Problem with sky cable can you extend it

I am having a conservatory built at the moment and I am planning to get sky multiroom in there. I want to hide the wires so I bought my own cable today to hide behind the plaster.

The problem is the cable is not long enough to reach the dish. My question is can the cable be joined and will the sky man be happy enough to do this when he comes round to install the box.

Thanks

 

Easy to do (assuming the join is indoors)
Have a look here at '3. How should I join the cable?'

How do I extend my cable?

 

Sky installers are supposed to do the whole thing so that it's covered by the warranty.
They're all different so you won't know how he'll feel about it until he sees it.

 

So what length do you need? Beyond about 40m, signal loss becomes significant.