1. CONCRETE AND SUSPENDED TIMBER
Ground Floors
CONCRETE AND SUSPENDED TIMBER

2. TYPES OF GROUND FLOORS
Concrete
Suspended timber
Ground floors

3. FUNCTIONS Support imposed loads Provide a level surface
May differ depending what the building is used for
Factory floor needs to be capable of supporting larger loads than that of a dwelling house
Machinery/vehicles
Partitions/furniture
People
Provide a level surface
Strength and stability
Durability
The material used remain intact surface of floor does not ravel
Quality of concrete

4. FUNCTIONS Prevent damp rising Prevent heat loss Allow for finish
As a concrete floor rests on the ground dampness can rise up through it due to capillary action the use of a damp proof membrane can prevent this happening
Prevent heat loss
Allow for finish

5. CONCRETE GROUND FLOOR: COMPONENTS
Hardcore
Crushed stone dia. 100mm
Layers 225mm deep
Max. Depth 900mm
Insulation
60mm expanded polystyrene
Damp proof membrane
1200 gauge plastic sheet
Laid on sand blinding
Concrete
1:3:6 mix

6. FOUNDATION & RISING WALLS
soil
Concrete foundation

7. HARDCORE PLACED & COMPACTED
150mm min. hardcore

8. DAMP PROOF MEMBRANE
dpm carried up wall and over block work of inner leaf

9. INSULATION
25mm insulation
60mm insulation

10. REINFORCED CONCRETE SLAB
150mm min. concrete

11. WALLS CONSTRUCTED
150mm min. clearance

12. FLOOR OPTIONS The services can be laid in the concrete slab in advance
This will negate the need for a finished slab
It will however mean that there will be a reduced flexibility in dealing with services afterwards
Changes in the service layouts cannot be made without digging up the floor
With the inclusion of the finish screed service plans can be altered even after the walls are built

13. OPTIONAL SCREED A 75mm screed can be placed
on top of the floor to accommodate
service pipes such as central heating
and gas

14. RISING WALLS COMPLETED

15. HARDCORE INFILL

16. RADON BARRIER LAID

17. DPM / INSULATION /STEEL

18. CONCRETE POURED

19. POWER FLOATING CONCRETE

20. CONCRETE GROUND FLOOR: FINISHED

21. CONCRETE GROUND FLOOR: FINISHED

22. ALTERNATIVE METHOD Components: Hardcore Concrete subfloor Dpm
Insulation
Concrete screed (cement & sand mix)

23. CONSTRUCTION DETAILS
screed
insulation
dpc/dpm
slab
hardcore

24. FUNCTIONS OF SCREED Provide a level surface for finish
Carpet / Tiles / Timber
Take out any irregularities in the slab
Accommodate services
Pipes

25. ALTERNATIVE METHOD Advantages Disadvantages
Screed laid after heavy work
No need to protect floor during construction
Dpm less likely to be damaged
Disadvantages
Dpm not continuous from floor to wall
Screed must be barrowed in
Labour intensive / costly

26. SUSPENDED TIMBER FLOOR

27. When is a suspended timber floor best used?
Used where the depth of fill exeeds 900mm.
900mm

28. Underfloor Ventilation
Why do we need ventilation?
To avoid excessive build up of moist air in the underfloor space.
To keep the moisture content of the timber floor members below 20% of their dry weight, to prevent fungal attack taking place.

29. Dwarf wall Wall plate underside treated DPC Block sleeper wall 150mm
gaps
Gaps left between blocks to allow air circulation
150mm

31. How to calculate the number of ventilations opes required, for the house illustrated.

32. 150mm seated vent through cavity DPC GL Radon Barrier 100MM Insulation
22mm Timber floor
125 x 44 Timber Joists
DPC
100 x 75mm wall plate on DPC
Min 75mm For ventilation
Min 150mm
Dwarf Wall span 2m between
150mm Concrete slab GL
150
Radon Barrier
150MM LAYER OF HARD CORE T
`3T