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Renovation of old buildings: You have to reckon with this kind of damage

Old buildings were built under different construction standards than today and have defects in many places - also because the materials have suffered after all this time: from the weather, housing defects, poor maintenance and vibrations as a result of truck traffic. Nevertheless, the renovation of old buildings can be a good alternative to normal house construction. Read here what to expect when buying and which defects are typical for the respective year of construction.

Renovation of old buildings: You have to reckon with this kind of damage
Renovation of old buildings: You have to reckon with this kind of damage

Improper renovation of old buildings damages the house. Often, out of ignorance, important components are removed without replacement - such as stiffening wind panes in the rafter roof or load-bearing walls. At least every second order in the construction industry revolves around the repair, modernization or enlargement of old buildings. If the defect analysis is not correct, you build in new defects straight away - and pay twice for repairs.

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Common problems when renovating old buildings

Anyone who buys an old building should know the characteristic weaknesses of this generation of houses. In buildings from the turn of the century, for example, rusting steel girders sit as lintels over the windows and as girders under the balconies. 20s houses typically lack heat and sound insulation. Houses that were built after the Second World War usually have damp basements due to inadequate or missing insulation and insulation from the ground. Construction plans simplify the inventory.

Almost a fifth of all defective parts can be found in the bathroom, kitchen and on water pipes. The floors of undeveloped storerooms and wooden beam ceilings are also often faulty. The supply and disposal systems, heating and the electrical network are outdated. In the roof structure, water marks and rotten wood betray the moisture. Insects leave burrowing holes and heaps of dust. Always check all parts that are regularly checked in your home, such as paintwork, fittings, roof drainage, windows and doors.

The weak points of old houses at a glance

The most common construction
until 19201920-19401940-19601960-1980
Waterproofing the basement or the
Walls insufficient
(Basement) walls made of quarry stone*********
rusted steel beams in ceilings
and vaulted cellars
outdated, corroded plumbing installations***********
leaking gas pipes******
outdated heating
Incorrectly dimensioned smoke extraction systems*********
outdated electrical installations***********
uninsulated roof trusses************
lack of soundproofing (doors, stairs,
False ceilings)
lack of thermal protection*********
lack of fire protection**********
leaky windows with single-pane glazing************
Badly executed flat roofs*******
Legend: * = rather seldom ** = sometimes, now and then *** = often, mostly
Source: Advice from consumer centers: “Buying a used house” (8th edition 2012).

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Maintenance of old buildings

Regular care keeps a house fit longer. The rule of thumb for the maintenance effort is: During the life of a house, which is an average of 80 years, 1.3 times the construction costs are spent on maintenance.

Components last different lengths. It is best to always do foreseeable maintenance work immediately, such as freshening up protective coatings or replacing loose tiles: the prices for spare parts rise, small defects turn into major damage. Just cosmetic repairs don't have to be instant.

Living properly is easy on the building fabric. This also includes conscious heating and ventilation: It prevents damp walls and mold. Anyone modernizing an old building should choose suitable materials and methods and look for an architect with a focus on old buildings. Chambers of crafts and preservationists know the right methods and are experienced experts in the field of renovation of old buildings. Did you know: You can turn an existing property into a KfW 70 house and modernize it with state funding.

Typical damage from past decades of construction

Refurbishing an old building is almost inevitable when buying a house from earlier decades. But "anyone who knows the typical damage knows what to look out for," says Professor Meisel from the Institute for State and Urban Development Research and Construction of the State of North Rhine-Westphalia. He knows the weak points of old buildings. Older houses only show different constructions and components at first glance. If you look more closely, you can divide them into age groups. A typical exterior almost always includes a certain internal construction, which changed in parallel with the architectural styles. Therefore, similar damage often occurs in houses of one age group.

Old buildings from 1840 to 1900

The phase from 1840 to 1900 is also known as the "Gründerzeit" and was mainly characterized by industrialization. Typical of the so-called Wilhelminian style architecture is a three- to six-storey perimeter block development with more or less richly decorated facades. However, as popular as the old buildings from this period are, they have a number of shortcomings. You can see this in the example of this renovated old house, which was built around 1890.

Most of the time, the roof's sarking membrane is missing and the roof trusses are usually undersized. Furthermore, cracked or hollow wall plaster is not uncommon and there is a risk of pest infestation on exposed and walled-in wooden parts. The outer walls are usually characterized by cracks in load-bearing parts, leaky joints, rusting steel girders and damp basement walls due to a lack of sealing. Doors and windows are also insufficiently sealed and usually only have single glazing, so that there is hardly any heat or sound insulation.

As far as the heating is concerned, individual stove heating is common on numerous chimney flues, as well as undersized connections for gas and oversized, brick-built chimney flues, so that there is a risk of sooting. The electrical installation also requires improvement, because the cables, sockets, switches and lighting points have mostly become unusable. In the case of the sanitary facilities, clogged sewer underground pipes and undersized water and sewer connections must be expected.

Old buildings from 1900 to 1930

At the beginning of the 1920s, there was a clear departure from the richly decorated style of the Wilhelminian era. But the construction defects have hardly changed. Here, too, the roof covering is damaged and exposed and walled-in wooden parts are often marked by pest infestation. Typical defects in the outer wall are cracks in the plaster and chipped plinths. There are condensation problems due to thin walls and many protruding parts have damaged zinc covers. Balconies or loggias are also cracked; Basement walls mostly damp.

Windows and door frames made of wood are often warped, and single glazing was used here too, so that the heat and sound insulation is inadequate. The wooden floor ceilings often suffer from sponge infestation. The condition of the floors also requires a lot of work, because rotten storage timber was sometimes used for floorboards. Stepped wooden steps, worn at the front edge, can be seen on the storey stairs. The fire protection is inadequate due to the lack of plastering. The same deficiencies are to be expected in the heating, electrical installation and plumbing as in the old buildings from the period from 1840 to 1900.

Old buildings from 1930 to 1950

After the Great Depression in the 1930s, building was increasingly simple. The outer walls are simple plastered facades, which are marked by cracks and chipped plaster. The zinc cover on protruding facade parts is mostly damaged, and even during this construction period little emphasis was placed on a good seal, so that here, too, hardly any heat and sound insulation is guaranteed.

The humidity in the cellar often rises, so that pest infestation on wooden parts is almost inevitable. The thin panel walls between reinforced concrete columns or masonry walls inside the house offer only inadequate soundproofing and fire protection. And the floors have inadequate footfall sound insulation due to the screed, mostly composite screed. There are also many deficiencies in the heating, electrical and plumbing installations that hardly differ from those of previous decades.

Old buildings from 1950 to 1960

The buildings of the post-war period are characterized by economy and material scarcity as well as simple construction methods. In these years of construction, too, the sound and heat insulation was insufficiently considered and must be tackled when renovating old buildings. The roof is also one of the problem areas of these houses and is usually leaky, so that a new roof is almost inevitable.

In the 1950s, heating with individual stoves was still widespread. In the meantime, central heating has been retrofitted in many houses, but this has also reached a great age, so that it makes sense to change the energy source when renovating. When it comes to electrical installations, you usually have to deal with outdated cables, sockets, switches and fuses. Another problem can be the lack of a protective conductor. Because until the early 1970s, the so-called classic zeroing could still be used, in which the power supply was routed through the house with only two wires. Nowadays, when renovating old buildings, a standard-compliant condition must usually be restored. When installing plumbing, it must be borne in mind that water could often only be heated using a coal boiler.

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Old buildings from 1960 to 1970

Even in houses from the 1960s, no emphasis was placed on insulation, so that the waterproofing membranes on the flat roofs of bungalows in particular are outdated and leaky. For the outer walls, panel cladding with insufficient substructure, anchoring and insulation was often hung, which was also poorly compacted and therefore hardly kept the heat in the house. Damage from moisture can also be seen on balconies; Condensation accumulates on projecting concrete slabs. While the electrical installation is significantly better than in old buildings from the previous decades, the boiler or burner needs to be replaced with the heating. In addition, the water and drainage pipes may need to be repaired, and the water heater is definitely getting on in years and should be replaced soon.

Old buildings from 1970 to 1980

In the 1970s, industrial construction became very popular in Germany - the prefabrication of components became possible for the first time. The prefabricated building block, which still shapes the appearance of many German cities today, was particularly widespread.

The first thermal insulation ordinance was not issued until 1977, so that houses that were built after that were usually better insulated than in previous years. Most of the time, however, the insulation was only provided with a minimum level of thermal insulation, which means that much improvement is still possible and necessary today. The most well-known problem of the 1970s buildings, however, are the pollutants in the components such as asbestos, mineral wool fibers or formaldehyde, which in individual cases makes expensive renovation measures necessary. In addition, there can often be condensation problems inside, as components at building corners are integrated into the outer wall.

The joint renovation is another important point that is unavoidable in prefabricated buildings. However, since a complete facade renovation usually makes more sense, the joint renovation can be integrated into the overall renovation of the facade. As far as heating is concerned, essentially the same applies as for heating systems from the 1960s - with the difference, however, that the systems from the 1970s are not that old. However, what no longer corresponds to today's standards is in most cases the control technology. In addition, underfloor heating is now more common. Warning, these can be muddy!