Drying time for newly built chimney?

[LM_1973]

Hello
Our chimney has been dismantled and rebuilt. The material is solid brick (the same bricks as before) and mortar C. It is also plastered with plaster mortar C in a layer about 8 - 10 mm thick.
Is there anyone here who knows how long we have to let it dry before we start using it again? We have a stove (a newer version) connected to it and we miss the warmth

//Mia

 

[c_olsson]

Hello
Our chimney has been dismantled and rebuilt. The material is solid brick (the same stones as before) and mortar C. It is also plastered with plaster mortar C in a layer of about 8 - 10 mm.
Is there anyone here who knows how long we have to let it dry before we can start using it again? We have a stove (a newer model) connected to it and we miss the warmth

//Mia

At normal room temperature, the plaster should be dry after two days. But if it's colder or more humid (e.g., if you're wallpapering at the same time), it takes longer. Likewise, if the plaster is re-wetted (to make it more durable).

The mortar takes about a day to harden mostly. After about 2-3 days, it's so dry that the hardening stops if you don't re-wet it. If you start burning, you'll add a little water through the flue gases, and then the hardening continues a little.

My recommendation is to wait about 2 weeks before burning and to lightly water the plaster during the first week. (The recommended re-wetting is at least three days, which means you must wait at least five days before you can burn)

 

[Stefan1972]

No idea but don't tell the chimney sweep what you've done anyway. Doing it this way can certainly be considered as a new construction of the chimney and then suddenly fall under completely different rules.

 

[LM_1973]

At normal room temperature, the plaster should be dry after two days. But if it is colder or more humid (e.g., if you're wallpapering at the same time), it will take longer. Likewise, if the plaster is watered afterward (to make it more durable).

The mortar takes about a day to cure for the most part. After about 2-3 days, it is so dry that curing stops unless watered afterward. If you start a fire, you will introduce some water via flue gases, and the curing will continue slightly.

My recommendation is to wait about 2 weeks before starting a fire and to water the plaster lightly in the first week. (the recommended after-watering is at least three days, which means you have to wait at least five days before you can start a fire)

Thanks for the answer
We have watered the plaster for about a week to make it as strong as possible, and the masonry was completed 4 weeks ago, so we should be able to start a fire when the chimney sweep has inspected it in about 4 weeks, without any problems.
//Mia

 

[LM_1973]

No idea, but don't tell the chimney sweep what you have done anyway. Doing it this way could certainly be considered as a reconstruction of the chimney and then suddenly fall under completely different regulations.

We and the chimney sweep are fully aware of that. It is not considered a new construction if the chimney does not change in appearance and function. At least not in our municipality

 

[c_olsson]

Thanks for the answer
We have been watering the plaster for about 1 week to make it as strong as possible and the masonry was completed 4 weeks ago, so we should be able to light a fire when the chimney sweep has inspected it in about 4 weeks, without any problems.
//Mia

Yes, that's a very good margin. Two weeks after the last watering, everything should be bone dry. (Post-curing also consumes water which means that if it feels very dry before the end of the first week, you need to water a little more. When it's fully cured, it doesn't dry quite as quickly.)