Room layout with low beam that limits ceiling height - AVS Forum
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post #1 of 14 Old 05-10-2013, 09:44 AM - Thread Starter
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I'm in the early planning stages of planning my theater and have a few issues that I'm not sure how to handle. The room is roughly 16'x20'x 8'6" to the unfinished concrete floor from the joists. The big issue is a beam that runs across the theater that has an unfinished height of 7'7". I've attached a diagram to hopefully better show my rough plan. My plan was to have an AT screen (2.35 between 130"-140" wide (height with frame 62"-"66) and 2 rows of seats. Any issues with that screen size and having a 2nd row with a riser? Looking at projectors that would have a 15-20ft throw for that image size, so it would be behind the beam. Any thoughts?

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post #2 of 14 Old 05-10-2013, 01:27 PM - Thread Starter
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Just remeasured my room. The beam is actually 7'7" so maybe not as bad as I feared, but still lower than the 8'6". Not sure how I messed that up, but it's going to be a very long build if my measuring skills are that bad. Still looking for any insight when you get chance. Thanks.
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post #3 of 14 Old 05-10-2013, 06:40 PM
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Read the "Beam interruptus" thread and see what they did there. That might also be an option for you.

If the beam is 7'6" then you could have as much as 7'3" of clearance underneath that with OSB, drywall, and carpeting eating up some space.


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post #4 of 14 Old 05-10-2013, 07:20 PM
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You're going to need to draw it all out and just see how it fits together. The screen height calculator (sticky at the top of this forum) and some of the more complete projector calculators (the kind that include image offset) will be your new best friends. The challenge is getting a projector in the right position vertically to not be blocked by the beam, while still keeping the image at the right height for the second row to see over the first row. You could look into a table mount setup for the projector, to get the image higher, but then you give up the center line of the room for seating, unless the projector were in front of the seating, but it won't be - unless you know of some seriously short-throw high quality projectors. More likely, the projector has to suspend down from the ceiling and/or project down to clear the beam, but then the riser has to be taller for sight lines fro the second row. It all hinges on the positions of the beam and the seating and the screen, as well as the offset and lens shift of the projector.

IMO, do yourself a favor - since you're planning this carefully up front (a good thing), start with the speaker layout. Get the angles right for the speaker positions. Make some decisions about how much you benefit from an acoustically transparent screen. Define the seating area based on sound, and then see what seats fit in that area and what size screen is well suited to that seating area (distances). THEN you can look into the projection techniques that you'll need to get the image on the screen. If you start by saying you want a big screen, you make compromises for everything else to fit around it, and may not get the best result.

Maybe you've done it that way already... but that's a big screen that will benefit from a lot of lumens.

(Maybe I'm just being a downer, but I think the acoustics first plan puts you in a stronger position to make informed compromises and decisions)


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post #5 of 14 Old 05-11-2013, 11:19 AM
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Why the hall at the end of the theater? Could it be part of the theater square footage?
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post #6 of 14 Old 05-11-2013, 11:57 AM
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Quote:
Originally Posted by Tedd View Post

Why the hall at the end of the theater? Could it be part of the theater square footage?

Actually, why couldn't both hallways be part of the theater and the door flipped to the back right instead of the back left?....

Anyhow, I have almost EXACTLY the same measurements happening in my theater, I have a 140" wide 2.35:1 screen and a cursed beam running right across the middle of the room. There are a bunch of pics in my build thread, but I'll repost a couple here now. Here's a picture of looking toward the front wall of my theater:



and left wall looking toward the rear:



I'll be building a perimeter soffit and box in the beam across the middle at the same soffit height to make it an architectural element.

As for the projector, there isn't much you can do about the fact that the projector's light beam needs to clear the steel beam. I explored four options:
  1. Buy a projector that has a short-throw lens option and mount the projector off the ceiling, just in front of the beam. RESULT: No projector lens could reasonably fill that size screen with that short of throw distance
  2. Buy a projector with a short throw lens option and mount the projector on the underside of the beam. RESULT: same as above
  3. Buy a projector that has a long-throw lens option and fire the projector under the beam from the back of the room OR put the projector outside the room and fire through an optical viewport. RESULT: Would be preferred for my setup, but projectors with these lens options typically start around $20,000 and go up from there, so not an option because it is a budget-buster.
  4. Mount the projector in the 16' to 17' sweet spot from a post mounting coming down from the ceiling with the light beam just clearing the steel beam. RESULT: - The option I am going with.

Considering my second row of seating is at an 18' distance to the screen, I am going to try and either slightly advance the seating and/or slightly push back the projector so it ends up over the heads of the second row / over the potential back bar area.

The all-in option not mentioned above is to hire a construction company to pack out and recess the steel beam up into the ceiling. Had I known / realized the situation with this beam I would have paid the extra $$$ during construction to recess the beam. Now I am stuck with it and trying to make lemonade out of lemons.

You are subscribed and I will be following along!


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post #7 of 14 Old 05-11-2013, 01:03 PM
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I've got a beam across my room and I'm doing exactly what TMcG said. My projector power/HDMI is run to about 17'. The beam/HVAC/pipes are a few feet forward of that. I'm boxing them in with with as small a soffit as possible. The projector will have to hang down enough to throw past it. I'll try my best to locate the projector in such a way that it isn't a constant head banger when getting in/out of seats.

Picture of my rear wall taken from the screen:


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post #8 of 14 Old 05-11-2013, 06:42 PM - Thread Starter
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Thanks for the great responses. A lot of great suggestions and options. I misunderstood my wife on the hallway, so that's gone. She wants the little corner in the left for a mini concession stand and popcorn machine. That would make the room 16'4"x25'. Any issues with not having a rectangular theater? The rear wall would be a tad over 22'. I have a lot more planning to do and I think focusing on the room vs the equipment as HopefulFred suggested is what I really need to do.I got so worried about the beam being a "theater killer" that I didn't know what to do. TMcG and xjagor thanks for the photos. I'll start digging into your threads to see how you guys are making it work. Thanks!
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post #9 of 14 Old 05-12-2013, 03:03 AM
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Has the Mrs considered the smell of stale popcorn getting in the theater's fabrics, and the fine film of air born oil that can coat surfaces and the screen over time?

Recessing the beam into the joist cavity, would be money very well spent, in such a spacious room.
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post #10 of 14 Old 05-12-2013, 04:22 AM
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+1. Don't junk up the theater with a snack bar with a noisy fridge and popcorn oils settling everywhere.

In my situation, recessing the beam was a $6300 proposition. Elimination would be nice, but not $6300 nice....


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post #11 of 14 Old 05-12-2013, 07:59 AM - Thread Starter
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I'm hoping the popcorn machine will be purely for looks. My original idea had a hallway and area separate from the theater for that stuff. Now that the hallway is gone, I need to figure out how to put some of her wants in the theater. My hope is to get by with a mini candy bar and a non operating popcorn machine. Basically, as little as possible but enough to keep the project a go. Thanks for the advice and suggestions.
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post #12 of 14 Old 05-12-2013, 06:18 PM
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Is the door location fixed? You could have a hall, and a small snack bar area, and recess the av rack if this entry location works.

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post #13 of 14 Old 05-12-2013, 08:45 PM - Thread Starter
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Yes the door location is fixed. The small area on the left has three cement walls so no real access. The rear of theater has another 5 ft behind my proposed wall, but it has drainpipes water pipes, etc. and support poles. We're going to use that for a small storage area. I'll take some pictures this week to give everyone a better visual.

If I kept the area on the left open does that cause any acoustical issues as the room would no longer be a rectangle? I would probably extend the right wall to enclosure an equipment room and possible column for surround speaker depending on the seat placements. Does that make sense?
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post #14 of 14 Old 05-13-2013, 10:14 AM
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This beam doesn't seem so bad to me. When I started my theater, I had a support beam that was only 5'11" off the floor cut across the room right in front of the entrance. I'm 6'1". I had to duck just to get into the room. That sucked. smile.gif

Fortunately, I have a good contractor who carved a new entrance for me.

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