Coroplast aka Corrugated Plastic Sheeting Underbelly Material Replacement

[Yoda]

After searching hear and on numerous other RV forums I did not find anything directly related to the topic. That is the replacement of the coroplast belly material and the hardware / trim pieces needed. It is also called corrugated plastic sheeting. The material is about 1/8" thick and looks like plastic cardboard.

Why?

After numerous adventures into the belly of the beast the attachment point are getting a little beat up. In addition the last time I put it back,I foamed/sealed the edges which caused a bit of tearing getting it off again. I am having to remove the material completely for my frame crack repair and though this might be a good time to improve the situation.

First - Finding Coroplast sources
For the material other than ordering from GD, Amazon, and RecPro seem to be the only places to get this stuff.. I need 70.5" wider for my trailer (outside frame to outside frame)
https://www.recpro.com/1-8-extreme-d...erial-74-wide/
https://www.amazon.com/Tough-Grade-C...25&sr=8-3&th=1
https://www.amazon.com/RecPro-Corrug...25&sr=8-2&th=1

Has anyone used any of theses sources, and have any first hand knowledge of theses products. I have asked RecPro to send me samples.

Front edge strapping
Now on my trailer across the front GD used what looks like aluminum vinyl trim channel to lock the material in place. I have seen other brand trailers with different methods, abut cants seem to find what they used.

Here are a few pictures if what I have. Its getting pretty beat up from my remodels and needing access to the front cross over area.

Photos are of the top, end, and bottom Its about 5/8" wide and about 3/16" thick.

There are some sources of this, but the only place that seem to actually match is;
https://babsrvmarine.com/product/4-p...er-5-8-x-3-16/ Fortunately the 72" length will work for me.
It this what GD used and does anyone know of any better sources?

Belly insulation. I was thinking of using closed cell foam rigid board insulation, and after watching a few U-Tube installs thought it was a bit messy. I then though about closed cell foam foil bonded metal building insulation
https://www.insulation4less.com/full-product-list The specific Item is the Prodex Total 72" 5M Plus R17 https://www.insulation4less.com/insu...-insulation-5M Its pricey, but I could probably do a double install given the 100' roll https://www.insulation4less.com/insu...-insulation-5M

As a price comparison https://www.homedepot.com/p/Owens-Co...ENGX/315197840 6 sheets would cost $204 plus tax and is only R% vers R17 for the Prodex. Has anyone used the Prodex or similar to insulate the belly of your trailer

Last - Cross Members To hold belly fabric up. In looking at DIY's on this subject I see some trailers are coming from the factory (other brands) or folks are adding what looks like L-Chanel from frame to frame to hold the belly fabric up. I'm am thinking this would take the load off the side seams where I am seeing tear out over the years. It looks like steel 1/2 by 1/2" by maybe 1/8 thick (could be thinner) placed about every 4 feet That a lot of weight in my mind. Would aluminum have the strength in that size, or would I need to go thicker?

Thanks for any help, ideas, and opinions on this. Will probably be a spring project as frame repairs are about 2 months out. Trying to plan and spread out the costs and have everything ready to go. If I do this I wan ti right the first time - otherwise I can probably patch the existing coroplast back together.

Keith

[Jlawles2]

Keith, For the front strip, any flat piece of steel or aluminum should work. Remember camper assemblers are using what is readily available on hand in the shop. The vinyl trim strips they are using could be drops or any other bulk material shoved in a rack in the factory. A trip to the local HW store or metal supply store may yield a much more wallet friendly solution.

As for the insulation, good find. If you have the skills, making panels like Rob did would be the way to go. Instead of making folding doors though, I might be temped to use hinges only on the edges where I could drive the pins out to have full access to the underside.

[TedS]

Yoda, I think 1/2 × 1/2 crossmember is too small in either steel or aluminum. The vertical leg should be at least 1 1/2 for that span.

[acoleman43]

Last - Cross Members To hold belly fabric up. In looking at DIY's on this subject I see some trailers are coming from the factory (other brands) or folks are adding what looks like L-Chanel from frame to frame to hold the belly fabric up. I'm am thinking this would take the load off the side seams where I am seeing tear out over the years. It looks like steel 1/2 by 1/2" by maybe 1/8 thick (could be thinner) placed about every 4 feet That a lot of weight in my mind. Would aluminum have the strength in that size, or would I need to go thicker?

Different materials have different values. Also the same material will have different values based on other variables (such as tempered for aluminum).

If you really want to know, you would have to know the weight supported by the cross member then size the supporting member appropriately to carry the load.

Below is a yield and tensile strength chart for many types of aluminum. Note the massive difference in strength between the different grades/types.

Most common aluminum angles are made from 6061 and 6063 (note the strength difference in tempered type). I believe most hardware stores will have 6061 T6.

The "killer" for any "beam" is span. And the load/span ratio is not linear. For example, we once supplied beams to carry a "floating walkway" in a house. It was a walkway level with the 2nd floor, through the main living area (which had 20'+ ceilings) to get from one end of the house to the other end and remaining on the 2nd floor. The load those beams carried was minimal.....the walkway was only about 42" wide meaning each beam carried just 21" of load. However, the span was over 30'. Because of this the beams were hefty 5 1/2"x16"beams. The same 5 1/2"x16" beam with a 10' span will carry 20X more load.

You also need to account for different types of loads. In a moving vehicle this will be different than in a static object......







Or, you can go old school and use the "eye-chrometer" like most of us do

[Yoda]

Yoda, I think 1/2 × 1/2 crossmember is too small in either steel or aluminum. The vertical leg should be at least 1 1/2 for that span.

Thanks Ted

[Scott'n'Wendy]

An acquaintance of mine used to be in the sign business....made signs out of coroplast. Contact the sign businesses in your area. Maybe one of them will sell you what you need.

[Yoda]

An acquaintance of mine used to be in the sign business....made signs out of coroplast. Contact the sign businesses in your area. Maybe one of them will sell you what you need.

i already checked. The don't carry anything 72" wide - I would haft to seam and the stuff is too rigid - not made the same as the roll stuff. But thanks for the thought
Keith

[JCR GD]

For belly sag I used 1" angle iron turned in a "V" orientation. Has worked well for 7 years now.

[Yoda]

For belly sag I used 1" angle iron turned in a "V" orientation. Has worked well for 7 years now.

Jim - Much thanks for posting

Interesting. - I never would have thought of mounting that way. Any chance of a picture and how you fastened them to the frame? (hardware used) What thickness was the 1" angle iron? Sounds like a great method.

Thanks Keith

[JCR GD]

Keith, when I get home I'll post up some pics. Probably Monday

Quick answer, drilled hole through "point" of angle iron and outside edge of frame flange. Seated carriage bolt in point and bolted to frame. 1\8" angle. I made two for the front drop frame belly.

[JCR GD]

Jim - Much thanks for posting

Interesting. - I never would have thought of mounting that way. Any chance of a picture and how you fastened them to the frame? (hardware used) What thickness was the 1" angle iron? Sounds like a great method.

Thanks Keith

Pics before clean up and paint

[Cate&Rob]

I made crossbars from 1" x 2" thin wall rectangular tube with plates welded across the ends of the tube that then bolt to the inside of the frame rails. I friction fit 1" rigid foam insulation between these crossbars and held this in place with twist tabs on the crossbars. All of this is above the coroplast. These cross bars provided lots of places to secure the coroplast where needed.

Under the tanks, there is not room for crossbars and 1" insulation. I have flat bar (factory installed) from crossbars forward and aft of the tank, in addition to the upper "T" support method. This flat bar will offer some support to the tank but will flex as the tank sags . . . maybe not a bad thing?

Rob

[Guest]

Technically, drilling the flange is not acceptable but since GD installs many self tapping bolts there, they must feel its ok since the frame flexes over its entire length? A clamp would be nice but the motion and flexing of the beam must be taken into consideration. It would not be good for a brace to come loose to become a spear if the attachment were not secure.

Jim

[acoleman43]

I made crossbars from 1" x 2" thin wall rectangular tube with plates welded across the ends of the tube that then bolt to the inside of the frame rails. I friction fit 1" rigid foam insulation between these crossbars and held this in place with twist tabs on the crossbars. All of this is above the coroplast. These cross bars provided lots of places to secure the coroplast where needed.

Under the tanks, there is not room for crossbars and 1" insulation. I have flat bar (factory installed) from crossbars forward and aft of the tank, in addition to the upper "T" support method. This flat bar will offer some support to the tank but will flex as the tank sags . . . maybe not a bad thing?

Rob

Rob, I REALLY like this. Saving this for later

[Guest]

Rob, I REALLY like this. Saving this for later

X2. The bracket can be canted to install it and its securely bolted into the web.

Jim