Wall and surface types
Why the calculator asks (optionally) for your wall type, and what each surface generally means for painting.
Wall type affects how absorbent the surface is, and therefore how much paint you'll actually use, as well as whether a primer is needed. This field stays optional: without it, the calculator applies general rules rather than inventing one for an unspecified surface.
| Surface | What's generally worth knowing |
|---|---|
| Plaster | A traditional surface, fairly absorbent when new; usually needs a suitable primer before the finish goes on. |
| Drywall / plasterboard | Plasterboard/drywall sheets, very common in new-build and renovation; the joints between boards are the most absorbent spots. |
| Render | A finish coat over masonry; how porous it is depends heavily on its composition and age. |
| Concrete | A dense but often surface-porous material; new concrete needs time to cure before it's painted. |
| Cement | Behaves similarly to concrete; cement renders are usually rougher and more absorbent. |
| Brick | Very porous when bare — exposed brick often needs more product than a rendered wall. |
| Concrete block | Bare concrete block: a very absorbent, uneven surface, rarely painted directly without a render first. |
| Stone | Porosity varies hugely by stone type; some softer stones absorb a great deal. |
| Wood | A surface that moves (expansion, moisture); needs wood-specific products rather than a standard wall paint. |
| Metal | Non-porous but needs good adhesion; not every standard wall paint is suited to it. |
| Wallpaper | Painting over existing wallpaper is possible in some cases, but the result depends heavily on the paper underneath. |
What about wall condition?
A wall's condition (new, previously painted, damaged, repaired) does change how much paint it takes, especially for the first coat. The calculator doesn't ask about it: no public source gives, paint type by paint type, a numeric difference between a new and a repainted surface, and guessing one would only create false precision. The coverage shown remains a category average; on a very absorbent surface, allow more than the built-in margin or go by the product's data sheet.
Surface not listed?
Choose "Other" and describe it in a sentence. The calculator never invents a compatibility for a surface it doesn't recognise — it applies general rules and flags this clearly.