A Guide Note to Maintenance and Repairs of Buildings

1. Structural Rehabilitation

The general health and performance of any building depends on its quality of maintenance. As a building grows old, ageing, use (or misuse) and exposure to the environment can affect the health of the building significantly.

Therefore, it is advisable to monitor it periodically by taking a professional opinion. Structural Audit is a preliminary technical survey of a building to assess its general health as a civil engineering structure. It is usually initiated as the first step for repair. This is similar to the periodic health checkup recommended for older people.

2. Structural Audit

The general health and performance of a building depends on its quality of maintenance. As a building grows old, ageing, use (or misuse) and exposure to the environment can affect the health of the building significantly. Therefore, it is advisable to monitor it periodically by taking a professional opinion. Structural Audit is a preliminary technical survey of a building to assess its general health as a civil engineering structure. It is usually initiated as the first step for repair. This is similar to the periodic health checkup recommended for older people.

When to do Structural Audit???

Model byelaw no. 77 specifies Structural Audit as a mandatory (necessary and binding) requirement. It stipulates that if the age of a building is 15 to 30 years, Structural Audit must be carried out once in 5 years and for buildings older than 30 years it should be carried out once in 3 years. You may, however, go for it even earlier if you suspect the condition of your building to be bad.

How is it carried out???

Structural Audit is commissioned by appointing a Consulting Structural Engineer registered with the Municipal Corporation of Greater Mumbai (MCGM or BMC) or in our case, TMC. The Consultant carries out as a visual survey of the building covering its faces, stilts, staircase, terrace, flats, shops and ancillary structures such as pump room, compound wall, etc. Repair history of the building and specific observations/ experiences of the members are also noted. Critical observations, probable causes of distress, remarks on structural health and recommendations for further action are given in the Structural Audit Report.

Why Structural Audit / Status Report???

• Exact details of distress at columns/beams/slabs (cover or core) 25%-50%-75% are known.
• Useful for loan application to bank, useful for insurance claim.
• Additional proof of sound structure before purchase or sale flat
• Members can understand the exact status/condition of their individual flat
• Easier to convince, to get co-operation and fund from members
• To produce if required by registrar or TMC or ant other Govt. Dept
• Helps contractors to understand the exact nature of distress before touching the structure for repairs, so chances of increasing the work/cost is minimum.
• Even members can visualize the extent of repairs during work and can experience
• The condition of water distribution and water protection system also forms part of structural status report.
• Cost effective solutions and specification will give full justice to your contributed amount. (Every single rupee of yours should be put to good use)
• It has remedial measures
• Estimated repair cost priorities are taken care

On the strength of authentic reports even after some years if problem arises you can contact consultants or contractor for rectifications.

Consultant’s involvement in repairs (proper planning-systematic/methodical repairs) improves the work –effectiveness by 95%

3. Repairs To Structures

Repairs to reinforced concrete structural members like columns, beams and slabs is becoming increasingly necessary, on account of the corrosion of reinforcement steel. Corrosion leads to several other distressing aspects like cracking, spalling, delamination etc. Repairs to these damages calls for special techniques and materials. Proper identification of the extent of repair is the first step. Removal of damaged plaster, concrete or mortar follows. At same time it is also essential to support or prop various elements, so that during repairs there is no possibility of unforeseen yielding of any structural elements.

REPAIR TYPES

(a) Minors
Minor repairs can generally be looked upon as those that do not require attending to the structural skeleton. Such repairs as water proofing, replastering, filling up non-structural cracks can be minor jobs.

(b) Major
Major repairs would need to tackle with the structural skeleton - at least attend to some of its members. This calls for an evaluation of the likely extent of repairs and strengthening measures required. A proper plan of the execution of the job, the choice of materials and method need to be decided.

The following sections explain typical repair items like:

1. Cleaning & surface preparation
2. Preparation of repair materials
3. Use of Bonding coat
4. Execution of repairs
5. Curing
6. Guidance or Supporting Systems.
7. Safety precaution

Preparation of Repair Material

The range of chemicals available for repairs are many. Some are to be used as they are, or "off-the-pack" whereas others require to be "prepared". The preparation would generally involve addition of water or cement or both sand is another material often added.

The prepared materials could be broadly classified as mortars, grout or slurries :

POLYMER CEMENT BONDING COAT (PCBC)

To prepare a polymer based bonding coat, take 1 part cement and 1 part Polymer based chemicals (by weight) and mix thoroughly. Use a mechanical mixer preferably. The materials thus mixed, form a thick slurry, of a consistency easily applicable by brush. The slurry thus prepared is ready for use as a bonding material.
The surface on which the bonding coat is to be applied, has to be cleaned with a water jet approximately 24 hours prior to application. This will help in making the substrata, slightly moist.
After application of the slurry on the requisite surface, place the next screed or mortar etc. that is to come over it. ("wet on wet" application)
Note:
The slurry is prepared using Polymer based chemicals only as the mixing liquid. ( Do not add any water).
The cement to be used should be fresh and OPC only.

POLYMER MODIFIED CEMENT MORTAR (PMCM)

To prepare a composite mortar of Polymer and cement base, use 1 kg Polymer based chemicals, 5 kg (fresh) Cement, 15 Kg Quartz sand (graded). This is same as using 1 bag of cement (of 50 Kgs), 10 Kg Polymer based chemicals and 150 Kgs of graded sand.
First dry mix the cement and sand in a mixer. Separately mix Polymer based chemicals with the requisite quantity of water. Then add this water-polymer mix to the cement-sand in the mixer and mix for 3 minutes at least use a mechanical mixer. (see item 3 of note below). The mortar is now ready for use.

POLYMER CEMENT GROUT (PCG)

To prepare a polymer based cement grout, use 1 kg Polymer based chemicals, 3 kg Cement (fresh) and 2 kg water. Mix Polymer based chemicals and water first and add this to the cement using a mechanical mixer till slurry of uniform consistency is formed. This is now ready for use.
(Important: see item 2 of 'Note' below)

POLYMER RICH CEMENT MORTAR (PRCM)

To prepare this mortar, use 2 kg Polymer based chemicals, 5 kg cement (fresh) and 15 kg quartz sand (graded). Mix the three ingredients (without addition of any water) preferably in a mechanical mixer, till a soft mix of uniform consistency is formed. This is now ready for use.

General Precautions
Prepare only as much quantity of material as can be used in 30 minutes.
Use fresh Cement only.

CURING:
Curing is best achieved by a fine spray of water. Curing should begin after 24 hours of application & continue for 3 days.

NOTE:
1. Clean all tools with water immediately after use.
2. The mixes given above are by way of general recommendations. For special mix designs using Polymer based chemicals you may please get in touch with a Civil Engineer.

3. The mixer consists of a shaft with spiral blades, filled in place of the drill-bit of the hand held electric drill.

4. Flat Roof Leakages

Flat roof are those roof which have a slope from 1 degree to 5 degrees. This roof is constructed in the same way as a floor and acts as a level platform to support the load. Flat roofs are not considered suitable where rain fall or snowfall is heavy. Flat roof requires weather covering and careful water proofing.

Causes of Leaks in Flat Roof

• Improper slope.
• Obstacles in rain water pipes.
• Unfinished junction of roof and walls.
• Damaged water proofing layer.
• Depression on the top of the roof.
• Defective joints of rain water pipes.

How to repair leaks in flat roof?

Step 1: Clean roof and check all rain water pipes

Clear all debris from the roof. Check all rain water pipes if there is any blockage in pipes as they provide direct access to rain water and repair defective joints of rain water pipes also.

Step 2: Mark actual area of leakage in daylight

Know actual causes of leakage and mark leakage in daylight while it is raining. Take help from professionals in leakage treatment. Actual area of leakage should be calculated with the materials required for repair. The repair of roof leaks should be done before the beginning of rainy season.

Step 3: Repair Tar felt water proofing coat and cement concrete ‘gola’

Repair Tar felt water proofing coat if it is damaged and restore damaged cement concrete ‘gola’ in junction of wall and roof slab.

Step 4: Keep proper slope of tile tracing for smooth flow of rain water

Check the surface of roof and keep the slope of tile terracing in 1:40 ratio to drain off rain water quickly and to avoid leakage. Restore defective joints and repair depressions existing on the top of roof to avoid stagnant rain water which leads to leakage.

Step 5: Restore the joints of tile tracing

Mend the joints of tile terracing if they are cracked and repair defective/damaged cement pointing to avoid leakage.

Step 6: Check mouths of rain water pipes

Restore the mouth of rain water pipes and repair their cracked joints with tile terracing to avoid leakage.

Step7: Repair leakage in over head water tank

Repair leakage in over head water tank; which destroys water proofing of roof. Fit proper ‘Bal’ cock and over flow pipe in over head water tank to avoid unnecessary over flow of water which damages the roof.

5 . Waterproofing External Walls

Often external walls develop wet spots and leakages. Causes are generally the absorptive nature of the plaster, due to age and degradation (or otherwise) as also the absorptive nature of the brick-work or block work behind the plaster. These walls need to be waterproofed effectively.

Case I
If the dampness is not widespread this can be remedied by the following method, using Polymer based chemicals with good quality cement paint.

Method:
a) Clean the surface thoroughly to remove all loose material, fungus, old paint etc. and moisten with water.
b) Mix Polymer based chemicals in the water used for preparation of the cement paint. Mix thoroughly to a uniform consistency. For the first coat use 20% Polymer based chemicals by weight of (dry powder) cement paint. For the second coat add only 5% Polymer based chemicals
c) Cure the paint after 24 hours.
d) Follow all the usual steps taken in painting using cement paints
(powder form).

Case II
If walls are extensively damp and plastering is deteriorating, replastering would be called for. In this case following steps are recommended:

Method:
1. Remove the old plaster, remove all the loose particles, and dust etc. and wash with a jet of water.
2. Prepare a mortar mix 1:4 [cement : sand], or as directed by the engineer-in-charge, and admix thoroughly 3% Polymer based chemicals by weight of cement in this mortar.
3. Provide a first coat plaster using the mortar in item 2 above. Keep its surface rough to receive the second coat. Apply the second coat after the first coat has hardened.
4. Cure as usual as per regular construction practice.
5. External walls may be finished further as per method in Case I

Case III
If walls are extensively damp and plastering is deteriorating, replastering would be called for. In this case following steps are recommended:

Once the plastering is completed, cured and dried out (to the extent possible) external painting with Polymer based chemicals can be taken up.
Please follow the detailed instructions in the literature on Polymer based chemicals for 'Instructions for use'.
In case it is desired to finish the exteriors using cement paint only, then use Polymer based chemicals to improve several qualities of the cement paint coating. The combination of Polymer based chemicals and good quality cement paint upgrades the ultimate performance of the decorative finish to a plastic-emulsion or acrylic type of finish to provide an effective water proofing & long lasting service.
The details as in case I may be followed for application.

Bonding New Concrete to Old

Whenever new concrete is to be placed over old concrete or hardened concrete (even if it is only 24 hours old) there is a fear of inadequacy of bond between old concrete and new concrete.

To overcome these situations provide a bonding coat of Polymer based chemicals & Cement.

Method:
a) Clean the surface of all loose particles and moisten it
b) Apply Polymer based chemicals & Cement in the proportion of 1:1 (by weight) by brush.
c) Provide a thin layer (chat coat) of 1:2 cement sand mortar.
d) Immediately place a new concrete over it and carry on with the rest of the work as usual.

Note:
Provide a thin layer of 1:2 cement sand mortar.
It is advisable for the mortar mix to nearly match the proportion of cement sand part of the concrete e.g. if mix of new concrete is 1:1 ½ : 3 then the thin mortar layer should preferably be 1:1 ½.
Sometimes longish aggregates are left protruding above the lower concrete and this would be helpful to increase integrity.

Method:
a) Clean the surface of all loose particles and moisten it
b) Apply Polymer based chemicals & Cement in the proportion of 1:1 (by weight) by brush.
c) Provide a thin layer (chat coat) of 1:2 cement sand mortar.
d) Immediately place a new concrete over it and carry on with the rest of the work as usual.

6. Waterproofing Water Tank

Water Tanks or storage Reservoirs (as they are known when they are large in capacity), are specially designed structures to store water from which supplies are made to the surrounding localities. Leakages and deterioration of many tanks have taken place over the years. Many of them need restoration.

Repairs to existing tanks.

A detailed procedure for repairs to a water tank is provided for guidance.

The following steps have to be taken:
1. Surface preparation
2. Anti corrosive Treatment
3. Steel Strengthening
4. Repairing damaged patches
5. Curing
6. Grouting any voids in concrete
7. Restoration of wall surfaces.

Specification for Concrete Repairs.

Surface Preparation
Surface preparation is of prime importance in any repair work. The success of the repair work depends upon this to a large extent.
I. Chip off all loose concrete and remove the damaged concrete by using a chisel and hammer or other suitable mechanical means.
II. The presence of any delamination should be detected by sounding the vertical (or other) surfaces of concrete on a regular pattern, using a small hammer. The areas should be marked out.
III. After the whole area has been covered remove the damaged concrete from the delaminated areas, till sound concrete is seen.
IV. Expose the reinforcement in all damaged areas using steel wire brushes, normally or mechanically. There should be at least 6mm gap behind reinforcement to facilitate cleaning, coating etc.

ANTI-CORROSIVE TREATMENT & STEEL FOR STRENGTHENING.

V. Apply a suitable rust removal compound as per manufacturer's specifications. Clean the reinforcement so that it shines uniformly.

VI. Wherever the reinforcement is reduced by more than 20 % of the original area, extra new main steel is to be provided by welding it to the existing steel or suitable lap (40 d). In case of columns and beams, provide welded wire mesh (4" X4" X 10 guage) along with two layers of woven GI wire square mesh (½ X ½ X 19 guage) so that the repair material is properly tied up with the sound core. The mesh is to be clamped on to the concrete surface by means of plumber nails and building wire.

VII. Apply a suitable corrosion inhibitor to the old and all new reinforcements.

REPAIRS: METHODOLOGY
VIII. Provide a suitable bonding coat over the reinforcement and concrete surfaces, which is to receive the repair material. Follow the bonding material manufacturer's specifications.

MORTAR & FINISHING
IX. Using polymer modified cement mortar (PMCM) fill up the area to be repaired, with aid of jacked up floating shuttering. The render of the PCMC should be done in layers of 15 mm, (the min being) minimum and at least two coats are to be provided. The material should be evenly applied and well compacted and finished using a wooden float or steel trowel.

CURING
X. Cure the PMCM as per manufacturer's instructions.

GROUTING VOIDS
XI. In case the original concrete is suspect or found to be honey combed or
has internal voids, it may be necessary to grout the concrete. This may be done by drilling holes of 16 mm diameter up to at least 100 mm in concrete to receive the nipples and grouting.

Use a polymer-cement grout as per the manufacturer's specifications.

7. Waterproofing Wet Areas In Buildings

The areas in residential or commercial buildings that call for waterproofing effectively are the wet areas: Toilets and bathrooms. These areas need to be "water-proofed" at the construction stage only. Otherwise after the tiling and sanitary fittings and fixtures are completed and there arises any leakage, the jobs of attending to the problems, at that stage would be costly and cumbersome.

The usual construction practice adopted is to have a drop or a sunken slab, the RCC slab forms a sort of a mini tank having a side outlet for drainage pipe. Further the normal slab also has one more small sunken area for the "Nahni Trap"

Firstly it is essential to have the concrete in this construction to be good quality and sound. A proper slope also has to be provided in the slab so that water will drain off quickly without stagnation. The waterproofing should be carried out by having Polymer based chemicals and Cement mix applied directly over the structural slab. (Consult Engineer for detailed application procedure) over this waterproof layer further finishing like plaster tiles etc. can be taken up.

It is also necessary to take this waterproof layer onto the walls and up till a height of 3 ft or the level of glazed tiles.

8 . Repairs and Maintenance Funds

Creation of the Repairs and Maintenance Fund by the Society

1. The repairs and Maintenance Fund, at the rate fixed at the general body from time to time, subject to the minimum of 0.75 per cent per annum of the construction cost of each flat for meeting expenses of normal recurring repairs.

Creation of the Sinking Fund by the Society

1. Major repairs fund, as and when required and decided by the General Body- the rate is fixed on area basis.
2. The Sinking Fund, at the rate decided at the meeting of the general body, subject to the minimum of 0.25 per cent per annum of the construction cost of each flat, excluding the proportionate cost of the land.

Utilisation of Funds by the Society

Reserve Funds: - The reserve fund of the society may be utilised for the expenditure on repairs, maintenance and renewals of the society's property.

Utilisation of Repairs & Maintenance Fund

The Repairs and Maintenance fund may be utilised by the Committee for meeting the expenditure on maintenance of the society's property and repairs and renewals thereof.

Utilisation of Sinking Fund

On the resolution passed at the meeting of the general body of the society and with the prior permission of the Registering Authority, the Sinking Fund may be used by the society for reconstruction of its building/buildings or for carrying out such structural addition or alteration to the building/buildings, as the society's architect deems necessary to strengthen it/them or for carrying out such heavy repairs as may certified by the Architect and on approval of the General Body.

As in the case of the rented premises, here too, there are certain practical difficulties on the successful implementation of these provisions. The sinking fund and the building repair fund is normally insufficient. Thus, the provisions, though incorporated in law, hardly make any difference to the situation.

Conclusions:

Thus in conclusion we can infer, that though the laws have made provisions for redevelopment yet they are not sufficiently stringent, and there is no authority either to keep a check over the implementation of the provisions. Hence it is the responsibility of the Society Management to have inbuilt systems and controls so that the task on hand is completed to the satisfaction of the members.