The white tank retrofit: Isokristall®

Story – The history of ISOKRISTALL

Successful recrystallization processes for permanent waterproofing have been used in the USA and Canada for more than five decades. However, to this day they have only succeeded in reliably drying concrete.

In Germany, by contrast, a recrystallization process was first developed 19 years ago that not only seals concrete reliably for life, but also normal masonry of any mineral type (sand-lime brick, rubble stone, brick, natural stone, Poroton and even hollow concrete blocks, among others).

The same German laboratory that achieved the revolutionary breakthrough with recrystallization for “interior building waterproofing” in 2006 developed the ISOKRISTALL system in Germany in 2020–2021 exclusively for the building protection network of 1a-Gebäudeabdichtung GmbH. Using the active ingredients proven for 19 years in many thousands of basements and ground floors, a new pioneering waterproofing system was created by replacing several additives, pigments and auxiliaries and modifying the consistency.

This system works so reliably that, when applied correctly, there has not been a single complaint since then – success rate: 100 %, even in the most severe cases of pressurized water.

Product testing between July 2024 and January 2025 according to WTA quality standards at the “Gesellschaft für Materialforschung für das Bauwesen” (MFPA Leipzig), Germany’s leading testing institute for watertightness tests under the authority of the “Deutsches Institut für Bautechnik”, also provided clear evidence of the absolute reliability of the ISOKRISTALL process.

Finally, in May 2025 all ISOKRISTALL components were awarded the renowned WTA certificate – the highest possible distinction in Germany for interior basement waterproofing applied retrospectively.

The rehabilitated walls and floor slabs are also 100 % tight against radon after using the ISOKRISTALL® system. This radon tightness was officially confirmed in writing by the well-known IAF Dresden radon laboratory after extensive series of tests.

According to the Federal Office for Radiation Protection of Germany’s Environment Ministry, radon in basements or buildings is the second most frequent cause of fatal lung cancer after smoking.

Isokristall® is radon-tight, certified by the IAF in Dresden.

Isokristall – WTA-certified basement waterproofing against water & radon

Retrofitted white tank without excavation

Damp basements, wet walls or pressurized water? With Isokristall, you choose a WTA-certified recrystallization process that permanently protects your masonry – without excavation, digging or drilling. The active ingredients penetrate deeply into walls and floor slabs on their own via the concentration gradient, bind the moisture and convert it into a mineral masonry structure. Your building structure itself becomes a watertight “white tank”.

Protection even against pressurized water – tested up to 1.5 bar

Isokristall has been awarded in both WTA certification categories – for soil moisture/seepage water and for pressurized water. The system withstands water pressure up to 1.5 bar, which corresponds to a depth of about 15 meters below the groundwater level.

100 % radon-tight – certified by IAF Dresden

After smoking, radon is the second most frequent cause of lung cancer. As a noble gas, it enters houses through leaking basement walls. Isokristall has been officially tested and certified by IAF Dresden as 100 % radon-tight. In this way you protect your family and at the same time increase the value of your property.

The 5- or 8-layer system for maximum safety

Our 5- or 8-layer system (depending on the usage class) combines primer, crystalline slurry, fine filler, protective coating and finish coating into a durable complete solution. The waterproofing acts simultaneously as a horizontal and vertical barrier, stabilizes the masonry and permanently prevents rising damp.

Your benefits at a glance

•   WTA-certified in all categories of retroactive structural waterproofing
•   100 % radon-tight – tested by IAF Dresden (Germany’s most renowned radon laboratory)
•   Watertight up to 1.5 bar
•   No drilling, no excavation – minimally invasive
•   Horizontal & vertical barrier in one
•   Suitable for basements, floor slabs, underground garages, elevator pits and listed buildings
•   Optional warranty up to 30 years

More living quality, more safety

After renovation with Isokristall, musty odors, damp walls and health risks are a thing of the past. You gain dry living or storage space, protect the building structure and your health, and increase the energy efficiency of your property.

Request your free consultation now

Secure your free consultation now for WTA-certified basement waterproofing with Isokristall.

Interior basement waterproofing with Isokristall

Damp basement walls? We make them permanently dry. With Isokristall, you rely on a WTA-certified waterproofing process that requires no excavation or drilling. The active ingredients penetrate deep into the masonry, bind moisture and convert it into a solid mineral structure. The result: your basement stays permanently dry – even with pressurized water.

Why interior waterproofing with Isokristall is so effective

•   Minimally invasive: No damage to outdoor areas, no excavation
•   Durable: Active ingredients remain active for decades and do not age
•   Strong in extreme cases: Also effective at water pressure up to 1.5 bar
•   Protection against radon: 100 % radon-tight – certified by IAF Dresden

Procedure of the renovation

1. Free building analysis and on-site consultation plus a non-binding cost estimate
2. Application of the first 3 layers (primer, crystalline slurry, fine filler)
3. Drying time of three weeks
4. 2 protective coatings and optionally bonding bridge plus finishing plaster or tiles
5. Final acceptance and warranty certificate

Do you have problems with damp basement walls or rising damp?

Secure your free consultation now for WTA-certified basement waterproofing with Isokristall.

Radon protection with Isokristall

Live healthy – eliminate the invisible danger: Radon is a radioactive noble gas that enters buildings through leaking walls. According to the German Federal Office for Radiation Protection, it is the second most common cause of lung cancer after smoking. Isokristall has been officially tested as 100 % radon-tight and therefore reliably protects against this health hazard.

Radon protection & basement waterproofing in one

With Isokristall you kill two birds with one stone: you seal your building against moisture and at the same time stop radon from entering.

•   100 % radon-tight – certified by IAF Dresden
•   WTA-certified against pressurized water
•   Long-term protection with an optional warranty of up to 30 years

Suitable for new builds and renovations

Whether for existing properties or new builds – the Isokristall system is flexible to use and meets the highest requirements for health protection and structural waterproofing.

Would you like to learn more about radon protection with Isokristall?

Secure your free consultation now for WTA-certified radon sealing with Isokristall.

Create a white tank retrospectively

Retrofitted white tank without excavation: With Isokristall, your masonry itself becomes the waterproofing. The active ingredients use the existing moisture to penetrate deeply into the wall, bind water molecules and convert them into a mineral masonry structure. The result: a durable, watertight “white tank” – without damaging the outdoor areas.

Advantages of the retrofitted white tank with Isokristall

•   WTA-certified in both categories
•   Watertight up to 1.5 bar – even with pressurized groundwater
•   Radon-tight – certified by IAF Dresden
•   Horizontal & vertical barrier in one step
•   Minimally invasive – no heavy construction work

Ideal for

•   Basements
•   Floor slabs
•   Underground garages
•   Elevator pits
•   Listed buildings

Do you have problems with damp walls or rising damp?

Secure your free consultation now for WTA-certified waterproofing with Isokristall.

Isokristall vs. conventional basement waterproofing – the direct comparison

Why Isokristall is different

Most waterproofing systems simply keep water out. The problem: the moisture remains in the masonry and the building structure continues to deteriorate. Isokristall takes a completely different route – it uses the existing moisture to transport active ingredients deep into the wall and floor slab, binds the water and turns it into a mineral masonry structure. The result: durable, self-active waterproofing.

The comparison at a glance

The weaknesses of conventional methods

• Negative waterproofing (e.g. sealing slurry): wall remains damp, only visually dry.
• Drilling methods: create artificial barrier layers, but do not rehabilitate the building structure.
• Excavation from the outside: high effort, often not possible with built-up or sealed surfaces.

The strengths of Isokristall

•   Double WTA certification – also for pressurized water
•   Radon-tight – certified by Germany’s leading radon laboratory
•   More protection in one system – horizontal & vertical barrier combined
•   Sustainable – active ingredients reactivate when new water penetrates
•   Fast and clean – no damage to outdoor areas

Conclusion: The smart choice for long-term protection

Anyone who wants to keep their basement permanently dry and protect it from radon at the same time can hardly ignore Isokristall. Thanks to state-of-the-art recrystallization technology, official certifications and minimally invasive application, Isokristall is the future of basement waterproofing.

Become a partner – your opportunity with Isokristall

Imagine being able to offer your customers a structural waterproofing system:

•   Where the wall or the floor slab itself becomes the waterproofing
•   Where all system components are WTA-certified in all test categories for retrospective interior waterproofing (against pressurized water, soil moisture and seepage water)
•   That seals as long as the building stands, because the active ingredients used do not age and remain active even after 20, 30 or 50 years, binding penetrating moisture in the wall and converting it into mineral structures
•   That is also certified tight against the entry of the noble gas radon that causes lung cancer – a decisive advantage in many regions
•   That closes small cracks and significantly strengthens the wall structure
•   That always works when applied correctly – even in extreme cases

Wouldn’t that be an excellent way to make money?

Would that be interesting for you? Then get in touch with us:
Phone: 0800 – 66 00 555

Are you interested in a partnership?

Secure your free consultation now about a partnership.

Frequently asked questions about Isokristall – basement waterproofing & radon protection

What is special about the Isokristall system?

Isokristall is a WTA-certified recrystallization process that does not simply block out moisture, but actively uses it. The active ingredients penetrate deep into the masonry, bind the water and convert it into a mineral masonry structure. This turns the wall itself into the waterproofing – without any excavation or drilling.

How does Isokristall differ from conventional waterproofing?

While classic methods such as sealing slurry or drilling methods only create barrier layers, with Isokristall we rehabilitate the masonry itself. The system is WTA-certified in both categories, resistant up to 1.5 bar water pressure, acts as a horizontal and vertical barrier at the same time and is 100 % radon-tight.

Is Isokristall suitable for pressurized water?

Yes. Isokristall is one of the few systems that has also received WTA certification for pressurized water and withstands water pressure up to 1.5 bar – equivalent to about 15 meters below the groundwater level.

Does Isokristall provide protection against radon?

Yes, Isokristall has been officially tested and certified by IAF Dresden as 100 % radon-tight. This protects against the radioactive noble gas radon, which after smoking is the second most common cause of lung cancer.

How long does an Isokristall waterproofing last?

Our active ingredients remain active even after decades and reactivate as soon as new moisture penetrates. Depending on the specialist company, the warranty can be extended up to 30 years.

What applications is Isokristall suitable for?

Isokristall can be used for damp basement walls, leaking floor slabs, underground garages, elevator pits, parking garages, tunnels and even listed buildings.

How does waterproofing with Isokristall work?

1. Analysis of the moisture situation on site
2. Application of the first three functional layers (primer, crystalline slurry, fine filler)
3. Drying phase of 3 to a maximum of 4 weeks (often 2 weeks are already sufficient)
4. Application of the protective coatings and finishing layer
5. Completion with warranty and optional maintenance contract

Can Isokristall also be used in extreme cases?

Yes. Especially where other methods fail, Isokristall shows its strengths – whether in cases of heavy pressurized water or very high moisture exposure.