This project tasked our team and two others with designing and constructing a new porch with wheelchair access for a family with a child with autism. The current porch is run-down and in need of replacement. The end goal of this project is to deliver the family a safe and structurally sound front porch that can be enjoyed for many years to come. The porch will be slightly larger than the current porch on the front of the house, featuring railing, a non-slip wheelchair ramp, a roof that covers the porch, space for a porch swing, and potential for a future add-on. Our group is specifically in charge of the non-slip wheelchair ramp.
The family’s porch is currently in a rundown state. The porch is currently a safety concern for this young kid. The roof is too shallow, causing the front door to hit it when opening, and the boy has the potential to end up in a wheelchair, which is not supported by the current porch. The family has also expressed interest in hanging a porch swing from the roof, which we are aiming to make possible.
The new porch design is primarily aimed at increasing the safety and accessibility. Our group was primarily in charge of designing and constructing the ramp. This ramp will be vital to this family should their son end up in a wheelchair.
Size:
Ramp Material:
Safety:
We researched the ADA standards for ramps, which includes: slope and rise requirements, “clear” width requirements, landing dimensions/requirements, handrail requirements, cross slope and surfaces, edge protection requirements, and outdoor condition preparation. Certain choices heavily affect how we design the ramp itself, such as: the angle of the slope, and how many landings we want/need. Due to porch requirements and allotted amount of on-site space to work with, we are unable to create many designs for the ramp.
Requirements for the ramp include:
This was our first design idea. This design, although unsightly, was primarily to get familiar with the codes and try to produce a ramp that will be easily accessible for their kid to get up and down. This ramp is at a 1:16 slope. This slope is recommended for the elderly or for people who are less comfortable or newer to wheelchairs. This design has the most gradual slope of the designs, but has the most wasted space.
Pros:
Cons:
This design is much cleaner. This design focuses not only on the standards and regulations but also on how the deck will look. This design has a steeper slope (1:12) but is still compliant with the ADA. While it does not bend towards the back of the house as the family requested, it makes a much better use of the available space.
Pros:
Cons:
This design is the closest to what the family originally asked for. This design also focuses on the standards and regulations without giving up how the deck will look. This design has the medium slope of the 3 (1:14), so it is allowing for easier mobility going up without adding as much ramp length as the first design. While it does start at the front of the porch, it still makes a good use of the available space, and goes towards the back of the house (like the family requested).
Pros:
Cons:
Based off of personal preference, but mostly the design matrix, we selected concept design 2 to be our design. It is the simplest, cheapest, most linear, and most aesthetically pleasing of all of the designs.
After talking with the family, we decided on design 2. This design features two sections of ramp and two platforms. The design effectively meets the needs of the family, prioritizing both safety and reliability while also having a better aesthetic.
A key feature of the design is accessibility. This was a key need of the family that we knew was crucial. We are installing grip pads along the length of the ramp to ensure that even in harsh conditions, their child will be able to safely make it onto the porch.
Platforms: This design has 2 5×5′ platforms. One is 30″ off the ground, and the other is 25″. The 30″ platform is connected directly to the porch and is supported on the outer edge by two 4×4″ posts. The 25″ platform serves as a segway between the two ramp segments and is supported by three 4×4″ posts on the outer corners. Both posts extend 3.5′ off the top of the deck. Both platforms have 2×8″ joists, spaced 14.625″ on center, and headboards. The deck and ramp are both topped with 1.25×6″ deck boards with a 0.5″ overhang at the outer edge of the porch.
Ramp: The ramp has a 1:12 slope for both sections. The ramps have 2×6″ boards as joists and blockings to support the ramp boards. There is a 5′ section connecting the two platforms, and a 25′ section extending from the first platform to the ground. There will be grip pads to help ensure that the wheelchair will still have traction even in wet conditions.
Handrails: The handrails are in place 3.5′ off the top of the ramp and platform sections to ensure that they cannot be climbed over and provide a comfortable support for anyone walking down the ramps. It also has only a few inches between the bottom of the railing and the deckboards to ensure that their kid cannot slip through.
This simple analysis was done to ensure that the deck platform will support a distributed load of 500 lbf, which is approximately how much a wheelchair with a person would exert over about 3 ft. The maximum allowable compressive stress for our wood is approximately 1000 psi. Even with many simplifications made, we can see that the posts alone are more than capable of supporting this distributed load without breaking.
This analysis looked at the deflection of the deck boards. Looking up standards, the maximum allowable deflection is L/360. Assuming a point load of 375 lbf and fixed end conditions, we can see that the defelection is within the maximum allowable deflection.
For the final analysis, we examined the safety factor of the shear force that a single joist could withstand. First, we calculated the force in a single joist, and then we found the shear force. We then compared the shear to the max allowable shear and found a large safety factor, proving that the joists will be able to withstand the shear it may be under.
After finalizing our design, we then made prints of the landings, the railings, the ramp segments, and the full ramp before constructing. Each print had relevant dimensions as well as numbered boards to help make the cutting and assembly process easier. We first started building off of the porch team’s structure with the first landing, which allowed us to make sure that our landing was level and square relative to the porch. We built up the frame of the landing, dug the holes for the posts, used bracing to connect to the porch, and poured concrete for the posts once it was level. We then moved on to the second landing and the first ramp section. We constructed the frame for both sections and then connected the ramp to the first landing before repeating the process for the second landing. Finally, we moved onto the long ramp section, which we made changes to from our original design to reduce costs, improve stability, and ensure easier installation. After constructing the long ramp section, we added the deck planks, cut the posts down, and constructed the railing.
To ensure that this ramp would be accessible to the family, we asked Easton to ride his bike up and down the ramp once we were finished to make sure he was able to get up and down easily. We also made sure the railings were secure by putting our full weight against them in multiple spots to ensure they would not give out. We also made sure the surface of the deck boards was as flat as possible to ensure that wheels could not get hung up on any part of the ramp and create unsafe conditions.
This project provided a highly rewarding hands-on experience, allowing us to broaden our skill sets by applying engineering principles to a real-world scenario. It was incredibly fulfilling to design and build something that directly improves the safety and accessibility of a local family’s home. Throughout the process, we learned how vital it is to consider construction constraints during the design and modeling phases. While we faced some challenges with fabrication foresight and structural alignment, overcoming these hurdles made the final result deeply satisfying. The lessons learned from this project will be invaluable as we move forward into our engineering careers.
