External Plastering Plain Float Finishes

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

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)

Materials Sand Cement Plasticiser Lime Prepared laths Clean water

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

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

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

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

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

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.

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

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

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