty thorough. As far as the vibration that will depend on how sturdy you built the roof. I don't know if I would go with fiberglass, I myself would go with rubber as that is what alot have these days, and it should be lighter. I would also make the roof in one section and then put it up. But the way it is built is what is going to determine how long it will last as well. I hope this has helped you, Bill