Martello Tower Extension

Project scope: This Martello tower in South Dublin was purchased with an existing planning permission for an extension however the permitted scheme did not fully realise the vision that our client had for the development of the historic site. Working closely with our client GoKu developed a radically altered design within the confines of the volume of the previously granted scheme, changing the structural approach, internal layouts, elevations, the material palette and most notably the design of the link bridge spanning between the Martello tower & the new structure. After a comprehensive process of engagement with Dun Laoghaire Rathdown County Council a revised planning application was submitted for the proposed alterations and planning permission for the new scheme was approved.

Context: The Martello Tower at Bartra Cove in Dalkey, a defensive fort built in 1803, is one of about fifty Martello towers built around the Irish coastline. The tower is about 12m high (with two floors) and it’s round structure and thick (2.4m) walls of solid masonry made it resistant to cannon fire. The proposed addition, physically removed from the tower and linked via a lightweight stair structure, extends the functionality of the original tower to create a distinctive family home.

Sustainability: The detailed design of the building fabric has been developed using passive house principles. The primary structure is a thermal bridge free passive house timber/ steel hybrid frame; with a full-height passive house certified curtain wall glazing system fixed to thermally isolated steel frame clad in timber. The structure is topped off with an extensive green roof with a sedum selection appropriate to the coastal location. A decentralised heat recovery ventilation system will be installed to ensure indoor air quality & comfort as well as reduced energy demand.

Design challenge: GoKu has, through the use of modelling & shadow studies, developed the layout of the interior to ensure that the living spaces benefit from the best natural light available on the site. The proposed link stairs extends from the new structure and touches lightly on the national monument. The Corten steel used in the link structure is perforated to reduce its visual and physical impact. The material pallet externally includes glazing, untreated oak cladding, which will weather to a soft grey and weathered corten steel to the fascia, cills and bridge. Corten steel in the context of historic buildings in maritime settings is well established and as with the untreated oak is tonally and materially harmonious with the weathered granite of the existing Martello Tower. Internally the use of natural materials such as charred oak cladding & reindeer moss as well as the re-use of granite excavated from the site in the polished concrete floor provide a wonderfully tactile experience.