Table of contents:
- Planning the bitumen painting
- Backwater, leachate, soil conditions
- Select products for the bitumen coating
- Prepare the surface and surroundings before painting the bitumen
- Allow enough space for the bitumen coating
- Apply bitumen paint
- Layer thickness and drying time of the bitumen coating
Video: Apply bitumen paint: you have to be aware of that
Bitumen painting is one of the most popular and most widespread techniques for waterproofing buildings: thanks to its chemical and physical properties, as a horizontal and vertical seal, bitumen effectively prevents water from penetrating into components in contact with the ground (floor slab and walls), it is easy to process and very durable. Even laypeople can save money by doing their own work.
Planning the bitumen painting
You can't do without waterproofing: the consequences of inadequate moisture protection range from an unpleasant and unhealthy indoor climate to mold to impairing building stability. Simply painting away is not a good idea - you have to follow a few rules. Essential for the success of bitumen waterproofing are:
- The correct determination of the moisture to be warded off
- A corresponding selection of the product
- Thorough preparation of the surface
- The exact adherence to the processing instructions of the manufacturer
- The final protection of the bitumen layer
Backwater, leachate, soil conditions
Depending on the effects of moisture or water, experts differentiate between different load cases based on the largely replaced DIN 18195. These are classes of different levels of exposure to moisture to the buildings to be protected in different environments. It is not always easy to determine which load case is to be secured. If in doubt, this must be analyzed by a specialist who may also determine the need for drainage. For example, a different soil condition in otherwise identical applications can make one and the other a completely different bitumen waterproofing in the other situation. Non-stagnant leachate in the floor next to a basement wall, for example, represents a lower load than stagnant water or pressing groundwater.
Select products for the bitumen coating
In addition to the price, the processing instructions play a decisive role in the product selection, because bitumen is not just bitumen. Some products can still be processed at very warm outside temperatures above 35 degrees Celsius, others at a maximum of 25 degrees Celsius, and there are also differences at the lower temperature limits. Depending on the season, some products are excluded.
A great advantage of modern bitumen emulsions is that they no longer need to be heated before processing. Bitumen sealants are also available as single and two-component products. The advantage of two-component bitumen insulation is that it dries much faster when a thick coating is applied.
With all product variants, you always have to strictly adhere to the processing regulations. Because even though bitumen is the main ingredient in all products, the exact compositions differ. Modern bitumen emulsions are the results of research and each have their own characteristics as so-called KMB or PMB (plastic-modified or polymer-modified thick bitumen coatings). Bitumen painting is only one possibility during processing, masses for filling are also widespread.
Even the smallest contamination from dust or traces of soil impair the adhesion of the bitumen coating and thus the waterproofing. So clean the surface before applying bitumen.
Photo: iStock / Volodymyr_Plysiuk
Prepare the surface and surroundings before painting the bitumen
The preparation of the substrate depends on how the surface of the component to be sealed is made. Basically, bitumen is very versatile and adheres to solid masonry, sand-lime brick, bricks and concrete.
Before painting the bitumen, the surface must be dry, fat-free, frost-free and clean. Even the smallest contamination from dust or traces of soil impair the adhesion of the bitumen coating and thus the waterproofing. Incompatible old coatings must also be removed. In the past, tar coatings were used especially in old buildings, which are not a suitable surface for PMB. An old bitumen coating can possibly remain on the component. Cracks and bumps must be repaired beforehand using suitable agents such as repair and leveling mortar.
Other preparatory measures can be the application of a synthetic resin layer on a coarse-pored surface or the spreading or filling of sealing slurries. It is a water-repellent, water-vapor permeable (diffusion-open) mix of cement and plastics. The advantage of the sealing slurry is that products with a high proportion of plastic adhere to old bitumen coatings and provide an ideal base for a new bitumen coating.
Allow enough space for the bitumen coating
Another essential preparation step is the creation of fillets on edges, corners and where the foundation protrudes. Fillets are fillets that chamfer the edges and can be molded from leveling mortar or rubber mortar itself. Your leg length should be between four and six centimeters. Due to their shape, they take the pressure of any water that may build up from the component.
When planning renovation work, one must not forget to ensure sufficient freedom of movement around the area to be worked on. This means that the pit around the base of the building or the basement walls must be at least 80 centimeters wide. The slope of the excavated trench must be chosen so that the edges do not break off and so contaminate the work surface. The only way to avoid a lot of sweaty work with the shovel is by renting a small excavator or placing the order with a company.
Apply bitumen paint
When we think of "bitumen painting" we think of simply applying the bitumen using a roller, brush, brush or even a syringe. However, this simple form of painting is not the only way to use bitumen for waterproofing buildings. And this method is not always Bitumen, for example, can be spread on roofs, but there are also special bitumen welding tracks in different versions.For the plinth and basement waterproofing, different variants of bitumen use are also possible. In the simplest case - with natural soil moisture without further requirements, that is Painting constructed as follows:
A bitumen primer or a bitumen primer is painted onto the components prepared with fillets and sealing slurries. Depending on the manufacturer's specification, several passes may be required. After drying, the actual bitumen coating follows, also called top coating or insulating coating. This layer is usually built up in three work steps, whereby each order must first be dried before the next one.
Bitumen can easily be spread with a roller or brush.
Photo: iStock / Volodymyr_Plysiuk
According to DIN, such a coating should protrude 15 centimeters above the ground. The conclusion is an appropriate protection of the bitumen insulation against the soil, water, stones and roots that have to be refilled later. Various solutions are available for this: barrier sheets made from bitumen products, special foils and knobbed sheets are conceivable. It is best to attach perimeter plates that combine mechanical protection and thermal insulation.
A simple bitumen coating is not sufficient for heavier loads. In this case, a bitumen thick layer or thick coating is required. Here, too, several operations are mandatory. A KMB layer applied with a trowel or syringe is placed on the prepared surface. Before it is dry, it is advisable to insert a reinforcement made of a suitable fleece. After drying, the second layer of KMB can be applied.
The bitumen layer must be protected from rain, dirt and damage between operations. In the best case, perimeter sheets or nubbed plastic sheets also form the end of the thick bitumen coating. There are also different versions to choose from, for example there are plates with and without channels and additional fleece for the discharge of incoming water. Cross joints should be avoided when using panels. Employees in the hardware store can give tips for the most practical application.
Layer thickness and drying time of the bitumen coating
The layer thickness and drying times of the bitumen coating vary: in general, the finished bitumen thick coating should be between three and six millimeters. When processing, make sure that the moist material is only applied as thick as the manufacturer specifies. As a rule, the wet thickness is twice as high as the dry one. Otherwise complete drying and compliance with the planned layer thicknesses in the dry state cannot be guaranteed. Depending on the weather and product, drying takes three to seven days.
At the end of the project, the trench is filled with soil and compacted again and the bitumen painting project has been successfully completed.