This project involves the design and construction of a safe and functional pool deck for a child with autism. The deck incorporates essential safety features, accessible design elements, and durable materials to provide a secure and supportive environment. Our team applied engineering principles in planning, analysis, and construction to ensure the structure meets both safety standards and the specific needs of the family.
This project addresses the need for a safe and functional pool deck for a young child with autism. The child is high energy, prone to knocking his head around, and requires an environment that minimizes injury risks while still supporting play, movement, and caregiver supervision. The goal is to design a deck that prioritizes safety, provides open and structured space for activity, and creates a secure outdoor setting tailored to the child’s unique needs.
Safety Railings: The pool deck needed to be designed with safety in mind. We want to make sure that there is no risk of the child falling off the side of the deck, or falling into the pool. This is why we will be designing a deck railing to go around the deck, with a composite snap on railing to go onto the edge of the pool. With both of these rails in place we should be able to prevent any accidental falls off of these edges.
Alarm System: The parent wanted to make sure that they could monitor if their child was trying to go onto the deck, or if they were trying to leave. They wanted to be able to get a notification on their phone whenever the gate to the deck was open, and live camera footage along with that.
Plenty of Space: The deck needs a lot of space for this very active child, and while designing the deck we need to keep in mind how much space will be free for the various activities and hobbies the child has.
Shade: The child has a fair complexion, and is sensitive to exposure to sunlight. The parent asked us if we could make sure that we design the deck in such a way that a canopy could be added to ensure that there are shaded areas on the deck. Along with possibly adding simple shade over some of the other features to ensure that there is plenty of shade on the deck.
Storage: The deck requires a lot of storage to be able to house the various needs of the child. The parent has asked us to add a small storage box and a small shed in order to help with these storage needs. These storage compartments would allow them to ensure that the child’s items are kept safe during inclement weather, and to help clear the deck when it is needed.
Areas to Hang Things: The child has a punching bag, and a sensory swing that will need to be hanged up. The parent would like for that to be on the deck as well, and so we need to consider during the design process how we are going to make sure that we have a structure with the strength to hold up the weight.
New Slide/Ladder: Since we are building this deck around the pool we need to keep in mind that the original ladder that came with it will not work with the deck being there. This means that we will need to purchase or design a new ladder that will work with the deck being in the way.
Due to the nature of the design, there is not a lot of creative freedom when it comes to the fundamental construction of this design. A lot of our research up to this point has been understanding building codes and how to design it so that it complies with said codes. Decks have very specific design requirements for post placement, beam sizing, joist separation, etc. The difficulty with designing this comes from the creative freedom of selecting material sizes. Different sizes require different spacing so once we start a detail blueprint of the deck we will need to try a lot of different formations to find the most cost effective design. In our research we could not find any Livingston or Overton County deck building codes available online. For preliminary purposes we looked at the Knoxville City building codes.
Table 1 is footing sizing chart based on beam and joist spans.
Table 2 is the maximum joist spans depending on what beam sizing is used.
Table 3 is the maximum allowable span of joists depending on joist size.
A lot of the uniqueness with this project that will make it specific to the family will come after the deck itself had been constructed. Most of our initial research has been invested in the fundamentals of deck building. We do, however, already have a running list of safety features that we will be adding to the deck.
Each design is a top down view only because they all need to be level with the 42″ tall pool so height differentiation was not necessary.
The original idea behind design 1 was to leave one large area on the deck. This would also make building the deck a little simpler because the pool would just be replacing one of the corners of the pool.
Design 2 is a very uniform design. Centering the deck around the pool gives a pocket in each of the corners for different sensory stations. There is also ample space to walk around the entire pool. This design would require special attention to post placements so that building around the circular pool is structurally sound.
Design 3 is another uniform design. Since this design was two circles, the structural design would have been more consistent. The major downside to this design was losing all the space that the corners would provide.
For choosing the design of the deck there were 5 different criteria (safety, cost, practicality, complexity, and design preference of the family), with an emphasis on three of them (practicality, complexity, and design preference). Since we are using official building codes to design our deck, safety was not too important in our considerations. We placed heavy emphasis on providing what the family wanted and trying to design something that would not end up being unnecessarily complicated.
We decided to move forward with design 2. The family said that being able to walk around the entire pool was very high on their list of necessities and that the wanted the pool centered in the deck. This eliminated option number 1 from considerations. Choosing between options 2 and 3 came down to space. We had been given a lot of ideas for current and future sensory stations that would be implemented on the deck. A square deck with corners felt like the obvious choice.
These are the current 2D drawings of the deck. On of the drawings shows each post placement, as well as joist and beam placements. The second drawing shows where the stairs are going to sit and where the railing posts will be placed. An example of how the double 2×10 are going to be nailed together and attached to the 6×6 beams is also included.
While thinking about our design, we wanted to make sure that the concrete poured under the posts was strong enough. With a lot of weight being placed upon one side of this deck, we need to make sure that it can carry it.
Taking note of inherent symmetry in the design, I was able to find the area of one quarter of the deck, and find the weight of the boards being used on it. With an assumption of one post, and one section of concrete being responsible for holding up the weight of the entire quarter of the deck. With a total area of 184.81 ft^2 we find that the boards would have a weight of 4,713 lbs. This would be placed onto a 6×6 pressure treated post. Taking that load, and placing it on an area of 6 inches by 6 inches we get 130.91 psi. Concrete has a compressive strength of approx. 2,500 psi.
This is a very safe load to put onto the concrete that would not put any risk failure. The issue is that this is without any load on it. The heaviest thing that has been asked of us is a sandbox to be placed onto the deck. While we will not be designing the sandbox at this stage of the project, we do need to prepare for it.
Assuming that the entire surface area previously stated is not covered in sand up to a depth of 1 ft (This will not be the case when the sandbox is actually designed). We end up with a weight for the sand at 18,461 lbs. Adding our board weight we get a total weight of 23,174 lbs. Placing that back on our 6×6 we get a value of 643.71 psi. This still is under our compressive strength for concrete by a factor of 3.88. Which means that at what can be assumed to be our most extreme conditions with only one concrete section, the concrete itself should not be compressed from the weight and fail.
The objective of this design is to analyze and validate the structural integrity of the stair assembly for the proposed pool deck. The stairs will be constructed using four 2×12 stringers, supporting regular deck boards as treads. Each stair tread will span 3 feet in total width, with four equally spaced stringers providing intermediate support, resulting in an approximate 9-inch clear span between stringers.
2×6 decking boards (actual 1.5″ × 5.5″)
Results show:
For 2×6 treads, maximum bending stress = 328 psi, providing a safety factor >2.5.
Maximum deflections are negligible ( 0.004 in for 2×6), far below serviceability limits (L/360).
The structural analysis confirms that the proposed stair design utilizing 2×6 pressure-treated deck boards for treads is safe and efficient.
