Wall flatness: how to check it and what to put in writing

What changed in 2026

Amendment No. 3 to SP 71.13330.2017 “Insulating and finishing coatings” (Ministry of Construction order No. 918/pr of 26.12.2024) has been in force since 1 February 2026. The new wording of clause 7.2.13 says that the quality of plastering work must meet the client's requirements. The finishing tolerance tables were removed from the code.

What this means for you: if the contract doesn't say how flat you expect the walls to be, there is nothing to refer to in a dispute with the contractor. Requirements for flatness and surface category are now written into the contract or the design brief. The same goes for tiles: tiling must meet the client's requirements (clause 7.4.17 in the new wording), and the surface category for tiling is set by the design depending on the tile size (clause 7.4.4).

These are Russian standards; other countries have their own.

Which figures to start from

Rather than inventing tolerances, it's convenient to take the former values of table 7.4 of the code. They are no longer a standard, but contractors know them, and in a contract they are clear to both sides.

Plaster: deviations

• Basic - out of plumb no more than 3 mm per 1 m and no more than 10 mm over the full room height, horizontally 3 mm per 1 m.
• Improved - out of plumb no more than 2 mm per 1 m and no more than 10 mm over the full height, horizontally 3 mm per 1 m.
• High quality - out of plumb no more than 0.5 mm per 1 m and no more than 5 mm over the full height, horizontally 1 mm per 1 m.

Reveals

Deviation of reveal width from the design: basic plaster 5 mm, improved 3 mm, high quality 2 mm.

Wall tiles

For internal ceramic tiling the former table 7.6 gave: out of plumb no more than 1.5 mm per 1 m (4 mm per storey), unevenness under a 2 m straightedge no more than 2 mm, joint width deviation ±0.5 mm.

Surface category

The former K1-K4 scale has also stayed in the trade's vocabulary:

• K1 - for tiles and sheet materials; scratches and tool marks up to 3 mm deep were allowed;
• K4 - the strictest: for gloss paints, Venetian plaster, vinyl and metallic wallpaper; scratches, pits and shadows in side light were not allowed.

The category is chosen by the finish: tiles need a lower one, gloss paint needs the highest.

How to check walls yourself

The route hint for the item “Check geometry and moisture” says: a 2 m straightedge and a level are your main tools at acceptance. You will need:

• a straightedge or a straight batten 2 m long;
• a spirit level or a laser level;
• a tape measure and a set of feeler gauges or a ruler to measure the gap;
• a square for corners.

How to check:

1. Flatness. Hold the straightedge to the wall vertically, horizontally and diagonally in several places. Measure the largest gap between the straightedge and the wall.
2. Plumb. Put the level on the straightedge or project a vertical laser line and measure the deviation at the top and bottom of the wall.
3. Corners. Put the square to the corners where the kitchen, wardrobes, bath and large tiles will go: even a small lean later turns into a gap between the furniture and the wall.
4. Reveals. Measure the width of the window reveals at the top and bottom and compare with the design.
5. By touch and light. Shine a torch along the wall: side light shows waves and shadows you can't see head-on.

Photograph every spot where the figure is above what was agreed, with the straightedge and tape measure in the shot, and write it down: room, wall, what's wrong.

What to put in the contract

• Plaster grade for each room or wall: basic, improved or high quality - and the deviation figures from the list above.
• Surface category for the finish: for tiles, wallpaper, paint.
• Square corners where built-in furniture, the kitchen and the bath will go.
• Reveal width and its tolerance.
• How it's checked: with a 2 m straightedge and a level, in the client's presence or from photos.
• When it's checked: after plastering, before skim coating.
• What happens if out of tolerance: the contractor fixes it at their cost, with a deadline.

The strictest requirements aren't needed everywhere. A tip from the route: perfectly square corners are needed where built-in furniture, the kitchen, the bath or large tiles go, and elsewhere they may be wasted money. The plaster grade affects the price, so it's chosen before the estimate. More about the contract is in The contract with a crew: what to include.

What to do if the walls are crooked

1. Don't accept the stage. Write down remarks for each spot with photos and give them to the contractor.
2. Check the contract. If the figures are written down, it's simple: the wall is either within tolerance or not.
3. Decide where it matters. A deviation behind a wardrobe and a deviation on a painted wall by the window are different stories.
4. Fix it before skim coating. After skim coating and painting, the fix costs noticeably more.
5. Check again after the fix, and only then accept the stage.

If there are no figures in the contract you can still negotiate: show the measurements and photos and refer to the former values of the code as a familiar guideline. A dispute that talking doesn't resolve is a matter for a lawyer.

How to run it in the Doma app

The “Rough finishing” stage has the item “Check geometry and moisture”: walls for plumb, 90° corners, screed flatness and residual moisture. Attach photos of the measurements to the item, write remarks as a comment, and accept the stage when everything is fixed. The order of rough work is in Rough finishing: order of work. Master Kistya will answer a question about tolerances and show which document a figure comes from.