How to Read a Floor Plan: Symbols, Abbreviations and the Legend
A floor plan is a horizontal section through a building: imagine the house cut through about a metre above the floor, and you are looking down at the lower half. The drawing shows the walls, door and window openings, stairs and room dimensions. If you have a floor plan in front of you — from the local authority archive, a property listing or your builder — and some of the marks make no sense, this guide covers the floor plan symbols, numbers and abbreviations you actually need. You will learn how to tell a load-bearing wall from a partition on a plan, which way a door swings, what the dimensions, level marks and circled numbers mean, what W/D, WIC or HP stand for — and when an old plan is worth redrawing.
Title block and scale: what to check first
Before the symbols, look at the corner of the sheet. On a project drawing you will find a title block: the scale (floor plans are usually drawn at 1:50 or 1:100), the drawing title and number, the date and the project stage or revision. The scale in the title block applies to the original — you can only measure from a copy if the scale survived scanning and printing; an illustrative plan from a listing or a copy photographed on a phone should not be assumed to be to scale. If the sheet carries a north arrow, it shows the building's orientation — in other words, which way the windows face. One more principle before the symbols: conventions vary between practices and over time. If the drawing has a legend, the legend takes precedence; what follows are the most common conventions. How to judge whether a plan can be trusted is covered in our separate guide to accurate floor plans.
Walls: load-bearing walls and partitions
Walls are the most important part of the plan. A thicker wall, often solid black or hatched, is usually an external or load-bearing wall; a thin line is normally a partition. On older drawings, hatching may indicate the material — brick, concrete and timber are marked with different patterns — while on more recent drawings a load-bearing wall may simply be filled darker; graphic conventions vary, so check the legend. One warning: the line weight on a plan is no proof that a wall can be removed. Whether a wall is load-bearing is for a structural engineer to say, not an old drawing.
On an alterations drawing, walls are typically shown in three categories: existing, to be demolished and new. Demolition is usually dashed and new walls darker or hatched, but the exact meaning is set by each drawing's legend — there is no single universal rule.
Doors, windows and stairs
Door. In the wall opening there is the line of the door leaf and an arc: the arc shows the swing — the direction and path of the leaf. A sliding door has no arc; the leaf is drawn inside or alongside the wall.
Window. In the external wall there is an opening with one or more thin parallel lines representing the frame and glazing. Read the window size from the stated dimensions or the window schedule, not by eye.
Stairs. The treads are usually parallel lines and an arrow shows the direction of travel, often labelled UP or DN. A diagonal break line across the stair generally marks where the cutting plane passes through it.
Dashed lines can show what is above the cutting plane or hidden — an opening in the floor above, a canopy over the balcony, the top of a wardrobe — but on an alterations drawing, a wall to be demolished. The legend tells you which applies.
Numbers: dimensions, areas and levels
A dimension line is a thin line with oblique ticks or arrowheads at its ends and a number above it. The unit depends on the country. On Estonian plans, dimensions are given in millimetres with no unit shown, so 3940 means 3.94 metres; UK building drawings also commonly use millimetres, often with a note that all dimensions are in millimetres unless stated otherwise, while drawings from the United States use feet and inches, such as 12′-11″. When in doubt, look for the unit in the title block or the legend. Next to each room name you will usually find the floor area in square metres or square feet. The level mark ±0.00 is the building's datum, usually the finished floor level of the ground floor, and +2.80 or −1.20 show how much higher or lower another level sits.
Circled numbers, grid lines and abbreviations
A number in a circle inside a room is the room number: its name, use and area are listed in a separate room schedule. The circles with letters and numbers along the edge of the sheet are grid bubbles: they identify the grid lines, a reference grid that designers and builders use to describe positions. A marker with an arrow at the ends of a line (A–A, 1–1) is a section marker: it shows where a vertical section has been cut and which way you are looking; the marker also references the section drawing and where to find it in the drawing set.
Property listing plans in particular make frequent use of abbreviations, and they vary by country and drawing type. You may see W/D for washer and dryer, WM for washing machine, DW for dishwasher, REF for refrigerator, MW for microwave, WH for water heater, HP for heat pump (where the legend defines it so), WIC for walk-in closet, CL for closet, CH for ceiling height, AFF for above finished floor, FFL for finished floor level, FD for floor drain, DN for down and NTS for not to scale. Always check the drawing's own legend, because several of these abbreviations have other meanings elsewhere. Old drawings from other countries may use a different alphabet — Soviet-era plans carry Cyrillic labels, and the letter-and-number codes beside doors and windows are usually door and window type references, not an error. Toilets, basins, baths, showers, hobs and sinks are drawn in simplified form and show position, not the specific model.
The same apartment before and after
The archive copy below is a typical example of the source material we receive most often: hatched walls, dimensions in millimetres, type references beside doors and windows and some labels in Cyrillic — in this case, an apartment in an Estonian block built in the Soviet era. As above, the hatching alone does not establish whether a wall is load-bearing.
We redrew this apartment's plan in AutoCAD, with room names written out in full, areas and dimensions added, and consistent symbols throughout. The numbers in the picture refer to the symbols explained in this guide.
1 load-bearing wall · 2 partition · 3 door and swing · 4 window · 5 dimension line in millimetres · 6 room name and area · 7 sanitary fittings · 8 hob and sink
Frequently asked questions
How do I tell which way a door opens? From the arc beside it: the arc is the path of the door leaf and sits in the room the door opens into.
Can I measure a floor plan with a ruler? Only if the plan is at the scale stated in the title block and was not resized when scanned or printed. Reading the dimension lines is safer; on a blurry scanned copy or a listing plan, do not trust the ruler.
What does a number in a circle mean? Inside a room it is the room number, whose name and area are in the room schedule; at the edge of the sheet the circle identifies a grid line.
When the plan is old, blurry or in a foreign language
If you have no plan at all, start with our guide to finding the old floor plans of your house. If you have a plan but it is hard to read, we redraw it by hand in AutoCAD: you send the scanned file or a photo, we assess the scope and send a free quote. The result is a clean plan with room names, areas and dimensions, supplied as a PDF and an editable DWG file that a designer or builder can work from. Its accuracy depends on the source material and the measurements you provide. If part of the original is illegible, we mark it clearly on the drawing rather than guess. A redrawn plan is a base drawing, not a construction drawing.
Need the same for your drawing? We can do it for you: Floor plan and drawing digitization — send us your drawing and get a free quote.
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