# Forum Home Renovation Heating & Cooling  Fireplace repair - sealing flu/brick gaps

## John_

G'day, I'm repairing a jetmaster open wood fireplace and have a few questions that hopefully someone here can answer. My first step is to seal the chimney and secondly I am going to replace the firebox with a second hand one I have picked up (exactly the same as the original one minus rust).  *Question:*
What should be used to seal the gaps between the metal pipe (not sure on the correct terminology) and the brick?   *Details:*
As per the photos there is a gap the whole way around, water is getting in when it rains. Additionally in one of the photos you can see near the flashing that the inner pipe is exposed - I pulled out a small triangle shaped bit of what looks like mortar from this gap, the mortar was cracked but I still have the bit in case I can put some kind of silicone around it? I was worried about silicone not being heat resistant enough for the inner pipe but maybe it is ok for sealing where the outer pipe comes through the brick?

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## Smurf

There's some proper cement-like putty for sealing flues etc. Not sure if all their stores sell it, but I saw some in BBQ's Galore a couple of weeks ago.

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## PDub

Bunnings sell fireplace cement in tubs like putty - I'm guessing that's similar to what Smurf was referring to 
If you did want to go with a silicone, Selly's 401 is temperature rated to just over 200 degrees and also available from Bunnings. I used in on the flue of my pot belly for one season and it seemed to stand up alright, but where I used it was about 2 metres above the fire so I'm not sure how much heat it acutally got.

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## John_

Thanks guys, previously I had asked a Bunnings staff member about fireplace cement and they said they didn't stock it - I guess it's not a big seller  :Smilie: . 
I went back an I found the stuff at bunnings, Selleys Fireproof Cement (Selleys Fireproof Cement). It's for interior use only but I bought a tub and I also got some 'Selleys Silicone 401'. I'll use the 401 for the gaps around the outer pipe and the the cement to seal the gaps around the inner pipe.

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