Question about FRP bonding method


Well-known member
Hi all,

Need to pick brains for a moment. My M1010 project is slowly moving along and I am getting close to the point I need to attach the inner wall panels. I have researched a few things but really don't have a clear winner on what to use.

I am using .090" FRP panels to do the ceiling and wall panels. This will be mounted to aluminum studs, 16" on center. I am using an aluminum extrusion profile that will join the panels at the joints, which will add stiffness to the FRP as it spans between studs.

I have been looking at 3M VHB tape or Sikaflex adhesive. The wall panels I am not as much worried about as the ceiling panels. For the ceiling, I am going to rip my 4x9 FRP panels in half, so with the extrusions, there is only 2 feet between extrusions that the tape/adhesive needs to hold. The channel in the extrusion will hold the span between the studs. The inside will get hot as it sits (as cars do) so this is a consideration as I don't want it to de-laminate and cause waves.

My question is, which is likely to be the better choice, 3M VHB (looking at # 4952) or Sikaflex (# 221) or something else?

Here is a pic of the extrusion that will run the full length of the box, making a "grid pattern" across the studs. The large surface on the studs, the narrow part exposed inside and the FRP held in the groove.


Thanks for any input.


If I've read the above correctly the FRP will be bonded to the studs and the extrusions connect the FRP between the studs. if this is the case I would use the VHB in small sections to both hold the FRP in place till the sikoflex dries and provide a sufficient clearance for the sikoflex.
I have used both sikoflex 11FC and Wurth KD Bond adhesive. and found both to be excellent products.
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I have a buddy that used to build elevator panels. At first he swore by vhb, but after a while he said it was pretty finicky. He said if you did not get your prep just right, it would over time fail.

Based on his comments, I would only use vhb as a temporary method to hold stuff while the sika adhesive cures. Or only use sika with some bother way to hold it.

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Active member
… and provide a sufficient clearance for the sikoflex…
My understanding is that one of the key benefits of the VHB is that is allows the appropriate gap/spacing for the Sikaflez - way cleaner and easier than using washers which is also often recommended.

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