Traditionally Reinforced Floors

Standard depth available 150mm
Standard width 900mm
Non-standard widths in 100mm increments
Minimum concrete strength 40MPa
Mean concrete strength 50MPa
Min concrete strength at 28 days 50MPa
Suggested maximum span/depth ratio L/30 for deflection
Reinforcing type 450MPa high tensile
Minimum bearings On brickwork 60mm
On concrete beams 60mm
On steel beams 60mm
Fire rating 1 Hour standard
Higher ratings are possible when a 30MPa structural topping is applied

crosssectionsthroughsectionofechoslabs

Weight/m2 slab only 2.30Kn/m2
Finishes slab and joint 2.42Kn/m2
slab, joint and 40mm levelling screed 3.38Kn/m2
slab, joint and structural topping (50mm)
(60mm)
(70mm)
(80mm)
3.62Kn/m2
3.86Kn/m2
4.10Kn/m2
4.34Kn/m2

  1. All clear spans 5.0m and over should be propped in the centre during the casting of the joints.
  2. All clear spans over 5.0m require a structural topping on the slab in addition to concrete in the joints.
  3. Props should be left in position for a minimum of 10 days after the casting of joints and topping.
  4. External walls at first floor level can be built while props are in position. Internal walls which are supported by the slab (i.e. no wall underneath) can only be constructed after props have been removed.
  5. Openings up to 2 metres wide can be covered by a lintel plus five courses (with brickforce in between the courses). This is suitable for the support of slabs up to 7.8m long.
  6. Openings wider than 2 metres should be referred to the engineer for the detailing of additional structural steel support.
  7. Bearing for 200mm deep beam or channel or angle – 220mm minimum on brickwork on either side of opening.
  8. Bearing for 250mm plus deep beams – minimum 330mm on brickwork on either side of opening.
  9. Cantilevers:
    a) Steel is required in a structural topping on all cantilever panels.
    b) For an Echo slab, twice the length of the cantilever must sit on the building
    c) For a steel beam or channel, three times the cantilever length must sit on the building.
    d) Cantilevers up to 1.8m long can be done with Echo slabs with a structural topping and reinforcement.
  10. Where Echo slabs are used as roof slabs, balconies, external walkways or flat roofs, we recommend a minimum reference 100 mesh in the screed/topping over the slabs.
  11. Where the Echo slab soffit is to be plastered, we recommend a minimum reference 100 mesh in the screed/topping over the slabs together with a fibreglass bandage over the V joint on the soffit.(see Finishes to “Echo Floors” slabs). A mastic filler may also be used.
  12. It is reccomended that either a textured paint or Tyroleen finish is used on the soffit of the slabs.
  13. Echo Floors keep stock at all times, in lengths of up to 8.2m in 100mm increments. Standard width 900mm and depth of 150mm.
  14. The slabs are cut to shape and size to suit your building.
  15. Maximum clear spans should not exceed 6.8m

typicical-slab-layout-echofloors

Live load Kn/m2

Slab Type

C

D

E

H

X / Z

No topping
1.50 3.40 3.80 4.20 4.60 5.00
2.50 3.40 3.80 4.20 4.60 5.00
5.0 3.00 3.30 3.80 4.60 5.00
50mm Topping
1.50 3.40 3.80 4.20 4.60 5.70
2.50 3.40 3.80 4.20 4.60 5.70
5.0 3.40 3.80 4.20 4.60 5.70
60mm Topping
1.50 3.40 3.80 4.20 4.60 6.00
2.50 3.40 3.80 4.20 4.60 6.00
5.0 3.40 3.80 4.20 4.60 6.00
70mm Topping
1.50 3.40 3.80 4.20 4.60 6.30
2.50 3.40 3.80 4.20 4.60 6.30
5.0 3.40 3.80 4.20 4.60 6.30
80mm Topping
1.50 3.40 3.80 4.20 4.60 6.60
2.50 3.40 3.80 4.20 4.60 6.60
5.0 3.40 3.80 4.20 4.60 6.60
90mm Topping
1.50 3.40 3.80 4.20 4.60 6.90
2.50 3.40 3.80 4.20 4.60 6.90
5.0 3.40 3.80 4.20 4.60 6.90
100mm Topping
1.50 3.40 3.80 4.20 4.60 7.20
2.50 3.40 3.80 4.20 4.60 7.20
5.0 3.40 3.80 4.20 4.60 7.20

Note: The dead weight plus joint filling, as well as standard finishes up to 1Kn/m2 are included in the above tables.

Reinforcing content of various slab typesSlabs are cast in lengths of 1000 to 8 200mm in 100mm increments. Slabs are cast with standard steel reinforcing top and bottom dependant on the length of the slab.

Slab Type

Slab length

(mm)

Top steel

Qty/Dia

Bottom steel

Qty/Dia

C

1000-3400

3xø8mm

5xø8mm

D

3500-3800

3xø8mm

6xø8mm

E

3900-4200

3xø8mm

8xø8mm

H

4300-4600

3xø8mm

6xø12mm

X

5800-7700

3xø8mm

9xø12mm

Z

7800

7xø8mm

9xø12mm

EK

5500-7400

3xø8mm

8xø8mm

EZ

7500-8200

7xø8mm

8xø8mm

Note: Echo slabs have a fixed depth of 150mm. The overall depth is increased by the thickness of the structural topping required

crosssectionsthroughsectionofechoslabs

kN.m per 1.0m width of slab

Total slab depth mm

150

200

210

220

230

240

250

Structural topping

0

50

60

70

80

90

100

Slab type

C

13.73

19.20

20.32

21.44

22.56

23.68

24.79

D

16.40

22.93

24.28

25.61

26.94

28.30

29.64

E

21.64

30.29

32.07

33.78

35.64

37.43

39.22

H

34.88

49.12

52.14

55.16

58.17

61.19

64.21

X / Z

50.43

71.16

75.69

80.21

84.74

89.27

93.78

Total Weight

kN/m2

2.42

3.62

3.86

4.10

4.34

4.58

4.82

Note: Although slabs to a maximum of 8 200mm can be supplied, please note that the maximum clear span should not exceed 6.8m for deflection purposes.

propped-300x165

Propped Slab

conduit-300x165

Conduit laid on top of the slab

mesh-300x165

Mesh in screed/topping

beams-on-slabs-LR

typical-sections-echofloors-walls-on-formwork-300x203

walls-on-slabs-LR

on-beams-LR

skylight-or-staircase-opening-LR

anchoring-in-flanges

crosssectionsthroughsectionofechoslabs-gr-
cantileverdetail
Structural-Steel-DetailsLR
typicalsectionsplasteredsoffit
typicaldetailerroofsbalconies
cross-section-of-downlight-hr1
typicalsectionthroughopening2mwide
typicalsectioninsutustaircase

laying-of-floor-slabs

open-slab

Service holes up to 150mm diameter may be made in Echo slabs. Any service holes lager than 150mm should be referred to the Design Engineer to check the detail.We recommend that all service holes should be cut from the underside up. This minimises patching to the soffits of the units. Openings required for staircases or skylights are made with steel hangers which are supplied and erected by Echo floors. Alternatively a steel/brick beam can be used as support around the opening.

Downlights can be used in the Echo slab. The height of the light fitting must be determined in conjunction with the overall depth of the slab including the structural topping or levelling screed.

In the past electrical contractors have dissuaded their clients from using the Echo system believing that downlights were not possible when using hollow core precast floors, unless false ceilings were used. This is incorrect. Consider the following points :

downlights-300x164        downlights1-300x164

  • The placing of any light point into Echo hollow core floors is not only possible, but simpler and more economical than with traditional in-situ or beam and block floors, which require the positioning of concrete boxes between the steel and/or blocks. These are sometimes not only difficult to locate once the shutters are removed, but in many instances lining them up accurately is difficult.
  • Fitting downlights into Echo slabs is simply a matter of coring holes through the slab, or using a chisel and hammer (we recommend chiselling from the bottom up) to form the required diameter hole to accommodate the downlight. For suspended or other light fittings, simply drill a hole through the slab and into the slab’s hollow core to fit the electrical wiring through. Any excessive edge chipping is easily repaired with Rhinolite or similar material. Coring is done only once the slabs are placed into position on the building and the light positions have been marked. This results in accurately aligned lights so that false ceilings are not required. This means that there is virtually no preparation necessary, as is required before traditional in-situ or beam and block concrete is placed.
  • Echo has researched the suitability of coring through slabs by drilling 7 cores and cutting through the reinforcing steel in each core. The slab was then loaded and the deflections measured over a period of time. Results were assessed by a professional civil engineer who found the slabs to be well within allowable tolerances, making coring for downlights through Echo slabs technically safe and acceptable.
  • The cost per light point is also more economical. Electrical wires and single light transformers can be placed into the horizontal hollow cores of the slabs after coring. This instead of the traditional method of fitting light boxes and conduits before in-situ concrete is placed and then returning to pull wires through once shuttering and scaffolding have been removed several weeks later.
  • Conduits can be laid across the slab, i.e. perpendicular to the slab direction. They must be placed onto the Echo slabs before the builder places the screed.
  • Echo provide the builder with copies of the slab layout from which the layout of the wiring is easily determined by using the formed horizontal cores in the slab as conduits. This eliminates any necessity for criss-crossing conduit. Ask your builder for a copy of the layout drawing if you know that Echo slabs will be used.
  • To accommodate 12 volt single light transformers into the slabs from a maintenance aspect, a minimum core diameter of 70mm is required. This will easily allow short cylindrical transformers to be taken out and replaced for maintenance. Longer transformers will require bigger diameter cores or it won’t be possible to take them out. For 230 volt downlights smaller diameter cores can be used.
  • Heat dissipation from the downlight globe and transformer is not a problem because the hollow core of the Echo slab has 67% more void space (per linear meter) than a conventional concrete box.

Some don’ts when working with Echo Floor slabs:

  • Don’t lay conduit into the V joint above the slab, unless the joint runs directly above a wall or beam. In this case however, be aware of where the expansion saw cuts will be.
  • Don’t glue wiring into the smaller V joint below the slab.

cross-section-of-downlight-hr

Steel size and type

Ze x 103 mm3

200IPE – 22.4kg/m

IPE

194.0

203x133x25.3 kg/m

I Beam

231.2

203x133x30.0 kg/m

I Beam

270.3

254x146x31.3 kg/m

I Beam

352.1

254x146x37.2 kg/m

I Beam

433.4

203x203x46.2 kg/m

H Beam

449.3

200x75x25.3 kg/m

RSC/PFC

191.1

150x90x18.2 kg/m

RSA

53.29

150x150x27.3 kg/m

RSA

67.75

100x100x12.2 kg/m

RSA

19.94

125x75x12.1 kg/m

RSA

29.60

We can supply Y12 bar cut to length for cantilevers, hangers made from angle iron or steel channels and other steel sections on request.

Structural-Steel-DetailsLR

Specifications for the following are available from Echo Floors on request:

  • Tiling of Echo floors
  • Grouting between the joints (generally undertaken by Echo Floors)
  • Structural topping
  • Levelling screed

cartoon

That’s great guys! Level walls wil help us to have level ceilings.
We only need a centre line of adjustable props where the clear spans exceed 5,0m. This also levels the soffits with each other. These props remain in possition for 10 days.

cartoon1

cartoon2

Clean off debris and thoroughly wet the slabs before grouting and the V-joints and casting of concrete topping or screed where specified. A detailed specification is available on request.
Ten days after casting the joints and topping, remove the props and finish the butted joint with Rhinolite and a piece of conduit or use ‘Profill’ or similar to prevent hairline cracks.

cartoon3

This is easy! No plastering required – tyrolean the ceiling before painting or apply a textured coat of paint to the ceiling.

cartoon4

Slabs may be Rhinolite plastered for a completely smooth soffit if required – specifications are available.

  • With the introduction of Echo’s new manufacturing plant in Muldersdrift, several benefits which have advantages not previously possible with suspended hollow core floor slabs resulted.
  • The new smooth soffits slabs no longer have grooves at 300mm widths. Joints only occur on the underside at 900mm centres. This makes finishing the soffits a much easier and simpler matter by just applying an undercoat and textured paint, or Tyrolean and painting over.
  • A completely smooth soffit, with a greatly reduced risk of hairline cracking under the joints has been successfully tested and is now possible. This eliminates the visible joint and eliminates the expense of false ceilings. To achieve this the joint is filled with flexible mastic filler, available from “ProMaster Products” or “Polycell Products”. Once dry, sand to a smooth finish, apply bonding liquid to the slab ceiling, Rhinolite plaster the soffit smooth and paint.
  • The mastic, which creates a permanent, malleable, crack free filler, remains flexible so that cracks caused by thermal and other movement in the slabs do not readily transfer through to the plastered soffit, leaving a lasting smooth look.
  • Echo do however specify a minimum mesh ref 100 to be placed into the 30MPa screed or topping for any plastered finish.
  • A further advantage is that the hollow cores through the new slab are all the same large size. This allows for the placing of downlights simply and quickly because the slab can be cored vertically through, wherever required – fitting in the downlights and permitting transformers to fit into the hollow core of the slab. Added to this, the fact that the actual sizes of downlight fittings and globes are much

plastered1-300x164      plastered1-300x164

typicalsectionsplasteredsoffit