© 2020 by BWAO

Rooftop House

屋顶之家

BEIJING 北 京

Client is a tech company that occupies an entire office building. The office building rooftop has great corner views, either to the city or to the mountains in the background. A rooftop house is built to take advantage of this as well as providing a home like space for staff members.

 

Existing Conditions
The site is on the rooftop of a five-story office building with a dimension of 33mx25m in plan. Surrounded by a 1.2 meter high parapet at the periphery, the only built structures on top is a T shaped shed that houses staircase and elevator equipment, and a series of air vents that puncture through the floor slab.

 

Design Strategy
To maximize the building volume and to be unnoticeable from the street level, the building mass is offset from the parapet boundary. The outer limit of the building is shaped by this restriction and locations of existing air vents.

In order to have an unobstructed view over the parapet, the entire building mass is elevated for one meter, gaining a vantage point out to the open for all activities happening inside.

The new building plan matches the T shaped shed with a U configuration. The western portion houses programs such as kitchen, dining, bar and lounge. The eastern portion has a tea house and a living room, relatively private in terms of usage. The middle portion is comprised of service programs such as a mechanical room and a bathroom.

Four distinctive windows are placed at four corners to provide different viewing experiences to the outside sceneries. Three courtyards are introduced as to create inner views as well: a tree yard to the west, a water yard to the East, and a sun yard in the middle. These courtyards bring natural elements such as light and shadow further into the house.

 

Structural Strategy
In order to elevate the building for one meter, a new datum is established on the existing roof structure. This new floor structure is anchored to the main beams and columns at the floor below, allowing the house structures to grow freely on this new platform.

The cavity space in-between the new floor plate and existing roof not only helps with the thermal performance of the new house, but also provide depth for earth and water features of the courtyards and space for air vents that feed into the rooms.
 

Building Material

The main building structure is steel, with CMU blocks as wall infill. Insulation foam panels are applied to the exterior with plaster and paint as final finish. Interior is furnished with wood floor and plastered ceiling and walls. Due to a tight budget, the visual interests are focused on views into the courtyards and out to the landscape, rather than on exquisite materials.

本次改造项目的业主是一家有着独立办公楼的科技公司。办公楼屋面景观潜力很好,除了东西南北,沿四角方向都可看到远处的景观。利用这一优势,屋顶需要提供一个可以供员工活动休息的家。


场地现状
场地位于办公楼的楼顶,场地尺寸为33mx25m,屋面现有构筑物为中间的一对剪刀楼梯间以及电梯机房。除了周围由1.2米高女儿墙环绕,屋面集中部有通风管道的屋面排风口。

设计策略
在不改变主楼体街道感知体量的基础上,加建平面试图将可应用范围体量最大化。边界距离女儿墙进行适当的退让,另外考虑场地现有屋顶通风管道的制约。

建筑将整体体量抬升1米,以使人们在室内视线看出去的时候超越现有女儿墙,提供毫无遮拦的观景机会。


基于现有楼梯间与电梯间的T形体量,新建建筑平面以U形平面嵌入。西边员工区相对开放,由厨房、餐厅、吧台、休息区等功能组成;东边起居区相对私密,由茶室和起居空间组成;中间连接区域布置机房、卫生间等辅助功能。


四个不同的角窗分别布置在建筑四角,提供了外向的景观机会。三个不同的院子也带入了向内的景观。西边树院,中部天院,以及东边水院,将光影与自然带到空间组织中来。

结构策略
为了在屋顶上实现提升1米的做法,建筑需要建立一个新的平台。此平台结构对位生根于五层的柱梁结构之上,建筑体的结构在此平台上再按自身逻辑生根。

新的地平与楼面板之间形成了空腔夹层,不但很好实现了热工性能,而且为院子的覆土、鱼缸水池以及空调管道提供了空间。

建筑材料

建筑主体为钢结构,轻质混凝土砌块为墙体填充,外加泡沫保温板材,外立面为抹灰加涂料。室内地板为复合实木地板,墙面为抹灰加白色涂料,天花为石膏板加抹灰白色涂料。建筑材料预算成本很低,主要将视觉焦点集中在最精彩的向外与向内的自然景观。