ᐅ Rust stains, water marks, roller shutters – Next steps

Hello everyone,
we are currently building with a contractor, and I would like to ask about your experiences with the following issues:

1) It seems that many people struggle with rust stains on the ceiling. In our case, they appear sporadically on the precast concrete slabs, always circular (not elongated) with a diameter of up to 2cm (0.8 inches) and very dark rust-colored. Installing a suspended ceiling with drywall is not an option, as we need the full room height on both floors. The painter wants to cover everything with a sealing primer and not sand it down, saying that the rust comes from the rods inside the concrete slab. Do you think this will permanently conceal the rust stains? Are there better alternatives to cover these rust spots?

2) After the screed was laid, the house was briefly humid enough that permanent water stains appeared on the plaster. The painter also wants to cover these with sealing primer. I’m not really comfortable with this idea, especially since this is a new build and I don’t want to cover up and hide the problem or, worse, have to deal with the contractor’s mistake in incorrectly heating the screed. Are there alternative solutions for this issue?

3) The roller shutters have been installed, and it turns out the preparation work was poorly done. First, all the shutter tapes run very crookedly—they are not parallel to the window but instead angle downward away from it. This means the upper outlet and the box for the shutter tape are not aligned. Second, the upper outlet is set so deep into the plaster that the tape rests on the plaster surface. Is the only solution here to break open the masonry and reposition the box for the shutter tape? I’m getting a bit desperate.

Thank you in advance for your advice.

I would suggest consulting an expert as soon as possible.

Rust is one of the most durable and effective pigments available. Conducting a test area would be helpful, although it is uncertain whether it might still bleed through in two years. However, often it does bleed through once moisture reaches the next layer.

Moisture should be allowed to dry out, possibly with the use of construction dryers, and not be trapped inside. A moisture measurement can provide clarity here. Leak detectors have good devices, and the screed installer also has some. There are also moisture meters available for home use that cost in the double-digit range. If you plan to cover the screed, residual moisture will have to be measured beforehand anyway, so perhaps you can combine these tasks. Unfortunately, your post does not specify the age or appearance of the issue.

If the roller shutters or their straps are installed so poorly, it may be worth considering changes before the painter begins their work. For me, this would definitely be a defect complaint and a case for an expert—possibly a specialist or an architect.

When situations like this occur, you often have to choose between spending more time or ensuring quality workmanship. You should make this decision for yourself and act consistently. Once work has been done on top or further construction has taken place, corrections can become disproportionately costly, and then your options are limited. In principle, complaints should be well documented with photos, sent as a polite but clear registered letter, and a request for remediation should be made.

I wish you patience in dealing with this; it will likely not be the last challenge.

Good luck Gabriele

The rust stains on the ceiling are quite common. A primer sealer is applied as an undercoat and that’s sufficient.

Rust stains on the precast concrete slab are very common and occur during manufacturing. This is due to the reinforcing steel in the slab rusting. Usually, sanding off the stains is sufficient. I have had many construction sites where the stains disappeared after wallpapering. Since the ceiling is then dry, the rust does not continue. Applying a primer is also a good idea. However, for exposed concrete surfaces, additional measures are necessary.

It is completely normal for the house to resemble a dripstone cave after installing the screed. Start ventilating intensively with short bursts of fresh air ventilation (avoid continuous drafts!) after one week, and the issue should be resolved within 14 days. The walls also dry quickly. Please do not paint anything during this time.

You should report any issues with the installation of roller shutter boxes and/or plasterwork and demand proper installation from the responsible contractors. As described, it is unacceptable workmanship.

1. Let the painter handle it; they know what they're doing.
2. Again, let the painter take care of it. Just make sure they use a standard paint. The moisture from the screed is completely normal and will dry out.
3. Request a repair. Crooked straps, etc., are by no means state of the art and are simply incorrectly installed components. It may also be easier (and more cost-effective) to switch directly to electric drives rather than breaking everything open again to realign.

...Sorry, that confused me... either more construction time or accepting the lower quality...