Walls Part 1

Walls Part 1

1. Walls

   • External
     • Loadbearing
       • Walls designed to carry load other than self weight, if removed load is unsupported
     • Non-loadbearing
     • walls from envelopes to a building; define the boundary between internal/external environments
     • Types
       • Solid
       • Cavity
       • Timber Frame
       • Structurally Insulated Panels (SIPs)
       • Steel Frame
   • Internal
     • Loadbearing
     • Non-loadbearing
       • Walls that support only self weight ; if removed there is NO impact on structural loads
     • divide the internal space
     • Factors to consider...
       • Acoustic performance
       • Resistance to spread fire
       • Thermal performance

2. Strength

   • way materials are put together
   • strength of material in resisting compressive and tensile stresses

3. Stability

   • Foundation movement
   • Ecentric loading
   • Lateral forces
   • Expansion due to changes in temperature

4. Weather Protection

   • Building regs, states that walls should adequately resist passage of mositure to the inside of buildings
   • Water/Snow can penetrate walls depending on exposure to wind-driven rain which is determined by location
   • DPCs DPMs Cavity walls help protect

5. Conservation of heat and power

   • Provide adequate thermal insultaions
     • against excessive loss or gain of heat
     • Lightweight materials of low conductivity are more effective than dense materials
   • adequate thermal storage capacity
   • Internal walls at reasonable temp

6. Heat Transfer

   • Basics
     • Conduction - direct transfer between adjoining molecules - warm -> cold
     • Convection - transfer of heat through liquids/gases, transfer of heated air to cooler surfaces
     • Radiation - transmission of energy through space by electromagnetic waves, head moves at the speed of light
   • u -value
     • measures thermal transmittance
     • takes account of conduction/convection and radiation
     • heat flow through a material is expressed in terms of Thermal Resistance (R)
     • 1 element
       • U = 1/R
     • a house
       • U = 1/sumR
     • thermal resistance
       • R = thickness of material (d) / thermal conductivity of materials (y)
     • max in a house : 3 W/m2K ideal: 0.18 W/m2K

7. Thermal Conductivity

   • Heat flow in Watts across a thickness of 1m of material with a surface area of 1m2 when the air temp either side differs by 1 degree
   • High Conductivity
     • copper, aluminium
   • Low conductivity
     • Glass Mineral wood
     • Rock mineral wool