Sealing and Waterproofing Eagle Walls

[sparkplug188]

I have never seen anything like this before.  The only thing holding the painted aluminum panels in place is the shiny aluminum trim strips ...no rivets under the trim strips... no sikaflex under the panels... no butyl or sealant under the trim strips... zink plated wood screws holding the trim strips on...

Is there anything wrong with putting a bead of Sikaflex 221 under the aluminum panels and riveting them every 6"?  What about instead of wood screws, use 2-1/2" stainless steel machine screws and weld on flange nuts to hold the trim on?

My parts book doesn't show enough detail to see how the side walls were attached originally.

[Seangie]

I'd do the silkaflex and loose the rivets.  Leave the trim if it looks nice.  I think those wood screws will eventually back themselves out with the heating/cooling over time.  Might be better to replace those with rivets if possible.

-Sean

Wandering the country in a 1984 Eagle 10S. 
www.herdofturtles.org

[sparkplug188]

I planned on doing Sikaflex under the panels and rivets under the trim strips.  The rivets are needed to hold the panels in place while the Sikaflex cures.  They won't be visible once the trim strips are in place.

My main concern is thermal expansion.  What is going to happen in the summer if I lock these panels in place with rivets and glue?  Thermal expansion of the panels ripped the previous owner's wood screws out of the trim and the panels buckled outward.  I am sure the same thing would happen if I replaced the screws with rivets.  Stainless steel machine screws and flange nuts aren't going to rip out.  I am concerned something else will give out, like my window glass.

I had a thought while typing this up.  What if I slot the holes where two panels overlap?  The exposed panel could have regular holes and the overlapped panel (hidden) could have slotted holes to allow for expansion.  Rivets won't grip a slotted hole. Countersunk 7/8" stainless machine screws and flange nuts should work well in place of those rivets.  I have watched the panels expand and contract 1/2" over the length of the bus.  There has to be a way to deal with that expansion.

[sparkplug188]

Don't be shy!  My building experience comes from residential construction, not bus building.  I know laminate floor will buckle if it can't expand... the same must apply to aluminum panels too.

[Jeremy]

The aluminium roof skin on my bus is entirely attached with double-sided tape rather than Sikaflex, with the only rivets anywhere being those that fasten the fibreglass front caps on. There aren't any rivets in the side skins either, although those are held-on with Sika. I mention the tape because it might be the answer to the 'waiting for the Sika to cure' problem without needing to resort to rivets - which I'd personally try very hard to avoid, not only because pop rivets distort the panels (look at the wavy bodywork on any Land Rover), but they would also prevent the panel from 'floating' in a way that's going to best compensate for any expansion and contraction. The double-sided tape is equivalent to Sika in terms of adhesion etc I believe, so if it were me I'd definitely be investigating whether it'd be suitable for your wall panels

Here's an example of the specialist double-sided tape used by bodybuilders:

http://www.technibond.co.uk/Applications/CommercialVehicles/tabid/55/language/en-GB/Default.aspx

Jeremy

[ArtGill]

Ten years ago I followed the Sikaflex instructions and put spacers in the bead od sikaflex and weged 2 x 4's between the panel on my coach and the brick wall of a building.  I live on the North Carolina coast with temperature changes from over 100F and 0F and the alum is still on the side of my coach without and screws or rivets.  Have confidence in the sikaflex.

Art

[sparkplug188]

Jeremy-  That looks like a promising product.  Unfortunately, I won't be able to use it on this project.  I have an extra case of Sikaflex left over from the subfloor project that needs to be used before it expires.  I will try to get some test samples for future projects.

Art- So that is how you use Sikaflex without rivets! I must have read a dozen threads about Sikaflexing panels, but none of them said how they were clamping the panels while it cured.

I am guessing... if the panels are locked in place with Sikaflex and trim on the top and bottom and rivets on the left and right, there isn't any reason to be concerned about expansion?

[niles500]

HI Sparky, ideally the properly sized (thickness) panels are heated during application which negates or diminishes the buckling. FYI Sika manufactures a vast number of adhesive products. To simply use a Sika adhesive does not warranty its success, but the right product installed per their instructions will permanently install your panels with little to no visual or structural distortions - HTH

[sparkplug188]

Niles- I have white Sikaflex 221elastic polyurethane sealant for bonding wood, metal, ceramic, and plastic.  What Sika products do you know work well for this application?

[niles500]

The archives of this board, and other boards, have documented what others HAVE used in the past, but my suggestion would be to call Sika tech support and explain your proposed use and see what they suggest. Technology is progressing way to fast to rely on old experiences - good luck with your project.