Which silicone? please help!

Cazilou

I hope someone can help. I am fitting a new upvc door with a upvc sill onto a concrete base. I know I need to use silicone to stick the sill and seal around the edges but I have no idea what type of silicone I should be using as there are countless different types and they all state that they do the same thing. What is the best waterproof sealant on  the market for this purpose please?
Tia Caz

Swasterix

My recommendation would be something by Dow eg. 

https://www.screwfix.com/p/dow-791-weatherproofing-silicone-sealant-white-310ml/33876

Or

https://www.screwfix.com/p/dow-796-upvc-silicone-sealant-brilliant-white-310ml/40004

Cazilou

Swasterix said:

My recommendation would be something by Dow eg. 

https://www.screwfix.com/p/dow-791-weatherproofing-silicone-sealant-white-310ml/33876

Or

https://www.screwfix.com/p/dow-796-upvc-silicone-sealant-brilliant-white-310ml/40004

Thanks, it's in the basket. I had looked at a Dow one and put it in my basket but then realised it was an interior one and couldn't find an alternative exterior suitable one. One door coming up!

Jonesya

I always look for "low modulus" for outdoor sealing, it means low modulus of elasticity, so more stretchy and will accommodate more movement of the joint. It tends to be a little bit more expensive but should seal better and not break as easily as high modulus silicones.

ElephantBoy57

Cazilou said:

I am fitting a new upvc door with a upvc sill onto a concrete base. I know I need to use silicone to stick the sill and seal around the edges but I have no idea what type of silicone I should be using as there are countless different types and they all state that they do the same thing.

I didn't think UPVC installers used silicone, flexible acrylic sealant would generally to quite adequate. Silicone sealer is used around baths etc. Perhaps a pro will come along soon and tell us if acrylic is better and if silicone has its downsides?

https://www.screwfix.com/p/no-nonsense-exterior-frame-sealant-white-310ml/21638

neilmcl

ElephantBoy57 said:

Cazilou said:

I am fitting a new upvc door with a upvc sill onto a concrete base. I know I need to use silicone to stick the sill and seal around the edges but I have no idea what type of silicone I should be using as there are countless different types and they all state that they do the same thing.

I didn't think UPVC installers used silicone, flexible acrylic sealant would generally to quite adequate. Silicone sealer is used around baths etc. Perhaps a pro will come along soon and tell us if acrylic is better and if silicone has its downsides?

https://www.screwfix.com/p/no-nonsense-exterior-frame-sealant-white-310ml/21638

Yes, silicone sealants are used for upvc window applications, see the Dow ones linked to above. Acrylic sealants tend to be used best with wooden windows as one of the big advantages is that it can be painted over. The advantage of silicone, particularly low modulus sealants, is they're much more flexible which is what you want for sealing around upvc windows.