The Franklin tower in Montreuil builds an image for itself
Thin aluminium frames
Manuel Montès and Jacky Favrou, contract construction managers for Ouest Alu, explain that the choice of a façade typology with a breathing air gap (in contact with the outside through orifices fitted with filters permeable to water vapour) was a natural choice. " Blocks prefabricated in the factory, with heights equal to the height of the floors, must not deform due to differences in air pressure between the outside and the inside of the air gap. A pressure balancing system was thus necessary. Otherwise, glass deformations would have resulted in reflections from façades", says Jean-Louis Galéa, who had supervised CSTB's Technical Experimental Assessment. The thickness of the oven-baked aluminium frames was also minimised. Manuel Montès tells us: "Simple ventilation of the air gap with air inlets and outlets at the top and bottom of the gap would never have been sufficient to make an 85 mm visible external glazing bead for a hollow joint of only 20 mm!"
Obviously, the concrete breast walls and old door and window frames were eliminated in the effort to achieve this aim of making the building satisfy acoustic and thermal comfort standards. All floor edges were extended as far as the column outside surfaces. The 3.30m high blocks composed of 10 mm toughened monolithic external glass and an insulating internal panel made of laminated glass, were then fixed by means of steel cleats adjustable in the 3 dimensions to cover the concrete structure built in the 1970s.
Finally, at first sight the new skin leaves no hint of the original brutal appearance. The illusion of a completely new building is almost perfect. The old columns, with a changed colour and perceptible behind the new glazing, offer the only glimpse of the past. They are just visible through the transparent surface, and participate in animating the plane and smooth facades to which they give some depth, helping the tall building blend into its urban setting.