Filling to Q1–Q4: which surface quality for which wall?

Q1 and Q2: basic jointing and standard finish

Quality level Q1 is purely functional basic joint filling: joints between plasterboards are filled, joint tape is embedded and visible screw heads are spotted over. This suffices for surfaces without visual requirements, such as behind wall tiles or a second layer of boarding.

Quality level Q2 is the standard finish for most residential and commercial rooms. After basic jointing, board joints are feathered out with fine filler and sanded until the transition to the board face is seamless. Q2 is suitable under woodchip wallpaper (Raufaser), medium-to-coarse textured non-woven wallpapers and matt, high-build emulsion paints. Under flat raking light, however, slight joint marks or sanding traces may remain visible.

Q3 and Q4: special finishing for smooth walls

With quality level Q3, the joints are feathered out wider and the entire remaining board or plaster face is tightly scraped over with filler to close pores and equalise absorbency. Q3 is the right choice beneath finely textured non-woven wallpapers, painter's fleece (lining fleece) and matt paint finishes on un-textured walls.

Quality level Q4 is the highest surface finish: the entire wall or ceiling area is skimmed full-surface with fine skimming compound in a layer at least one to two millimetres thick and finely sanded. Full-surface Q4 skimming is required for smooth, thin wall coverings, silk or gloss paint finishes, polished plaster techniques and demanding feature walls.

• Q1 (basic jointing): filling joints beneath tiles or cladding without visual requirements
• Q2 (standard finish): flush joints beneath woodchip, textured wallpaper and matt emulsion paint
• Q3 (extended finish): wide joint feathering and tight pore scraping beneath fine wallpapers, painter's fleece and smooth matt paint
• Q4 (full-surface skimming): skimming and sanding the entire wall for smooth walls, satin/gloss paints and decorative finishes

Raking light: why lighting angle affects the quality grade

Raking light occurs when daylight from floor-to-ceiling windows, lighting coves or wall sconces grazes flat across a wall or ceiling surface. At such a shallow angle, even tiny imperfections or slight differences in texture between joint and board cast visible shadows.

Even on a full-surface Q4 skimmed wall, shadow marks under extreme grazing light can only be minimised, not physically eliminated. Discuss lighting and window axes before filling work begins: often, combining Q3 or Q4 skimming with smooth painter's fleece and dead-matt interior paint is the most economical and visually uniform solution.

Choosing the right quality level economically

Decide on the final wall finish first: if woodchip wallpaper is to be hung and painted white, clean Q2 jointing plus filling of plug holes is usually sufficient. If, however, the walls are to be painted smooth and modern without textured wallpaper, Q3 (with painter's fleece) or full-surface Q4 skimming is needed.

State the desired quality level explicitly in the specification of your quote. Without a specific agreement, Q2 is the standard trade benchmark; agreeing on the grade upfront avoids differing expectations at handover.

What we need for your quote

For an accurate estimate, tell us the square metre area of the walls and ceilings, the current substrate (drywall, old plaster, stripped wallpaper), send a few photos and state the desired final finish. Also mention if large window fronts or wall lights create raking light.

TF Clean carries out Q1 to Q4 filling and skimming work in flats and commercial premises in Riesa and the surrounding area — if desired as a complete package including wallpaper stripping, painter's fleece, wallpapering, painting and post-construction cleaning. Describe your project in the contact form.