Two Bedroom Lake Cabin

The purpose of this project is to wrestle with multiple design and engineering issues to develop the best collaborative design solution your team can produce. Every attempt is made to simulate a real world design problem. Housing designs are driven by the needs and budget of the client, the restrictions of the site and the creativity and talent of the professional design team.
Your team will be expected to:
  • Design  a plan that is functional and provides flexibility to live well.
  • Plot  a set of Auto Cad floor plans and a cross section that meet all of the site and client criteria.
  • Maintain project budget guidelines.
  • Engineer a structure that is safe.
  • Meet current energy standards.
  • Create a sketch up model of the project.
  • Build a professional looking physical model for your project presentation.
  • Present the Completed Project to the class with appropriate support documents and a physical model you actually build.
You are working either by yourself or with a team of two or, possibly, 3 members. 
Your task:  
Design a lake front house which
   meets a budget of $200,000. 
   meets the structural issues outlined below, 
   meets specific family requests, 
   meets current energy codes,  
   meets liveability issues,  
   and looks great. 

Construction Costs:
   Main Floor Area:                $130/SF
   2nd Story Area:                  $90/SF
   Basement Unfinished Area: $50/SF
   Basement Finished Area:    $80/SF
   Carport Area:                     $35/SF  
   Deck Area:                         $20/SF
Customer Room Requests (Requirements):
This property will be owned by a couple and will need two main bedrooms with privacy in the event of guest stay overs. 
In addition you need a bath on each floor, a functional kitchen, a great room, a sleeping area for guests with closets and a hobby area for craft s. You may have to place some rooms on the first floor and some rooms on the second. A carport is strongly desired and you need secure storage for bicycles, kayaks, beach boards, and other beach gear. Best view of the lake will be from the great room. Maintain privacy from possible neighbors on either side. 

Site Requirements:
The $100,000 site is located on Mason Lake, Washington. The property is about 100 feet wide by 100 feet to the bank of the low bank waterfront. The building area is approximately level to the road which makes the access from the rear. Property could have houses on both sides and view of the lake is to the West.

How to Start the design:
You will need to determine if you are building this house as a single story, as a double story, or as a double story with a basement. Then you will need to figure out what functions work best on what level. For example, do you want the kitchen on top with the view or close to the ground level so groceries are easy to unload.
I would start with a simple bubble chart on a blank piece of paper. Write down what direction is South (for potential solar gain), which direction is view (To group view priority rooms toward the vistas), and indicate from what direction to access the property (driveway). If there is a steep slope, indicate that. 

Then draw circles (bubbles), move them around, and label them. The bubbles are sized to match the space allocated for the rooms.
Then make a pencil sketch of the rooms. Take gridded paper and start a sketch. This shows room sizes and their inter relationships. I can provide paper if necessary.

Only then go to the computer and begin fitting the rooms together in Auto Cad.

Part 1:  One or two concept sketches per team. 

These are hand drawn. They can be quickly developed, but they need to reflect quality thought. I must approve these before you start computer drawing. These sketches should allow us to see if you are in budget. So we need to know square footage of garage, floor 1, floor 2, deck, etc.

Part 2:  Preliminary auto cad drawings of the first and second story floor plans.

These will show exterior walls (2x6 probably), interior walls (2x4 probably), closets, bath fixtures, kitchen cabinet and applicance layout, all windows and doors with sizes shown,  wood stove location, stairway, and total square footage noted. 

Part 3: Revised floor plans and a cross section done in Auto Cad.

Floor Plans plotted at 1/8" = 1'. Plans include room names and sizes, window and door sizes, all door swings shown, all appliances shown, including hot water tank. Drawing must be dimensioned.

Cross section is plotted at either 3/8" = 1' or 1/2" = 1'. The parts of the cross section are labeled. Section should indicate siding, sheathing, stud thicknes, insulation thickness, interior sheathing, Footing sizes, rebar, treated sills, Support beams and proper bearing footings, floor joist sizes, insulation under house, roof rafters, roof pitch, roof sheathing, roofing material. Code required smoke detectors also need to be located
Your project also has to meet current energy minimums for the state of Washington. Window area can't exceed 15% of your total heated floor area. So if you have 1600 SF of floor area, window area can't be more than 240 sf.

On your cross section drawings indicate the R rating of exterior wall insulation, floor joist insulation over crawl spaces and roof insulation. The above chart shows state minimums. 

Part 4: Google Sketchup Model

This is a to scale model with rooms and materials applied to all surfaces.

Part 5: Engineering    Look at websites on right and be prepared to answer the basic question of what holds up the roof, what holds up the floors.

Part 6:  Class Presentation and Critique.
Roof rafters here could be 2x12 placed 24" on center and cannot exceed 20’ in length. You will probably have to support any rafter spans  with a support beam if you exceed 20’. We will look at real span tables.

 You could use trusses instead of rafters. Do you know what trusses are?
How would you support the load of the roof? 
Can you trace how that load transfers down to the earth?
How would you prevent failure?

How to Start the Engineering:

We do not want the building to fall down.

We will calculate roof and floor loads. Begin by understand that you do not want rafters to exceed 20', that floor Joists should probably not exceed 10' in length, that 6x12 Beams should probably not exceed 20' in length.

In class we will learn how to do the calculations and apply them to your building to make sure it is safe.  If you exceed safe loads, we will have to deny your building permit.

To begin, you will be required to explain to me how your roof loads will transfer down through the building. Look at the cross section of the salt box above and be sure you understand the physics of the forces.

The ground holds up the roof.


 The building attaches to the ground with gravity and the connection is with a concrete footing, normally. Your saltbox has two stories so in Pierce County you would be required to have a footing that is 15" wide and 7 or 8 inches tall with normally two pieces of 1/2" rebar to keep it together during ground swell or earthquake.  The square inch footprint of the footing and of support piers is the bearing surface of the building. All of the weight of the building is held up by the ground under that bearing surface.

Understanding how the house frame goes together.