Accepted Answer

hi
most, if not all, of jayco's motorhomes utilize a fiberglass roof.. this is a vacuum bonded laminate, comprising of the interior panneling, a foam core and then fiberglass roofing. there is no plywood in the roof, although in some cases there is a thin layer of plywood beneath the fberglass, usually 3/16th" or 1/4" but the structural integrity comes from the foam core layup, and aluminum framing.
usually the entire laminate is about 5" thick. it is plenty strong enough to walk on, however, in the case of securing a roof rack, you need to be careful you dont just screw it to the fiberglass, as it can rip out easily. to secure it properly, you really need to get the mounting screws into the aluminum rafters built into the roof. finding these however can be tricky.. usually they are on 4 foot centers starting from the back, but this is not 100% accurate, as it can vary due to vent locations or other structural requirements. aluminum not bein magnetic makes most stud finders useless. often walking on the roof and watching it flex can reveal framing but it wont flex much due to the laminate.
so the roof is strong enough to support a kayak, you issue will be securing the roof rack properly so it doesnt get ripped out when on the road.
one sure way to do this is to use strips of aluminum, and secure them along the roof, front to back, spaning the distance you put the roof rack. then secure it with screws every 6 inches or so. or better still, drill a series of test holes in a line, using a small drill bit and mark locations of frames.. then once you have them marked, use sealant over the holes and then attach strips of aluminum over them to hide them, and then attach your roof rack to the aluminum... this method will ensure you hit the frames with screws, as well as spreading the load across 2 or 3 of them, increasing the carrying capacity of the rack.
this rack however usually mounts pretty close to the edge of the roof. there will be aluminum framing along the edge and across the back, to secure to, if the rack is secured at each side and rear of the motorhome...

Thankyou for your question.. please remember this is the answer page and to click accept if you are satisfied with my answer so i get paid for my efforts.. Please also note, accepting my answer does not terminate our correspondance, you may continue to reply after accepting and i will work with you until the problem is solved.
thankyou and please let me know if you require further assistance.....
:Nick:

Expert:	Nick
Pos. Feedback:	100.0 %
Accepts:
Answered:	10/2/2009

RVIA Certificati&on

5 years RV repair and reconstruction, Fleetwood RV Training course completion.