A typical new extension wall, designed to meet current building regulations, is approximately 300mm thick.
Here's a breakdown of the common components and their typical dimensions, resulting in this overall thickness:
- Inner Leaf (Insulating Block): 100mm
- Insulation: 100mm
- Outer Leaf (Brickwork): 100mm
This construction method aims to achieve a U-value (a measure of thermal transmittance) of not exceeding 0.18 W/m²K, meeting modern energy efficiency standards. Wall ties, typically stainless steel, are crucial for structurally connecting the inner and outer leaves. A common arrangement is 750mm horizontal and 450mm vertical centres, reduced to 300mm vertical centres around window and door openings (reveals).
Important Considerations:
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Building Regulations: Local building regulations and specific design requirements can influence the final wall thickness. Always consult with a qualified architect or building control officer to ensure compliance.
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Insulation Type and Thickness: Different insulation materials offer varying levels of thermal resistance. The thickness of the insulation may need to be adjusted based on the chosen material to achieve the desired U-value. Some extensions might use thicker or thinner insulation.
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Wall Construction Type: While brick and block construction is typical, other methods like timber frame or SIPs (Structural Insulated Panels) can result in different overall thicknesses while still achieving the required U-value.
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Finishes: Internal plasterboard and external rendering (if used) will add a small amount to the overall thickness.
Therefore, while 300mm is a good general guideline, it is critical to confirm specific dimensions and materials with a professional based on the extension's design and local regulations.
