Before you buy a plot, five questions are worth asking: will water flood it, is the slope moving, is there a mine working beneath it, does it lie on a mineral deposit, and is it contaminated? Each one is answered by a different authority and a different map. This article sets them side by side and complements the article How to choose a plot, which walks through the whole pre-purchase check.
Which official map answers which question?
Some sources set a building ban, others only show what has been documented so far. The table lists the public sources I opened while writing this article.
| Risk | Official source | What you find there | What it means for design and cost |
|---|---|---|---|
| River flooding | Flood hazard and flood risk maps (2023) in the SVP map viewer, linked from the Ministry of Environment website | Flood extent, water depth or level for three flood scenarios | No house in an inundation area. Outside it, floor level, ground-floor materials and insurance decide. |
| Landslide and other slope deformation | Register of documented slope deformations, ŠGÚDŠ (Geofond registers) | Point and area landslides with a link to the final report | Scope of the engineering-geological survey, foundation type, retaining walls and slope drainage |
| Old mine working | Old mine workings and mine workings database, ŠGÚDŠ | Location and basic technical data of mine workings | Survey for voids in the ground, the position of the house on the plot, or securing the working |
| Protected deposit area, mining area | Deposits application, ŠGÚDŠ; spatial plan; land cadastre | Boundaries of protected deposit areas and mining areas | A binding opinion under the mining act and the district mining office as an affected authority |
| Environmental burden | Information system of environmental burdens (Ministry of Environment, run by SAŽP) | Sites in registers A, B and C by region, district and municipality | Contamination survey, terms in the purchase contract and the risk that the owner bears the clean-up |
| Earthquake | STN EN 1998-1/NA + Z4, the national annex to Eurocode 8 | Nationally determined parameters for seismic design | The structural engineer applies them to the load-bearing structure, together with the ground type from the survey |
How do you read a flood hazard map?
On its flood risk management page, the Ministry of Environment lists flood hazard maps from 2013, flood risk maps from 2015 and the 2023 maps, which it opens in the SVP map viewer.
The hazard map shows, as an indication, the flood extent, the water depth or level and, where needed, the flow velocity (7/2010 § 6 ods. 3). When buying, look at all three scenarios, not only the 100-year flood. If a high-probability flood, one that returns about once in 10 years, already reaches the plot, expect the water to come back during the life of the house. If only the low-probability scenario reaches it, the question is more about design than about buying.
The flood risk map uses the same flood line but adds consequences: the estimated number of people at risk, economic activities, operations that could pollute water when flooded, and other sources of pollution (§ 7 ods. 1).
The municipality must draw the flood lines from the maps into its spatial plan at the next review of the plan. If it has no spatial plan, the building office uses the maps directly in its work (§ 6 ods. 10). An older spatial plan may therefore not show them, and the map in the viewer may be more recent.
What does an inundation area mean, and what does a line on a map mean?
A flood line bounds an inundation area. It is the calculated line of the 100-year flood or a surveyed line of a flood that returns less often than every 50 years. A flood-protection line structure that holds back the 100-year flow can also bound it. For an unembanked watercourse, the district office sets its extent by a regulation (7/2010 § 20 ods. 1, 2). In an inundation area it is forbidden to place residential buildings, fencing that worsens runoff and earthworks that can worsen runoff (§ 20 ods. 5, 6). The entry flood-prone area explains the context.
A flood protection authority or a municipality can also designate, by a decision, an area with retention potential as a flood area to flatten the flood wave. The same bans as in an inundation area then apply there (§ 21 ods. 1). In an inundation area with retention potential, even minor structures and building alterations that would elsewhere need no notification must be notified to the building office (25/2025 § 18 ods. 3 písm. i).
If the plot lies within a mapped flood but outside an inundation area and an area with retention potential, the ban does not apply. The risk remains, though, and the design deals with it: a ground floor above the expected water level, a house without a basement or with a watertight one, materials that dry out after flooding, and services run high up. The entry flood-resilient design describes the approaches. Count their cost into the price of the plot.
Where can I find out whether the slope on a plot is sliding?
The State Geological Institute of Dionýz Štúr (ŠGÚDŠ) runs, among its Geofond registers, the information system of the Register of documented slope deformations. It distinguishes point landslides of smaller extent and area landslides that outline larger territories. It draws on the Atlas of slope stability maps of the Slovak Republic, completed in 2006, and on the current Geofond landslide register.
A blank spot on the map does not mean a stable slope, only that nobody recorded a landslide there. If a landslide area reaches into your plot or lies above it, make the purchase conditional on an engineering-geological survey that assesses slope stability. Planning authorities follow the results of geological work, landslide areas included (569/2007 § 20 ods. 1), so you may also find the landslide in the spatial plan. The same paragraph also names radon risk. The article House on a slope covers design on a slope.
How do you check for old mine workings and undermining?
The law does not define undermined territory. In practice you are asking whether an old mine working lies beneath the plot, that is, an abandoned underground working whose operator and legal successor do not exist or are unknown (44/1988 § 35 ods. 1). The Ministry of Environment identifies old mine workings and keeps their register (§ 35 ods. 2). The geology act assigns the keeping of the old mine workings registers to ŠGÚDŠ (569/2007 § 36 ods. 1 písm. x bod 10).
ŠGÚDŠ has run the Old mine workings and mine workings map database since April 2009 and adds to it continuously. The data come from reports by the public and organisations and from archive material. Each working has a link to the final report. The origin of the data also sets its limit: a working of which no record survives will not be in the database. In mining districts, an engineering-geological survey should therefore also look for voids in the ground.
Why look for a protected deposit area in the cadastre too?
A protected deposit area protects a reserved deposit from structures that would prevent or hinder its extraction (44/1988 § 16). There need not be any mine under the plot. The district mining office sets it by a decision, and its boundaries are marked in the spatial planning documents and in the land cadastre (§ 17 ods. 1, 5).
The ŠGÚDŠ Deposits application shows the boundaries of reserved deposits, protected deposit areas and mining areas. The data are updated from decisions that change these boundaries. In a protected deposit area, structures unrelated to extraction may not be set up unless a binding opinion under the mining act has been given (§ 18 ods. 1). In the proceeding on the building intent, the district mining office is an affected authority (§ 19).
How do you find an environmental burden, and what does it mean for the buyer?
The information system of environmental burdens is run by the Slovak Environment Agency for the Ministry of Environment. It sorts sites into three registers: A probable environmental burden, B confirmed burden and C remediated or reclaimed site. You can search by region, district and municipality, or through a map. The ministry also feeds its data into the spatial planning and building information system (569/2007 § 20a ods. 2).
If the originator is unknown, or no obliged person can be named under ods. 1, the regional district office names the owner of the property as the obliged person (409/2011 § 4 ods. 3). The exemption for an owner who did not continue the activity and could not have known about the burden when acquiring the property rests on what you knew at purchase (§ 4 ods. 5 písm. b). Whether you can rely on it for a site listed in a public register is a question for a lawyer.
If the seller is the originator or the obliged person and also the owner, the property may be transferred only after an environmental geological survey. Its final report forms part of the transfer contract (§ 7). If this rule applies to the seller and the seller cannot show the report, do not sign.
Do you need to deal with the seismic zone when buying a plot?
The building act does not mention earthquakes, and no building ban follows from them at purchase. They do belong in the brief for the structural engineer. The Slovak national annex STN EN 1998-1/NA + Z4 was issued in November 2023 under class number 73 0036. It is a consolidated text with amendments 1 to 4 and replaced the annex of April 2009 and its three earlier amendments. It holds the nationally determined parameters for Eurocode 8. I do not quote specific values here, because the free preview of the standard does not contain them. The entry seismic zone gives more detail.
According to the EU Joint Research Centre, EN 1998 applies to the design and construction of buildings in seismic regions, and the level of protection varies from country to country. The structural engineer also needs the ground type, which the geological survey determines.
What should you do when the check finds something?
What matters is whether it is a legal ban, a condition set by an affected authority, or a risk the design can solve at a higher cost. The entry land due diligence before purchase describes the whole check.
| Finding | Next step | When to walk away |
|---|---|---|
| Plot in an inundation area or an area with retention potential | Check the extent at the district office and with the river manager | If you wanted a family house, because residential buildings are banned there |
| Mapped flood outside the inundation area | Ask for an insurance quote for the address, brief a flood-resilient design and a hydrogeological survey | If a raised floor and ground-floor protection do not fit the budget |
| Landslide in the register on the plot or above it | Read the final report in Geofond, order an engineering-geological survey with slope stability | If the survey confirms slope movement where the house would stand |
| Old mine working nearby | Ground survey aimed at voids, move the house to a safe part of the plot | If the working lies under the only possible position of the house |
| Protected deposit area or mining area | Ask the district mining office about its conditions and tie the purchase to a positive binding opinion | If the office will not allow the building |
| Site in register A or B | Ask for the final report, check the obliged person at the regional district office, give the contract to a lawyer | If the burden is unresolved and it is unclear who will remove it |
| Seismic data for the site | Pass them to the structural engineer with the geological survey results | On their own they are not a legal reason to withdraw |