Why cellars need designed moisture resistance
Building Regulations require walls and floors to resist ground moisture, with sub-soil drainage where needed. That is the regulatory frame for a wet cellar — not a scare piece. See GOV.UK Approved Document C (site preparation and resistance to contaminants and moisture) and the related requirements in Building Regulations Part C. This page is not legal advice; it is plain English for Alwoodley homeowners before a survey.
What “tanking” usually means (barrier / Type A-style)
In everyday talk, tanking means a continuous barrier — cementitious slurry, sheet membrane, or similar — intended to stop water coming through the wall or floor. Under BS 8102 that idea sits closest to Type A (barrier) protection. Detailing, substrate condition, and joints matter: a coat that cracks or loses bond at a party wall or coal chute is how many Alwoodley cellars end up wet again.
Not every product marketed as “tanking” is automatically Type A without a survey. For how this practice talks about failed coats on LS17 stock, see cellar tanking in Alwoodley and what tanking a cellar involves.
What Type C cavity drain does
Type C is drained protection: a cavity membrane on the inside face, drainage channels at the floor joint, and a maintainable discharge path — often a sump and pump to an existing drain. BS 8102 frames Type C as managing water that reaches the drained space rather than asking the original structure to be a perfect boat.
That system needs access for service and a plan if a pump fails. We do not invent service intervals here; the survey records access and contingency for the room you have. Plain English for this stock: Type C cavity drain for Alwoodley cellars.
Side-by-side: when each approach is typically considered
These are questions a surveyor answers on the house — not hard rules invented on this page. Overview language only; see BS 8102:2022 on BSI Knowledge and the Basement Information Centre BS 8102 overview PDF for published summaries (we do not reproduce copyrighted standard text).
| Question a survey asks | Barrier / tanking (Type A-style) | Type C drained cavity |
|---|---|---|
| How does it deal with water? | Aims for a continuous barrier so water does not enter | Accepts some water past the structure and manages it to a controlled outlet |
| What must stay reliable? | Barrier continuity, joints, substrate bond | Channels, sump/pump (where used), maintainable access, legal outfall |
| Future access | Defects may be hard to find until the space is wet again | Designed for inspection and service of the drained path |
| Typical survey trigger on Alwoodley stock | Failed slurry/bitumen, or a dry cupboard where a full system is not justified | Used room on clay groundwater, or after a failed barrier coat |
Damp-proofing of above-ground walls is not the same job as below-ground cellar waterproofing. If you only have salts on an upstairs wall, this comparison page is not your brief.
How this affects cost conversations (no prices)
Cost drivers are access, system type, finish level, and drainage or electrical needs — never a fixed quote without seeing the room. We do not publish invented £ bands on this spoke. For what changes the price on Alwoodley plots, read what changes cellar waterproofing cost.
Can you get a fixed price without a survey? No. The survey is the filter.
Flooded cellars are a different first step
Active flooding needs safe first response and diagnosis before anyone specifies a full barrier or Type C system. That is a different visit from a dry-room comparison. See flooded cellar first response.
Practical next steps for Alwoodley homeowners
- Decide how the space will be used (storage, occasional room, or future conversion).
- Book a cellar discovery survey in Alwoodley.
- Ask which BS 8102 type(s) are proposed and why.
- Ask what maintenance or contingency the system needs.
Start from the money pages, then request a survey: cellar tanking in Alwoodley, Type C cavity drain for Alwoodley cellars, contact.
FAQs
What is the difference between tanking and Type C cavity drain?
Tanking / barrier approaches aim to keep water out with a continuous waterproof layer. Type C cavity drain manages water that reaches a drained cavity and takes it to a controlled outlet. They are not the same system.
When is Type C typically considered?
When the room will stay in use and groundwater or a failed barrier coat means a maintainable drained path is more honest than another coat — the survey decides on the house.
Is tanking the same as Type C?
No. Tanking is the barrier idea; Type C is drained protection.
Is damp proofing the same as cellar waterproofing?
Not usually. Above-ground damp treatments and below-ground cellar systems answer different moisture paths. A survey separates them.