A basement can be more than a bare storage room. The advantage if you expand the basement and transform the basement into a cozy room, then you have one more room in the house, which of course can increase the value of the house. Here you can find out how to expand your basement and what to look out for.
What should you watch out for in the cellar extension?
If you need more space in your home but don’t want to move, a converted basement might be the right choice. Before creating new living space in the basement, there are a few things to consider:
Before you expand your basement, you need to get a building permit. Because anyone who converts a basement into living space is making a change in use. In order to receive a permit, your building concept must comply with various building regulations – such as the correct size of the windows and the clear height of the room. Depending on where you live, the building regulations may vary.
If you expand your basement, the requirements for fire protection also change. You may need a second escape route – for example an outside basement staircase. In addition, the living area must be separated from the utility cellar with an F90 fire protection wall and a fire protection door. Such protective walls can withstand fire for 90 minutes.
Submit a building application for the cellar extension
For the building application, the best thing to do is to get support from a planner and an architect.
You will work out the building application for your cellar extension together with a planner and an architect. The architect creates a space and lighting concept, while the planner makes drawings that the craftsmen can use as a guide. In addition, he submits the building application to the building authority, takes on the tender for the work and takes care of the process of extending the basement. The choice of craftsmen, however, is up to you.
Heating and water: what should you watch out for?
The basement expansion also includes basic requirements such as heating and water. Since only a few basements have a radiator right from the start, you will usually need a new one.
Underfloor heating is often not an option due to the low ceiling height. However, there are alternatives such as classic radiators or wall heating.
Floor insulation is an additional measure for pleasant temperatures. You should equip the ceiling of the expanded basement with impact sound insulation. You can use it to reduce noise in the new room when people are walking around on the first floor above.
In addition, find out about the height of the sewerage system before expanding the basement. If this is above the deepest drain in the basement, you need a waste water lifting system. By raising the water above the backwater level, the system prevents wastewater from flowing back through the pipes and flooding your basement.
The right time to ventilate the cellar
Avoid moisture damage when ventilating the basement. You shouldn’t let in warm, moist air.
By ventilating properly, you ensure a favorable indoor climate. However, the basement needs to be ventilated differently than the rest of the house to avoid moisture damage. The seasons also play a role in ventilating your cellar. Since warm air stores more moisture, more moisture gets into the basement with the summer air. Condensation quickly forms on the cold cellar walls, which promotes mold growth.
In summer, you open the basement windows early in the morning when the air is still cool. In winter, it’s best to ventilate on cold, dry days. If the humidity is too high, you heat for several hours in winter to draw the moisture out of the walls. Then you let cold air in. If necessary, a hygrometer can help you keep an eye on the humidity. Nowadays, many thermometers also show the humidity.
Which wall material for the expansion of the cellar?
Plastered basement walls can be painted or wallpapered perfectly.
For a good energy balance, you should equip the outer walls of your basement with an insulating material. Make sure that this is non-flammable and lets moist room air through. Calcium silicate or mineral foam panels are suitable for this. They protect against moisture and prevent mold. On the other hand, you should avoid plasterboard, as it quickly absorbs moisture.
Sealing slurry is also suitable for sealing surfaces against ingress of water. The slurry is a liquid cement-plastic mixture. You apply it in two layers. In order to effectively protect against moisture, the sealing slurry must be able to dry out slowly.
Restoration plaster is ideal for further protection of the walls. The open-pored plaster enlarges the drying surface and thus accelerates the drying of the walls. In addition, renovation plaster binds dissolved salts.
Finally, you apply plaster to the cellar wall that does not contain any plaster. Because similar to plasterboard, the plaster of paris also absorbs water. When painting walls, you use diffusion-open paints. They allow the wall to better remove the room air. Lime or silicate paint is particularly suitable for this.
Seal and dry the basement
Avoid moisture in the basement by carefully sealing it.
Moisture spreads quickly in basements. With the right waterproofing, you can prevent damp walls and mold from growing in your basement.
External waterproofing is an effective method. However, it is relatively complex and expensive. When sealing the outside, you expose all basement walls up to the foundation base. One advantage of the method: You get the opportunity to lay a circumferential drainage that drains back water.
Bituminous or mineral waterproofing is suitable for sealing the outside of the cellar. Alternatively, you can use a clay-clay mixture.
The horizontal sealing provides good protection for the walls. You inject a horizontal layer into the basement ceiling. It prevents moisture from penetrating the masonry. Acrylic gel or resin can also be injected into the wall through drill holes to seal the masonry.
If you do not have the opportunity to seal your house from the outside, we recommend an interior seal. You apply a multi-layer insulation system to the inner wall and the floor. This ensures that the moisture does not penetrate the basement and instead remains in the outer wall.
If you follow these instructions, your newly built basement will be protected from moisture and you can use it as additional living space without any problems.