Cabling through the roof

[8DashP]

So I had some basic answers on this in my original thread, but I'd like to follow up on some specifics if I can.

I Have a colourbond roof, and have to decide whether to drill holes in it to feed my coax through, or whether to try and run the cable under the bottom of the sheets where they come out at the gutter, and curl them back to the dish.

I climbed up over the weekend and found a small section of chicken wire has been run between to the roofing sheets and the gutter, I assume to vermin-proof the gap. I think I can still fit the cable through, but might have to be careful to to rip it apart or pull it out in the process. The problem with going this way is, it'll force me to add a joiner to extend my cable long enough to reach the dish.

The other option is to just drill holes through the roof sheeting, half way up the roof. That way I don't have to extend the cable, but then have to deal with holes and sealing them.

If that's the better option, I'd like to see if I can find some rubber grommets to fit the cable and whatever size hole I need to drill. Anybody done this? If so, any suggestion on drill and grommets sizes I should be looking for? Also, where do you buy individual grommets? Do hardware stores have them, or do I need a plumbing supply shop?

Also regarding the grommets, do silicon sealant and rubber play nice together? Should I silicon seal around a grommets, or should it be good enough to seal itself?

Am I asking the right questions here? Is this the right approach to take? I'd really rather go out the gutter and save drilling through the roof with the potential long term issues, but was trying to avoid joining the cable.

Anything extra people have to add about getting through or around the roof sheets would be appreciated.

Thanks. Russell.

[michael_sa]

Drill it, silicone it. Forget the grommit idea.

Michael

[viewer]

I'd do what michael says, however I remember one bloke always using old spark plug covers to slide over the rg6, into the tin (grommet style), then siliconed.

[porkop]

Cable glands!!

[Tasman]

Cable glands ideal but add to the cost. To go through the hole in the roof, make sure that the cable can not be pulled either from inside or outside as this will stress your silicone bond and eventually water will penetrate. Always go through the apex of the roofing iron. A grommet does help to protect your cable from chaffing. The various compositions of rubber and silicone sealant compatibility are beyond me but I have not had a problem to date. If you have to join the cable, wrapping the joint in amalgam tape provides complete water resistance. Cover this with black insullation tape. Cheers.

[8DashP]

Thanks guys.

Is it better to have a larger hole and more silicon, or as snug to the cable as possible? There's some grommets on eBay - 8mm hole, 5mm cable. Would tHat be a good fit?

[porkop]

Thanks guys.

Is it better to have a larger hole and more silicon, or as snug to the cable as possible? There's some grommets on eBay - 8mm hole, 5mm cable. Would tHat be a good fit?

I still think cable glands are you best option. They arnt that expensive to purchase, protect the cable and water proff the installation (yes with a touch of silicone on non flat surfaces). I have been using them for years in external to internal cable runs with no issues.

good luck

[8DashP]

I still think cable glands are you best option. They arnt that expensive to purchase, protect the cable and water proff the installation (yes with a touch of silicone on non flat surfaces). I have been using them for years in external to internal cable runs with no issues.

Ok can you provide some more info? I googled them, and it was mostly manufacturers or 25mm sized ones for $5. What sort of retail store do I need to find to pick them up locally?

Thanks.

[johnwinger]

i would suggest dont drill it unless you really must.

you could use a dektite on the topside, pick the smallest one you can get. cut it to size and then feed cable through so its snug then fill the dektite with silicon and around the edges so its sticks nicely. they usually come in black or grey and depends if you want it to be visible or not. maybe around 35mm square.

i would also suggest saddling the cable to something solid inside your roof to remove the strain on the cable pulling and stressing the penetration. the plumbing industry commission states you must use one dektite for each penetration, so this is a standard.

if you are to join your cable use amalgam tape and wrap it around tightly only over the exposed connections and joiners. use UV stable tape to cover over these if they are exposed to sun light.

i would also suggest drilling the smallest hole possible, you want minimum holes in your roof.

[johnwinger]

you can get a 0-35mm dektite in black or grey for $10-$15 from a plumbing supply store Reece, Tradelink etc or Bunnings. Choose the ones made by Deks (melbourne company) rather than the chinese imports.

use roof and gutter silicon rather than bathroom silicon