Sealants: butyl tape, dicor, sikaflex, etc. - plugging holes


Bedding and bonding (adhesives) is not the same thing.
Of course, butyl has nothing to do with adhesion, why I was talking bolts.

I thought the question here was sealing.

VHB tape works well with butyl, but needs very diligent surface prep, closely following the data sheets wrt to temperature range etc.


On doors, windows, etc, that are designed to mount but not be adhered, I stick to gaskets...

MD branded self adhesive EPDM works incredibly well, just stick it to the backside of the door, window, etc you are installing.

Just be sure to orient the cut ends on the bottom.

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For roof vents I generally use butyl, stainless hardware and then cover that with a silicone or caulk. I've done many this way on fiberglass roofs and not had a problem. I think my method could be improved with Sikaflex instead of box store caulk/silicone over the hardware and around perimeter but I've never tried it.

I think Idasho is spot on using gaskets for windows/doors.

@Abitibi, isn't Eternabond tape really expensive these days? I've always loved the idea of it but not the price.

EDIT: Just Googled it. I was wrong, it's really not expensive at all compared to other quality methods/sealants. About $1/foot. Left my question intact for the benefit of others.
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Speaking of roofs...

Substrates and camper construction will vary, but I will always advocate for a liquid applied silicone roof coating if adhesion isnt an issue.
This is a place where there really is no such thing as overkill. Redundant sealing against roof moisture/leaks is key.

I use GacoRoof. Its a single part silicone that you can touch up, re-coat, etc.
Many silicones once cured has trouble bonding even to itself, not Gaco

As an example.... take this "solar tube" dome I used on ours for a sky-light.
Our camper exterior surface is marine ply, epoxy coated and painted with a single stage alkyd enamel.

Bedded in a layer of clear silicone caulk, pre-drilled and fastened with stainless wood screws, then overcoated with a few coats of GacoRoof.

After the first coat.... it goes on thick

Similar method applied to wire glands on the roof for solar cables.
No silicone used for adhesive, the roof coating already installed acts as a gasket when the gland is fastened down.
Then over-coat with more Gaco.

Same goes for roof attached tabs like solar panel brackets.
Fastened down with stainless wood screws to existing silicone roof coating, then overcoated with Gaco