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Coatings or plasters applied to cellular concrete constructions (also known as Siporex, its historical manufacturer, became Xella) can pose some specific problems, however easy to solve.

How to clean the plaster facade of a cellular concrete house?

Although in excellent condition, the asphalt cement rendering of a cellular concrete house becomes gray when wet. Can it be cleaned with a pressure washer and products like Batifaçade, Alginet... chlorinated or not?

The fact that this house is in Aerated concrete has no impact on the cleaning of its facade plaster. It is clear that it is not necessary not use a pressure washer which may take off the plaster, unless it is used with great care, at very low pressure (if it is adjustable) or by moving the nozzle away from the surface of the wall.
The fact that the facade blackens in wet weather seems to indicate proliferation of mosses or lichens. Chlorinated products are very aggressive for the environment and their discolouring power is not necessarily ideal.
Begin by applying a commercial, biodegradable antifoam product using a telescopic wand (which can reach 8 m), natural rinsing or jet. If this does not work, it will be best to use the services of a specialized company (established and recognized as such).

How to close a crack on a concrete wall?

A cellular concrete partition (Siporex) is cracked over its entire height. Is there a specific product to seal this lizard, knowing that it did not work with plaster?

For concrete, there are plasters specifically formulated for this material (at Ytong, Sika, Bostik, etc.).
Having said that, it is first necessary to check that the crack is stabilized. If this is not the case, any plugging, even made in the rules of the art, will eventually give up. On a partition, theorigin of cracks often has a bridle (lack of expansion space) between the top of the partition and the ceiling. In this case, it is necessary to restore a space between the top of the partition and the ceiling.

How to paint a roughcast applied on cellular concrete?

A cellular concrete house (Siporex) is covered with a plaster. The set is in very good condition and without any crack. What paint to use to restore the plaster? How to proceed to obtain an optimal result?

Most of refastening paints, Pliolite®, hydro-Pliolite®, acrylic, siloxane, even mineral, are compatible with the painting of an old plaster.
They must generally be diluted to penetrate all the interstices of plaster: consumptions are, therefore, always high (+50 \%, on average, compared to an application on a smooth support).
Beforehand, it is necessary clean the old plaster using a high-pressure machine, taking care do not put the nozzle closer to the plaster, probably a monolayer coating relatively "tender".
Then you have to apply a background fixer sufficiently diluted and can be tinted, it will also play the role of printing layer.
On a plaster that has never been painted, two topcoats will probably be needed, the first layer being a little more diluted than the second.

Is it possible to plaster and paint a cellular concrete barbecue?

Can a plaster be applied to a cellular concrete barbecue before painting? Which product to use? How to proceed?

A barbecue is by definition intended to be soiled by dust, grease stains, charcoal, etc.
Applying a plaster, which is a structured finish, is not necessarily wise, because it will retain dust, clog very quickly and will be difficult to clean.
Before painting the cellular concrete, it is advisable to coat it. A smooth satin paint (floor paint type), easily washable, seems more appropriate.
Another possible track: if the assembly of the blocks of cellular concrete is sufficiently precise, with regular joints, why not leave the cellular concrete apparent, by simply applying a water repellent which will make it less porous and less susceptible to fouling.

What product to apply to a cellular concrete facade?

The facade of a house built in 1987 in Siporex was plastered. According to the facade, the plaster used was not suitable for aerated concrete. To redo the facade, it should therefore start with "scratching" before applying a suitable product. Is it true that cellular concrete requires a specific plaster? Is it necessary to strip everything before remaking the facade?

It is true that it takes a specific coating for covering facades and external walls in cellular concrete (Siporex). Xella, the main producer of aerated concrete, offers a waterproof coating for aerated concrete adapted, but many other brands also, the important thing is that the coating is compatible with this type of material (referenced support OC1, applied according to DTU 26.1). A lime plaster is also compatible. In the present case, it is to be feared, indeed, that it is necessary to strip everything before remaking the plaster in the rules of the art.

On the same topic

  • DIY tips
    • Tips and tricks for resealing holes in the house
    • Smoothing a wall with a coating
    • Treatment and protection of facades against mosses, algae and lichens
  • Questions answers
    • How to solve a problem of humidity and crack on a balcony?
    • How to renovate a scraped plaster?
    • Resistance of cladding boards behind a stove
    • What painting on a clinker facade?
    • Which facade paint to use?
    • How to remove traces on an outside wall?
    • Cellular concrete house plaster.
    • How to clean red traces on a facade?
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    • Charcoal "restaurant quality"

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