Flood risk
The England flood map shades the plot and the house sits on a raised plinth with no tide mark inside. Why is the plinth not a flood model?
The plinth is not a flood model. It is a raised base the survey could see, and the lack of a tide mark inside is only the lack of a stain the survey could see. The England flood map shades the plot as a flood-risk product of its own. The survey has not modelled flood depth, not replayed a past flood, and not decided that a raised plinth takes the house out of the shaded area. A dry interior on the day of inspection is not a hydrology result. The map still shades the plot.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Flood mapping uses information the surveyor does not recreate by looking at brickwork. A plinth may lift the floor above the surrounding ground, but the height was not turned into a model and no depth was calculated. No tide mark means no mark was seen. It does not mean water has never reached the plot, and it does not mean a future flood would stop at the garden. The survey records the building. The flood check records the map. They are not the same sentence.
Ask the solicitor what the flood search or the environmental search says about the shaded plot, and what insurance or lender questions follow from it. Do not ask them to delete that shade because the plinth looked tall or the skirtings were clean. If you need a flood-risk assessment beyond the map, that is a separate instruction. The home survey has not provided one, and it has not measured a flood depth.
What should you ask your surveyor?
- Did you record the plinth and the lack of a tide mark without modelling flood depth?
- Have you left the flood-map shading as a separate product?
- Did a dry interior on the day become a statement that the plot does not flood?
What are the typical next steps?
- Keep the flood map separate from the plinth note.
- Ask the solicitor what the shading means for the purchase.
- Do not treat a missing tide mark as a flood model.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the floor is two steps up, has the house left the shaded area?
Not on the survey's say-so. Steps show a change in level the surveyor could see. They are not a flood model and they do not redraw the England flood map. No depth was calculated. The plinth remains an observation about the building, and the shade remains a shade on the plot.
Does clean decoration prove the last flood missed the house?
No. Clean decoration proves the surfaces look clean now. It does not date a flood, measure a depth, or contradict the map. The survey has not investigated flood history beyond what it could see, and it saw no tide mark. That is an absence of a stain, not a history.