In the past a cellar was used primarily to keep provisions. Today a modern basement has various functions: In addition to the furnace and the house service connections (water, sewage, gas, regional heating, etc.) it might include a wash room as well as space for work rooms, hobbies and fitness and even a wine cellar in a way that does not affect the actual living space. Fruits and vegetables can still be stored in a cellar. Further, a basement increases the value of your property. Here, too, good planning and accommodating whatever the future brings are the primary rules.

• Before building a home, check the terrain and ground composition.
• This determines the technical design of the foundation and the walls as well as measures regarding moisture (drainage and water-tight basin in the event of a high ground water level), which in turn is decisive for the costs.
• Plan in detail how you intend to use basement space and where you will need water (sauna, wash room). Do not forget insulation, vapor barrier, windows and overhead lighting.
• Before the foundation is cast, all ditches for water and sewer, drainage, electricity, telephone, cable TV, etc. must be prepared. Dimension these adequately.
• Leave room for fuel or an opening for fuel delivery.
• For the components, you can choose from a range from prefabricated steel-reinforced concrete to masonry walls. Seek the advice of a professional.
• Thermally separate heated and unheated basement rooms. Avoid thermal bridges to outside walls.
• Consult your local office of construction to ask whether they recommend the installation of back pressure valves to avoid later flooding during heavy rains.
• Caution: Provide drainage for light shafts.
• Good water-proofing is important. Retrofitting improvements involve significant effort and expense. Even for waterproof prefabricated concrete, experts recommend outside sealing against moisture. Seek advice from professionals.
• Tip: If you do not have level outside access to your basement, then you should plan an outside stairway to the basement. This eases the storage of garden equipment. Select a slip-proof and frost-proof variant.

Inside sealing and insulation of old basements

What we overlook in new construction regarding sealing and insulating outside walls cannot be compensated fully with measures on inside walls. Retrofitting inside insulation or sealing makes sense only if the effort of exposing the basement walls is too great.

• Inside sealing is recommended only for rooms with less than 60% humidity; otherwise there is a danger of condensation and mold.
• Remove loose plaster and seal cracks in the masonry and concrete walls.
• Also seal intermediate walls.
• A horizontal vapor barrier under the basement ceiling prevents the rise of moisture into the living space.
• Sufficient thermal insulation of the basement ceiling significantly reduces energy costs.
• Call upon professionals to avoid errors that can be corrected later only with high costs.

Rule of thumb for the basement: ventilate in winter and keep closed in the summer.