Porous joints in chimney

[Marcussjogren]

Hello!

Long story short - the chimney sweep condemned our chimney from 1893 because the joints were so porous that he could push a screwdriver into them, and it leaked smoke between the flues. He said we need to install liner pipes to get it approved, so we have done that.

However, I've become partly devoted to building conservation and also understand that the lifespan of liner pipes can be as short as 5-10 years in some cases.

What I then wonder is - if you remove the liner, can you fix such bad joints by ensuring that the external render is good, and by slip casting with support so that no flues collapse, or something else? If there was a risk of collapse, it wouldn't have been allowed to remain standing (I assume), and the tightness should definitely be resolved with the above measures.

I have also understood that there aren't really any laws other than that the chimney must be tight between all flues + the outside and not pose a fire risk.

Does anyone know how we should proceed if we want to restore the chimney to normal condition without liner pipes?

 

[sinuslinus]

http://www.byggnadsvard.se/byggnads...-eldstäder/en-frisk-skorsten-i-ett-friskt-hus
http://www.byggnadsvard.se/byggnads...h-eldstäder/murstock-och-skorsten-råd-om-vård

There are some threads about glidgjutning here on BH too.

 

[Marcussjogren]

Will read the pages, thanks! But answering them on slipforming and ensuring the exterior plaster is okay is enough for me?

I'm quite well-read on how slipforming works, but I'm more interested in whether I need to do anything else.

 

[scim]

What are you burning?

 

[Marcussjogren]

I have read the pages and they are very informative, but do not directly answer my question.

 

[Marcussjogren]

What are you burning?

Wood in tiled stoves and wood stove

 

[scim]

Okay, as I understand it, it's better to use an insert pipe than to slip-cast if you have a low flue gas temperature and risk condensation in the chimney, but that's not a risk if you are burning wood.

 

[Marcussjogren]

Mja - tiled stoves do have quite a low flue gas temperature but have also heard that the lifespan of these pipes is incredibly short, 5-10 years. But I have not researched it much.

However, it would have meant that I could have put my ventilation ducts back into operation, that would have been positive.

 

[scim]

Lower than other forms of wood burning possibly, but hardly so low that there is any risk of condensation in the chimney.

I do believe that the lifespan of liner pipes is generally significantly longer than 5-10 years. The one in my mom's chimney is probably 15+ years, and there's nothing wrong with it yet anyway.

 

[-RB-]

Our liner is about 22-23 years old. For the first 17 years, it likely wasn't used much, but since we bought the house 5 years ago, it's been used quite a lot in the winter. That said, if I need to redo the chimney, I would probably choose to apply slip casting. This way, the rest of the chimney also gets warm when you use it. Currently, it's only the liner and a few spots on the chimney stack where the liner touches the brick that get warm. The rest is insulated with vermiculite.

If I had such porous joints in my chimney, I would scrape them out and press new mortar in before slip casting and exterior plastering.

 

[Marcussjogren]

Our chimney liner is about 22-23 years old. During the first 17 years, it probably wasn't used much, but since we bought the house 5 years ago, it's been used quite a bit in winter. That said, if I need to redo the chimney, I would probably choose to use slip casting. That way, the rest of the chimney also becomes warm when you use it. Currently, only the pipe and a few spots where the pipe is against the brick get warm. The rest is insulated with värmekulit.

If I had such porous joints in my chimney, I would scrape them out and press in new mortar before slip casting and external plastering.

Yes, it might be that what I read was old info or something then!
If you want to scrape out the joints and fix them from the outside - how do you go about it? Do you only scrape halfway through and then fill, or how deep do you go?
You mustn't press the mortar through so that it comes out and sticks out in the flue channel.

 

[-RB-]

Yes, it could be that what I read was old info or something then!
If you want to scrape out the joints and fix them from the outside - how do you do it? Do you just scrape halfway through and then fill, or how deep do you go?
You shouldn't push through mortar so that it comes out and protrudes into the pipe channel.

That's how I would have tried to do it.