Works specification for contract to waterproof and repair Central Block roof Introduction Central block was constructed during 1922 till 1925 when it was opened. In 1931 a fire destroyed the central section and it was re-built from 1937 to be re-opened in 1940. The building therefore has two structural system and different approaches to the roof. In 1965 the West annex extension was constructed and in 1968 the East annex extension was completed. This project is one of a number of projects that will be undertaken by the university over the next few years to address long term maintenance to the building. This projects concerns the waterproofing of the roof and the repairs to the parapets, coping and precast concrete walling necessary to waterproof the upper sections of the roof. In addition, some structural work is necessary to concrete beams over clearstory windows. Later projects will be the replacement of the soft roof to the 1922 Northern section of the building, repairs to the precast cladding to the general façade and water ingress to the basement areas. The reinstatement of the lightening protection to the roof will be a separate independent contract. Repeated waterproofing applications have been carried out over the years compromising the levels, draining and system, hiding defects making assessment and problem identification difficult. A Large portion of the work will be to expose the substrate and make good before installing new waterproofing. The main areas of the roof require maintenance and can remain intact. The contractor is to take care in the treatment of the exposed piping for the space heating system. These pipes will be replaced in a later project.

Contents Introduction ............................................................................................................................................................ 1 Programme ............................................................................................................................................................. 3 Scope ...................................................................................................................................................................... 3 KeyPlan ................................................................................................................................................................... 5 Specification ........................................................................................................................................................... 5 1.

New waterproofing ................................................................................................................................... 5 1.1. Inverted Beams ................................................................................................................................. 5

2.

Maintenance and repairs to waterproofing .............................................................................................. 7 2.1. Failed waterproofing ........................................................................................................................ 7 2.2. Isolated damage, ponding and relevelling of fall to outlets ............................................................. 8

3.

Repairs to parapet walls ............................................................................................................................ 9 3.1. Parapets generally ............................................................................................................................ 9

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3.2. Parapet wall between old and new structure ................................................................................ 11 3.2.1. Plaster cracks (< 4mm) ........................................................................................................... 11 3.2.2. Damaged cement plaster and concrete areas ....................................................................... 11 3.2.3. Delaminating plaster: ............................................................................................................. 11 3.3. Parapet wall to atrium lecture theaters ......................................................................................... 12 3.3.1. Overcoating solvent based enamel with waterbased paint or solvent based enamel .......... 12 3.3.2. Damaged cement plaster and concrete areas ....................................................................... 13 3.3.3. Filling cracks ........................................................................................................................... 13 4.

Sheetmetal rain water goods .................................................................................................................. 13 4.1. Sheetmetal rainwater outlets ......................................................................................................... 14 4.2. Sheetmetal rainwater heads and downpipes ................................................................................. 14

5.

Precast concrete blockwork .................................................................................................................... 14

6.

Repairs to structural beams .................................................................................................................... 15 6.1. Spalling concrete............................................................................................................................. 16 6.2. Spalling plaster cover ...................................................................................................................... 17

7.

Plastered walls to high roofs ................................................................................................................... 17 7.1. Repair plaster cracks (< 4mm) ........................................................................................................ 18 7.2. Repair damaged cement plaster and concrete areas ..................................................................... 18 7.3. Delaminating plaster:...................................................................................................................... 18 7.4. Structural Joints .............................................................................................................................. 18

8.

Paint and putty to clearstory windows .................................................................................................... 19

9.

New cat ladders for access to lecture theater roofs ............................................................................... 19

10.

New Access Bridge to raised parapet wall .......................................................................................... 19

11. Repair and re-painting of existing steel access cat ladders and stairs ................................................ 20 11.1. Plascon Plascothane Polyurethane Enamel to existing solvent based coated exterior mild steel. 20 12.

Access Control to restricted doors on roof. ........................................................................................ 21

13.

Polycarbonate Roof Sheeting .............................................................................................................. 21

14.

Lining of rainwater downpipe ............................................................................................................. 21

15.

Removal of redundant air conditioning .............................................................................................. 21

16.

Work to Direct Expansion Condensing Units mounted on the waterproofing ................................... 23

17.

Work to exposed hot water pipes ....................................................................................................... 24

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Programme While the contractors program needs to be submitted for approval there are a few areas that are of major concern and need to be attended to as a matter of urgency, in particular item 5 below where the waterproofing to the upstand has failed completely. The contractor needs to be aware of the 2016 University time table: Second teaching block Monday 04 April -Thursday 19 May (32 days) Examinations Tuesday 24 May - Tuesday 21 June (20 days) Winter Vacation/Study/Research break Wednesday 22 June - Sunday 10 July (19 days) Third teaching block Monday 11July - Friday 26 August (34 days) Mid-term Vacation/Study/Research break Saturday 27 August - Sunday 04 September (9 days) Fourth teaching block Monday 05 September -Monday 17 October (31 days) Examinations Thursday 20 October - Wednesday 16 November (20 days) Summer Vacation/Study/Research break Thursday 17 November Work will be curtailed during these periods while the examination venues are in use. This applies to noisy work and tasks such as painting can continue, if control is exercised over the trades’ people.

Scope The work is broken into several different work components and each work component is to be priced separately. The numbered work component (left side) is the cross-reference to the drawing annotations, while the number to the right, is the reference to the specification in this document. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.

Replace waterproofing completely (1.) Maintenance to waterproofing, isolated patching, ponding and re-leveling falls to outlets (2.) Maintenance painting (3.) Re-flashing upstand to underside of precast cladding (3.1.) Re-flashing upstand on old portion of roof to underside of coping (3.2.) Re-flashing upstand on wall to atrium lecture blocks, introduction of new sheet metal cover flashing and new plaster rendering to walls (3.3.) New sheet-metal rainwater goods (4.) Repair sheet-metal rainwater goods and make good waterproofing (4.) Re-point precast coping blocks (5.) Removal and re-seating of loose precast coping blocks with re-pointing (5.) Removal of precast concrete blocks to façade, reseating and fixing in accordance to engineers instructions and re-erection and pointing (5.) Repairs to structural beams over windows (6). Removal of loose and damaged plaster at structural joints in walls, re-plastering of wall with reinforcement and cutting of joint in render (7.) Paint and putty to clearstory windows (8). New Access cat ladders to lecture theater roofs for maintenance (9.) New access bridges to raised parapet walls for maintenance (10.) Repair and re-painting of existing steel access cat ladders and stairs (11.) Access control and mag lock to roof access doors and new the lift motor room door (12.) 3

19. Polycarbonate roof sheeting over service ducts (13.)

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KeyPlan

Specification 1. New waterproofing Remove completely, all existing waterproofing and clean all surfaces, open up downpipes and sleeves to receive new waterproofing. All loose or crumbling plaster rendering is to be removed and new rendering applied in preparation for waterproofing. Where necessary new sheetmetal rainwater goods are to be prepared and installed prior to the installation of the waterproofing. One layer Derbigum SP4 waterproofing membrane, with 75mm side laps and 100mm end laps, sealed to primed surface to falls and crossfalls by 'torchfusion' finished with two coats Roofcote bituminous aluminum paint. Waterproofing to be installed by an Approved Derbigum Contractor under a ten year guarantee. Flashing to parapets. Waterproofing to parapets to be Geoflex liquid plastic, including polypropylene re-inforcement, sealed to primed surface and dressed over Derbigum turn-up and finished with two coats of bituminized aluminium paint. Waterproofing to be installed by an Approved Derbigum Contractor. Or Alternative approved ‘torch-on’ single layer product and coating. Alternatives products are to be submitted with track record and 10 year warranty from supplier with the cost and description for first period’s maintenance.

1.1. Inverted Beams The building has a variety of inverted beams in differing condition. Where damaged Hydroblast substrate to remove all old and loose waterproofing, paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry. Inverted beams must be clad with SP3 fixed to the sides and capped with Derbigum SP4.

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Openings are to be sufficiently large as to enable proper dressing of the membrane where they pass through the beam. In most instances the old repeated application of waterproofing needs to be removed to expose the substrate so that the opening can be properly waterproofed.

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A flanged outlet pipe is to be inserted through the beam from the 'higher' side ensuring that the screed level on the 'lower' side is sufficiently below the base of the pipe as to be able to achieve a proper seal at that point. Where necessary the enclosed area is to be re-screeded to provide a proper fall to the outlets.

2. Maintenance and repairs to waterproofing 2.1. Failed waterproofing The area around the ventilation duct to the examination room is to be completely uplifted, openings through inverted beams opened up and screed re-laid to provide adequate fall to outlets. New waterproofing, as above, is to be laid on sand cement screed graded to falls as shown. The Cellular Aerial cable and pipe cover to be raised 150mm on a ‘Unistrut’ galvanised bridge above the waterproofing, care is to be take in relocating the cable and assistance requested from the operator if necessary. The cable is not to be removed from its pipe.

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2.2. Isolated damage, ponding and relevelling of fall to outlets Isolated damage to the flat existing surfaces are to be repaired with a Derbigum SP3/4 patch that overlaps any damage by at least 100mm.

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Where ponding is indicated on plan at outlets (3x instances) the waterproofing is to be stripped back from 600mm from the outlet, the outlet repaired, waterproofed with minimum 100mm laps and painted. Where ponding is indicated away from outlet (1x instance) the waterproofing is to be uplifted and new screed laid to fall.

3. Repairs to parapet walls 3.1. Parapets generally The general parapet to the roof on the inside has a plaster rendering with a horizontal formed 20mm drip ±150mm above the roof level. Old vertical waterproofing is to be stripped off this rendering and out of the recess. Where the drip is loose or cracked it is to be chopped away and a new plaster drip formed. Hydroblast substrate to remove all paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry. The cove is to be inspected and where it has deformed the existing waterproofing is to be cut immediately above the cove and pulled back to install a Cant strip. The vertical plaster under the drip is to be inspected and any remedial work carried out as before to it. New Derbigum SP3 waterproofing to be installed to the vertical, overlap the existing waterproofing 200mm on the flat and be sealed up under the plaster drip. Where the cove is well formed, the existing waterproofing is to cut down above the cove ±100mm. The vertical plaster under the drip is to be inspected and any remedial work carried out as before to it. New Derbigum SP3 can then be installed to overlap 200mm and be sealed up under the plaster drip.

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Where the drip has fallen away and been overpainted the substrate is to be prepared and a new plaster drip formed over the exposed brickwork – see below.

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3.2. Parapet wall between old and new structure The failed vertical waterproofing (Item 5) to the parapet is to be removed and cut down to just above the cove in the waterproofing ±100mm above roof. The substrate has failed and requires complete renewal.

Hydroblast substrate to remove all paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry. 3.2.1.Plaster cracks (< 4mm) Rake out cracks using an angle grinder to a minimum of 3mm wide and deep. Remove dust and prime repair area with Plaster Primer (UC 56 or PP 700). Allow 16 hours to dry. Fill with Mendall 90 (801601) and smooth off to match existing plaster. After 8 hours prime repaired areas with Plaster Primer (UC 56 or PP 700). After 16 hours make the repaired area invisible by rolling a coat of PWC 520 over repaired surface. 3.2.2.Damaged cement plaster and concrete areas Open damaged area sufficiently to allow plaster repair material to be adequately filled in order to achieve a mechanical bond. Clean away dust, grease and grim from surface. Prime repair area with Plaster Primer (UC 56 or PP 700). Fill areas with Masonry Patching Plaster, mixed 4 parts of powder to 1 part water, by using a putty knife or trowel. Smooth off whilst still wet. Allow to dry and sand smooth. Overcoat with one coat PWC 520. 3.2.3.Delaminating plaster: Hammer test suspect areas for adhesion. Hollow sounding plaster must be removed. The surface must be sound, clean and dry. Apply one coat of Masonry Paint to the entire surface. If necessary thin 5 parts Primer to 1 part Mineral Turpentine by volume for weak and friable surfaces. Allow to dry for at least 16 hours at 23°C. Prime repair area with Plaster Primer (UC 56 or PP 700). Plaster 11

areas under a meter square are to be finished with Plascon masonry patching plaster and worked to a smooth surface with a timber trowel. Larger areas are to be re-plastered over primer with a plaster mix with “Bondaid Plus” added to manufacturers specifications (Safeguard Chemicals www.safeguardchem.co.za). The wall is then to be primed. Once the surface is dry, new vertical Derbigum SP3 is to be applied in accordance with specifications and sealed under the coping. The waterproofing is then to be finished with two coats of Roofcote bituminous aluminum paint.

3.3. Parapet wall to atrium lecture theaters The silver coating waterproofing to the parapet is to be removed and cut down to just above the cove in the waterproofing ±100mm above roof. Hydroblast substrate to remove all paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry.

3.3.1.Overcoating solvent based enamel with waterbased paint or solvent based enamel Remove surface contaminants using Polycell Sugar Soap solution - 500 g Polycell Sugar Soap Powder (501703) dissolved in 5 litres water, or Polycell Sugar Soap Liquid (5018010). For stubborn contaminants use hot water in the above mix and a bristle broom or scrubbing brush. Rinse with tap water to remove all traces of sugar soap and allow to dry. Ensure surfaces are clean, dry and sound. Prime repair area with Plaster Primer (UC 56 or PP 700). Moisture content not more than 8% measured on a Doser Hygrometer BD2 scale (or equivalent) before painting. Apply either a coat of Plascon Universal Undercoat (UC 1) or Professional Undercoat (PU 800) to entire area. Allow 16 hours to dry; or Apply a coat of Plascon Multisurface Primer (WUP 1) to entire area. Allow 2 hours to dry.

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3.3.2.Damaged cement plaster and concrete areas Hydroblast substrate to remove all paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry. Open damaged area sufficiently to allow plaster repair material to be adequately filled in order to achieve a mechanical bond. Prime repair area with Plaster Primer (UC 56 or PP 700). Fill areas with Masonry Patching Plaster, mixed 4 parts of powder to 1 part water, by using a putty knife or trowel. Smooth off whilst still wet. Allow to dry and sand smooth. 3.3.3.Filling cracks Before filling the crack, apply one coat of Plaster Primer thinned 20% with Mineral Turpentine. Allow 16 hours drying at 23ºC before overcoating. In line with the bottom of the coping and clear of the spigots from the upper roof, a 50mm deep recess is to be formed in the wall to receive a counter flashing. Once the plaster is dry, new vertical Derbigum SP3 is to be applied in accordance with specifications, and covered with the galvanized sheet metal counter flashing. The waterproofing is then to be finished with two coats of Roofcote bituminous aluminum paint.

4. Sheetmetal rain water goods The main roof has a system of surface mounted box gutters and rain water downpipes. Several of these are either totally corroded or damaged such that they need replacement.

These replacements are to match the existing and be made from 0,8mm hot dipped galvanized steel sheet class Z275 to SANS 3575/4998. Joints are to be rolled and soldered.

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4.1. Sheetmetal rainwater outlets Sheetmetal rainwater outlets 380w x 130h x 360 long through parapet walls are to replaced where damaged as indicated on plans or severely corroded. Where new outlets are fitted the waterproofing is to be stripped back 600mm from the inlet and re waterproofed after installation as above to ensure that there is no ponding. The waterproofing is to be taken through the opening and sealed to the bottom and sides of the sheetmetal. New outlets are to have a galvanized wire mesh leaf/hail guard fitted.

4.2. Sheetmetal rainwater heads and downpipes New 530w x 230d x 320h rainwater gutter heads and 155w x 105d downpipes are to be installed to replace the existing corroded units as indicated on plan. Where the lower sections of the downpipes are corroded the bottom section is to be replaced and sealed in with cement grout. Each gutter head is to be fitted with bird proofing.

5. Precast concrete blockwork There has been extensive movement and sundry repairs to the blockwork to date. Generally, all of the copings are to be inspected and re-pointed where the grouting has fallen out. Where the coping blocks are loose they are to be lifted off, the surface prepared, reseated with Lime Mortar and repointed with Lime mortar to provide a waterproof coping. (1 part portland cement; 2 parts lime or lime putty; 6 to 9 parts sand and stone dust to match existing mortar as closely as possible)

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In the indicated areas the coping and sections of the external wall blockwork are loose, these blocks are to be removed and the substrate cleaned for inspection by the engineer.

Following the inspection, the remedial work is to be carried out and the blocks reinstalled as per instructions and the joints re-pointed with Lime Mortar to provide a waterproof wall for the building. These areas will require scaffolding and protection to allow for safe work overhead practices.

6. Repairs to structural beams The structural concrete beam over several of the clearstory windows has absorbed water and the corroded reinforcement has resulted in spalling of the concrete work. 15

6.1. Spalling concrete The work is to be undertaken in sections and the whole beam propped while work is undertaken. Remove concrete surrounding rebar where rusted rebar has caused spalling. Abrasive blast, needle descale or mechanical wire brush rebar to bright metal. Remove dust. Badly corroded rebar should be referred to a structural engineer for advice or replacement. Prime the suitably prepared rebar with two coats Professional Anti-Corrosion II High Build Zinc Phosphate Primer (UC 170) at 40-50 m DFT per coat. Allow 24 hours drying between coats. Repair defective areas using Polyfilla Masonry Patching Plaster (102003). Allow 24 hours to dry.

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6.2. Spalling plaster cover All loose and compromised concrete is to be removed. All old repairs are to be chopped away to the base material. The plaster/concrete surrounding the exposed reinforcement must be chipped away, or wet or dry sand blasting may be used to fully expose the rods. Investigate all areas by tapping to find any loose concrete areas. Chase a further 50mm into sound concrete at each end of the bar. All heavy rust, scale, etc. must be removed by sand blasting, needle descaling or mechanically wire brushing. At least 95% of the rust must be removed back to bright steel. If the steel is too badly corroded refer to a structural engineer for advice or replacement. After cleaning, apply a general coat of Plascon Rust Converter (EMS 21) to the entire area in accordance with the manufacturer's instructions. Wash off unconverted EMS 21 which has not turned black with water. The rods may now be coated with either SABS Coat Tar Epoxy (HD 2) or two coats of High Build Zinc Phosphate Primer (UC 170, CPD 256 or UC 183). Once dry, apply 'Plaster Key' to wet existing plaster areas, to provide a bond for new plaster. Replaster using Masonry Patching Plaster to match existing plaster profile/texture. Continue till the void has been filled. The final surface to be smoothed with a wood float and a new drip formed.

7. Plastered walls to high roofs In many areas the plastered walls to the higher exam hall roof have cracked at the structural joint at the top of the slab. All loose plaster and previous repairs are to be removed and the surface prepared to receive new rendering. The entire area is to be Hydroblasted to remove all paint, surface contaminants, friable materials and chalkiness. A rotating nozzle at 250-350 bar pressure should be used. Allow to dry. These walls are to be painted with Plascon Professional Superior Low Sheen.

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Surface to be dry, sound and clean and cured for a minimum of 14 days, with a moisture content measured with a Doser Hygrometer (or equivalent), of BD 2 scale - 8% or less. Prime with one coat Professional Plaster Primer (PP 700) with an overcoating time of 16 hours and finish with two coats Professional Superior Low Sheen (PEM 1000) with 2 hours drying time between coats, for a maintenance cycle of 6 years in a C1 - inland environment.

7.1. Repair plaster cracks (< 4mm) Rake out cracks using an angle grinder to a minimum of 3mm wide and deep. Remove dust and prime repair area with Plaster Primer (UC 56 or PP 700). Allow 16 hours to dry. Fill with Mendall 90 (801601) and smooth off to match existing plaster. After 8 hours prime repaired areas with Plaster Primer (UC 56 or PP 700). After 16 hours make the repaired area invisible by rolling a coat of PWC 520 over repaired surface.

7.2. Repair damaged cement plaster and concrete areas As before, open damaged area sufficiently to allow plaster repair material to be adequately filled in order to achieve a mechanical bond. Clean away dust, grease and grim from surface or Hydroblast a second time where the area is extensive. Prime repair area with Plaster Primer (UC 56 or PP 700). Repair areas with Masonry Patching Plaster, mixed 4 parts of powder to 1 part water, by using a putty knife or trowel. Smooth off with Wood trowel whilst still wet. Allow to dry and sand smooth.

7.3. Delaminating plaster: As before, hammer test suspect areas for adhesion. Hollow sounding plaster must be removed. The surface must be sound, clean and dry. Hydroblast a second time where the area is extensive. Prime repair area with Plaster Primer (UC 56 or PP 700). Repair smaller area using Polyfilla Masonry Patching Plaster (102003) and allow 24 hours to dry. Larger areas are to be re-plastered over primer with a plaster mix with “Bondaid Plus” added to manufacturers specifications (Safeguard Chemicals www.safeguardchem.co.za)

7.4. Structural Joints The structural joint is to be re- formed (cut open) through the new plaster and the immediate area reinforced with a mesh, where necessary. The joint is to be filled with flexible grout - Sikaflex®-11 FC+ or approved equal.

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8. Paint and putty to clearstory windows Once the repair work to the facades and structural beams have been completed the windows are to have all loose putty and broken glass removed, remove all paint and rust completely. Apply Plascon Rust Remover (RR 1) to rusted areas and scrub with hard bristle brush to remove rust. Rinse thoroughly with tap water. Repeat process if rust is not removed. Dry surface rapidly to prevent flash rust formation. In areas where rust cannot be removed completely, remove all loose rust by scraping and wire brushing, then apply Plascon Rusist Rust Converter (EMS 21) copiously, but only to areas where tightly adherent rust remains. Allow coating to turn black (minimum 4 hours) before overcoating. Remove Rust Converter with water where it has not reacted and turned black.

Ensure surfaces are clean, dry and sound. Prime repair area with Plaster Primer (UC 56 or PP 700). Apply either Plascon Universal Undercoat (UC 1) or Professional Undercoat (PU 800) to bare and repaired areas. Allow 16 hours to dry; or apply Plascon Multisurface Primer (WUP 1) to bare and repaired areas. Allow 2 hours to dry. Finish with two coats Plascothane Polyurethane Enamel (UP) with 2 hours drying time between coats, for a maintenance cycle of 6 years in a C1 - inland environment.

9. New cat ladders for access to lecture theater roofs Two new cat ladders are required to provide access to the lecture theater roofs. These are detailed on drawing 0214/D1 and are to be installed at the start of the work to ease access for the contractor.

10. New Access Bridge to raised parapet wall A single new steel bridge is to be installed over the division between the new and old structure on the west side as shown on the plans. This bridge is detailed on drawing 0214/D1 and should be manufactured as early as possible to assist for the contracts.

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11. Repair and re-painting of existing steel access cat ladders and stairs Existing steel work is to be mechanically wire brushed to remove loose material and rust, structure is to be inspected and repaired if necessary.

11.1. Plascon Plascothane Polyurethane Enamel to existing solvent based coated exterior mild steel. Remove all paint and rust completely. Apply Plascon Rust Remover (RR 1) to rusted areas and scrub with hard bristle brush to remove rust. Rinse thoroughly with tap water. Repeat process if rust is not removed. Dry surface rapidly to prevent flash rust formation. In areas where rust cannot be removed completely, remove all loose rust by scraping and wire brushing, then apply Plascon Rusist Rust Converter (EMS 21) copiously, but only to areas where tightly adherent rust remains. Allow coating to turn black (minimum 4 hours) before overcoating. Remove Rust Converter with water where it has not reacted and turned black. Ensure surfaces are clean, dry and sound. Apply either Plascon Universal Undercoat (UC 1) or Professional Undercoat (PU 800) to bare and repaired areas. Allow 16 hours to dry; or apply Plascon Multisurface Primer (WUP 1) to bare and repaired areas. Allow 2 hours to dry. Finish with two coats Plascothane Polyurethane Enamel (UP) with 2 hours drying time between coats, for a maintenance cycle of 6 years in a C1 - inland environment. The access stair over the air conditioning plant is to be dis-assembled and moved out of the way for the waterproofing to be carried out. The unit is then to be modified so that it can be bolted together, for disassembly in the future when further maintenance on the waterproofing is necessary. 100x100x6 mm mild steel pads with a 150x150 mm rubber belting spacer are to be installed where the steel structure is in contact with the waterproofing.

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12. Access Control to restricted doors on roof. Mag lock access control is to be installed to the two access doors to the roof. A new door and access control is required for the lift motor room.

13. Polycarbonate Roof Sheeting The existing steel IBR roof sheeting over the toilet ventilation ducts are to be replaced with Clotan Steel Craft-Lock profile 1,2mm thick polycarbonate translucent roof sheeting and accessories fixed to steel purlins or rails at 800mm centres. The two ducts without roofs are to be covered using a 75 x 75 x 6 MS Angle iron frame fixed to the precast concrete coping with chemical grout (not expansion bolts) to form 3x frames to support 75 x75 x 6 MS purlins running the length of the duct. The sheeting is to be min 250 above the duct to allow ventilation and overlap front and back 150mm

14. Lining of rainwater downpipe The rainwater down pipe on the western façade (W02 on plan) has been identified as a problem. The pipe was sealed off at the roof. There were no records of why this was done but there were still problems internally with water ingress. Ponding on the roof was causing further problems. The outlet was opened up and a camera survey was carried out on W02, W01 and E03 to gauge their condition. The overall condition of W01 and E03 rainwater downpipes were reasonable and they did not have to be lined. It appeared that there were open joints in W02 and the pipe was clear all the way through to the manhole. W02 is to receive an epoxy lining for its full length prior to work being carried out on the waterproofing around the roof outlet to ensure that the lining is properly bonded to the metal. The specification is to line the down pipe with ‘Nu Flow’ in place epoxy lining, or equivalent approved equal product. The outlet is to be fully exposed and the pipe prepared for lining by sand blasting to clear any corrosion prior to the lining being installed in a single operation from the outlet to the manhole outside the building.

15. Removal of redundant air conditioning There are three existing ducted air handling systems on the roof. The works in this contract does not call for the renewal of the system and simply the removal of redundant and unserviceable units. The systems were examined by a professional engineer and a report and recommendations prepared. 1) System #1 is a high level fresh air intake with filters. The supports are heavily corroded and the external system needs to be removed in its entirety and a protective grill with vermin proofing installed onto the duct opening. The duct is to be properly cleaned out before the grille is installed. The corroded steel mounting points for the structure are to be stripped away and waterproofing taken over the area.

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2) System #2 is a ducted system added after the building was constructed, to two lecture venues in the south eastern side of the building. The entire system including the small plant room and all ducts, both internal and external are to be removed and all openings made good by re-glazing the clearstory windows. The hot water pipes to the units are to be stripped back to their source on the ring feed and return pipes and the point properly insulated and waterproofed.

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System #3 is a vertical ducted system from the basement air conditioning plant. This is to be retained and waterproofing carefully sealed around when this roof area around and under is rewaterproofed. The external insulation is to receive a maintenance coat of aluminum paint. Future air conditioning of the building and the replacement of the systems to be removed is a separate contract.

16. Work to Direct Expansion Condensing Units mounted on the waterproofing The 13 operational units currently mounted directly on the waterproofing are to be lifted and a new galvanized frames of a height to allow for maintenance to the waterproofing, with bearing pads to the frame feet installed after waterproofing.

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17. Work to exposed hot water pipes Repairs to the exposed space heating pipes fed from the basement is outside the scope of this contract. The pipes are to have their mineral fibre thermal insulation renewed where they penetrate the waterproofing and the waterproofing is to be taken up the insulation to a point +/300mm above the roof surface to ensure that no water can come in contact with the metal pipe.

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