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Ahwahnee Comprehensive Management Plan Implementation: Emergency Presidential Suite Roof Deck Repair and Rehab (CFF 2020)

Yosemite National Park » Ahwahnee Comprehensive Management Plan Implementation: Emergency Presidential Suite Roof Deck Repair and Rehab (CFF 2020) » Document List

JUSTIFICATION:
The Ahwahnee Hotel is a National Historic Landmark and an architectural crown jewel in the national park system. Within the hotel, the Presidential Suite provides unique accommodations, including a 2600 sf wrap-around roof deck. The roof deck, made of reinforced, cast-in-place concrete, forms the roof of the Solarium below. The roof deck waterproofing has failed, and water intrusion is damaging the historic finishes.

The project will stop water intrusion that is causing damage to the building interior, including damage to the character-defining, historic stencils found on the walls and ceilings.

SCOPE:
This project will make emergency repairs to the existing roof deck, using fluid-applied waterproofing, in order to stop water intrusion into the building interior. The project will lift up the pavers on the deck in order to install a fluid-applied waterproofing system that is more compatible with the original design and in accordance with the treatment recommendations of the Historic Structures Report. Following the application of the waterproofing treatment, the pavers will be reinstalled.

Restoration of the historic stencils will be accomplished under a separate project.

1) How is the roof deck currently water proofed?
The deck is currently waterproofed with a three-ply (according to the dwgs) modified bitumen membrane. This and the copper flashing were installed in 2013. The drawings call for it to cover the lower terrace only, but from my observations, it appears to cover the upper terraces and column bases too.
2) What is the new waterproofing liquid that will be applied? (specific product info if you have it, otherwise product type)
The contractor will propose product(s) and method(s) for our approval before starting work.The repairs, including any new material, be applied to the existing membrane and copper flashing only. All of this will be removed when the deck is rehabilitated (scheduled for 2022).
3) Once the project is complete and pavers reinstalled, confirm if the appearance will be essentially the same as it is now.
The repairs not be visible once complete.