Can I use bathroom silicon sealant externally?

I’m attaching a piece of aluminium awning rail to the roof of my van. I’m bolting it to the mounts for roof rails, but I want to seal around it to make sure there’s no water ingress.

I have some silicon bathroom sealant like this:

http://www.screwfix.com/p/no-nonsense-sanitary-silicone-clear-310ml/88317

can I use that? I’m thinking that in the summer it’s going to be in a pretty hot and UV-heavy environment on the van roof, so I don’t want it to deteriorate and start letting water in.

They do exterior silicone for exterior windows etc so I would definitely think that would be more weatherproof?

For the sake of the £5-6 for a tube of stuff specifically formulated for exterior use, why risk it?

Dunno if it’s ok for your application, but it’s a great alternative to thread lock (I ran out of loctite and needed to finish a build)

it’s a great alternative to thread lock

:-) Have you tried to remove or replace any of them yet?

For the sake of the £5-6 for a tube of stuff specifically formulated for exterior use, why risk it?

Don’t be coming round here with your common sense advice :-)

Sikaflex 512 Caravan Adhesive & Sealant for Caravans, Motor Homes & Trailers

Is what you should use

Use sikaflex or tiger seal. Silicone will discolour in uv and also contains sodium, which if on painted surface, shouldn’t be a problem but on raw metal can cause rust/corrosion.

ct1, i use it on my vanits holding the roof on . i have also used it underwater and it holds very well, the the white and the black have a better bonding strength than the the clear

Second ct1

Just to be clear, it doesn’t need to be strong, as it’s not holding anything on, the rail will be bolted on. It’s purely a sealant to stop water getting in around the bolt holes on the roof.

Still CT1, its a great sealant too.

Use an exterior sealant. Bathroom sealant is t designed for outdoor use so will fail prematurely. They’ll be external versions in the DIY sheds

I did this job just two weeks ago and used this stuff…

http://www.everbuild.co.uk/weather-mate

You can get stuff specially made for caravans etc. Go to a caravan dealer, you’ll be amazed at all the specalist stuff you can get.

I’d be using the rail sealant that comes in a strip – much much easier to use.