Ground Floor Approaches for Domestic Buildings PDF

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Notes on Ground Floor Approaches for Domestic Buildings...

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Ground Floor Approaches for Domestic Buildings Floor systems – horizontal planes that support live & dead loads - Provide a degree of thermal insulation. Functions of Ground Floor:  Structural stability (supports live/dead loads)  Thermal insulation  Durability (satisfactory lifespan)  Provision of appropriate surface finish (level & smooth finish) Factors Affecting Selection:  General nature of construction form  Nature of site  Anticipated loadings  Required surface finish  Cost

Rising Damp - Water within ground or from penetrating damp is absorbed by permeable materials/building assemblies (foundation/floor/basement), - Rises within the materials by capillary action. 2 Types of Domestic Ground Floors: 1) Ground Bearing Slabs 2) Suspended Floor Systems

Ground Bearing Slabs  In-situ concrete slab resting directly in contact with ground surface.

 Does not add to dead loads applied to foundation. Primary Components: - Hardcore o Reduces capillary action o Thin layer of sand laid over hardcore - Concrete Slab o With lightweight, wire steel reinforcing mesh - Thermal resistance layer (insulation) o Closed cell (airtight, water resistant) o Open cell (water/air permeable) o Can be positioned in different parts of assembly. - Various barrier membranes o Dependent upon design choice & arrangement of slab & insulation o DPM (Damp Proof Membrane)  Prevent moisture rising up from ground into the assembly o Vapour Barrier/Vapour Control Layer  Prevent water vapour from interior escaping into assembly

Damp Proof Membrane Barrier against rising damp which can be above/ below concrete slab. Damp Proof Course Barrier, usually formed by a membrane built into the walls of a property, typically 150 mm above ground level, to prevent damp rising through the walls. Types of Design: Concrete slab ABOVE insulation OPTION 1: Insulation above DPM  Slab acts as thermal mass o Retains heat through sunlight exposure/heating periods and releases it during evening/non-heating periods.

 Allows insulation that is not moisture resistant.

 Open cell insulation required (soft & flexible)  Polythene barrier = DPM (lapped, not sealed)

OPTION 2: Insulation below DPM (in contact with ground)  Slab acts as thermal mass  Requires insulation that is moisture resistant.  Closed cell insulation required (rigid & stable)  Single polythene barrier = dual purpose: DPM and Vapour Barrier o Must be taped and sealed at joints.

Concrete slab BELOW insulation OPTION 3: Screed Finish  Requires wet trade for interior finish – curing time needed  DPM below slab.  Vapour barrier between in o Depending upon insulati chieved by taping and sealing joints betwe

o Closed cell insulation

OPTION 4: Board & Sheet Finish  Dry trade o Allows faster completion on site. Minimal delays to other work o Combustible materials present higher hazard in fire conditions  DPM below slab.  Vapour barrier between insulation and board. o Sealed membrane o Taping & sealing joints between insulation boards o Fixing of boards must not compromise membrane

Risks: - Ground heave o Frost action o Ground swell

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Loading: - Joists/beams rest upon inner leaf of load-bearing walls - Adds load to walls, thus impact foundation design (increased loading)

Primary Compon - Floor jois - Thermal resistance layer (insulation) - Vapour/Air Barriers o Dependent upon design choice & arrangement of above components. - Ventilated Air Space o To avoid formation of condensation within void. - Internal honeycomb brick sleeper wall - timber o Allows cross-ventilation - DPC between exterior walls

ng internal wall

- Has block slips - fit between beams on bearing ends, maintain coursing heights and aid the installation of block & beam flooring

- Often made off-site

Taped joints on closed cell ins - making an air-tight seal

Radon Risk  Basic Risk o Ground bearing floor

o Suspended floor

o Suspended floor...