How do I calculate the overall height of my house?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KC0BUS, Sep 9, 2013.

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  1. KC0BUS

    KC0BUS Ham Member QRZ Page

    It seems like in the past, somewhere I read an article that explained how to calculate or guestimate the height of your house from ground level to the peak of the roof. This would be good to know for selecting antenna's, especially for those selecting and mounting their antenna's out in their yards and would like to know how tall their roof is so that their antenna clears the peak of the rooftop. Does anyone know of a method or trick for doing this?

    Thank you,
    Scott, KC0BUS
  2. W9DTC

    W9DTC Ham Member QRZ Page

    Measure a distance out and away from your house. Find the angle from that spot to the peak of your roof. With those two measurements do a little geometry. Given your distance away from the house and the angle you find, I believe the tangent function will provide the height. Remember to add on the height at which you measured the angle as well. :)

    Good luck
  3. K8ERV

    K8ERV Ham Member QRZ Page

    This is probably not helpful, but who knows?

    I have Fluke 411D true laser range finder that does the above calc for you. You just measure the distance to your house horizontally at ground level, then tilt the beam up to the top of the wall, and voila! (or something like that) you get the
    vertical distance.

    Maybe you can borrow or rent one? Great little meter, measures to 100' within 1/8". Works.

    TOM K8ERV Montrose Colo
  4. KH6AQ

    KH6AQ Ham Member QRZ Page

    You can measure the roof height using the optical method described by W9DTC. If you want to do this you will need to build a homemade device. Your device measures the angle between the horizontal and the peak of the roof. This can be made with a protractor, a plastic tube (drinking straw), and a plumb bob (string and bolt) or a liquid level.

    However, a direct measurement might be easier for you. I don't see that an exact number is needed. If your measurement is within 5 feet of actual that should be good for any practical amateur antenna analysis. If the peak of the roof is at the edge drop a line from the peak to the ground and measure the length of the line. If the peak is away from the edge of the roof things get a bit more complicated and the theodolite method might be the easiest.

    Angle method
    To measure the RISE you will need to know the horizontal RUN from the peak of the roof to your measurement point. Measure the angle (ANGLE) between horizontal and the peak.

    RISE = TANGENT of angle x RUN

    RUN = 100'
    ANGLE = 20 degrees

    RISE = (TANGENT 20 deg) x 100' = 0.36 x 100' = 36'
    Last edited: Sep 9, 2013
  5. KA9JLM

    KA9JLM Ham Member QRZ Page

    In the day we called it a inclinometer.

  6. K3SI

    K3SI Ham Member QRZ Page

    Use the Boy Scout method, stand some distnce away and hold a stick at arms length and adjust stick in your hand so the top of the stick aligns to the top of the house and the bottom of the stick(above your fist) aligns with the base of the house then rotate your hand 90 degrees and see where the top of the stick meets ground level then you can measure easily from the house base out to that point. It should be close enough.
    73 Dave K3SI
  7. K8ERV

    K8ERV Ham Member QRZ Page

    As Cleopatra said "I'm not inclined to say no". At least that is what I heard. She was mumbling and hard to understand.

    TOM K8ERV Montrose Colo
  8. K8ERV

    K8ERV Ham Member QRZ Page

    That's a neat trick. I was an Eagle but don't remember learning that one. Maybe I was too busy chasing Girl Scouts.

    TOM K8ERV Montrose Colo
  9. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I think she was telling you "Get your hands off of my asp."
  10. KI8HA

    KI8HA Ham Member QRZ Page

    You can also use sun shadows to calculate it. You need to have an object you can measure the height of, such as a fence post. Then mark the top of the fence post shadow, and the peak of your house shadow. Do these at the same time, since the earth is always moving, therefore so are the shadows.

    Then measure the actual height of the fence post, the length of the fence post shadow, and the length of the house peak shadow. Be sure to measure from the point on your house that is directly below the peak of your house. Then it is a simple matter of cross multiplying then divide.

    Example, the fence post is 6 feet high. Its shadow is 20 feet long. The house peak shadow is 45 feet long.

    6 = x
    20 45

    so 6x45 = 270

    270 / 20 = 13.5 ft <--- Peak height

    If you use exaggerated shadows of morning or evening, it will be more accurate.
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