Adhesive for tiles on step

[geraldthehamster]

I need to fix some tiles to the face of an exterior step.

My builder's merchant being shut, I went to B&Q and bought some Unibond Standard Set Floor Tile Adhesive (cement based). I now notice that the bag says it's for interior use.

Either I can do a 20 mile round trip to take it back, or I can use it. Does the team think it will be OK in this application? Is there anything to be said for adding more cement to it, to harden it and make it more water resistant?

Thanks
Richard

 

[geraldthehamster]

Oh well, I've done the job now