Trusting VHB or Sikaflex?

[MrNatural22]

NEVER RELY ON ANY ADHESIVE AS THE SOLE WAY TO MOUNT PANELS ON YOUR RV!!!
Always use a secondary safety attachment such as a steel cable!! This is a VERY real possibility no matter how well you follow clean installation guidelines!!
Those rookie youtube VHB panel mounting videos are creating a dangerous possibility on the road.

 

[WA5IDX]

Looks to me like that first ( large) panel was just secured via "Sikaflex" or something similar. As I indicated in the other thread, I did use VHB tape but also used sheet metal screws on the front mounts. I did not mention that I also did a full covering of Sikaflex 221 over the entire mounting foot. So 1st the VHB tape, then the screw, then the Sikaflex.

I may yet add a "safety cable" as there can never be too much redundancy.......

 

[MrNatural22]

Your putting screws thru the mounts adds more adhesion for sure. I am also using SikaFlex because I didn’t want to penetrate the thin aluminum roof skin on my cargo trailer with screws and provides a better contact area that VHB tape on roofs not perfectly flat, but I am also putting a cable thru two eye bolts secured into the leading edge of the panels frame and attached to the front upper aluminum frame on the nose of the trailer.
I am also making an aluminum fairing across the leading edge and down 1/3 of each side for aerodynamics. Cheap and easy peace of mind. My panel only sits about 1” above the roof but I don’t want any safety concerns to dampen a trip.
I am also going to cover the mounting feet with 3” eternabond tape to protect and add strengthen the joint.

 

[gecko]

Can't defend every installer but 3M VHB Commercial Vehicle Tapes are utilized in the transportation industry for permanent attachment of sidewall and roof panels on commercial vehicles such as cargo trailers, truck bodies, ambulances, fire trucks, buses and rail cars.

3M VHB Commercial Vehicle Tapes

A single 42x19 panel with Z brackets attached to eight 2x5 (80 square inches) VHB mounts. The proper surface preperation, application and cure temperature. VHB tape edges sealed with non-sag Dicor. After four years and 60,000 miles they're still secure.

 

[Whinny]

My concern with VHB installs is not the 3m tape, but what it is applied to. If it is on a regular RV with EPDM roof the results may not be satisfactory....

 

[WA5IDX]

That's alot of VHB.....given the tensile strength of 1 sq inch of VHB (advertised as 25 lb per inch of adhesion), It's not suprising it stays put!!!!

 

[gecko]

That's alot of VHB.....given the tensile strength of 1 sq inch of VHB (advertised as 25 lb per inch of adhesion), It's not suprising it stays put!!!!

Holds like a ton... literally

 

[MrNatural22]

Can't defend every installer but 3M VHB Commercial Vehicle Tapes are utilized in the transportation industry for permanent attachment of sidewall and roof panels on commercial vehicles such as cargo trailers, truck bodies, ambulances, fire trucks, buses and rail cars.

3M VHB Commercial Vehicle Tapes

A single 42x19 panel with Z brackets attached to eight 2x5 (80 square inches) VHB mounts. The proper surface preperation, application and cure temperature. VHB tape edges sealed with non-sag Dicor. After four years and 60,000 miles they're still secure.

View attachment 37318

Those z brackets all look like they have two
Screws or bolts on each going into the roof. ?

 

[gecko]

Those z brackets all look like they have two
Screws or bolts on each going into the roof. ?

No screws or bolts going into the roof. The mounts have female threads. Each Z bracket is bolted to the mounts. The mounts attach to the roof with VHB. tape. Before anyone asks, these were custom made four years ago. I do not make or sell these mounts. I do not have a source to purchase them.

 

[pvdude]

Absolutely right:
- Using the correct type of VHB tape for the application
- Surface prep
- Application of the required number of square inches of adhesive for the load required
- Protecting the VHB tape from UV

Done this way, works perfectly!

 

[sshibly]

FYI: VHB is used to build high end campers/rvs, I have used VHB to mount my Hummingbird transducer and take my boat up to 40 knots and the transducer is still there hanging out the back of my boat.

It is all about prep and installation, good point, driving around at 70 with a 50 lb solar panel on VHB is not prudent and might land you in jail. CA has mandatory sentencing rules since a CHP office was unfortunately killed by unsecured cargo.

 

[gecko]

My single panel weighs 14 lbs. If I were installing mulitple panels on a van I would use a roof rail/rack system attached to the factory rack mounts.

 

[LanduytG]

The vhb might be good stuff. But if the rubber on the roof is not held down cotrectly to the wood you are in trouble. Srcews will not hurt or leak if installed correctly. Also you need to use a large screw so you have more holding power. VHB only is asking for trouble.


Greg

 

[Luthj]

Many of those RVs have a rubber membrane roof. Urethane adhesives and VHB are not suitable for that surface.

Properly prepped (per the instructions) sika 252 with sufficient bond area will exceed the strength of common screws.

VHB is similar, but needs flat-ish or matched surfaces. Remember, VHB is used to attach glass panel to skyscrapers. You need to have the right bond area and substrate.

On metal bodied vehicles I like to use rivnuts, even small ones like 10-24 are fine, in combination with a urethane adhesive/sealant.



I have seen roof racks come straight off a roof during a mild fender bender. So mechanical methods are no guarantee either. Its incumbent on the installer to safely attach gear like that.

 

[redhatengineer]

No screws or bolts going into the roof. The mounts have female threads. Each Z bracket is bolted to the mounts. The mounts attach to the roof with VHB. tape. Before anyone asks, these were custom made four years ago. I do not make or sell these mounts. I do not have a source to purchase them.

View attachment 37342

Hey where can I get those mounts?! (jk, nice set up though)

 

[Loadtoad]

Hey where can I get those mounts?! (jk, nice set up though)

The guy says, " I do not make or sell these mounts. I do not have a source to purchase them".

 

[redhatengineer]

The guy says, " I do not make or sell these mounts. I do not have a source to purchase them".

and I said "(jk [just kidding], nice set up though)". I just wanted to compliment their mounts.

 

[gecko]

CA has mandatory sentencing rules since a CHP office was unfortunately killed by unsecured cargo.

Unsecured loads are dangerous. Was that the guy who was hauling stolen kitchen appliances in the back of his truck when an unsecured stove fell onto the roadway causing an officer to swerve and hit a cement truck?

 

[Loadtoad]

and I said "(jk [just kidding], nice set up though)". I just wanted to compliment their mounts.

Did not know what jk meant. I learn something every day. They are nice mounts.

 

[MrNatural22]

? ......... custom mounts, surface prep, roof racks bolts and screws..... When an inexpensive, easily mounted steel cable
could solve all those safety issues.
-Not rocket science.- ?