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External Plastering Plain Float Finishes. Backgrounds Concrete blocks Brick E.m.l. Cement boards.

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Presentation on theme: "External Plastering Plain Float Finishes. Backgrounds Concrete blocks Brick E.m.l. Cement boards."— Presentation transcript:

1 External Plastering Plain Float Finishes

2 Backgrounds Concrete blocks Brick E.m.l. Cement boards

3 Suction Control Damp wall with brush and water Reduces risk of cracking Allows plasterer more time work with material Prevents material from drying out too quickly (curing)

4 Materials Sand Cement Plasticiser Lime Prepared laths Clean water

5 Scudding Mix sand and cement at ratio 2.5 to 1 Mix to a wet consistency Apply with a dashing spoon Scud evenly no bare patches Scud coat assists in prevention of blocks showing through Provides grip for scratch coat

6 Scratch coat Mix at 3 to 1 with water proofer Apply 10 mm thick approx. Straighten with edge Scratch immediately with wire scratcher (comb key) Leave for a period of 72 hours before render coat Waterproofer regulates suction for finish coat

7 Plain coat finish Should be mixed at 3 sand 1 cement.25 lime or 12:4:1 Applied approx. 10mm Straighten with straight edge Fill out any “wants” or hallows Float when steady in a circular motion Float 1m square at a time

8 Reveals Patent, Plain, Band. Clean prepared laths Release oil

9 Nap finish Prepare background as with plain float Coat material 10mm approx. Float material while sprinkling water to bring material to a “fatty” consistency Nap gently with a napping sponge

10 Plinths Recessed nail a 2*1 lath with top of lath along damp coarse. Form a bell cast. Stepped nail a 2*1 lath with bottom of lath along damp coarse. Stop beads can also be used.

11 Dry dash Mix material 6 parts sand 2 cement 1 lime Dashing coat should be “fatty” White cement may be used for decorative effect Colouring agents can also be used Walls must be well dampened Best carried out by 2 plasterers one applying dashing coat and the other casting the pebbles from a dashing spoon Pebbles size range from 6 to25mm

12 Dry dash Pebbles are cast when dashing coat is still wet Pebbles should be spread evenly on dashing spoon no bare patches should be left If dashing a tall buildings joints should be cut in saw tooth fashion to make less obvious Joints can be hidden in short areas such as doors or windows A net should be left on the ground so that falling pebbles can be collected washed and reused A dry dash receiver can also be used

13 Wet dash 2 Scratch coats one 1 comb scratched 2 nd scratched with yard brush Mixed at ratio of 4 chips 3 sand 1 lime 1cement Chips sand and lime can be mixed a day in advance and cement added just before use this is called “souring” and will stop material from splashing Pebbles are included in mix


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