Olbrich Botanical Gardens Royal Thai Pavilion Roof Replacement project
The KALAM US team is carrying out work to replace the roof of the Olbrich Botanical Gardens Royal Thai Pavilion in Madison, Wisconsin.
The scaffolding that will allow the work to be done over the winter has now been installed. The first preparation, inspection and dismantling tasks have begun, and the fabrication of replacement clay tiles has started after a rigorous sample manufacturing process, achieving exact replicas of the original tiles, and significantly improving its quality and durability to withstand the extreme climate of the area. The roof is made up of three types of tile: a long scallop and a short scallop, in keeping with the two planes of the roof slope, and a flat edge tile as a first course at the bottom of the eave.
This project is a collaboration between City of Madison, WI, Olbrich Botanical Gardens, and University of Wisconsin-Madison. The Prime Architect Consultant is InSite Consulting Architects (ICA).
The pavilion is located on the northeast side of Olbrich Botanical Gardens, across Starkweather Creek. It was a gift from the Thai Government and the Thai Chapter of the Wisconsin Alumni Association to the University of Wisconsin–Madison. It is a significant building to the Madison community, constructed in Thailand using traditional techniques and materials and then shipped to Wisconsin to be reconstructed by Thai craftsmen at Olbrich Botanical Gardens in September 2001. It is one of the few pavilions of its kind outside of Thailand and the first Thai Pavilion in the continental U.S.
It on a T-shaped plan, 40 feet long, 22 feet wide and 30 feet high.
The condition of the pavilion’s various components was uneven. According to the Condition Assessment Report prepared by InSite Consulting Architects, the structure is in good condition, while the finishes and decorative elements have weathered less well, with the state of the tiling and lead flashings being critical. Hence priority has been given in this intervention to rehabilitating the roof.
The Assessment Report analyzes all of the pavilion’s components. The roof tiles are made of clay with a buff glazed finish on exposed parts, in three distinctive shapes: short and long scaled scallops, and a third with a flat edge. All are slightly concave with a tab at the underside on the up-slope side for fastening to roof battens, and they appear to be handmade. The tile shapes are in keeping with the roof layout, with flat edge ones as the first course at the bottom of the eave followed by short scallops on the lower slope and long ones on the steeper slopes.
The roofing tiles were splitting or shaling due to exposure to water and the freeze-thaw cycles of Wisconsin’s climate. More than 40% of the tiles are assumed by the assessment to be damaged. In addition to the matter of preserving the tiles themselves and of possible infiltration to the whole structure, this poses a risk of tiles falling off onto the public.
The architectural team recommended a complete replacement of the tiles. This will involve using recreations with the same shape, size, and glazed color, but fired at higher temperatures so as to make them resistant to the local climate. The tiles must also have the original convex shape, and be laid in the same pattern using tabs prepared accordingly. Yet improvements will be incorporated, such as modern fastening materials with underlayment, sub-tile membrane, and flashing systems. All must be compatible with the system while helping to prevent water seepage into the interior, and being breathable to water vapor.
The intervention will also appropriately restore the lead flashings, which were found to be in critical condition. Poor material quality and the use of carbon steel fasteners in the original construction have caused faster than normal degradation and fastener failure. This, together with the action of water and wind, has resulted in detached and deformed areas and water getting at areas of untreated wood.
For these elements a complete replacement is recommended, with new materials similar to the existing ones but of higher quality and fastened with double hot-dipped galvanized nails that have been confirmed to be compatible with the new flashings.
All this work is to be carried out by KALAM’s team of specialists, putting their experience and knowledge at the service of the intervention so as to ensure its success.
Information and images: KALAM and websites: