How-to: Design and Construction for Community Fridge Shelter
Madison Community Fridges x Wonka’s Harvest Collaborative Design
Disclaimer: Below are steps that we took to build our fridge shelter, but we want to disclose that we are not carpenters. We used the “Freedge Yourself” guide found on the Community Fridges website as a base design and added insulation and framing to accommodate for our Wisconsin winters. This design will not be best for every single location or fridge so feel free to make adjustments based on the needs of your space and community! Best of luck to you and your Freedge!
Please provide feedback to us regarding what is and is not working with your design and build to better inform future builds for us all!
Considerations Before Building:
Do you have a space to build a shelter?
Do you have the tools that you’ll need? Protective gear (eye/ear/hand protection)?
Do you have the funds to purchase materials? Be prepared to spend upwards of $900 if you have to purchase all of the materials, excluding tools.
Are you storing your shelter and fridge indoors or outdoors?
If outdoors, what are the average temperature variances where the shed is located?
Where are you building the structure? Will you build on site or plan on transporting?
If transplanting, do you have access to a truck or trailer?
How will you weatherproof the wooden shelter? Will you use a sealer paint or purchase treated wood?
Do you need additional space designated for a community board? Dry storage?
What COVID considerations are present with your location, fridge, and suppliers? Will you need to build in shelves for cleaning supplies, hand sanitizer, etc?
What are your local city codes and health codes associated with permanent structures and food distributions?
Tools we used:
Circle saw
Sawzall
Clamps
Sawhorses
Measuring tape
Chalk line or straight edge
Screws and nails
Hammer
Mallet
Drill (Star bit, Philips bit, and hole bit)
Driver
Exacto Knife
Sander
Markers
Caulking gun
Ladder
Ratchet straps for transporting shelter
PPE:
Work gloves
Eye protection goggles
Ear protection
Material List:
*These are the quantities that we used for a fridge that is 66’’ tall, 33’’ wide, and 29’’ long. You will need to adjust quantities based on the specific dimensions of your fridge.
4 - 4’ x 8’ x ½’’ Plywood
4 - 4’ x 8’ x 1’’ R-5 Foam Board Insulation Sheathing
4 - 1’’ x 4’’ x 12’ Board
10 - 2’’ x 4’’ x 8’ SPF Lumber
1 - 8 ft. Metal Roof Panel
1 - 48’’ x 96’’ x ⅛’’ Double Layer Polycarbonate Sheet
3 - Door Hinges
1 - Door Handle
1 - Wooden Gate Latch (we made our own from scrap plywood)
2 Rolls - Door Seal Weather Stripping
1 Roll - Garage Stripping
1 - 125 Watt Incandescent Heat Lamp Bulb
1 - Socket (be sure the socket can withstand your wattage)
1 - Outdoor Extension Cord
1 - Powerstrip
1 - Silicon Caulking
1 - Wood Caulking
1 - Caulking Gun
1 Gallon - Waterproof Wood Sealant *if you do not purchase pretreated wood
2 - Wood Paint Brushes
1 Roll - Duct Tape
1 Box - 3-½’’ Wood Screws
1 Box - 1-⅛’’ Wood Screws
1 Box - 2’’ Framing Nails
1 Box - 1-¾’’ Roofing Nail *buy a small box, you only need these to nail in the metal roof
Notes on Construction:
Always wear eye protection and a mask.
Cuts and bruises may occur; have an idea for simple first aid.
Check out a great way to align boards and corners -> https://www.youtube.com/watch?v=vkGdFVVR7qw
Read the SDS of all chemicals: paints, caulking, silicone sealants. Work in well ventilated areas if possible to avoid excessive exposure to these chemicals
If issues arise during your construction, be creative by using scrap materials to make adjustments.
Steps to Build:
1. Once you find a location for your fridge and shelter, be sure to assess the area. Look for potential obstructions,, assess the level of the ground, find electrical sources, and make a plan on how to elevate your structure off of the ground to reduce the likelihood of precipitation and or pests entering. If your shelter will be placed immediately next to a building, make sure to look above to make sure that the building’s overhang and or gutter is not directed toward your shelter.
2. Measure the fridge dimensions, accounting for the fridge door handle, where the plug in cords are located, and which direction the door swings open.
3. Start to draw out your design. Considerations for your design may include:
a. Size: Be sure to account for the thickness of the chosen materials and account for space requirements of the heat lamp. Plan to make the shelter bigger than the fridge, but not too big. For example, our design added 12 inches in width (left to right) from fridge to shelter and 11 inches in depth (front to back). By ensuring there is enough extra space, it is a lot easier to move the fridge into the shelter, make minor adjustments, and install a heat lamp along the side of the fridge if needed.
b. Heat: What is the lowest temperature that your fridge will be exposed to in the winter months? Will you need insulation and a heat lamp? See the “Nerd Corner” below for more information and guidance!
c. Extra space: Will you need extra space for a lightbulb heat lamp, dry storage, a compost bin, extra shopping bags, etc?
4. Purchase or gather materials and tools. This might be a challenging step if you do not have access to all of the tools listed above or funds for materials. Make use of any and all social media presence and call for donations!
Note: Some hardware stores will cut the wood for you or you can cut your own at the store. If you are having difficulty finding tools, material, or space to construct, contact local farmers or construction companies that might donate time, space, expertise, or materials.
5. Use the circle saw or sawzall to cut the lumber according to the design (2x4s, plywood, 1x4s)
6. If you are not purchasing pretreated wood, you will need to paint waterproof wood sealant in advance of the construction. Paint the waterproof wood sealant on all sides of wood that will be exposed outdoors and the front and back of the bottom of the structure. You should paint two coats of this sealant and allow each coat to dry for at least 12-24 hours.
Note: You can purchase pretreated wood and would not have to do this step, but the wood is more expensive.
7. Find a flat/level space of ground to cut and assemble material
8. Cut your 2x4 shelter framing to the specifications of your shelter. Do not cut the door framing until after the entire shelter has been built because it is likely that the door dimensions will shift slightly.
9. Assemble the 2x4 shelter framing:
a. Front framing (refer to image 2): make sure you have the bottom board flush with the ground. This will match up with the base plywood of your structure so it is important that these are screwed in at a 90 degree angle. The longer 2x4s will be cut at an angle to match the pitch of the roof.
Image 2: Front framing
Image 3: Back Framing
b. Back framing (refer to image 3): make sure that the bottom cross board is flush with the ground. The longer boards will again be cut at the same angle of pitched roof.
c. Attach the final two 2x4s for the base framing on the front frame (refer to image 4). Note: these boards will be attached in the same direction as the angled cut.
Image 4: Front frame extended
d. Attach the 2x4s that will become that roof support (refer to image 5). It may be helpful to lay your shelter on its side to make sure the framing is flush. Add the additional two cross beams on the front and back framing (refer to image 6).
Image 5: Complete frame side view
Image 6: Complete frame back view
10. Cut your plywood to the specifications of your shelter. Remember that the side walls must be cut at the same angle as your roof is pitched (refer to image 7).
11. Attach the plywood walls to the outside of your structure frame. You may need to rotate your structure on different sides to install the walls (refer to image 7).
a. Screw the bottom plywood onto the bottom of your structure
b. Screw both of the side plywood pieces onto the side frames.
c. Screw the roof plywood onto the top framing.
d. Screw the upper front facing plywood rectangle above where the door will be inserted.
12. Apply a thin layer of caulking to the corners of the inside of the structure to seal air gaps.
13. Install the remaining material to the base of your shelter.
a. Cut the insulation to size using an exacto knife. You likely will need to cut both sides of the insulation.
b. Insert into the bottom cavity. You may need to use a mallet to fit insulation in because it should be snug.
c. Place the final piece of plywood on top of insulation.
d. Hammer or screw into place.
14. Cut and insert the roof and sidewall insulation pieces.
a. For easy insertion, you can use something flat to wedge it in, google “shoe horn” for concept.
b. Hammer in nails halfway and then bend heads into insulation to secure.
Image 7: Shelf no door or fridge
15. After the shelter is built, you will want to remeasure the door space to account for slight changes that are caused by human error. Because polycarbonate is one of the most expensive materials, it is important to assemble the door after shelter has been constructed.
16. With the adjustments made, build the door.
a. Cut the frame of the door and screw in the 2x4s (refer to image 8).
Image 8: Door frame
Image 9: Plywood triangles
b. Use scrap plywood to cut 4 triangles that will frame and support the polycarbonate onto the door. For the best support, make sure you cut the triangles to meet equidistant in the center (refer to image 9).
c. Cut the double layered polycarbonate to size using a carbide tip blade. Have safety glasses on at the very least!
d. To seal the polycarbonate to the door frame, you will need to apply silicone on the inside of the triangle supports and then firmly press polycarbonate onto silicone. It is helpful to lay spare plywood on the outside of the belly of the door during the curing process to prevent the polycarbonate from moving.
e. Immediately after applying silicon, install 1x4s on the inside of the base of the 2x4s to secure and seal the polycarbonate to the door. After this step has been completed, the silicon should be left untouched to dry for at least 12 hours (refer to image 10 and 11).
Image 10: Polycarbonate inlays
Image 11: Donkey board inlays
17. After the silicon has cured, you can attach the hinges to the door. Attach the door to the shelter by screwing in the hinge to the shelter frame (refer to image 12).
Image 12: Hinges
18. Test the door by opening and closing. If there are specific points where the door does not move smoothly, use the sander on both frames till there is free movement. NOTE: If you are not building your shelter at the site of the fridge, bring the sander with you when transporting. The door and the structure will move during transportation and will likely have a new high friction point that will need correcting
19. Use the door seal weather stripping or garage stripping to seal any gaps between the door and shelter. If the air gaps are larger than the stripping seal, use scrap 1x4s.
20. Do a little happy dance! You are almost there! Now visualize your cozy fridge snuggled inside this warm structure (refer to images 13 and 14)!
Image 13: Full door open
Image 14: Full door closed
21. Cut the metal roofing with enough room for an overhang with a carbide tipped edge hand saw. Have enough overhang to redirect enough precipitation but not so much that it droops too much or could be a safety hazard for folks using the fridge. You will need safety glasses and ear protection on for this.
22. If you have not constructed your shelter on site, plan a day and time to transport your shelter to its site. Consider rush hour traffic and other local traffic considerations that could interfere with drop-off.
If transporting shelter to the site, bring the following: the metal roofing to install at site, a ladder, sander, extra insulation, drill, hammer, extra screws, a large wood drill bit, and duct tape.
23. On site, drill a hole with the hole drill bit on the back of the shelter for the outdoor electrical extension to enter into before the fridge has been inserted. Run the cord through the hole and then use extra insulation to plug the hole. Use duct tape to seal the hole.
24. Insert the fridge into your shelter! After plugging in the power strip to the extension cord, install the heat lamp. Since heat rises, the heat lamp is most effective if it is placed on the side instead of hanging from the ceiling of the structure.
25. Attach the metal roof using nails or screws, make sure the selection will go through the metal roofing and sink into the 2x4 frame and not just through the plywood.
Woohoo. You are officially finished with your fridge shelter! We hope this has helped you reach your Freedge hopes and dreams. Tag @wonkas_harvest in a picture on Instagram of your fridge shelter if you found this helpful or email us at wonkasharvest@gmail.com for any and all feedback. Happy Freedging!
NERD CORNER: Maintaining Temperatures in Your Shelter
Everyone can harness their inner engineer to problem solve complex problems and develop their own problem solving toolbox! The following explanation of thermodynamics will help you optimize your own design to your unique climate. Depending on climate conditions, you may or may not need to install insulation. Lets begin!
The primary objective of the shelter is to keep the elements out and maintain a minimal operating temperature around the fridge. By using principles of the study of heat and energy transfer, or thermodynamics, our design can be better informed by the site specific conditions and threats. Our specific design has been built for harsher winter conditions, so you may need to either upgrade to better insulation or you may not need insulation at all. This exercise will help you figure out what you need.
Refrigerators are not designed to function if the outside air is colder than the air inside the fridge. For this reason, we must set a value as the minimum internal temperature that the shelter can be set at to ensure that the fridge functions properly. We will call this value Tin. For our model, we have set Tin as 50 degrees F or 10 C. Next, we will need to find out the variances that our specific site will experience in temperatures. To find your Tout value, search what the minimum annual temperature your city experiences. For Madison, WI, our Tout value is -20F or -28C.
Now we will move onto your design.
To simplify the model of heat loss, we will be assuming that the entire system is at a steady state. Steady state, in other words, means that the outside and inside temperatures are constant. This means that each material has a constant temperature gradient throughout its thickness thus having a constant amount of energy moving through it (refer to diagram 1). In reality, there will not be a constant gradient of heat loss because the door will be opening and closing but this gives us a good depiction of what is happening.
To calculate the heat transfer (q) across a single layer of material we will apply Fourier’s Law:
q=(Tin-Tout)/R
where R is a thermal resistance established by
R=L/(k*A)
and where k is the thermal conductivity constant for the material.
If a material has a high R value, then the material is a better insulator which retains more heat. If a material has a high k value, then the material transfers energy better, allowing more heat to escape from the shelter. R and k are thus inversely proportional.
If you have two layers of material (i.e. plywood and insulation), then the thermal resistance (R) is then a function of both materials’ thermal resistance.
Rside= Ri = Ra + Rb
Where Ra = La/(ka*A) and Rb= Lb/(kb*A)
Providing that the specific heat transfer (q) of a designated side of your structure be
qside = (Tin - Tout)/Rside
Repeating the above equation for each side of your structure, you can sum the total heat loss of your shelter with
qi = Σqi = qtop + qbottom + qleft + qright + qback + qfront (no door) + qdoor
Make sure that your units cancel out and only Watts (W) remain for the total heat loss.
Using this modeling, we configured a net heat loss and retention from specific material combinations. It helped us pick where and how much insulation should be installed into our shelter as well as what wattage heat lamp would suffice to keep our shelter at 50F. Make note that because this modeling does not take into consideration the door opening, you should oversize your heat lamp wattage from your calculation.
Looking for more? Go to youtube and search steady state heat conduction or contact us and we would be happy to help however we can!