There are several good reasons to re-insulate your house. Retrofitting can reduce your heating bill, improve the indoor climate and increase the value of the house. A lower energy consumption will also help to reduce CO2 emissions and benefit our climate.
What is post-insulation?
When you post-insulate, you either add extra insulation to structures in your house that are already insulated, or you insulate where there was no insulation previously. Both parts are something you do after the house is built.
This means that it is not only older and very old houses that can and should be retrofitted. Houses that are 20-30 years old can benefit from being post-insulated.
Good reasons to post-insulate
If your house is poorly insulated and leaky, it can be difficult to heat up, and this is a good reason to insulate. If you insulate your house, it will retain the heat better, and you will thus save money on the heating bill. In addition, you achieve a much better indoor climate by insulating, you reduce the risk of mold growth, and you minimize the fallout from cold and draughts.
When buying a home, energy consumption can be one of the main reasons for choosing or not choosing the home. This can affect both the selling price and the sale itself.
CO2 is emitted when electricity and heat are produced for our houses. 40 percent of the total energy consumption in winter goes to heating houses. If you re-insulate your house and thus lower energy consumption, you are also helping to reduce CO2 emissions.
Where in the house is post-insulation typically done?
Almost everywhere in the house’s climate screen can be post-insulated. The climate screen is the part of the house that shields the home from weather and wind, i.e. windows, roof, and walls.
You should always start by post-insulating the ceiling. In older houses with missing or insufficient insulation in the attic, up to 30 percent of the heat loss occurs through the roof. It is a greater heat loss and can be up to 15 percent greater due to radiation to the outdoors. There are no building parts or vegetation to “stop” the heat.
It is good to start with post-insulation where it is easiest to do. And that is usually also where it immediately pays off the best.
Second, only to the ceiling, the external wall is the part of the building that is easy to post-insulate, especially if it is a heavy external wall with hollow walls. Even if you cannot do the work yourself, it is an effective yield at a relatively low price.
An improvement in windows and doors can also have a major impact on heat loss.
What advantages does post-insulation provide?
You will immediately be able to feel a difference in terms of comfort. Homes and rooms, which were previously difficult to heat properly, can now be heated to a comfortable room temperature. Air currents in the home, which can feel like drafts, also become less of a problem, as the air along the outer walls and windows (if these are improved) is not cooled to the same degree as before.
The indoor climate will also become healthier, as it will be easier to keep the temperature in the home at a constant level instead of it following the temperature outside. When post-insulating and sealing the house’s climate screen, more frequent ventilation must be expected in order to maintain a good indoor climate. It is recommended to ventilate the home three times a day for 5-10 minutes at a time with drafts.
The temperature on the inside of the outer walls and ceilings will also rise, and this means that any moisture in the air will not condense to the same extent and increase the growth of mold in the home.
Another advantage is that your energy consumption will be lower and that you will thus reduce your heating costs. The savings can be felt from the day you get your home re-insulated. Of course, this must be kept up against the costs you have for additional insulation.
The home’s value will typically increase, as a well-insulated home with low consumption can be significantly more attractive than a poorly insulated home with high consumption. The energy labeling report, which is required when selling the home, will clearly state how well or poorly insulated the home is. It shows how large the heat consumption is, calculated based on how well the house is insulated and with the heat source that has been installed.
A good energy label can therefore mean a lot for your house when you have to sell it one day.
How do you find out which types of post-insulation are worthwhile?
It is always a good idea to insulate, especially if it involves laying an extra layer of insulation on the ceiling or filling the cavity wall with insulation. These are easy interventions, where the costs are largely limited to the material price and execution.
Which insulation materials can you use?
Paper insulation (cellulose fibers) is made from old newspapers and is an alternative to mineral wool. It is available both as granules and as sheets.
There are several different insulation materials. Some can be used in most building parts in both floors, walls, and ceilings, while others are limited to certain building parts.
Although most people are familiar with mineral insulation types such as rock wool and glass wool, bio-based insulation materials such as wood fiber and paper insulation are gaining ground. By using more wood and other bio-based materials in construction, we help reduce CO2 emissions, as the bio-based materials are like a kind of “bank” for the CO2 that is absorbed in the growth of the tree.
Bio-based insulation materials include:
- Wood fibers that are blown in small pieces into unused attic spaces or into wooden frame structures, typically in walls.
- Flax fibers that are produced as mats or rolls and are used for insulating ceilings, in roof cassettes (prefabricated roof elements), and in wooden frame constructions.
- Hemp fibers that are produced as mats or rolls and are used to insulate ceilings, in roof cassettes (prefabricated roof elements), in timber frame constructions, and for cavity insulation.
Are there risks with post-insulation?
If the post-insulation is not carried out technically correctly, problems can arise with moisture and thermal bridges, i.e. places that get cold because the insulation does not close tightly or there is no insulation.
Regardless of whether you insulate the ceiling, the external walls, the basement walls (from the outside), or the crawl space, you must, among other things, be careful with moisture. Moisture can cause great damage to your house both in the short and long term and further worsen your indoor climate in the form of mold if it is not done correctly.
Advantages of external post-insulation
- You avoid problems with vapor barriers, which become leaky and thereby cause problems with the growth of rot and fungus.
- Insulation on the exterior is 30 percent more energy efficient than interior insulation because it is “wrapped” around the entire building. All thermal bridges are eliminated, as internal walls are also covered by the external insulation.
- The existing wall is kept warm and dry.
- The work can take place without affecting the interior spaces. This means that you do not need to clear a room before and clean afterwards.
- The living space will not be reduced.
- Radiators, stucco, and similar. must not be moved or removed.
- The electrical installations can remain in place.
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