Screwed or screwless
Opinions will differ on which method is the best for cargo trailers.
The exterior walls of an enclosed trailer are attached using one of two methods:
- Screwed
- Screwless
While most are built using screws, some factories offer screwless as an option. Some offer semi-screwless which simply means that they use the screwless installation method but still add a few screws in some areas.
Regardless of which method is used, it is important that each aluminum sheet overlaps the adjacent sheet. The first sheet gets installed at the back of the trailer so that each new sheet can overlap the one that was previously installed. The seams will all face backward so that the wind cannot get under the sheets and cause problems.
Advantages and disadvantages
Screwless exterior trailers have advantages over screwed trailers, but, they have to be prepped and installed properly.
Screwless trailers look smooth and provide a nice flat surface for decals and wraps, since there are no screws heads that create humps in the vinyl.
Another big advantage over a screwed exterior is that the aluminum sheets are installed so that they can expand and contract with temperature changes. This greatly reduces wrinkles, especially noticeable on darker colors.
Screwed exteriors cannot expand or contract. As a result, the screws often cause the aluminum sheets to spider crack around the screw head. Since trailers vibrate while being towed down the road, vibration also causes the exterior to crack or split, especially over time.
These cracks often create openings and allow water to seep into the trailer. The holes will continue to expand and cause the sheeting to become loose.
In high temperatures, screwed exteriors can wrinkle very badly, especially black and other dark colors.
Screwed exterior installation
Aluminum sheets are cut in sheets and then held in place while screws are inserted from the outside, and into the stud walls. The stud walls can either be tubing, hat-post, or z-post.
To insure that the screws do not miss the wall stud, a chalk line is used as a guide. If the screw misses the wall stud, a hole is left in the exterior aluminum sheet. Although the sheet with the open hole should be replaced, workers often try to hide them by using caulk, or by tilting the screw in the hole just enough to make it go into the wall stud.
In some cases, the hole may be located where trim can be installed over the hole so that it will not be noticed.
Screwless exterior installation
Screwless installation takes much more time and requires greater care and preparation.
The aluminum sheets are held in place by very strong high bond adhesive tape. If properly installed, it is impossible to pull the tape off the sheets.
Proper preparation prior to installation is very important to ensure a good bond.
If the preparation is not done properly, the sheets can pop loose and may even blow off while towing the trailer down the road.
Since all metal normally has a thin oily film on the surface, it must be carefully cleaned prior to installation of the aluminum sheets.
First, a wire brush that is attached to an electric or air tool is used to clean the surface area where the sheets will be attached.
Then, a chemical is wiped over the metal studs to clean and remove all remaining residue. The high bond tape has adhesive on both sides of the tape. The paper covering is first removed from one side and the placed on the exterior of the wall studs.
When tape has been applied to all the wall studs, the paper covering is removed from the outside of the tape. Each aluminum sheet is then carefully placed on the tape. Since the tape is very strong, care must be taken to place each sheet in just the right place since the sheet cannot be pulled loose and reinstalled.
After the sheets are installed, a roller is used to press down on the sheets firmly against the tape and the trim can now be installed.
In summary, a screwless exterior looks great and will hold up as good as or better than screwed if it is installed properly.
Proper supervision of the workers that install screwless exteriors will help ensure that the trailer is carefully prepped and that the sheets are installed correctly.
For more information, be sure and discuss your options with your dealer.
