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Getting ready for the MPJ Theater build 2.0 at our new house and strongly considering digging a section deeper instead of doing a floating riser when you walk in. According to how the house is set up with support beams and layouts, this is the best plan I could come up with. My question is this: Instead of building a step up at the entrance of the theater then a step down inside the theater leading to the 1st row, is it possible to dig a section of the basement deeper where I wouldn't need to build a riser and the first row would have a total height of about 9 1/2 while the rest would be 8'? I don't mind the labor, I understand the muscle that will go into this digging but the end prize would be well worth it. Is this even possible or do I need to go back to square 1?
 

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Getting ready for the MPJ Theater build 2.0 at our new house and strongly considering digging a section deeper instead of doing a floating riser when you walk in. According to how the house is set up with support beams and layouts, this is the best plan I could come up with. My question is this: Instead of building a step up at the entrance of the theater then a step down inside the theater leading to the 1st row, is it possible to dig a section of the basement deeper where I wouldn't need to build a riser and the first row would have a total height of about 9 1/2 while the rest would be 8'? I don't mind the labor, I understand the muscle that will go into this digging but the end prize would be well worth it. Is this even possible or do I need to go back to square 1?
This is about the only thing in HT on this forum I feel fully qualified to comment on. I JUST finished up doing exactly this. A word of warning, it's hard. Here's an edited list I wrote from my thread with a few different details as it might pertain to you:

1 - Get an engineer to sign off on digging close to the footer if that's your situation. In some cases a person may need to do what's called a bench footing pour with the concrete. Google "bench footing basement" and it'll all make sense.

2 - You’d need to saw cut an area not only for the section for the first row of seating, but also possibly trench cut to a new sump pit location, as well as the sump pit itself if you go deeper than the current drainage tile/sump pit in the house. The new sump pit would be needed since this could become the lowest exposed section of the house once complete. If you do the saw cutting yourself, rent an electric one. Don't risk the gas one and poison yourself.

3 - You’d have to jackhammer out the entire area and hand-carry buckets of concrete out of the basement, OR (and this is what the pros would/should do…) you’d get a huge pneumatic saw with a power pack and cut lots of smaller sections, crow bar them out, and haul away the squares. There are some other options depending how close you might be to an opening, including renting conveyor belts.

4 - I had to dig and install a new sump pit, routed the discharge up the wall, and drilled a new hole in the concrete on the side of the house to get it out.

5 - I had to dig the whole floor down about 22-24” and fight the fractured bedrock the whole way.

6 - I had to jackhammer out the pier pours that weren’t supposed to be there in the first place underneath my slab. (60x60x18”) Not sure if you have anything like that hiding under there. (There would almost have to be one where your support column is.) Also, make SURE there isn't any pipe crisscrossing under the slab where you're digging down. Often, the cracks in newer homes in the basements follow where the pvc pipes are buried underneath.

7 - You’d need to pour 24”x8” walls around the perimeter and wait for them to be cured and waterproof them on the outside. (Plastic membrane, no big deal.)

8 - You’d need to do another radon gas test to make sure nothing was unearthed digging that extra 2 feet.

9 - Then you’d finish up with a bed of smaller gravel, a proper plastic mil sheet, drilled holes into the 2’ walls for the rebar, place the rebar on chairs, and pour the 4-5” slab on top. I ended up getting an extra 18" from it. Now that it's over, I'm glad I did it, but it will probably be 30% of the effort of your whole build.

If you want to see if my journey talks you out of it, see the link below. The part that you'll care about starts at post 307.

https://www.avsforum.com/forum/19-dedicated-theater-design-construction/2580921-cinema-midwest-2-0-a-11.html#post57354312
 

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I was looking for your thread and found it, came back and you already posted, I'll post a teaser pic, the OP should read your thread

It was a total coincidence. I rarely get Tapatalk notifications, and this thread title popped up. I was like, "Well, I pretty much have to answer this one." LOL
 

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Just curious. It seems you have a large area to work with and you didn’t mention how many seats you are trying to accommodate.

I would love such an area and if the seating count wasn’t going to be real high I would do a single curved row and a lower larger screen CIH or better yet CIH+IMAX.

Multi row with 8 or 9 foot ceilings limits screen size because the back row has to clear the heads and then with reclining seating the back row has to be set back more and the combination gives the second row poor immersion. The fix many times is a higher screen and then the front row suffers with viewing angle compromises.

With a single row IMAX immersion isn’t a problem even with 8’ ceilings and all seats get the same immersion. One drawback is the outer seats are a little off angle and not optimal for sound but sound balance for the second row can also be compromised.

The two biggest advantages for me would be it is a more social seating arrangement and most of the time if you are like me there is one-four people watching anyway. The main advantage for me would be IMAX immersion and no digging. That sounds like a lot of work not to mention cost.
:)
 

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Discussion Starter #9
There is no drain tile piping going into existing sump....only thing there is are holes at the bottom where you can see gravel so I guess there is no drain tile running along the foundation? If there is, I can move new sump over like this....otherwise I can have it even with current one where it's along the wall
3025658
 
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