Equipment and Hydraulics
A roof top pool is much like any pool from the perspective of its hydraulic operation. The location of the equipment is the always of key importance and requires thought as to size and ease of access for maintenance. Equipment which is pl aced in a location that is hard to reach or hard to service is rarely well maintained. We always recommend that the equipment be placed in a way that is enclosed but easy to access.
Weight of Structure
One of the two most important concerns of roof top installations is the Weight of the pool structure and the water it contains. Residential roof top installations tend to be smaller and shallower due to these concerns. Water weighs about 62.4 lbs per cubic ft so a pool that is 4 ft deep exerts a force of 250 lbs per sq ft.
Loads such as these must be designed to be transferred to the structural framework of the building in a way that minimizes point loads and prevent any problems with defection of horizontal structures.
Because Concrete is extremely heavy we recommend that roof top pools be constructed of stainless steel and be contained inside a steel framed and reinforced structure. This type of construction minimizes weight and concern about leaks that occur in concrete vessels.
Because stainless is strong, stable and creates a much lighter vessel we always recommend it for above the first floor installation. For large installations the vessel is made in sections and lifted to its installation location with a crane and then TIG welled together. The frame below is also welded and mechanically fastened to make the vessel as structurally sound as if it had been built as one unit.
The structural sub frame is designed with the buildings structural frame in mind so as to transfer the weight of the vessel and the water to the walls or structural columns and evenly transferring stresses on the building’s horizontal members. This also helps to minimize the entire structures profile and reduce the required thickness of floors or roofs.
We recommend the use of 304 or 316 stainless steel in a thickness of 3/16 – 1/2 inch which creates an extremely strong vessel which will not leak. It is also capable of accepting tile and the quality of the overall vessel is exceptional. The additional cost of a stainless vessel is greatly outweighed by the cost of constructing a structure that will carry a concrete vessel. With concrete a hairline crack can be problematic at best and catastrophic at worst, so extreme measures must be taken to prevent leaks and to control leaks if they occur.
Preventing a Problem
The worst thing that can happen with a roof top installation is a leak. Most commonly leaks are related to plumbing problems and not structural problems. Human error is most commonly the cause of the problem. Service people and owners can accidentally do all types of things that can cause a serious problem.
Because of this we recommend that all instillations be over a surface that can contain and manage a leak. The surface below the vessel and plumbing should basically be just like a roof in that it can prevent water from entering the structure below and manage a large volume of water. We recommend a drainage system with oversized lines, inlets, and multiple points of entry. There should be no area where a broken or frozen pipe could allow the vessel to empty into the dwelling.
Choosing a contractor for a roof top project
A roof top pool or fountain is never an easy installation and great care should be taken when choosing a contractor and designer. The criteria for this choice should be experience with such projects, technical knowledge of both pools and building structures, the ability to work on a team with the other members of the design and construction team, outstanding communication skills, and lastly the ability to analyze a project and all the structural and aesthetic components in a way that takes into account the owners needs and the a willingness to do everything in their power to meet those needs.
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