As-built survey of a music club building, Prague 1

An eight-storey building on the Vltava embankment in the heart of Prague, a music club operating inside, and a plan where neither the outline nor the floor levels follow a regular grid. For PRAM ABS a.s. we laser scanned the whole building and delivered as-built documentation covering 526.50 m² of built-up area, with a set of nineteen drawings produced from a Revit model.

The building is reached from the Smetanovo nábřeží embankment road and from Novotného lávka, and it lies both in the Prague Heritage Reserve and within the UNESCO World Heritage site of the historic centre, so any building work here is reviewed from a heritage point of view as well. The building itself carries no registered protection of its own, the protection applies to the area. How much has changed inside shows in the layout. Former swimming pool spaces on the second and fourth above-ground floors now serve as dance floors, and part of the ground floor is an open arcade connected straight to the pavement. PRAM ABS a.s. needed reliable documentation of the existing condition as a basis for the next design stages.

The whole building was captured with a 3D laser scanner. The result is a single coloured point cloud of 1.75 billion points, stored in E57 and ReCap format. A systematic photographic record was made alongside it, 469 images in total, 295 of them sorted floor by floor from the basement up to the seventh above-ground level. The point cloud then became the base for a Revit model, and the drawings were generated from that model. Drafting ran directly over the cloud, which is still visible in the working versions of the sheets, where the cloud sits under the linework.

The delivered package comes in two parts. The report follows the Czech structure of a covering sheet, a summary technical report, a site sketch and a drawing schedule. The drawing set contains nineteen sheets, each supplied in PDF and DWG. Eight floor plans at 1:100 cover every level from the basement to the top floor, and three sections at 1:150 cut across the building to show how the levels relate to one another. The remaining eight sheets are supplementary. Six of them mark the laminated chipboard wall cladding, and two are schematic plans of the sixth and seventh above-ground floors, with the areas of twenty rooms shown on the sixth. The point cloud and the Revit model stay available as the source to return to whenever a dimension is missing from the drawings.

Project challenges

Square corners and level floors are the exception here. The entrance floor alone holds three different floor levels, at ±0.000, -0.550 and -1.100, and the sections reveal intermediate levels inserted between the main storeys. Cladding is the second difficulty. Laminated chipboard panels cover the walls from the basement up to the fifth above-ground floor and in places they run straight across window openings, so the real face of the structure disappears behind them. The drawing set answers that with two series of floor plans, a plain one and a second one marking the cladding. Anyone preparing a layout change can tell from the pair what is structure and where the structure is merely covered. Finally, the survey was carried out without probes and without destructive testing. This type of record documents what can be seen, so the report explicitly recommends a structural engineer and a targeted geotechnical investigation before any work on the load-bearing structure.

Project outputs

• Report in the Czech pasport structure, covering sheet, summary technical report, site sketch and drawing schedule
• Eight floor plans, basement to seventh above-ground floor, scale 1:100, in PDF and DWG
• Three sections through the building, scale 1:150, in PDF and DWG
• Six floor plans marking the laminated chipboard cladding, basement to fifth above-ground floor
• Two schematic floor plans of the sixth and seventh above-ground floors, with the areas of twenty rooms on the sixth
• Merged PDF of the full drawing set and a second version with the technical report included
• Description of the load-bearing system, roof, windows and vertical circulation including the lift and all staircases
• Visual assessment of the building condition, carried out without probes or destructive testing