Cost Analysis
Using Extraction and Area Commands
At this point your floor plan should be complet. You will now have ArchiCAD calculate the total area of your house in order to calculate the cost of your house. You will use this information to come up with some cost estimates for your new home. To complete this activity you must turn in the following:
A House Drawing showing the room name and area of each room.A Building Cost Estimate Chart:
Room
Area
Total Area
Cost/ft
Estimated Cost
The Zone Tool
You will calculate an estimated cost for your house using a value of $75-$125/ft2. Label this as Projected Building Costs. To determine this total value you will have to determine the square footage of your house. This is a unit which is frequently referred to when comparing houses and when estimating building costs. Because this unit is used so often ArchiCAD has a tool that calculates the area automatically, the Zone tool. Draw a picture of the Zone tool icon found on the tool bar.Creating zones for each room – Complete Lesson 6 - Zones.
Calculating Total Square Footage of your House
Once you have created your zones you can now determine the total square footage of your house. You could add up the individual areas and find the total but remember that ArchiCAD is made for architects so this capability is built into the program.
- Go to Document > Schedules and Lists > Zone Lists > Basic
- Scroll over to the end of the chart to find the area for each room. Notice that the total area is also displayed for you.
- Open an Excel spreadsheet file and create a table to copy the following columns into excel:
Room Name (zone name) Category Area
- Copy the info from ArchiCAD to your Excel spreadsheet and save the file as Name – House Cost Analysis.
This demonstrates one of CADs valuable features; it can be used as a database to automatically store valuable information that is used by architects and builders.
Estimating Cost
1. Use the following formula to calculate the cost of your house:
Cost =Total Area *Per Foot Cost
In your excel spreadsheet use the formula tool to have excel calculate the total cost.
Cost Analysis – Mortgage Payments
Based on your calculations so far you now know the total cost for building your house (the price of the lot was not included). Now calculate what your monthly payments for such a house would be. Go to http://www.mortgage-calc.com/mortgage/simple.php and calculate what your monthly mortgage payment would be. Copy the following chart into excel and fill in the information you used to calculate your monthly payment.
Principal Amount (cost of house)_________________________
Interest Rate _____________________________
Loan Length (30 years)______________________________
Monthly Payment__________________________
If you had a variable rate loan and the interest rate went up to 9% what would your monthly
payment jump to?______________________ 12%?_____________________________
What would your monthly payment be if you took out a 15 year loan?________________
Typically home loans require 20% down although some banks are offering loans with as little as 10-5% down. Calculate how much cash you would need to obtain a loan at each of these percentages. 20%_________________ 10% ________________ 5% _________________
Monthly mortgage payments should not exceed more than 40% of your monthly income. Use this to calculate how much your monthly salary would have to be in order to afford this house.
Use this monthly salary value to calculate the required annual salary.
Now go to http://www.salary.com/salary/layoutscripts/sall_display.asp and find out if your planned career will allow you to afford your house. Record the results of your findings and list two other careers you might be interested in and their associated salaries.
Summarize the information you have gained from this page in your cost analysis page for your portfolio so it is included in your report.