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what prep reqd for using sikaflex?


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My brother in law who fits alarms/electrics etc to motorhomes for a living said simply clean the area using a degreaser.....such as brake cleaner which has been suggested above to ensure a grease/polish free contact area.  He said there is no need to 'roughen' the area.
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birdybiker66 - 2013-09-26 8:03 AM


I have some brake cleaner which is very effective, I'll try that. One more thing, do I need to seal the gap between inner and outer skin, there's no mention of it in the instructions! I thought maybe some type of waterproof tape. ?

You could put some silicone sealant round the edge of the hole.
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SIKA does market a preparation product, but it's not cheap and 1-litre is the minimum quantity:




You don't say what type of aerial you'll be gluing to the roof, but you need to remember that a joint made with Sikaflex-512 should not be too thin. A 2mm thickness of adhesive is recommended.


Guidance on Sikaflex-512 usage can be found by using the following link and clicking on the top entry that's retrieved headed "[PDF] Sikaflex®-512 Caravan - Sika UK"




Surface preparation advice is


"Clean surfaces are important.

If a key is required use a polyester scouring pad or fine abrasive paper.


For degreasing and final cleaning use a spirit based solvent that contains no oils (eg. Sika Remover-208 or white spirit). For maximum bond use Sika Cleaner-205 which contains an adhesion promoter."

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Don't use white spirit to prepare the area. White spirit is quite good at removing 512 as has been said. Neither do you need to key the area. 512 is quite happy on clean / dry grp or painted aluminium.


If the area is a bit grimy, it's best just to polish it back with a bit of cutting compound but make sure you remove all traces of the compound before applying 512. I've also used a dab of cellulose thinners to good effect but you must let the thinners fully evaporate (wipe with a paper towel to help) before using the 512.


Having said all that, not sure I'd be bonding an aerial to the roof. Not sure why you would need to?

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Hi Dave..

Have you got any other, ageing seals that you can trim out and re-cap, while you're at it?...


Because opening a fresh tube of Sika', just to run a seal around one tele aerial, does seem a bit of a waste..because it doesn't "keep" once opened.

(..it's a bit like having ready-mix dropped of...it's always best to somewhere else for it go, just in case you've ordered too much! (lol) )


I resealed a large seam on our roof a while back(with 512)..and while I was at it, I tidied up all the original, manky looking seams around the roof vents...

(..even if it's not "needed", at least it gives extra peace of mind.. ;-) )

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