Foundation and drainage: lifespan and cost
The foundation holds the house up and the drainage keeps water away, and it is moisture at the bottom that causes the most expensive damage. The table shows how long the parts last and what a fix usually costs.
The ranges apply to a normal-sized house. Actual cost depends on size, access and region. Lifespan means technical lifespan with normal upkeep. In a share-based flat the big repairs are a share of the housing company’s project and show up in the charge or the company loan.
| Component | Lifespan | Replacement cost |
|---|---|---|
| Foundation | 80 yrs (60-100) | 20 000-80 000 € |
| Drainage | 40 yrs (30-50) | 8 000-25 000 € |
| Crawl space | 50 yrs (40-70) | 8 000-30 000 € |
| Slab-on-ground | 80 yrs (60-100) | 15 000-50 000 € |
How long does drainage last?
The concrete foundation itself is nearly permanent, but the drainage around the house is a wearing part that needs redoing at intervals. When it stops leading water away, moisture rises in the foundation and basement. Signs are damp or salt on the basement wall and water pooling near the house. The table shows the typical interval.
What does redoing the drainage cost?
Redoing the drainage means the ground is dug up around the house, new drainage and moisture proofing are laid against the foundation wall and the soil is filled back. The price is driven by the digging depth, how close the house sits to the plot boundary and shrubbery, and whether the ground slopes. Crawl spaces and slab-on-ground have their own risks and fixes. The cost in the table applies to a normal-sized house.
What the age of the house tells you
Certain build years carry known risks for exactly these parts. Here are the most common ones.
False plinth (valesokkeli) Houses built 1960–1990
False plinth — the most common Finnish risk structure; investigate the moisture.
Double concrete slab (kaksoisbetonilaatta) Houses built 1960–1995
Double concrete slab — the timber in the void can rot; investigate.
Basement timber against ground Houses built 1900–1975
Basement timber against the ground rots — investigate.
How do I know if the drainage needs redoing?
Ask for the year of the last drainage work. Damp, a musty smell or white salt deposits on the basement wall and water pooling against the house are signs it is no longer doing its job.
Is a crawl space a risk?
Crawl spaces from certain years often have poor ventilation and a ground moisture barrier and can develop mould. Checking smell and moisture in the crawl space is part of a condition inspection; see the age note below.
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