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Timber stud details

 Timber strength class C16 Width b = 47 mm Depth d = 72 mm Stud spacing s = 600 mm Stud wall comprises of 4 or more studs
Diagrams not to scale

Timber stud wall height details

 Stud wall height Lwall = 1,000 mm Stud height L = Lwall - (2 × b) = 906 mm Stud effective height Leff = L × 0.85 = 770 mm BS 5268-6.1 Clause 4.6.2 recommends L x 0.85 for stud walls restrained by sheathing or plasterboard lining.

 Total load Ftotal = 4.7 kN/m Total load per stud F = Ftotal × s = 2.82 kN

Modification factors

 Load duration factor K3 = 1.00 Bearing modification factor K4 = 1.00 Load sharing modification factor K8 = 1.10 Compression member factor (calculated using equation in BS5268-2 Annex B) K12 = 0.81

Section properties

 Minimum modulus of elasticity Emin = 5,800 N/mm² Cross sectional area A = b × d = 3,380 mm2 Second moment of area I = b × d³ / 12 = 1,460,000 mm4 Radius of gyration i = √ ( I / A ) = 20.8 mm Slenderness ratio λ = Leff / i = 37.05 37.05 < 180 therefore OK

Check compression stress parallel to grain on stud

 Compression stress parallel to grain σc,par = 6.8 N/mm² Permissible compression stress σc,adm = σc,par × K3 × K8 × K12 = 6.08 N/mm² Applied compression stress σc,a = F × 10³ / A = 0.833 N/mm² σc,a <= σc,adm (0.833 N/mm² <= 6.075 N/mm² ) therefore OK

Check bearing stress perpendicular to grain on rail

 Compression stress perpendicular to grain σt,c,g,perp = 1.7 N/mm² Permissible compression stress perpendicular to grain σt,c,adm = σt,c,g,perp × K3 × K4 = 1.7 N/mm² Applied compression stress σc,a = F × 10³ / A = 0.833 N/mm² σc,a <= σt,c,adm (0.833 N/mm² <= 1.7 N/mm² ) therefore OK

Design summary

 Permissible Applied/Actual Utilisation Result Slenderness ratio 180 37 20.6 % OK Compression stress parallel to grain on stud (N/mm²) 6.08 0.83 13.7 % OK Bearing stress perpendicular to grain on rail (N/mm²) 1.7 0.83 49 % OK

Notes

This design is in accordance with BS 5268-2:2002 Structural use of timber – Part 2: Code of practice for permissible stress design, materials and workmanship.

Timber to be covered, this calculation is not to be used for timber which is fully exposed to the elements.

The studs are restrained in the plane of panel by sheathing or plasterboard provided and constructed in accordance with recommendations given in BS 5268-6.1.

The limitations on bow in most strength grading rules are inadequate for the selection of material for columns. Particular attention should therefore be paid to the straightness of column, for example, by limiting bow or spring to approximately 1/300 of the length.

The effect of holes need not to be calculated where circular holes with diameters not exceeding 25% of the width of the member are positioned on the neutral axis at between 25% and 40% of the actual length from the end.

These calculations are only applicable for stud walls consisting of four or more studs.

DEMO