Not sure why this happened; nonetheless, In order to re-attach the back end of the long horizontal mid body trim molding, need to repair at least 2 fiberglass screw holes under the cover strip (photo). What's the most effective material/procedure to use to anchor the screws and minimize the risk of a repeat.
I know it sounds like a gimmick, but I have used the stuff linked below with great success. If the hole is not boogered up too bad, just stick a small strip of this material in the hole and reuse the original screw. It has worked great for me (Mr. Shadetree Mechanic).
Woodmate 2498 Mr. Grip Screw Hole Repair Kit - Wall Surface Repair Products... (https://www.amazon.com/Woodmate-2498-Grip-Screw-Repair/dp/B001B38ALG)
OR, you could fill the holes with epoxy, let it set up, then drill new properly sized screw holes. This fix is likely more "professional".
Marine Tex is good stuff............Semper Fi.
I have fixed many of these and I use the wooden tooth picks dipped in glue then stuff 2 or 3 into hole and gently use a hammer to drive them in. Cut off flush and voila-it works every time. Do remember the yellow/whit glue as that binds them together.
JohnH
I think just putting in a polyester resin or epoxy into a hole in fiberglass, letting it cure and expecting it to hold a screw will not be a very long duration solution. The epoxy or resin will just crack as the screw goes in. It will hold for a while but not long.
If you have some left over fiberglass mat (short fiberglass fibers spun into a non-woven mat) or get some at NAPA or any car repair parts place, take a small piece and some resin and mix them together until the fiberglass is wet and then use a small nail or toothpick to stuff it in the hole. If some sticks out let it go until the resin firms up, sort of hard rubber, and then use a razor blade to cut it off flush. You can get some pretty fast setting epoxy or polyester resin so this doesn't take long but give the resin time to fully cure. The screws you took out are likely drill point screws that will drill a new hole of the correct size. Don't over drive the screw, snug it up tight.
The resin reinforced with the fiberglass fibers where the screw threads go in will hold well. John's use of toothpicks and yellow glue might work but I don't think the yellow glue will bond to the fiberglass very well and the toothpicks are subject to getting wet.
Lots of ways to fix almost anything. Whatever works for you is OK.
I just "jumped" up to the next larger diameter stainless screw. So the head of the screw sticks out a hair more. The old ones weren't holding but were painted to match the coach base paint. Now I have a much, much better hold that should last another 28 years.
And I don't think I will be around then, as that would make me 103 years old.
I used toothpicks on mine when I took that trim off.. I think I did read steel wool? helps? could be wrong.. it has happened
Cant get to big of a screw or the trim will not go back on
Larger screw and grind the head down or if it's an option you can enlarge the countersink for the larger screw
I use fine steel wool and a really good epoxy, mix it and fill the hole. When its dry I usually drill a small hole and then screw it together.
I haven't had one let go yet. There is a lot of difference between epoxies so fined a good one.
quote" John's use of toothpicks and yellow glue might work but I don't think the yellow glue will bond to the fiberglass very well and the toothpicks are subject to getting wet."
If they get wet you have a problem that should have been addressed before. I believe that these screws are going into the wooden floor material, so caulking these issues would first be done. I found that the metal frames these screws go thru had a problem with water entering at the top of door frames (looking under the angle iron that is at top of door frame) and after caulking all along this metal have had no more issues. The tooth picks have stood up well and last year when I had this trim off along with the fenders I found all screws fitted as "new" and did not have to redo any. So to me it is working. I also used exterior waterproof glue when set.
JohnH
Waterproof glue and toothpicks. Over 15,000 miles and haven't had to retighten one yet. ( fingers crossed ).
I have gone to the larger screw on almost all the screws along the beltline trim strip. All are holding tight.
I noticed when I first started replacing loose screws that it felt like there was only the wall thickness of the steel sill floor wall that had actually lasted long enough to provide holding power.
Maybe wrong but try probing a hole and you find absolutely nothing after a very short distance in. To me this indicates a void and voids exist inside the box beams.
John's toothpicks and waterproof wood glue should be fine along the trim line where there is the wooden floor structure behind the holes. If you are trying to fix a lose screw hole in fiberglass (like a marker light) with nothing behind it then some other approach might work better. Choose what works for you.
On my coach and probably yours too, those screws pass through the thin fiberglass skin and then into the plywood floor, but at the ends of the strip there may be no plywood. Toothpicks and glue work well where there is wood, but you may need something else if there is no wood. Many good suggestions from others above.
After waiting a day for curing, JB Weld Steelstick from my toolbox worked; drilled a pilot hole on each; screws nice and tight. Hope it holds. BTW, probing the last screw hole showed it was almost 6 inches deep???. Inserted a stopper ~1.25" deep before stuffing it with the JB Weld; the hole previous to the last one was only ~1" deep.
Sincere thx to all for your suggestions. Great forum; great support as always.