ᐅ Applying Exterior Wall Plaster While Interior Plaster or Screed Is Still Wet

Hello,

the interior plaster in our house was applied about 5 weeks ago. The screed was laid at the beginning of October. Heating started last Saturday, and since then the house has been ventilated several times daily. Naturally, the house is still damp. The plan is to start the exterior plaster in one week. My questions are:

1) Is it possible to begin the exterior plastering while the interior plaster and screed are still not fully dry? My concern is that the masonry may no longer be able to release moisture either inward or outward, which could potentially lead to defects sooner or later. Is this worry justified? We are building with Juwö Poroton S9.

2) Would it be more advisable to postpone the exterior plastering until next spring, or should we take the risk and apply it this year? From my research, exterior plaster should only be applied at temperatures above 5°C (41°F). Will the results already be negatively affected if temperatures are below 5°C (41°F) only at night but above 5°C (41°F) during the day, or is some cold overnight temperature acceptable?

Thank you very much in advance!

To both questions. No problem. The house will continue to dry even after plastering. Cement-based plaster still sets at temperatures around 0°C (32°F), as it produces heat during curing. And it will be some type of cement plaster anyway.

Nordlys schrieb:

Regarding both questions: no problem. The house will continue to dry even after plastering. Cement plaster still sets at temperatures around 0°C (32°F), as it generates heat while curing. And it will be some type of cement plaster anyway.

Thanks for the feedback. But where is the moisture currently inside the masonry supposed to go if the plaster creates a seal on both sides? Does the plaster absorb the moisture from the masonry and release it either to the interior or the exterior?

By the way, the exterior facade will be treated with a lime-cement lightweight base plaster, followed by a mineral topcoat plaster.

BiffBiff schrieb:

Thanks for the feedback. But where is the moisture currently in the brick supposed to go if both sides are sealed with plaster? Does the plaster absorb the moisture from the brick and release it inward or outward?

There shouldn’t actually be much moisture inside the brick. The interior plaster dries inward, and the exterior plaster dries outward. But yes, any moisture contained in the brick will also evaporate through the plaster.