Drilling through a tiled roof

[HDRW]

I'm a Radio Amateur ("Ham") and I want to run cables to antennas on the chimney, in the middle of the pitched roof, which is tiled with red (Marley?) tiles and has a 45 degree pitch.

I have some flexible conduit which is 32mm o/d, so what I'm thinking of doing is drilling a hole (35mm perhaps) through the tiles and then putting one of the "pipe flashing" units on the outside to keep the water out. "Dektite" and "Masterflash" seem to be the most common makes, and they consist of a rubber stepped-cone with a square flexible (aluminium?) base. I believe you cut the cone to give a tight fit around the pipe (or conduit in my case) and then fix the base to the tiles.

Some show a series of screws holding the base down, and recommend using a mastic to seal the base to the roof.

Is this likely to work, or am I setting myself up for a leaky roof?

I'm not sure of the right place to drill the hole - in the middle of a tile, or between them? You end up with a single hole in one layer and two semicircles across two tiles in the other, but which would be better on top?

I'm worried about screwing down to the tiles - I have a nasty feeling they'll crack around the screw-holes, and maybe join up the holes and unzip a whole section of tile! Would a good mastic/adhesive, such as Sikaflex, be good enough to hold it down?

Has anyone done anything like this? I presume it would usually be used for vent pipes or solar hot water piping.

Any thoughts/hints/advice?

Cheers, Howard
PS. I won't be doing it in this weather, so it's unlikely I'll be clambering up there within the next four or five months, so plenty of time to gather opinions!

 

[noseall]

A lead multi-slate would allow you to pass some round tubing/conduit through the roofing material and provide a weather-tight seal.

However, the weather-tightness relationship is between the tubing and the slate meaning the tube itself could still admit water unless you pug-up the hole once you pass your cables through.

 

[noseall]

P.S. The image shows a flat multi-slate but you would require a pitched fella.

 

[HDRW]

Thanks for that - I hadn't seen that type of flashing unit before.

The open end of the conduit won't be exposed - it's going into an IP66 box that's screwed to the chimney, and all the connections happen inside there.

Cheers, Howard

 

[datarebal]

Water tracking down the outside of the coax can be an issue .. I have used a lead slate sim to the picture but with a hook shaped tube instead of the usual straight tube designed for straightforward pipes. (used on a BT building)

You fit the lead slate as you would any other (no Screws).then simply slide your coax/s up and round the corner, you wont need to gunk it up with silicon
Obviously if you are going to be using a rotator then this may not be ideal