Toilet waste pipe

[GREYHEAD]

I am installing a new close coupled wc in a first floor bathroom on an external wall. The soil stack is fixed externaly to this wall. I intend to run the waste pipe directly from the wc through the wall into the soil stack. Over this relatively short distance is it ok for it to be horizontal or do i need to have a fall on it into the soil stack
Thank you in anticipation

 

[Softus]

You won't have an option.

The connectors available to join to the stack don't have a horizontal input - the branch is forced to be at 2.5º from the horizontal.

 

[GREYHEAD]

Thats great, thanks for your prompt reply.