Annexure-I

Recommendations of the Workshop held on 7.3.09 on Construction Hazard Management during addition/alteration to existing Multistoried Buildings

The development controls norms in respect of multistoried buildings like group housing have been revised in MPD-2021. The FAR has been increased from 167 to 200, and height restriction has been removed subject to clearance from AAI, Fire Deptt. and certain other bodies. On account of these changes made in MPD-2021, a trend has been observed where group housing societies are proposing additional construction in existing structures. Proposals in this regard are being sent to the local bodies who in turn are referring the cases to DUAC for approval.

            While scrutinizing such proposals the DUAC has observed the following :-

(a)        Proper information regarding structural feasibility of these additional constructions with reference to the structural framework of the existing structures lacks clarity in these proposals. This issue is critical considering that geographically Delhi is in seismic zone-IV. The present provisions in the building bye-laws are silent on this aspect.
(b)        During construction many equipments like large trucks, cranes etc. would be required to be installed at site for a considerable period and would occupy the available open spaces meant for children’s play area, green areas, breathing space for the people living in the apartments.  This would virtually transform an inhabited environment into a building site for a substantial period of time and will have considerable public health and safety implications.
(c)        Since these are multistorey schemes, very large scaffoldings would be required to be erected at site and these would hinder mobility of the residents on foot as well as in cars. Also, space within the housing is likely to be used for stacking of building materials like bricks, cement, aggregates etc. Site office may be also required to be constructed. All these would occupy available open spaces and create hazard to the life of the residents.
(d)       During construction, especially as it would be undertaken at a large scale, pollution, specially dust pollution at the site would pose health hazards for the residents.
(e)        There are norms laid down for the safety of the workers working at a building site, but in these cases, which seem to be without precedent, there are no safety norms or code which can be adopted in respect of the existing residents of the buildings and which are sought to be added to on each floor.

The objective of the workshop was to examine the implications of the above issues and suggest how they may be addressed.  The list of participants is annexed. After detailed deliberations the following recommendations emerged :-

1.         However, if horizontal expansion is considered, structural stability should be of paramount concern. It may therefore be necessary to add additional column to frames the expansion. Existing structural design would need to be taken into account and submitted for review while making any horizontal expansion. The increase in FAR permitted should be viewed in an overall urban context. A Group Housing cannot grow in the same way as individual units. Thus, if FAR has to be increased it cannot practically be extended by adding a balcony or an extra room in multistory situations. Increase in the FAR could be utilized in a separate cluster or block taking into consideration all attendant issues like scope for expansion, additional requirement for services, parking, green spaces etc.
2.         As regards individual proposals of group housing, as no norms exist for horizontal addition to multistoried Group Housing, Structural Feasibility Certificate together with all necessary supporting documents pertaining to method of construction, site safety etc. from a competent Structural Engineer could be made mandatory before consideration is accorded to such a proposal. Horizontal expansion to multistoried buildings should not be permitted if it entails stressing existing cantilever area.
3.         The situation becomes al the more sensitive in place like Delhi which is situated in Seismic Zone IV. Thus, while considering a proposal in this regard, microzonation plan of Delhi needs to be taken cognigence of. Places like Dwarka and Trans Yamuna areas, where the soil is soft, besides the structural feasibility, geo-technical safety of these additions and alterations should be made mandatory.

The situation becomes all the more sensitive in the place like Delhi which is situated in seismic zone-IV. Many such buildings are located in earthquake prone area like Dwarka and trans Yamuna. Thus, while considering a proposal in this regard the microzonation plan of Delhi needs to be taken cognizance of. Thus, in areas like Dwarka and trans Yamuna where the soil is soft, besides the structural feasibility, geotechnical safety of these additions should be made mandatory. 
4.         Increase in FAR entails increase in the parking requirements also, which eats into existing greens and is an aspect that needs consideration.
5.         Horizontal expansion would also reduce open spaces, play areas and parking spaces. Therefore these must be considered as per bye laws requirement before any expansion proposal is made. The expansion proposals need also to be considered from the point of movement of fire tender.
6.         In case some separate additional construction is allowed in these schemes, for safety of the inhabitants of these buildings a good management manual for the construction phase is required.
7.         Vertical expansion of multistoried buildings would normally entail addition of dwelling units. Such a case is likely to impair adversely the services pertaining to the building complex. Thus, the concerned authorities need to satisfy themselves as to how the additional requirement of services would be met in case addition of dwelling units are involved on expansion in such buildings.
8.         DDA should also consider the fact that the additional FAR - horizontal, vertical or additional building would change the building mass and urban form. Additional FAR should be used as an opportunity to create a positive street and urban form. If it does not do so, additional FAR should be disallowed specially in certain cases horizontal expansion can encroach upon public places set back and street form. The measures to develop checks and balances to address the aforesaid issues could be formulated in terms of short term and long term measures. The DDA needs to urgently develop practical guidelines for these kinds of additions. The short term measures may include steps for revising the proformae for submission of proposals incorporating necessary details that would require to be indicated by the project proponent to examine proposals for additions/alterations. The long term measures may entail modification of the National Building Code and Building Bye-laws etc.
9.         In conclusion, a particular aspect which deserves serious consideration is, whether in the light of the above, it is at all feasible to permit horizontal additions to multistory group housing apartments. Additional area where feasible may be planned in a separate block.