Bigfoot sagged roof restoration - Fiberglass RV

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Old 04-05-2016, 06:55 PM   #1
Junior Member
Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
Bigfoot sagged roof restoration

We purchased a 1980 Bigfoot 17 in the fall. It was in pretty good condition and had the wavy, sagged roof that is typical in the early Bigfoots. I knew right from the start that I wanted to fix and reinforce the roof. Over the winter I came up with a plan how to do it. On the weekend my Dad and I started the project. He is a retired civil engineer, so he is quite well versed with the structural aspects. I know a bit about fiberglass.

The first ceiling panel was cut out with an air powered cut-off tool. Very smoky and noisy. Proper protection was essential. The extruded styrofoam had not delaminated and was hard to pull off. Next came the task of cutting curved ribs and then attaching. Getting the right technique took a bit of practise. Reinforcements were added between the ribs. Also, at this time I noticed some pinholes in the fiberglass skin. These were circled for later repair. Today we finished cutting ribs for where the second and third panels were. We had to add some bracing for one side of the ribs to sit on. Tomorrow we plan to finish with the woodworking and maybe get a start on reattaching the styrofoam. The following day, all going well, should see us putting up new ceiling panelling. I will try to post some pictures soon.

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Old 04-05-2016, 07:14 PM   #2
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Name: Carol
Trailer: 22' Airstream Formerly 16' Scamp
British Columbia
Posts: 11,731
Hope you have it all put back together for the Langley Meet.

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Old 04-06-2016, 04:42 AM   #3
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Name: Mike and Linda
Trailer: 1980 BIGFOOT 17'
Posts: 25
We also acquired a 1980 model last spring that requires the same repair. It would be great to see some photos and additional details of your approach to restoring the roof to its original shape.
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Old 04-06-2016, 03:03 PM   #4
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Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
Pictures of saggy roof restoration

Today is day 5 on the roof project. All ribs are now in. Starting to glue in the original styrofoam.
Attached Thumbnails
DSCN3665.JPG   DSCN3666.JPG  

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Old 04-06-2016, 03:13 PM   #5
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Name: Zach
Trailer: 91 Bigfoot 17
Posts: 1,386
It would be nice to see what the structure was before you added extra support, for comparison. My 91 has the sagging, wavy roof too.

Not sure if I'll get around to doing anything about it anytime soon.

Nice work!
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Old 04-06-2016, 06:51 PM   #6
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Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
I wish I had taken a picture before we started the project. The saggiest part was probably down an inch or two. I'll continue to post more pictures. Should be finishing up the styrofoam tomorrow and then panelling on Friday. Picking up a 100w solar panel tomorrow that will go on the roof next week after I put on a layer of gelcoat. We hope to take the trailer for our first camping trip in just over two weeks.
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Old 04-06-2016, 06:53 PM   #7
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Name: Val
Trailer: 1988 Bigfoot Deluxe B19 19 ft / 2007 Nissan Frontier V6 NISMO 4x4
Posts: 431
Please do post more shots as you continue your progress. Very elaborate and impressive repair - nice work!
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Old 04-06-2016, 07:26 PM   #8
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Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
P { margin-bottom: 0.21cm; } Thank you for the kind and thoughtful comments.

Anyone contemplating a saggy roof restoration should plan on a couple of weeks' worth of work...and that's with two people. It would be extremely difficult to this job by yourself. A few things we've learned along the way:

  1. According to the folks at Bigfoot, the roof is supposed to be arched a bit.
  2. When pulling off the styrofoam, be careful as the fiberglass is very thin. We found that a putty knife (1 and 2”) works well to gently pry the foam away.
  3. Don't bother trying to scrape away the original adhesive as you will likely do more damage than good. Just aim to remove any loose, poorly attached remnants.
  4. Mark off any pinholes in the fiberglass for later repair. We found lots.
  5. We used PL construction and foamboard adhesives
  6. Every rib is a custom cut and fit.
  7. Originally we used a jigsaw to cut the curved portion of the ribs, but found that even when going very slowly there was some blade deflection that angled the cut away from the vertical. We then had to use a jointer in a very unusual way to remedy this problem. We eventually gave up on the jigsaw and did freehand cuts on the table saw. Some hand planing was usually needed to tweak things a bit.
  8. Cedar shims were used on the front curved surface under the foam.
  9. The wall behind the upper bunk was not a good candidate for resting the ribs on so we built a support. It will eventually be concealed when things are put back together.
  10. There was a lot of sag around the roof vent. We boxed it in and tied the structure to the ribs.
  11. The loads from the roof structure need to be transferred to the floor somehow. When the ceiling is buttoned up, we plan to add some supports underneath the cabinets.
  12. Everything is glued and screwed.
Stay tuned for more updates.
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Old 07-31-2016, 09:12 PM   #9
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Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
More pictures of sagged roof restoration

We preloaded things a bit and then put in some permanent supports.
Attached Thumbnails
DSCN3672.JPG   DSCN3675.JPG  

DSCN3678.JPG   DSCN3671.JPG  

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Old 10-04-2016, 04:01 PM   #10
Name: Amy
Trailer: BigFoot
Posts: 58
I have to do the same roof repair to my Bigfoot. I am wondering if you built around the upper cabinents and bathroom/closet area or overtop of them to the walls on the street side of the unit?

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Old 10-09-2016, 09:04 PM   #11
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Name: Shawn
Trailer: Bigfoot
British Columbia
Posts: 23
The new lateral supports rest on top of the edges of the cabinets and the closet/bathroom. The supports do not go to the walls. Any roof loads are then transferred to the floor structure via some additional vertical supports that we installed. For the upper bunk/cabinet area we extended the ribs quite a bit past the face of the cabinet and built a longitudinal support wall to rest the ribs on.
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Old 10-10-2016, 05:55 PM   #12
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Name: K C
Trailer: 1971 Trailswest Campster
Posts: 2,154
For the cross wise curved beams that have an arc in them make a pattern for the first one that is cut accurately and then for all the rest you can screw that pattern to the others and use a pattern following bit in a router to trim them to be identical shapes. Setting that following bit up in a router table works well instead of trying to balance a router onto a narrow piece of wood. If you don't own a router table just use a piece of plywood with a hole in the middle that the router can screw underneath to make a temporary router table top.

For the length wise (longitudinal) shorter pieces at each location mark out the angle on a short piece of lumber by setting it against the ceiling. The height of those pieces will vary at each location across the width of the RV although they will be mirrored across from the center so you will only need to measure across half the RV. Letter or number those positions on your little height gauge template you just made with the number that corresponds to where on the ceiling it will be. Now you can set your tablesaw blade to that angle using a bevel gauge and set the fence distance from the blade using that same gauge block. You will be able to run long lengths of wood that way and then just cut them to fit between the spaces between those crosswise beams.

When you install those crosswise beams if you make yourself some plywood spacing blocks that will keep all the beams set at the same distance which will reduce your time for cutting the longitudinal pieces as you can set up your power miter saw with a stop on the fence so you don't have to measure the length of each longitudinal piece individually. The same plywood spacing block method can be used to layout the locations for those longitudinal pieces.

It is all about having a methodical system when you want to reduce labor time and gauge blocks are essential to that method. As it is not much fun to retrofit stuff overhead reducing labor time is essential.
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Old 11-04-2016, 05:27 PM   #13
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Name: lee
Trailer: trailswest campsterl, 1996 Scamp 16 foot
Posts: 459
We have a 1971 17 Bigfoot ( complete with the standard sagging roof ) and after viewing the great job you did on your trailer and imagining what it would look like if I gave it a try I have made a decision. I think I am going to take the " Antiques Road Show " approach and consider the roof sag the same as " patina " and hence not to be messed with. Lee
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Old 11-05-2016, 08:50 AM   #14
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Name: Tom
Trailer: 1980 Bigfoot 17 ft
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Shawn did a great job. But, I'm with you Lee, mine sags without causing any leaks. For now, I'm happy to leave it alone.

1980 Bigfoot 17' & former owner of 1973 Compact Jr
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