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Glossary, properties and capacities of scaffold elements

The below scaffolding glossary, properties and capacities are based on UK market.
I take no responsibility for the below information, use it at your own risk and make sure to double check the values.

Properties and capacities


Properties of standard scaffold tubes
in accordance with TG20 / BS 5973: 1993 / BS 1139 - 1.2 / BS EN 12811-2
 

Outside diameter =
Wall thickness =
Cross sectional area =
Mass =
Inertia =
r =
Zp (S in TG20) =
Ze =
Allowable bending moment =
Allowable shear =
Min yield strength =
Modulus of elasticity =

Steel tube (as new U.N.O.):
48.3 (+/- 0.5) mm
4.0 (+0.47/-0.4) mm
5.57 cm2
4.37 kg/m
13.8 cm4
1.57 cm
7.87 cm3
5.7 cm3
1.12 (used tubes: 0.99) kNm
26.1 (used tubes: 23.3) kN
235 N/mm2
210000 N/mm2

Aluminium tube:
48.3 (+/- 0.5) mm
4.47 (+0.56) mm
6.15 cm2
1.67 (-7.5%) kg/m
14.9 cm4
1.56 cm
8.61 cm3
6.18 cm3
1.33 kNm
25.5 kN
255 N/mm2
70000 N/mm2

Allowable scaffold tube strut loads
(based on 'as new' scaffold tube as given above) in accordance with TG20
 

Effective length:

0.6 m
0.8 m
1.0 m
1.2 m
1.4 m
1.6 m
1.8 m
2.0 m
2.2 m
2.4 m
2.6 m
2.8 m
3.0 m
3.2 m
3.4 m
3.6 m
3.8 m
4.0 m

Safe axial load:
Steel tube

70.9 kN
65.0 kN
58.6 kN
51.9 kN
45.3 kN
39.2 kN
33.7 kN
29.1 kN
25.3 kN
22.0 kN
19.3 kN
17.1 kN
15.2 kN
13.6 kN
12.2 kN
11.0 kN
10.0 kN
9.1 kN

Safe axial load:
Aluminium tube

79.3 kN
64.8 kN
48.9 kN
36.5 kN
27.9 kN
21.8 kN
17.5 kN
14.4 kN
12.0 kN
10.1 kN
8.7 kN
7.5 kN
6.6 kN
5.8 kN
5.2 kN
4.6 kN
4.2 kN
3.8 kN

Properties of scaffold boards 
in accordance with TG20 / BS 2482:1981
 

Width =
Thickness =
Mass per unit length =
Mass per unit area =
Max support =
Min section modulus =
Allowable B.M. (1 board) =
Allowable B.M. (4 boards) =
Board overhand - min =
Board overhand - max =

Standard
225 mm
38 (+/- 2) mm
6 kg/m
25 kg/m2
1.2 m (+100mm)
47.5 cm3
0.48 kNm
0.71 kNm
50 mm
150 mm

Super Boards
225 mm
38 (+/- 2) mm
6 kg/m
25 kg/m2
1.5 m (+100mm)
47.5 cm3
0.63 kNm
1.01 kNm
50 mm
150 mm

Omega Timber Batten
225 mm
63 (+/- 3) mm
10 kg/m
41 kg/m2
2.5 m
132 cm3
1.30 kNm
1.30 kNm
50 mm
250 mm

Scaffold coupler safe working loads
in accordance with TG20 / EN 74 / tests by others
 

Coupler type:
Right angle coupler (Class A) =
Right angle coupler (Class B) =
SGB MK3A right angle =
Swivel coupler (Class A) =
Sleeve coupler (Class A) =
Sleeve coupler (Class B) =
Parallel coupler (Class B) =
Putlog coupler =
SGB Brace D/H =
Spigot pin =
Adjustable base / FH =

Slipping force
6.1 kN
9.1 kN
12.5 kN
6.25 kN
3.60 kN
5.45 kN
6.10 kN
0.63 kN
5.0 kN
-
-

Shear
-
-
-
-
-
-
-
-
-
21 kN
-

Axial
-
-
-
-
-
-
-
-
-
-
30 kN

Steel Scaffold Beams
in accordance with BS 449 / BS 5973
 

Beam type:
Ladder
Unit
Layher 450 mm
Layher 750 mm

Iyy
2600.0 cm4
10572.0 cm4
4481.0 cm4
13702.0 cm4

Self weight
0.1275 kN/m
0.1300 kN/m
0.1000 kN/m
0.1600 kN/m

Max allowable B.M.
13.70 kNm
27.70 kNm
24.98 kNm
55.16 kNm

Max allowable shear
18.0 kN
20.0 kN
18.54 kN
27.27 kN

Modulus of elasticity = 210000 N/mm2

NOTE: Beam capacity is a function of spacing of lateral bracing. This to be provided in accordance with manufacturer's specification.

Aluminium Scaffold Beams
based on manufacturers' specification
 

Beam type:
Combisafe Ubix 450
ASP 610
ASP 750
Combisafe Ubix 780
Haki 450
Haki 750
Layher 450
Layher 750
Rux 450
Apollo Cradle X

Iyy
4957.86 cm4
16563.1 cm4
17340.8 cm4
17340.8 cm4
4483.0 cm4
17182.0 cm4
4481.0 cm4
15195.0 cm4
not given
not given

Self weight
0.045 kN/m
0.060 kN/m
0.060 kN/m
0.060 kN/m
0.050 kN/m
0.074 kN/m
0.050 kN/m
0.060 kN/m
not given
not given

Max allowable B.M.
19.60 kNm
18.50 kNm
43.80 kNm
36.50 kNm
15.70 kNm
41.90 kNm
13.94 kNm
42.50 kNm
18.12 kNm
42.90 kNm

Max allowable shear
17.10 kN
24.00 kN
31.50 kN
30.70 kN
12.70 kN
30.60 kN
12.32 kN
25.60 kN
9.70 kN
45.40 kN

Modulus of elasticity = 70000 N/mm2

NOTE: Beam capacity is a function of spacing of lateral bracing. This to be provided in accordance with manufacturer's specification.
NOTE: ASP was bought by Combisafe and now only Ubix 450 (previously ASP 450) and Ubix 780 (previously ASP 780) are available. Other ASP sizes are listed for reference.

Main scaffolding terms

Anchor - an element that transfers forces between a scaffolding tie and a supporting structure. Can be temporary or permanent.

Base Plate - a rigid plate under a standard, used to spread reaction.
Bay - space between two adjacent standards along face of a scaffold.
Bay Length - distance between centres of two adjacent standards.

Coupler - an element that connects two scaffold tubes together.

Ledger - a longitudinal scaffold tube (normally) parallel to a building face. Supports putlogs or transoms, and frequently for ties and ledger braces. Usually connected to adjacent standards. Perpendicular to transoms.

Putlog - a scaffold tube with flattened end. Rests in or on part of a brickwork structure.

Safe working moment - is a characteristic moment of resistance divided by a factor of safety.
Scaffold tube - any tubular element of a scaffold: standard, ledger, transom etc.
Standard - a vertical scaffold tube.
Swivel coupler - a coupler for joining tubes at an angle (i.e. other than at a right angle).

Tie - connects a scaffold to an anchor.
Transom - a scaffold tube spanning across ledgers and supporting scaffold boards forming a working platform or connecting outer standards to inner standards. Perpendicular to scaffold boards.

Working load - a load that can be safely carried by a structural member.

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