Which Sealant?

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I am fitting a bike rack to the rear wall of my motorhome, the instructions say to use silicone sealant under the mountings. Which sealants are suitable, bearing in mind I only want a small amount. The Sikaflex seem to be expensive compared to some of the generic brands at places such as Screwfix. I still have a nearly full tube of Carafax mastic that used to be used as a general sealant on caravans, would that be suitable?
 
hi . use sikaflex or another is bostick matrix . the choice is yours . i,m sure there are other good products . but in this case good isnt cheap.
 
I would suggest you use one with Microban (mildew and fungus inhibitor) in it.
 
£10 worth of sikaflex or hundreds of pounds worth of bike rack and bikes strewn across the motorway .
is there a option ??????????
 
The rack will be bolted through the rear wall (I would never rely on screws), I am also making some larger reinforcing plates. Don't think that the silicone would add to holding the brackets as it only shown round the holes under a rectangular rubber packer, the fitting just shows a small amount around each of the holes. The bracket sits on top of the rubber, personally I will put whatever I use on all the interfaces.

Thanks for the advice anyway, pity they don't make a small tube as the amount I would need would probably be less than an egg cup full.
 
i would of guessed that as your bolting the rack on, all you need is to make sure no water can get in through bolt hole, so a non setting substance to seal. but unless someone near you has some you'll have to buy a roll or tube. pity you not near lincoln, i'd of given you a piece of ribbon mastic

al
 
just to let you know no silicone on the market is an adhesive and at work we don't use silicone on two different materials as the expansion and contraction will be different causing the seal to fail.
 
Thanks for the offer Al, but I have a nearly full tube of Carafax Caraseal IDL99 non setting mastic. This is the stuff they used to use on caravans for sealing stuff like awning rails.

I actually tried ringing around to see if I could get any Siaflex locally, although some of the places I rang had heard of it nobody stocked it they all had what they said were similar or better. Amongst the ones I tried was a place where they did caravan repairs & servicing, the guy I spoke to said he had lost count of the number of caravans/motorhomes that had damp after using a silicone based sealant, he said to use a non setting mastic. So thanks for the advice, I think I'll use the stuff I have, I will keep a close check on it & seeing as it doesn't set I can always remove it if there are any problems.

The bolts / plates & bottom brackets supplied are supposed to be stainless with the top fittings being some type of alloy.
 
Hi I work in a builders merchants and we sell sika building products,one of the products is called SIKA EBT, the sika rep has told me it it the same product as sikaflex but re named for the building industry.I have sold this to many caravaners and motorhome owners who have said the same.It is also half price of sikaflex and comes in many colours.............................Hope this helps you regards.................Jeff
 
Are you putting a spacer on the bolt to ensure that the shell isn't compressed?

Guess the sealant is to stop the ingress of moisture rather than form a bond, therefore if rack needs to be removed/replaced then it's just a silicon seal that needs to be broken

I too would never just rely on the fixing power of self tappers.
 
Bought my last tube of sikaflex from clwyd caravans Ruabon think they may have the smaller marine type tubes as well? used it for everything thats bolted or screwed to mine also used it for an awning deflector no bolts stuck and sealed fine.

Mal
 
I have some small bore stainless tubing to make spacers, can't make them until I can determine the wall thickness. I will cut them just a bit smaller than the thickness so I can be sure it is tight.
Just need to get a nice dry day to fit it, weather seems to be very changeable one minute clear blue sky the next it's rain or sleet :mad2:
 
you may think i'm wrong but silicone is a sealer not an adhesive it may stick things together but it is not made to do that job.ask dow corning
 
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