Floor Screeding

1. Floor Screeding Lesson no 1

3. Learning outcomesby the end of this lesson you should be able to • Identify the bonded floor screed • Describe the monolithic floor screed • Recognise a Floating screed

4. Types of floor screed systems • Bonded. (Monolithic.) • Un Bonded • Floating screed

5. Bonded ( monolithic) floor screed • Bonded systems tend to be the most common methods it fits better with the nature of construction and the set and leave approach of concrete. • In this method a screed is applied to a previously laid concrete base • Bonded thickness is from 25mm to 40mm

6. Bonded floor screed

7. Un Bonded floor screed • An unbonded floor is where no bond to the concrete base is possible owing to its condition. Minimum thickness is 50mm. • A number of different forms of floor construction are included in this type, and are often grouped on their own, e.g. laying a screed on a damp-proof sheet membrane.

8. Un Bonded floor screed

9. Floating floor screed • Floating screed • • An Floating screed floor is where no bond to the concrete base is possible owing to its condition. Minimum thickness is 50mm. • • A number of different forms of floor construction are included in this type, and are often grouped on their own, e.g. laying a creed on a damp-proof sheet membrane, and laying a floor on a layer of insulation

10. Floating floor screed

11. Task • 1. How much mixed material is needed to complete a floor screed 5.000 m long by 4.000 m wide • and 0.050 m thick? • Answer • 1 m3

12. Task • Tools and equipment for floor screeding will generally include: • sweeping brush, trowel, float, mixer, shovel • splash brush, small tool, gauger, trowel, float • spirit level, trowel, buckets, mixer, float • levelling equipment, trowel, float, shovel buckets, mixer • Answer • 4

13. Answer

14. Types of materials used • Mixing is one of the most important jobs of the whole operation • The quality of the sand is important and must be sharp,gritty and clean • The mix ratio is 3 parts sand and 1 part cement

16. Types of materials used • Some floors are laid using granite chipping • On large work , a pump mixer can be used.this will increase productivity and ensure an even mix

18. Preparation of floors • Remove all loose particles and high points on the floor • Brush all the area to remove dust • For certain floor surfaces , a mix of cement slurry and P.V.A can be brushed into the surface • Smooth surface should be scrabbled to form a key

19. Question Plastic sheeting below the structural floor is the: • damp proof membrane • vapour barrier • moisture trap • aid to curing the floor Answer • damp proof membrane

20. Question • The type of cement used in floor screeds is: • Masonry Portland • Extra Portland • Rapid Portland • Ordinary Portland Answer Ordinary Portland

21. Finishes • • Floors are generally finished with either a floated or trowelled surface. • • A wood fl oat produces a sand-faced texture. • • Trowelling gives a smooth finish which closes in the surface of a wood fl oat finish. • • Power floats, tampers and rollers can be used to assist the floor layer.

22. Finishes • Float finish • These are laid mainly to receive mastic asphalt, asphalt tiles, bitumen, concrete tiles and other heavy finishes. • Trowel finish • These are laid mainly to receive carpet, hardboard, vinyl and cork tiles.

23. Task make a copy of this chart

24. Questions • What is one of the most important jobs in the whole operation • Answer • Mixing is one of the most important jobs of the whole operation • What is the mix ratio of a floor screed • Answer • The mix ratio is 3 parts sand and 1 part cement

25. Curing • It is essential that sufficient moisture is available for the continued hydration, or setting action, between the Portland cement and water for up to seven days after laying. • This is achieved by restricting the moisture loss of evaporation from the mix by covering • the finished topping with: • Building paper. • Polythene sheets. • Damp hessian sacks.

26. A floor scrabbling machine • How do we key a smooth floor to receive a screed • Answer • With a scrabbling machine • Basic floor • Scrabbled floor • Scrabbling machine

28. Grinding High Spots • The screed is ground using a power operated grinding machine. • Throughout the process the surface is kept wet. • Any ground material is removed using squeegees or some modern grinders collect the material as they operate

30. Question • How should we prepare the floor to receive a screed • Answer • Remove all loose particles and high points on the floor • Brush all the area to remove dust

31. Floor screeding • Floor area is calculated by volume • i.e length x width x depth. • Length = 29m, x width = 30m, x depth = 0.035mm, = 30.45 m3

32. Question • How do we key a smooth floor to receive a screed • Answer • With a scrabbling machine

33. Monolithic floor screed • Monolithic in construction terminology means 'one body' or 'laid as one'. • That is to say when materials such as a concrete base and its screed are laid within three hours, they are deemed to be laid as one • Monolithic thickness is from 10mm to 15mm

35. Question • Name the three types of floor screed • Answer • Bonded (Monolithic) • Un-bonded • Floating screed

36. Floor screeding • Monolithic thickness is from 10mm to 15mm • Un-bonded thickness is 50mm • Bonded thickness is from 25mm to 40mm • Separate Minimum thickness is 40mm..

37. Task • Now work in groups to answer questions 14-22 on pages 324 –326 of your work book

38. Floor Screed Lesson no 2

39. Floor screedingby the end of this lesson you should be able to • Recall why we use a datum line, and how to set out levels • Understand the term Curing • Be aware of common faults that might occur when floor screeding

40. Recap on lesson no 1 • Name four types of floor screed Answer • Monolithic • Bonded • Un-bonded • Floating screed How do we key a smooth floor to receive a screed • Answer • With a scrabbling machine

41. Recap on lesson no 1 • How should we prepare the floor to receive a screed • Answer • Remove all loose particles and high points on the floor • Brush all the area to remove dust

42. Datum line • A datum line is a level line around the room • This can be drawn by using a sprit level , or a laser level, or a water level. • The height of the screed can be set from the datum line by using a builders square

43. Water level • The green pipe is filled with water . • Then with two operatives each take an end of the water level, • By raising the end of the water level up or down they will both reach a point where both reading are the same • At this point a mark will be made on the wall, this is a datum point,from which datum lines can then be drawn

44. Water level • Setting datum level to wall areas • Set the liquid container at a suitable height for working • Set adjustable gauge to zero at the level of liquid in container

45. Water level • Move instrument rod 3 from station point 1 to point 2,3,4 in sequence. • Raise or lower the rod until liquid is at zero on gauge and then mark this datum point on the wall at each of the points 1 – 2 • Join up station points to obtain level datum line

46. Water level

47. Water level

48. Laser level • The laser level will project a level line around the room it is located in

49. Laser level

50. Laser level