Damp the chimney - does it make sense?

Again and again one hears of chimney insulation. Whether this actually makes sense and what effect it has will be clarified in the following article.

Natural insulation of the chimney

A masonry chimney consists of mantle stones with an internal exhaust pipe. In between, insulating material is often used in modern chimneys. This type of insulation is already more effective than an external insulation could be.

Possible protection against sooting

Sooting always occurs when the exhaust gases cool down too fast on the way through the chimney and the water vapor and some acids, including sulfuric acid, condense.

The condensate can seep into the outer shell of the chimney, lead to the swelling of the cement and thus burst the chimney. Constant moistening with the condensate also damages the chimney and can cause frost freezing. In addition, in the affected areas often produces a pervasive, sulfuric odor.

Damping measures on the chimney are to prevent too rapid cooling of the exhaust gases in the unheated roof area and thus condensation. That can be effective - but it does not have to be.

Reasons that speak against insulation

  • Sooting can also be prevented or eliminated by increasing the exhaust gas temperature
  • The simple installation of a ventilation flap for a higher chimney draft fulfills the same purpose
  • Due to the insulation measures, the fireplace only dries very slowly until not at all, the condensate continues to work. The smell will stay that way. Therefore, other solutions are often more advantageous.

Insulation materials suitable for the chimney

Above all, it is important to use insulating materials that are not flammable. This is best used rock wool or mineral wool. Styrofoam plates must not be used (!). You must have a minimum distance of 5 cm to the chimney.

Tips & Tricks

Before insulating or enveloping a chimney with buried places, the plaster must be completely knocked off and the joints scraped out. Very damp masonry should be able to dry out first.

Video Board: Damp walls in an old house - why, and how to understand.