What is the hatch for concrete in a section?

Usually small scattered triangles and dots that suggest stones in the mix. Reinforced concrete is sometimes drawn with added diagonal lines; follow your office's standard.

What does a 45° hatch mean?

Most often brick or masonry. Some drawings use it for any cut material instead, so check the legend.

How do you show insulation in a section?

Soft insulation such as mineral wool is drawn as a continuous looping curve filling the layer. Rigid insulation boards are often drawn with a cross-hatch instead.

Do I hatch things I can see beyond the cut?

No. Only cut elements are hatched; things beyond are drawn with thinner lines and no fill.

Section hatch patterns: what each one means

Updated October 22, 2026

What a section is

A section is a drawing of a building cut vertically, like slicing a cake and looking at the cut face. It shows floor heights, how the roof, floors and walls are built, and how the building meets the ground. Where the cut goes is marked on the plan with a section mark.

The common hatches

Material	Usual hatch	Typical use
Concrete	Scattered small triangles and dots	Slabs, walls, columns, footings — concrete hatch
Brick / masonry	Parallel 45° lines	Cut brick and block walls — brick hatch
Earth	Groups of short diagonal strokes	Ground below the ground line — earth hatch
Soft insulation	A continuous looping curve	Mineral wool in walls, roofs, floors — insulation hatch
Timber (cut across)	End grain with a diagonal cross	Joists, posts, beams — timber hatch
Gravel / hardcore	Loose pebble shapes	Sub-base, drainage layers — gravel hatch

Rules that keep a section readable

Hatch only what's cut. Things you see beyond the cut — a door in the far wall, the edge of a stair — are drawn in thin lines without hatching.
Cut edges get the heaviest line. The outline of every cut element should be stronger than anything beyond it.
One meaning per pattern. Diagonal lines mean brick in many offices and "any cut material" in others. Decide, and keep it for the whole set of drawings.
Keep hatches lighter than outlines. A hatch that's too dense turns grey and hides the structure.
Add a legend. One small key with each hatch and its material saves every reader from guessing.
Scale matters. At 1:100, walls are thin enough that many drawings simply fill them solid. Hatches pay off at 1:50 and in details at 1:20 or 1:5.

Typical build-ups to draw

Floor slab: Concrete slab, screed and floor finish, with gravel and earth below on a ground floor. Floor slab.
Cavity wall: Brick outer leaf, insulated cavity, block inner leaf. Cavity wall.
Strip footing: The wall stands on a wider concrete footing set in the earth. Strip footing.
Flat roof: Slab, insulation and membrane, turned up a parapet and finished with coping. Flat roof.

Drawing a section in JotJam

1
Open a new design and set the units.
2
Draw the ground line, then the floor levels — add a level marker with the height at each one.
3
Draw the cut walls, slabs and roof with lines and rectangles at their real thickness.
4
Drop the hatches and details from the section symbols into the cut elements.
5
Add a scale figure — a 175 cm person — so the heights read at a glance.
6
Save, and export a scale PDF at 1:50 or 1:20 to print.

Questions

What is the hatch for concrete in a section?: Usually small scattered triangles and dots that suggest stones in the mix. Reinforced concrete is sometimes drawn with added diagonal lines; follow your office's standard.
What does a 45° hatch mean?: Most often brick or masonry. Some drawings use it for any cut material instead, so check the legend.
How do you show insulation in a section?: Soft insulation such as mineral wool is drawn as a continuous looping curve filling the layer. Rigid insulation boards are often drawn with a cross-hatch instead.
Do I hatch things I can see beyond the cut?: No. Only cut elements are hatched; things beyond are drawn with thinner lines and no fill.

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