Flood risk
How should a buyer separate attenuation crates, under the new drive and a store the survey could not open when all three are mentioned together?
Separate the crates, the drive and the store that was not opened. Attenuation crates are buried boxes meant to hold rainwater under the new drive and let it out slowly. The survey could not open that store, so silt, outlets and how much space is left were not seen. The crates were named, the drive is where they are said to be, and the closed store is the limit. The visit has not decided the crates are working. It has not measured flood depth. A long-term flood-risk check is a separate product from this inspection.
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?
Attenuation is storage, not a soakaway that must swallow all the water on the spot. Crates under a drive take runoff from the paving, hold it, and release it through a control so the outflow is slower. If the store cannot be opened, the surveyor cannot see whether the crates are crushed, full of silt or still empty. The new drive shows where the water is supposed to go. It does not show the boxes. GOV.UK offers a check of long-term flood risk for an area.
Tell the solicitor the crates were not opened, and ask for the drainage design that should show where they discharge. A drainage firm can inspect the store if there is an access the survey could not use. The report has not decided the drive will flood, and it has not cleared it. Do not present the new paving as proof the crates are sound. Keep the named crates, the unopened store and any flood-risk check as three different things. The home survey has not substituted for that check.
What should you ask your surveyor?
- What access to the crate store was missing or too difficult to open?
- Where is the drive supposed to send water, if that was visible at all?
- Did you see ponding on the drive, or only the unopened store?
What are the typical next steps?
- Keep the crates, the drive and the unopened store as three separate limits.
- Ask the solicitor for the drainage design and where the crates discharge.
- Do not treat this visit as a flood-depth measurement or as the long-term flood-risk check.
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
Are attenuation crates the same as a soakaway?
No. Crates used for attenuation hold water and let it out slowly. A soakaway is meant to disperse water into the ground. The survey named crates under the new drive and could not open the store, so it has not decided which role this installation plays, or whether it works. The design papers are the place to start. The closed store is not that design.
Does a dry drive on the day clear the crates?
No. A dry surface shows the weather at the visit, not the inside of a store that was not opened. The survey did not measure flood depth and did not see silt or outlets in the crates. GOV.UK's long-term flood-risk check is a separate product. Neither that check nor a dry drive inspects the buried boxes.