Michael CH
2016-03-06 20:00:47
- #1
Hello everyone
For my renovation project, the façade is scheduled for the next few months. We have decided on a ventilated wooden cladding façade. The house from the sixties consists of 12cm red brick and an exterior plaster. It has no existing insulation.
Our architect says that we can build the insulation (20cm wood fiber insulation board) directly on the old (original) plaster. A vapor barrier is not necessary. I can imagine that regarding the bricks. I just wonder if the plaster does not have a higher vapor diffusion resistance (μ) than the bricks. As far as I know, the highest resistance must be on the warm side of the wall and continuously decrease outward. Otherwise, condensation could form in the insulation, right?
What also confuses me is that the bricks were not mortared on their ends. That means moist air can pass directly to the plaster unimpeded (part of the walls will be paneled on the inside. The rest plastered with clay. The first is not really airtight).
If this has fine cracks, which after 70 years is quite possible, high vapor pressure can be expected. The architect said that a vapor barrier could possibly be applied on the outside, which somehow doesn’t make sense either. I don’t know...
The pictures are a bit older. Meanwhile, it is already being hollowed out considerably.
Does the plaster need to be removed?
Should I properly repoint the bricks?
Michael
For my renovation project, the façade is scheduled for the next few months. We have decided on a ventilated wooden cladding façade. The house from the sixties consists of 12cm red brick and an exterior plaster. It has no existing insulation.
Our architect says that we can build the insulation (20cm wood fiber insulation board) directly on the old (original) plaster. A vapor barrier is not necessary. I can imagine that regarding the bricks. I just wonder if the plaster does not have a higher vapor diffusion resistance (μ) than the bricks. As far as I know, the highest resistance must be on the warm side of the wall and continuously decrease outward. Otherwise, condensation could form in the insulation, right?
What also confuses me is that the bricks were not mortared on their ends. That means moist air can pass directly to the plaster unimpeded (part of the walls will be paneled on the inside. The rest plastered with clay. The first is not really airtight).
If this has fine cracks, which after 70 years is quite possible, high vapor pressure can be expected. The architect said that a vapor barrier could possibly be applied on the outside, which somehow doesn’t make sense either. I don’t know...
The pictures are a bit older. Meanwhile, it is already being hollowed out considerably.
Does the plaster need to be removed?
Should I properly repoint the bricks?
Michael