Apply Sealing Slurry – Instructions & PCI/MEM Information

Apply Sealing Slurry – Instructions & PCI/MEM Information

Wherever moisture could penetrate into a building or its substance, sealing slurry is a simple and at the same time ingenious solution. Sealing slurries are therefore the method of choice against moisture in many building renovations. Here you will find all information about sealing slurry and instructions for application.

The mud can be used to counteract the effects of increased humidity both inside a house and outside. Wet walls and the resulting damage from mold and fungus can be removed relatively quickly and easily with the sealing slurry. In the instructions, you will see how easy it is to use waterproofing slurry in the problem areas of the house. You can even prevent moisture damage on the terrace. Sealing slurry is not overly expensive, but prevents high follow-up costs.

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materials and preparation

You need this for applying the sealing slurry:

  • trowel
  • joint trowel
  • Hohlkelle
  • spatula
  • mason bucket
  • Rührquirl
  • Tassel / ceiling brush
  • bucket
  • high pressure cleaner
  • broom
  • Drahtbürste
  • Latte
  • level
  • repair mortar
  • close schlämme
  • water

costs and prices

There are always products from both variants that have been additionally refined or equipped with certain properties. Therefore, the cheapest sealing slurry is not necessarily the most sensible for your specific application. Our prices below are only the basic price, which you currently have to estimate in the most favorable case. How much sealing slurry you need per square meter naturally depends on whether you are applying several layers.

For example, the MEM sealing slurry can be processed in a layer two millimeters thick. The PCI sealing slurry should be applied in up to three layers, especially in the case of pressurized water. How much is actually needed varies from area of ​​application to area of ​​application. In any case, however, it is a cheap option for waterproofing that is relatively easy to work with.

  • MEM sealing slurry: 25 kg bag, from about 25.00 euros
  • PCI Dense Slurry: 25 kg bag, from about 27.00 euros

Tip: In addition to the simple cement-based sealing slurry, which is sold in sacks as a one-component product, there are also much more expensive two-component sealing slurry, especially from the PCI sealing slurry, which could also be interesting for special areas of application.

A 30 kilo set of the two-component PCI sealing slurry for the swimming pool area, for example, costs around 150.00 euros. Of course, these are processed very differently and should be used exactly according to the manufacturer’s instructions.


Before you buy the sealing slurry, you should check exactly what you need the slurry for. If you want to buy muds for completely different purposes, you might even want to buy different products. For example, sealing under a shower does not require the same sealing slurry as sealing the base of an external facade.

The MEM sealing slurries have slight advantages over the PCI slurries because this product can also be used on porous substrates such as wood or plasterboard. MEM sealing slurry can be applied to a damp substrate. In addition, the MEM sealing slurry remains more flexible and is somewhat crack-bridging. We would definitely use MEM for the interior because of its flexibility and PCI sealing slurry for the terrace, carport or garage.

We would also use PCI for a pool or the like, because this product is suitable for drinking water. However, there are also other variants that have special additional properties that can be very useful for special applications.

MEM sealing slurry

MEM sealing slurry is mostly fiber-reinforced and plastic-modified. As a result, this inexpensive seal is very abrasion-resistant. Similar to the PCI sealing slurry, the MEM sealing slurry can be used both inside and outside. It doesn’t matter whether you use the sealing slurry with non-pressing or with pressurized water. These sealing slurries are even crack-bridging to a certain extent and remain slightly flexible.

  • Can be used on concrete, wood, tiles, sand-lime brick, clinker, aerated concrete, screed, plaster and plasterboard
  • plastic-coated and fiber-reinforced
  • applicable inside and outside
  • frost resistant
  • flexible and breathable
  • waterproof from a layer thickness of two millimeters
  • to be used with non-pressing and pressurized water
  • crack bridging
  • abrasion and impact resistant
  • free of solvents
  • can be processed on a damp surface
  • fully dried after 12 hours
  • loadable after about two days

Mineral sealing slurry PCI

PCI sealing slurries are mainly used in the basement and on the outside of the basement. But the sealing sludge has also proven itself in the sewage sector. Even for the drinking water area, PCI sealing sludges are approved by an official test certificate.

  • Waterproofing of basement, swimming pool and drinking water tanks
  • Horizontal barrier and sealing at the base
  • Intermediate sealing under thick bitumen layer
  • Waterproofing under certain PCI plaster for renovation
  • Sealing of basement walls and basement floors
  • Interior sealing against pressing water and moisture
  • Resistant to municipal sewage
  • Resistant to strong chemical attack / exposure class XA3
  • high resilience to chemical and mechanical influences
  • Wet abrasion resistant in the waste water area
  • Sulfa resistent
  • Official test certificate for drinking water / DVGW worksheet W 347/W 270

Apply sealant

Care is particularly important when applying the sealing slurry. The respective layers of the mud must be applied covering and flat, but should be very thin. Thick layers will burst and crack over time due to shrinkage during drying.

Tip: There are slight differences between MEM sealing slurry and PCI sealing slurry when it comes to application and drying time. You should therefore always study the manufacturer’s information carefully.

1. Fill holes and cracks

If there is any damage to the walls or floor, they must first be sealed with repair mortar. In addition to the bricklayer’s trowel, a narrow jointing trowel or spatula is well suited for this. The repair mortar must first dry thoroughly before you can continue working.

Tip: You can clean solid walls with a high-pressure cleaner. If you want to coat smaller areas with caulk, you can clean the areas with a stiff brush, street broom, or wire brush. In any case, any loose plaster and paint that may be present must be removed.

2. Moisten the surface

Very dry areas on the walls or on the floor should first be moistened with a brush. Above all, if the spots may be a bit sandy, they must first be made damp. Otherwise, the sealing slurry cannot connect to the subsoil.

Tip: Don’t get the wall too wet and don’t let the moisture soak in for a long time. Not every waterproofing slurry can be processed on a really wet wall.

3. Mix sealing slurry

Check the manufacturer’s instructions for how much water to use. First put the water in the mason‘s bucket and only then the powder. Whisk the mass with the mixer until you have a smooth mass in your bucket.

4. Apply sealing slurry

The sealing slurry is applied with a brush or a wide, thick brush. You should apply about two to three layers of the sealant over a large area at short intervals. Make sure that you create a thin application evenly everywhere. If only a very small amount of waterproofing slurry is applied too thinly in some areas, it can shrink so much when it dries that cracks and gaps appear at this point.

Then moisture will still leak through or under the seal at that point, which can be worse. You often cannot see where the moisture that is causing the damage that follows is coming from.

Tip: The sealing slurry should be applied to a depth of at least 20 to 30 centimeters around the base of the building. If you live in an area with heavy rainfall or large amounts of snow, adjust the height of the protective layer as much as possible to the circumstances. The layers should be chosen to be similarly high in the basement area.

5. Smooth sealing slurry

Some products are mixed relatively viscous and either applied directly with a trowel or smoothed out with a brush after application. For example, if you want to seal a basement, you should always start with the walls. Apply the sealing slurry at least up to about 20 centimeters above the outer floor level. Only when you are completely finished with the walls should you start applying the sealing slurry to the floor of the basement. The sealing slurry must be smoothed out, especially on the ground.

Tip: In the garage, carport or on the terrace, it is important that the sealing slurry is pulled off smoothly, but a certain incline should usually be taken into account. This is the only way to prevent standing water from ruining the newly coated floor. Therefore, level the floor with a wide lath and a spirit level.

6. Cross out transitions

While you always have to pay attention to the most exact right angle possible with other work, a rounded transition is the better seal for sealing slurry. Regardless of whether it is indoors in the basement or outside on a terrace wall, the transition from the wall to the floor should be laid out in a semicircular shape like a channel. Therefore, apply a thick layer of sealing slurry at this point and smooth it out with a hollow trowel. In this way, these problem areas are sealed perfectly and safely.

Tip: You don’t have to buy a hollow trowel for this. You can simply put on rubber gloves and use a finger to scrape the sealing slurry into a gutter.

7. Dry and protect

Depending on the product, the sealing slurry has to dry for about two to four days. However, this means that you must protect the outdoor muds from rain, frost or direct sunlight during this time. Ideally, cover the treated areas with a tarpaulin. However, air should still be able to reach the sealing slurry.

Tip: If you have a simple folding gazebo, this is ideal for protecting these types of areas from the elements while the mud dries. Sealing slurry is very robust, but if there is a threat of frost, the sealant should not be applied anyway, as the frost will cause the slurry to crack on the inside. This damage will go unnoticed until moisture seeps in again and you notice the first moisture damage.

Tips for speed readers

  • Thoroughly clean the surfaces with a high-pressure cleaner / wire brush
  • Seal cracks and holes with repair mortar
  • allow deep holes and cracks to dry first
  • Moisten dry areas slightly first
  • Mix powder sealing slurry with mixing paddle
  • Apply sealing slurry to walls with a brush
  • apply two to three layers of mud
  • smooth out some sealing slurry with a mason’s trowel
  • Coat the floor area of ​​the basement with sealing slurry
  • level the floor with a smoothing trowel or smoothing board
  • Create a semicircular transition from wall to floor
  • Pull off the transition with a hollow trowel
  • Protect muds from sun, frost and rain
  • let it dry for two to four days
  • continue treatment only after complete drying