You treat it the same as a faux chimney and it doesn't sit on the tiles either. You'd trim around or prepare the rafters so that they seat the base of the structure footprint and that structure would protrude vertically upwards enough so that it is clear of the roof tiles by 150mm or so. You'd then tile and flash the upstand then add your clock tower later complete with weathering collar that laps over your upstand flashings
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local