Best sealant for around a stainless steel wood-burner chimney?

[David001]

Once during the recent winter, when the wind and rain were vicious and rather horizontal, I noticed some drips of water trickle down the outside of the stainless-steel wood-burner vent inside a bedroom.

 

So this summer I intend to get up on the almost flat dormer roof which is close to the stainless-steel chimney and fill any small holes I can find around the vent.

 

I imagine it needs to be something flexible, but also something that won't react badly when the metal is warm (when the fire below is burning).

 

What product should I use, please? 

[Gus Potter]

Post a photo and you'll get loads of ideas.

[Nickfromwales]

2 hours ago, David001 said:

Once during the recent winter, when the wind and rain were vicious and rather horizontal, I noticed some drips of water trickle down the outside of the stainless-steel wood-burner vent inside a bedroom.

 

So this summer I intend to get up on the almost flat dormer roof which is close to the stainless-steel chimney and fill any small holes I can find around the vent.

 

I imagine it needs to be something flexible, but also something that won't react badly when the metal is warm (when the fire below is burning).

 

What product should I use, please? 

WHOA!

 

Please define "vent", and DEFO post some pics before you begin doing anything  

[David001]

@Gus Potter& @Nickfromwales

Thanks for asking for a photo. I hope this one will do.

[Gus Potter]

Good photo. 

 

The localised wind vortices at the ridge and just behind the cylindrical flue pipe are going to be brutal. I would look to see if the water is getting forced up under the ridge and it's nothing to do with the mastic. 

[SteamyTea]

19 hours ago, Gus Potter said:

would look to see if the water is getting forced up under the ridge and it's nothing to do with the mastic

A relatively easy way to check that is look at windspeed and direction when it is raining. Them compare to water getting in.

Find your local WeatherUnderground station and see some actual numbers.

 

[saveasteading]

Slate and tiled roofs let water in  but then it stops at the underlapping slate and gradually goes down to the gutter.

If there is an underfloor, then that can catch any rogue drips that escape.

 

That looks a decent job, but at your vent i suspect that water can blow up over the top or side  of the zinc and has nothing under it.  Or some tiny gap where the slates are cut.

 

It would be necessary to take the ridge off to see how far the metal goes.. I think it should go all the way to the apex OR have another overlapping piece to intercept it. And wider too, hidden under the top slate.

Wind is the likely culprit. Gusts generally last just a few seconds, firing water upwards, but then releasing it. Hence a longer flashing might suffice.

 

mastic exists for flues but that should not be very hot there. It is nit very flexible so won't last long.Try a local stove shop.

 

There are special and foolproof rubber flashings for flues througb metal roofs but they are ugly and not appropriate to your lovely roof.