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Discussion Starter #1 (Edited)
Currently for the HT ceiling - I have 3 layers of 5/8” DW (DW+GG+DW+GG+DW) suspended from my ceiling joists (10” I think) via whisper clips and hat channels. The Room is about 13.5x24’ (13' side to side, 24' front to back) and the ceiling is separated in 3 parts:
(1) the right most is about 9.5’ wide of DW+GG+DW+GG+DW
(2) to the left of that is a 2.5’ wide U shaped enclosure (DW+GG+2x10 + GG+DW) on both sides & DW+GG+OSB+GG+DW on bottom) surrounding the waste pipe going from front to back.
(3) far left 1.5 feet of DW+GG+DW+GG+DW
All of this is supported by the ceiling joists
My wife would now like to replace the current hardwood and put tiles on the room above the HT. A couple of years ago I paid for a structural engineer to know how the joists could hold the weight and he said that they are basically at their safe limit - thus tiles would be too much weight for the joists. So my question is how to retrofit my HT without too much aesthetic sacrifices (though my HT is not so pretty anyway).
My thoughts:
• Put (4) 4x4’s along the right wall (front to back) with a 2x6 on top – I think that I can adequately hide this.
• (4) 4x4’s along the “U” enclosure – on the sides of it to directly support those 2x10’s
• (2) 4x4’s with 2x10 on top of them spanning from back to front except for the first 5 feet (putting a post there would block the image projection from the FP)
Let me know your thoughts
and anything I'm missing
Pictures added showing each of the 3 sections to show what I mean I didn't know how to make beams showing perspective so I drew via multiple red lines, vertical red = new 4x4 columns (forgive the mess in the room)




edit - Jan 3 - slightly corrected measurements
 

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Pay the structural engineer for an updated evaluation of the load and your plans? Since the tile is spread out it may still be within load spec. Much easier than redoing your HT ceiling, if you get the go-ahead.
 

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You probably have more weight to consider than just the tile. Unless the floor was designed for tile to be installed, it will likely have too much deflection, which will cause the grout lines to crack. This is usually the case any time that you are putting tile on a wood floor. This is generally fixed by adding a layer of plywood or OSB over the existing subfloor. Then you install a layer of thin-set and cement board or other suitable backerboard, followed by another layer of thin-set and the tile. That's a good amount of weight, especially if your existing ceiling has already maxed out the load carrying capacity of your joists.

I'm not sure that I am understanding your plans. Are you suggesting building a structure with what amounts to new joists built UNDER the existing ceiling? Before anyone can reasonably answer your questions, you may need to provide a more detailed plan with diagrams. You may get some suggestions, but you'll likely need to hire a structural engineer to get valid answers that you can rely on.

Are you suggesting that your structural engineer is a jerk if he charges you for new work? Why wouldn't he charge you? The only way to get an answer is to put in the work and do the calculations. No structural engineer is going to "eyeball" a proposed solution and say "yeah, that will probably work" without doing a full detailed analysis.
 

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I missed that last comment by the OP about the engineer requiring payment. I'd most definitely expect him to require payment!
 

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Discussion Starter #5
I take back the "jerk" comment - I thought he would have all of my info in his computer and be an easy thing to answer such that many would give it gratis- I see that was my ignorance and it's more involved than that
re: plans- yes I am looking to put joists UNDER my existing ceiling (in places that I can hide)
 

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I take back the "jerk" comment - I thought he would have all of my info in his computer and be an easy thing to answer such that many would give it gratis- I see that was my ignorance and it's more involved than that
re: plans- yes I am looking to put joists UNDER my existing ceiling (in places that I can hide)

Not sure this makes a difference, but this is an interesting concept to me. Are you looking to support the clip/channel suspended ceiling to relieve weight from the overhead joists, or add additional joists?
 

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Discussion Starter #7
Not sure this makes a difference, but this is an interesting concept to me. Are you looking to support the clip/channel suspended ceiling to relieve weight from the overhead joists, or add additional joists?
Looking to relieve weight from the overhead joists so that they can support weight from new tiling in room above (via adding post+beam below the ceiling)
 

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Think a discussion with an engineer would be prudent. There are a ton of questions here that are hard to answer from the pictures provided

Which way does the joists run? If the new beams added do not pick up the existing joists, they will not perform much good

Are you planning on cutting back the drywall sandwich to get this structural member to pickup the existing joists? If not this is not going to pick up much load and will couple the ceiling removing a lot of the work you did to put in chanel/3 layers DW

Adding more structure to existing walls will not appreciably affect the span of the existing joists. unless the built walls are just partition walls. You will reduce the span 6-8" which will gain some in the l/360 or l/720 for the tile above, but not much in the way of load.
 

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How would shoring up the edges of the clip-channel-drywall assembly remove any appreciable weight from the joist ? What you are suggesting to do would be the equivalent of only hanging your entire ceiling on clip at the edges of your room . The channel cant support that load across a 10' span supported only at the edges , so if you do as you are suggesting the majority of the weight will still be on the clips attached to the joist .

Get quotes on tile , and the cost of a structural engineer , and any work that will be needed , then see if your wife decides the cost is worth getting the tile . No one here is going to be able to provide what a structural engineer at your house will be able to .
 

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Discussion Starter #11 (Edited)
Which way does the joists run? If the new beams added do not pick up the existing joists, they will not perform much good
Are you planning on cutting back the drywall sandwich to get this structural member to pickup the existing joists? If not this is not going to pick up much load and will couple the ceiling removing a lot of the work you did to put in chanel/3 layers DW
Adding more structure to existing walls will not appreciably affect the span of the existing joists. unless the built walls are just partition walls. You will reduce the span 6-8" which will gain some in the l/360 or l/720 for the tile above, but not much in the way of load.
Correct the existing walls are just partition walls, all of the weight of the 3xDW ceiling is on the existing ceiling joists
The existing ceiling joists run parallel to the proposed new under ceiling beams
The proposed idea is to not cut away at any of the existing DW, thus not touching or directly support the existing joists, but instead relieve the burden placed on those existing joists by providing a support wall on both sides for the DW weight to rest on

BTW - correction the span of DW is 9.5' (not 10' as previously mentioned) - thus after accounting for the new (2) 4x4's- would have a 9' gap between the new supports
 

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I doubt that trying to support an already built ceiling with new joists under it will pass muster for a number of reasons. It just isn't a workable plan.

What supports the middle of the ceiling? That's where all the weight load is.

You can't just put beams or joists under the existing ceiling. You'd have to jack up the ceiling so that the weight was actually lifted and setting on the beams or joists.

A structural support needs to be mechanically tied to whatever is is supporting. There is no way of attaching new beams or joists below existing drywall.

What us directly under the posts that you are proposing? Whatever is there has the carry the weight downwards all the way to the ground. If it on a concrete floor, you would likely need to jackhammer out sections of the floor and put in new footers for the structural strength to carry the weight. If it is a wood framed floor, you can't just put support posts on top of the floor. The load needs to sit on load bearing members.

Any plan that is workable would likely involve removing the flooring from the floor above to expose the structure and sistering and reinforcing the joists, then reinstalling the floor.
 

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Discussion Starter #13
I doubt that trying to support an already built ceiling with new joists under it will pass muster for a number of reasons. It just isn't a workable plan.

What supports the middle of the ceiling? That's where all the weight load is.

You can't just put beams or joists under the existing ceiling. You'd have to jack up the ceiling so that the weight was actually lifted and setting on the beams or joists.

A structural support needs to be mechanically tied to whatever is is supporting. There is no way of attaching new beams or joists below existing drywall.

What us directly under the posts that you are proposing? Whatever is there has the carry the weight downwards all the way to the ground. If it on a concrete floor, you would likely need to jackhammer out sections of the floor and put in new footers for the structural strength to carry the weight. If it is a wood framed floor, you can't just put support posts on top of the floor. The load needs to sit on load bearing members.

Any plan that is workable would likely involve removing the flooring from the floor above to expose the structure and sistering and reinforcing the joists, then reinstalling the floor.
thanks for the info:
The floor is concrete (with a floating laminate on top)
So I'd need to add beams across also - as shown in pic below:?

 

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Yes, to support the weight of the ceiling, you would need to add joists as you drew into your picture. All of the other concerns would still apply.

The fact that your floor is concrete does not mean that it can support a load. Concrete floors are only a few inches thick and are only designed to support the weight of people, furniture and normal household objects. They are not designed to support the weight carried by a load bearing support column (post). This could crack the concrete and literally punch through the floor like this picture that I found in a quick Internet search.



You need to have a reinforced footer that is designed to support the load, like this picture.

 

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Discussion Starter #15
Yes, to support the weight of the ceiling, you would need to add joists as you drew into your picture. All of the other concerns would still apply.
The fact that your floor is concrete does not mean that it can support a load. Concrete floors are only a few inches thick and are only designed to support the weight of people, furniture and normal household objects. They are not designed to support the weight carried by a load bearing support column (post). This could crack the concrete and literally punch through the floor like this picture that I found in a quick Internet search.
You need to have a reinforced footer that is designed to support the load, like this picture.
Thanks!
Though how do people make a room within a room (Which I assume fully supports the weight of the ceiling without any attachment to the ceiling joists of the house) , don't they run into the same problem and break the foundation?
 

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Thanks!
Though how do people make a room within a room (Which I assume fully supports the weight of the ceiling without any attachment to the ceiling joists of the house) , don't they run into the same problem and break the foundation?
I think the big difference is the concentrated load of a support column versus a distributed load. In room within a room construction resting ceiling joists on an entire free standing wall distributes the weight.
 

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I think the big difference is the concentrated load of a support column versus a distributed load. In room within a room construction resting ceiling joists on an entire free standing wall distributes the weight.
Adding to this, in a room-within-a-room has no connection to the structural ceiling or floor structure of the floor above. Your situation is complicated by the fact that that your ceiling is already supported by the joists in the floor above. You can't just put new joists under the drywall and expect them to carry all of the load, leaving no weight hanging on the existing joists above. Determining and adjusting how much weight was carried by the joists under and the joist above would be impractical, if not impossible, especially over time as things settle.

If you want to carry more weight to the floor above, you need to do it the right way, which is to sister the existing joists. The link below explains how it is done. But in your situation, you can't easily access the joists from below. You could do the same procedures, but from above, by removing the flooring and subfloor to gain access from the top. You would need access to the entire span of the joists. If there are any walls in the way in the middle of the span, you likely wouldn't be able to do it without removing those walls. The alternative is to remove your triple drywall ceiling and go at it from the bottom.

http://www.hammerzone.com/archives/framecarp/supplement/floor/joist1/sister.htm

Backing up a bit, how big of an area do you want to tile? Is it a small bathroom or a large room that spans the whole space? Calculate the amount of weight that could be removed by taking out the hardwood floor, and how much would have to go in to install the tile floor. If it is a small bathroom, the weight delta might only be a few hundred pounds.

www.tinyhousecommunity.com/docs/weights-building-materials.pdf
 

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Discussion Starter #18
Sorry for the lag in response.
IF I were to demolish the existing ceiling (as it seems that providing new support is not really an option) - also high chance of us moving and thus the tiles upstairs will really show the house better/increase resale value (this will also give me the chance to build another HT in the new house :) )
Anyway, IF I were to tear down the ceiling - how would I do that as the ceiling is DW+GG+DW - so even if I were to locate the DW screws in the outer layer DW - it's glued to the 2nd (inner DW) which is screwed into the hat channels (which is attached to the clips to the joists - so how do you tear that down?
 

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cut it with a reciprocal saw into small 18x18inch (or so) chunks and you should be able to rip the few screws out the channel if you hang on it. Be sure not to slice the bottom of the joists once you figure out where they are. Be prepared for a really dusty project,
 

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An alternate would be to use a high quality Vinyl tile, sometimes abbreviated as LVL. Before you/your wife discount this as some crappy linoleum take a look at some and see what you think. It would be a lot easier to install this tile than to rip up your entire theater ceiling.
 
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