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INTERNAL PLASTERING. Internal Plastering Plastering helps provide better sound and thermal insulation and fire resistance. Plastering helps provide better.

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Presentation on theme: "INTERNAL PLASTERING. Internal Plastering Plastering helps provide better sound and thermal insulation and fire resistance. Plastering helps provide better."— Presentation transcript:

1 INTERNAL PLASTERING

2 Internal Plastering Plastering helps provide better sound and thermal insulation and fire resistance. Plastering helps provide better sound and thermal insulation and fire resistance. A good plasterer should have a sound knowledge of materials to use and their characteristics. A good plasterer should have a sound knowledge of materials to use and their characteristics. A plasterer should identify the correct materials and their suitability for any given situation. A plasterer should identify the correct materials and their suitability for any given situation. A good plasterer should be able to put right any problems with their work and that of others. A good plasterer should be able to put right any problems with their work and that of others.

3 BACKGROUNDS  The background is the surface that your first coat of plaster is applied to.  The background needs to provide a good bond for your plaster.  Preparation of backgrounds is key to a good standard of finished work.  If a background is not suitable or prepared well, your plaster will not stick to it properly.

4 SUCTION  A plasterer needs to check the rate of suction of the background before applying plaster.  Too much suction can cause the material to shrink or crack and loose adhesion.  It can be difficult to rule in or get flat because of the loss of water in the material.  The plaster will not reach its full strength and could fall off.  Too little suction can cause the material to slip down the wall making it hard to rule in.

5 High Suction Background  Can include Aerated Block, old brickwork and softer types of brick.  Can be wetted before plastering to control suction.  Can be controlled with two coats of PVA, one very wet to seal and a 50 / 50 mix for adhesion.  Use direct bond, hardwall, render.

6 Medium Suction Background  Can include lightweight aggregate concrete blocks and clay brickwork.  Generally has good suction.  Make sure is dust and grease free and clear of mortar snots.  Can use all plaster products.

7 LOW SUCTION  Includes in situ concrete, plasterboard, painted surfaces.  Never apply render until a good key has been formed or it will fall off.  Use spatterdash, gyp bond for key.  Use Carlite bonding, direct bond.

8 EXPANDED METAL LATHING  Can be used inside and outside.  Flexible so can be curved.  Fixed to wall plates to provide a key and resist movement.  If fixing rib lath the ribs should be in contact with and at right angles to the support.  Needs pricking up coat first.  Use Carlite Bonding.

9 COMPOSITE BACKGROUNDS  A background with a range of materials.  This can have different rates of suction.  Use different methods to create a key eg pva, gyp bond, spatterdash.

10 PREPARATION  1. Brush down the background to remove all loose materials and dust etc. to give a good sound background.  2. Remove all mortar snots from joints, internal and external angles.  3. Make a key, if needed to the background.  4. Test the background for suction ( splash some water on the surface and see how quickly it gets sucked into the background).  5. Treat if necessary.

11 PREPARATION  6. Place drop boards at bottom of wall to catch any material that is dropped. This can then be re used.  7. Fix EML to any timber wall and sole plates as necessary. This stops the plaster cracking and falling off the wood.  8. Fix any angle beads that are required.  9.Set up the spot board and stand.

12 METHODS OF WORK  BROAD SCREEDS.  Use on small areas.  Does not give the highest standard of work but better than freehand.  Apply screed to corner of wall and rule off.  Keep depth of material to no more than 11mm.  Place another vertical screed in other corner and rule off.

13 BROAD SCREEDS  Don’t place any screed in between the two end ones.  Form a horizontal screed top and bottom and rule off using the vertical screeds.  Using the screeds to rule off, fill in between the screeds.

14 DOT AND SCREED  Can be used on long or high walls.  Use if the finished work has to be absolutely plumb.  Gives the highest standard for tolerance purposes.

15 DOT AND SCREED  1. Place a dot of material near an internal angle, place a lath in the dot.  Dot should be about 300mm away from adjoining wall.  2. Place a second dot at the bottom of the wall, place a lath into the dot.  Dots should be about 2.5m apart.  3. Plumb in the two dots using a floating rule.  4. Either tap in or bring the wood out until the two dots are in line.

16 DOT AND SCREED  5. Place another two dots at the other end of the wall.  6. Place intermediate dots in the middle of the wall.  7. Line the intermediate dots through horizontally off the two perimeter dots.  8. Join the dots together as the Broad screed system.  9. Fill in between the screeds and rule off.

17 APPLYING A KEY  Each progressive coat of plaster needs to be keyed.  A key provides an Inter Surface bond.  The depth of key used depends on the weight of the next coat of plaster to be used.

18  After the wall has been keyed before skimming run the trowel over the wall to remove any pick ups etc.  All internal angles need to be ‘cut in’ using the trowel.  Any plaster along external angle bead needs to be cut back to allow room for the skim coat.

19 FINISHING  The finish coat provides the final, smooth coat for decoration.  Generally not more than 3mm thick but can be up to 5mm.  Always applied in two coats for the best finish result.  If matching to a lime plastered surface the finish used will be lime putty / fine sand mix.  Finish coats should not be over trowelled as this can prevent the paint sticking to it.

20 METHODS OF WORK  TROWEL,TROWEL  This is the most commonly used method of work for skimming.  1. first coat is the scratch coat.  2. each stroke should overlap the previous one.  3. fill any hollows, joints etc. with the scratch coat.

21 TROWEL,TROWEL  4. Once scratch coat has picked up – apply laying down coat.  5. this should be slightly tighter than scratch coat.  6. When laying down coat has picked up enough, apply first dry trowel.  7. Trowel twice more with just enough water to lubricate the trowel and to work the plaster.

22 TROWEL,TROWEL  Any hollows, marks etc. should be filled with the first trowel (fat). Any later than this the fat will be too watery and has no strength.  8. Clean angles out at final trowel and use brush to clean angles and beads.  9. Cross trowel at right angles to trowelling strokes to remove any water or fat marks.  10. Clean skirting line of excess plaster material (lips)

23 TROWEL,FLOAT,TROWEL  This method is useful on uneven backgrounds.  1. Apply scratch coat with trowel.  2. Apply second coat using a float.  Because the float is more rigid than a trowel, it will straighten out any irregularities in the floating coat.  3. When the second coat has picked up, apply thin laying down coat with the trowel.  4. Trowel the work as before.

24 BEADS  Float ( angle ) bead.  Used to form external angles.  Galvanised or stainless steel.  Fix using dabs of material.  Need to be plumb, level and straight along their length.  Make sure wings are behind finished edge.

25 STOP BEAD  Reinforces and finishes edge of plaster where no other material meets it.  Can be used to finish plaster if butting up to another material if there is no cover being used eg. No arcitrave.

26 FEATURE BEADS  Used to form shadow gaps along skirting board.

27 MOVEMENT BEADS  Fixed over any movement joints in the background to prevent cracking of the plaster.  Fix with dabs.  Can be formed with two back to back stop beads and mastic filler.

28 MATERIALS  Carlite Bonding  Undercoat plaster for low suction backgrounds eg. Concrete and plasterboard or surfaces treated with a bonding agent.  Purple bag.

29 THISTLE HARDWALL  Undercoat plaster with high impact resistance.  Quicker drying surface.  Use on medium to high suction backgrounds.  Blocks, bricks,thermalite.

30 THISTLE TOUGHCAOT  Undercoat with good impact resistance.  Use on medium to high suction backgrounds.

31 CARLITE BROWNING  Undercoat for backgrounds of moderate suction with a good key.  Make sure suction is controlled when applying.

32 DRI COAT  A cement based undercoat for re - plastering after installation of damp proof course.

33 LIMELITE RENOVATING  Lightweight cement based backing plaster.  Contains waterproofing and salt inhibiting additives.  Used in re- plastering after installation of damp proof course or in the renovation of old solid wall properties.

34 BOARD FINISH  Finish for low to medium suction backgrounds.  Plasterboards, Dri Coat.  Class B hemi Hydrate.

35 MULTI FINISH  Can be used on all suction backgrounds.  Good choice where both solid and plasterboard backgrounds are involved.

36 DURA GRADE  Specially formulated to produce a hard finish.  Used in high traffic areas.  Can be used on plasterboard, Dri Coat, Gypsum backgrounds and cement based backgrounds.

37 HIGH IMPACT FINISH  High impact finish is used to finish Limelite products.  This is a Class D anhydrite plaster.  Gives a very hard and high quality of finish.  All of the water is driven off when the powder is produced.  The plaster crystals take longer to form when the water is added when mixing.  An accelerator is added to kick start the reaction.  The slower forming crystals give a harder more durable finish coat.

38 RE CAP  Aerated blocks and old bricks are ………… suction backgrounds.  Concrete and plasterboard are ……….. suction backgrounds.  If plastering to a low suction background Carlite …………… should be used.  If re plastering after damp proof work the backing coat should be ……………….

39 RE CAP  After forming the perimeter dots on a wall the intermediate dots should be …………… in.  Internal angles should be ………. in after floating.  Different types of key are used dependant on the ………….. of the subsequent coat.  Angle beads should be fixed to concrete with dabs of Carlite …………………..


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