Basement renovation Vienna that makes the basement dry and keeps it dry.

Basement renovation Vienna: costs 2026

Net guide values, as of 2026, binding after moisture measurement. The range is so wide because a "damp basement" can have five different causes – with five different solutions.

Unit prices, so you can check a quote

After flooding or a burst pipe in the basement, the order matters: water damage restoration Vienna.

Five causes of a damp basement

The treatment differs completely. Anyone who assumes the wrong cause renovates past the problem – and that only becomes visible after two years. After flooding, waterproofing is always preceded by building drying, otherwise residual moisture is trapped.

Ventilating an old basement correctly

• In summer only ventilate at night or early in the morning, when the outside air is cooler than the basement wall. At midday at 30 °C and high humidity, every open door brings moisture in.
• In winter ventilating is no problem, because cold air carries little moisture and does not condense when it warms up in the basement.
• A hygrometer costs €15 and is the cheapest investment: only ventilate when the absolute humidity outside is lower than inside.
• Basement windows permanently tilted open in summer are the classic mistake – they create exactly the problem they are meant to solve.

Diagnosis: what is measured before every renovation

This diagnosis costs €800 to €2,500. It is the cheapest item of the entire measure and the only one that prevents €20,000 from flowing into the wrong method.

The methods in detail

Horizontal barrier against rising damp

It interrupts the capillary transport of water in the masonry. Two methods are proven: injection with silane or silicone agents, in which drill holes are made at 10 to 12.5 cm spacing and filled, and the mechanical barrier, in which stainless steel plates are driven into a continuous bed joint or wall sections are cut open.

• Injection €180 to €420/rm, gentle, no intervention in the load-bearing structure, works with brick masonry up to about 60 cm thick.
• Mechanical barrier €350 to €700/rm, the most reliable method, but an intervention in the load-bearing structure – therefore only in sections and with structural supervision.
• Electrophysical methods are not something we offer. Their effectiveness has not been reliably proven in independent studies.

Waterproofing against water penetrating from the side

The technically better route is waterproofing from the outside: excavate down to the bottom of the foundation, clean the wall, thick bitumen coating in two layers, dimpled membrane as protection, drainage to ÖNORM B 2506 if required. Costs €250 to €500/m² of wall area, including excavation and backfilling.

In Vienna this often fails because of the surrounding buildings: the neighbouring building is directly adjacent, the pavement lies above, the courtyard cannot be accessed by vehicles. Then internal waterproofing with sealing slurry remains, €120 to €260/m². It is technically more demanding because the water pressure comes from the wrong side – fillet, substrate preparation and connection details decide on success.

Renovation plaster: what it can and cannot do

A renovation plaster system according to the WTA guideline has a high pore volume. It absorbs salts, lets moisture evaporate and stays dry on the surface. It is not a substitute for a horizontal barrier but a supplement to it – and it lasts 15 to 25 years, not forever. Applying renovation plaster to actively rising damp delays the damage by a few years.

Drainage

A drain pipe with filter gravel and fleece carries water away from the building, €180 to €350/rm including excavation. It needs a fall, flushing shafts and a connection – without an outfall or soakaway the water stands in the pipe. Drainage without waterproofing is pointless: it reduces water pressure but does not seal anything.

Five special features of Viennese basements

1. Rubble stone masonry instead of brick

Many Gründerzeit basements have base masonry of rubble stone with irregular joints. There the chrome steel plate method does not work because there is no continuous bed joint. Injection is then the way – with higher material consumption, because the masonry absorbs unevenly.

2. Wall thicknesses over one metre

Base walls in old buildings are often 80 to 120 cm thick. This doubles the injection effort and considerably extends drying: at one centimetre of wall thickness per month, a 100 cm wall theoretically needs eight years to dry completely – in practice an equilibrium is reached sooner.

3. No possibility of excavating

Closed development, pavement, courtyard without access. External waterproofing, which would technically be the better solution, cannot be carried out on most inner-city tenement buildings. That is why the combination of horizontal barrier and internal waterproofing is the rule in Vienna.

4. High groundwater near the Danube

In parts of Floridsdorf, Donaustadt, Leopoldstadt and Brigittenau the groundwater is high. There, waterproofing against non-pressing water is not enough – a design against pressing water to ÖNORM B 2209 is needed, in extreme cases a waterproof tank. That is a different price class and must be clarified beforehand.

5. Old pipes in the basement

In Viennese tenement buildings, basements are pipe hubs: water, gas, electricity, sewer. During renovations, defective connections and leaking sewer pipes regularly come to light – a common, often overlooked source of moisture, which is checked as part of the diagnosis.

How a basement renovation works

The eight most common mistakes in basement renovations

• Renovating without a diagnosis. Five causes, five solutions – guessing misses in four out of five cases.
• Confusing condensation with rising damp. The most expensive mistake: a horizontal barrier for a ventilation problem.
• Renovation plaster on active damp. Delays the damage by three years, does not fix it.
• Hacking off plaster only up to the visible line. The salts sit considerably higher.
• Dense paint or tiles in the basement. They trap the moisture and the plaster flakes off.
• Drainage without waterproofing. Reduces the pressure, does not seal.
• Sealing too early. Sealing after three months traps moisture in the wall.
• Gluing polystyrene to the basement wall. Moisture condenses behind it, creating mould that nobody sees.

What the dry basement can do afterwards

Who pays for the basement renovation

Who we renovate basements for

When you do not need us

If the basement only seems damp in summer and is dry in winter, you probably have a ventilation problem and not structural damage – a €15 hygrometer clarifies this before you commission anyone.

If a basic renovation of the building is due anyway, the basement belongs in it and should not be awarded as a separate measure. And if there is a single damp patch that grows after rain, first have the downpipes and the fall in the courtyard checked – this costs nothing and in a third of cases is the whole cause.

Basement damp-proofing Vienna: specialists for wet basements

Damp-proofing is the first step of every basement renovation. Depending on the moisture path, injection is used (€180 to €420 per running metre) or a mechanical horizontal barrier is installed (€350 to €700/rm). Only when the wall dries do renovation plaster and fit-out follow. The methods in detail are on wall damp-proofing Vienna.

Renovating wet basements: what is usual in Austria and what is added in Vienna

Anyone searching for wet basement renovation in Austria finds two very different cases under the same word. In the first, the masonry is soaked, the plaster crumbles, it smells musty – the water rises capillary from the ground or comes in from the side from the soil. In the second, there is actually water standing on the floor after heavy rain or backflow. The first case is damp-proofing; the second is first a search for the cause at the sewer, light well or external waterproofing.

For damp-proofing moist masonry, Austria has its own set of rules in ÖNORM B 3355, which describes diagnosis and choice of method. Its basic idea matches practice: first measure how much moisture and how much salt is in the wall, then choose the method. In Vienna there is also the fact that many basements consist of mixed masonry with rubble stone, the courtyard side can rarely be excavated and groundwater is higher near the Danube. Methods that work in the countryside on a detached house with a free external wall therefore do not automatically suit a Gründerzeit basement. How injection and the mechanical barrier work in detail is explained on the wall damp-proofing page.

Renovating vaulted basements: what the vault requires and what it costs

Many old Viennese buildings have brick vaults under the ground floor – as a barrel vault over the whole room or as shallow segmental vaults between steel beams. These vaults are load-bearing and durable as long as they can breathe. The most common damage is caused by well-meant renovations: cement plaster, emulsion paint or tiles trap the moisture, salts crystallise under the layer and blow off the brick surface.

In the renovation, the dense old plaster is therefore removed first and the vault is examined for cracks. Longitudinal cracks at the crown or rusted beams in segmental vaults must be shown to a structural engineer before work continues. Then follow repointing, salt-tolerant plaster and a vapour-permeable surface. The individual prices above apply as net guide values: hacking off €22–45/m², renovation plaster system €55–110/m², poultice plaster with heavy salt load €35–75/m². A medium-sized vaulted basement with 40 m² of wall and ceiling area thus comes to around €3,000 to €7,000 for the surfaces alone, without horizontal barrier and floor build-up.

Basement renovation company nearby or specialist firm: what the choice should be based on

When choosing, how close the firm is matters less than how it proceeds. Three points separate serious damp-proofing from a quick plastering job. First: before the price there is a measurement with a written result, not a glance at the damp line. Second: the offer names the suspected cause in one sentence and assigns every item to this cause. Third: it states openly how long the wall must dry out afterwards and when it may be painted or furnished again.

If one of these points is missing, a second opinion is worthwhile. Anyone who wants to fit out the dry basement later should mention it right away – then pipe routing, floor and possible insulation of the basement ceiling can be planned in one go.

Frequently asked questions about basement renovation in Vienna

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