What this covers
Glazing and facade work is the visible skin of a public building, and it is judged twice: once on how it looks and once on how it performs in wind and rain. Every panel and profile we install enters site through a reviewed submission, goes in to an approved shop drawing, and is signed off by the engineer before we call it done.
Our reference works are station packages on MRT Line-6, including the ongoing glazing at Kamalapur Station S17, the line's terminus. Installation there proceeds while the station remains a guarded, active site, so measurement, fabrication and lifting are sequenced around railway operations rather than the other way round.
The sequence matters more than the material. We measure on site rather than from the drawing alone, because a structure as built is never exactly the structure as drawn. Shop drawings follow the survey, fabrication follows approval of the shop drawings, and nothing is cut before its drawing is signed. That order is what keeps a facade package off the critical path.
A facade is designed twice over. The building frame is checked against one set of wind pressures, and the cladding against another, because a single panel sees a sharper local gust than the structure as a whole, and corners and edges sharper still. Dhaka's basic wind speed under the Bangladesh National Building Code 2020 is 65.7 metres per second, measured as a three second gust at ten metres. No panel or fixing we install is designed below the code minimum net pressure of half a kilonewton per square metre.
The seismic requirement is the one most often missed. Dhaka sits in Seismic Zone 2, and every building here falls into seismic design category C or D, never B. That matters because the code's exemption for architectural components applies only to category B. In Dhaka, cladding must be designed for seismic forces as a matter of code, not preference. Panel joints and connections have to absorb twice the storey drift or twelve millimetres, whichever is greater; connection bodies are designed for a third more force again, and the fasteners for four times it.
Two of the materials in a facade are not left to the specification in Bangladesh. Float glass and extruded aluminium profiles both sit on the mandatory certification list, against BDS 1832 and BDS 1879, so the material has to carry a certification mark before it is lawfully sold. We buy to those standards and keep the certificates, because on a public project they are asked for.