What finishes can I use on IWI? – Can I Just Ask? | Ep.34

One of the more practical concerns people have about internal wall insulation is what they can do with the surface afterwards — and the answer is more flexible than most expect. For both direct-plastered wood fibre systems and NatureWall, the most common finish is plasterboard with a gypsum skim, painted with standard trade emulsion. The key requirement on paint is vapour permeability: vinyl-based paints should be avoided as they restrict moisture movement through the finish, but most acrylic emulsions are sufficiently vapour open for the application. Beyond VOC content and microplastics — which are worth considering for any interior finish — standard paint choices are largely unrestricted.

Bathrooms and wet areas require a little more thought. On a direct-plastered system, tiling is possible but limited to small splash-back areas rather than full wet room applications. NatureWall handles this more comprehensively: in wet zones, the plasterboard or thermal board is simply swapped out for a tile backer board, and the flexible wood fibre insulation in the batten cavity is omitted in that section, leaving a deliberate void behind the backer board that prevents any water ingress from reaching the insulation layer. This makes a full shower enclosure or wet room entirely achievable within the system without compromising the build-up behind.

Timber finishes are another option that comes up regularly — particularly ply panelling. On a direct-plastered solid insulation board, fixing large sections of ply is awkward; the insulation layer provides limited fixing capacity and the result tends to be impractical. The NatureWall batten structure resolves this cleanly, since ply or timber cladding can be fixed directly to the battens in exactly the same way it would be on any standard framed wall. The broader point is that NatureWall’s batten zone provides a practical service and fixing layer that makes a wide range of finishes and uses achievable without any compromise to the insulation or airtightness behind it.