Question re: Calculating Riser Height

Discussion in 'Home Theater Projects' started by Don.l, Feb 4, 2006.

  1. Don.l

    Don.l Stunt Coordinator

    Joined:
    Apr 9, 2005
    Messages:
    120
    Likes Received:
    0
    I know this type of question has been asked a bunch on here, and everyone is told to look at the riser calculator. I thought I would ask anyway. My HT room is going to be about 10' wide X 22' long. I will have a 101" diag. screen that is 90" wide and 67" tall. The bottome of the screen will be about 36" off of the floor (I know that's low). So, what do you think as far as riser height. I will have two rows of seats 2 in front and 2 in back. I was thinking of placing the first row at about 12' away from screen, and I guess about the second row would be about 5' behind that row which makes the second row at about 17'. So what do you think the riser height should be? The calculator annoys me in that it asks for the height from floor to eye level. I don't know this. Any advice?

    Thanks in advance.
     
  2. Jay Mitchosky

    Jay Mitchosky Producer

    Joined:
    Sep 6, 1998
    Messages:
    3,729
    Likes Received:
    0
    Hi Don

    The best thing you can do is create a scale drawing profile of your theater. This will let you easily visualize how high your riser needs to be for proper sightlines from the back row. Here are some things to consider:
    • Carefully measure the height of your eyes from the floor while reclined in your selected chair.
    • Consider placing your screen vertically such that your eyes are located 1/3 up from the bottom of the screen (so for a 100" diagonal screen its height is about 49", and your eyes would fall 1/3rd of that up from the bottom). I'm not sure about your 67" vertical measurement - is that a 4:3 screen? And if so why not 16:9?
    • Your eyes should fall about 1.5x screen width distance from the screen, so for a 7 foot'ish screen as you're indicating shoot for 11-12 feet (which you've already indicated). If you want to be more precise you can use trigonometry specify your viewing angle.
    • The second row should be far back enough to allow for comfortable leg room when the seats are reclined. So make sure you're measurement is from the back of the front seat to the front of the reclined/extended seat plus 1-2 feet for, well, feet and some relief (you wouldn't want someone's dogs in your while sitting in the front). Because you're looking at only 2 seat you don't need to worry about walking space between.
    • Measure the distance from the floor to the top of an average person's head while in the reclined position.
    • With this scale drawing run a line from the bottom of the screen to the top of the head in the first row and beyond. It will intersect at the distance from the screen to the second row. That is where the eyes will/should be located to allow an unrestricted view of the screen.
    • The difference between the scaled height of the eyes at the second row and height of the eyes while seated on the floor is the height of your riser.
    • The higher the screen is positioned, the lower the riser needs to be and vice versa.
    • The closer the second row seats are to the screen, the lower the riser needs to be and vice versa.

    You can see the value of the scaled drawing in figuring this stuff out. You'll also quickly realize that, depending on the dimensions you're working with, the required riser height might be ridiculous. You also need to weigh that height against your ceiling height, projector location if it needs to drop down, etc. My first run at this showed a riser height of around 16" which is too much. I ended going with 2x10 joists with a plywood stack (3/4", 1/2", 3/4") totalling 2". It's not perfect, but also not a problem for people in the back row. You can experiment with your drawing.

    You'll be limited in how high you can place your screen by the ceiling height, restricting bulkheads, and also the need to avoid getting to close and creating reflections. But try playing around with this nevertheless.
     
  3. Don.l

    Don.l Stunt Coordinator

    Joined:
    Apr 9, 2005
    Messages:
    120
    Likes Received:
    0
    Jay. That is so nice of you to give such detailed inormation. I really appreciate it. I hope that I can help someone out in here to the degree that you have helped me. Just as an FYI. The screen dimensions are 101" diagonal (16:9). Viewing size is 48" X 87" and screen size is 67" X 90". I hope that clears is up a little. I guess when I decide on the chairs I will go to the store, and bring a tape measure, and do some measurements to figure out numbers. Thanks again.
    Don
     
  4. Jay Mitchosky

    Jay Mitchosky Producer

    Joined:
    Sep 6, 1998
    Messages:
    3,729
    Likes Received:
    0

    That's exactly what I did. Which is why it's a good idea to settle on your chairs early in the game. Look for these measurements:
    • Floor to eyes, reclined
    • Depth of chair, reclined, from end of foot rest to end of seat back
    • Distance between back of chair frame and back of seat, reclined (useful for figuring out where the bottom of your riser can extend to)
    • Width of chair
     
  5. drobbins

    drobbins Screenwriter

    Joined:
    Dec 2, 2004
    Messages:
    1,872
    Likes Received:
    1
    Real Name:
    Dave
    Don,
    Jay has good advise. I had to do a layout in AutoCAD. I wanted my screen as high as I could, but the projector had to be mounted on the bottom of duct work that hangs down about 12" across my ceiling. I ended up with a 105" 16:9 screen. The bottom is only 30" off the floor. The front of my first row of recliners is 10' back (front of seat) & the second row is 17' back on a 10" riser. Sitting in the back row with the seats upright, the top of the first row is lined up with the bottom of the screen. I use 2 center speakers one above & one below the screen. The one below is the main one, but some of the sound is blocked by the front row of seats. The speaker on top is smaller and is aimed more to the back row. As Jay suggested, do a scale drawing and it should work out. I took me about a week to get all the viewing, speaker & projection angles. In the end it all paid off. EP3
    Dave
     
  6. Jay Mitchosky

    Jay Mitchosky Producer

    Joined:
    Sep 6, 1998
    Messages:
    3,729
    Likes Received:
    0
    Don

    Forgot to note earlier that you should try and use more descriptive thread titles. I've updated it from "question" - you'll get more traffic this way.
     
  7. TonyD

    TonyD Who do we think I am?
    Supporter

    Joined:
    Dec 1, 1999
    Messages:
    17,239
    Likes Received:
    443
    Location:
    Disney World and Universal Florida
    Real Name:
    Tony D.

Share This Page