Wij gebruiken cookies om uw ervaring te verbeteren. U kunt kiezen welke cookies u accepteert.
Structural Timber · For Architects
Timber frame specification covers far more than the C24 studs — wall panel assemblies, floor cassettes, connections, vapour control, and breather membranes all need careful specification. This template provides a complete clause for closed-panel timber frame construction.
Free Download
NBS-format clause, common errors checklist, and standards reference. Editable PDF format ready for your tender documents.
We respect your privacy. No marketing email — only project-related technical updates if you opt in later.
Specification Checklist
C24 standard. 38×140mm typical for external walls, 38×89mm for internal partitions.
400 or 600mm centres. 400mm gives stiffer walls, 600mm uses less timber.
OSB/3 (12mm typical), plywood (12mm), or DHF board. Affects racking strength and breathability.
Mineral wool, wood fibre, or PIR. Specify thermal performance (lambda value).
On warm side of insulation. Polythene VCL or intelligent membrane.
On cold side. Vapour open (Sd ≤ 0.3m), water resistant (W1).
Galvanised metalwork, M10 bolts to sole plate, joist hangers per Eurocode 5.
STA Bronze/Silver/Gold for verified manufacturing quality. CE marking on engineered components.
Example Clause (NBS Format)
TIMBER FRAME SUPERSTRUCTURE Wall panels (closed-panel system): - Studs: C24 to EN 14081, 38×140mm at 600mm centres - Sole plates and head plates: C24, 47×140mm, single members - Sheathing: 12mm OSB/3 to EN 300, racking nailed to studs - Insulation: Mineral wool, lambda 0.034 W/mK, full depth between studs - Vapour control: Intelligent membrane, Sd 0.5–10m variable - Breather membrane: Class W1, Sd ≤ 0.3m, UV stable 6 months - Internal lining: 12.5mm gypsum plasterboard Floor cassettes: - Joists: I-joists or solid C24, 240mm depth typical - Joist spacing: 400mm centres - Subfloor: 22mm P5 chipboard, glued and screwed - Acoustic insulation: 100mm mineral wool between joists Connections: - Sole plate to slab: M12 bolts at 600mm centres, stainless steel - Joist hangers: Hot-dip galvanised, sized per joist - Header plates: Continuous, no end-jointed material Certification: - Manufacturer: STA Silver minimum (Structural Timber Association quality scheme) - Components: CE marked per relevant EN standards - Sustainability: FSC or PEFC chain of custody
Copy and paste this clause into your tender. Adjust dimensions, grades, and project-specific requirements.
Common Errors
No breather membrane
Correction: Always specify Class W1 breather membrane on cold side. Without it, condensation forms in insulation and rots structure.
Polythene VCL with no air seal detailing
Correction: VCL must be continuously sealed at all joints, penetrations, and floor-wall junctions. Air leaks defeat its purpose.
No racking design verification
Correction: Racking strength must be calculated per Eurocode 5. Don't assume "OSB sheathing is enough".
Insufficient sole plate fixing
Correction: Specify M10 minimum bolts at 600mm centres for typical residential. Higher for taller buildings or wind exposure.
Reference Standards
Frequently Asked
Platform frame builds floor by floor, with each floor providing the platform for the next storey above. Balloon frame uses continuous studs from foundation to eaves with floors hung from them. Platform frame is the dominant modern method.
Open panel = stud frame only, insulation and finishes installed on site. Closed panel = factory-assembled with insulation, services, and breather membrane pre-installed. Closed panel costs more but reduces site time and improves quality.
Mineral wool is most common (good acoustic + fire). Wood fibre is best for breathability and summer comfort. PIR is highest U-value but worst breathability. Match insulation to wall build-up philosophy.
Need a tailored quote?
Our technical team supplies certified, traceable timber matching this specification. Quote within one business hour.
Request Quote