3+" thick T&G?

dwminnich

New User
Dave
I'm going to be working on a project at church hanging a couple of 100 lb. TVs in the sanctuary. The building is an A-frame type structure built in the mid 1970s with large glue-lam rafters (probably 6"x18"s) as the visible support element. The visible ceiling surface is made of tongue and groove boards. My first thought was that this was either 1x6 t&g applied to the underside of some other ceiling material or something like t&g car decking applied on top of the rafters. If the latter, then the t&g would be part of the structural support of the roof instead of just ornamentation. For a number of reasons I can't just hang the TVs from the rafters, so it's important to understand the structure of what's behind the ceiling

I am trying to figure out a non-destructive way to determine which of the two alternatives (or something else) I'm dealing with. Any thoughts?

Also, I'll get another look at it later in the week, but since I was in the building last, someone else took a look at the ceiling and thinks the t&g might be 3-3.5" thick! Anyone on the forum familiar with this sort of church ceiling construction? Could that actually be possible? If so, is there any way to non-destructively confirm that's what we might be dealing with?

Thanks,

--dave
 
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Oka

Casey
Corporate Member
Well, hmmm, Likely is it 2x T&G if the distance between the supports is greater than 24". Assuming that is so, you could either add an additional board (stringer) to the under side that would span between the 2 rafters, or you could add a piece of 3/16-1/4" flat stock steel pre tapped to attach the TV bracket to, same width as the wood, rafter to rafter. By doing so, you can add a number of screws with 1" penetration in to the rafter to attach the bracket or wood. If you decide on wood, then I would recommend Maple or Oak. Most TV's to day are 45-60 lbs (my 70" was 58 lbs). The reason for adding a bracket or wood stringer, is to allow additional fastenters to the existing structure. Since you do not know what you are really dealing with then overkill is recommended. This is the easiest wayto accomplish this
 

dwminnich

New User
Dave
Thanks, your reply made me realize I left out a couple of crucial pieces of information. First, those 6 x 18 rafters are spaced 16 feet apart (that’s not a typo). So, I suppose that maybe it’s not unreasonable to expect that they might have used really thick car decking up there. I did find some web pages advertising 3 and 4 inch thick by 6 inch wide car decking. It just seems like a colossal waste of wood to have done it that way.

Secondly, I do appreciate the thoughts on how to solve this but that’s not really the point of my question. I can come up with ways to do it given any particular implementation of the ceiling, but I really need to figure out how that ceiling is constructed.


Sent from my iPhone using Tapatalk
 

Oka

Casey
Corporate Member
I see then I would guess what you are looking at is a false bottom. This is not the framing structure that is above. They probably framed it with 2x 12 or something like that, then decked the bottom with T&G, then added the rafter beams below to give the appearance that it is framed in an open ceiling way.

Think about it, what board can handle a 16 ft span on flat ? 8x or 10x 2x10 or 12 can but must be on edge.

Take a carefull look at the wall to roof connection that will help answer your questions.. Regardless how it is framed you will need a wide bracket to handle spread the load for the TV. As a safety rule, for a commercial building 1.6 safety factor min should suffice.





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Phil S

Phil Soper
Staff member
Corporate Member
It probably is an engineered laminated wood roof decking.

Attached is a PDF from Fuller King - a week known supplier for churches.
 

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Henry W

Henry
Corporate Member
I see then I would guess what you are looking at is a false bottom. This is not the framing structure that is above. The probably framed it with 2x 12 or something like that, then decked the bottom with T&G, then added the rafter beams below to give the appearance that it is framed in an open ceiling way.
....
Oka's description is exactly the way our church is constructed. The visible ceiling is NOT the bottom side of the roof deck, it is a 'false ceiling.' I never knew this until I heard the description of how wiring was run through that 18" (24"?) gap between the ceiling and the (steel framed?) roof. Mid-50's construction.
 

Gotcha6

Dennis
Staff member
Corporate Member
It probably is an engineered laminated wood roof decking.

Attached is a PDF from Fuller King - a week known supplier for churches.
We built a sanctuary like this in the early 70s using laminated column/rafter members and 4 x 6 t&g decking. Light conduits had to be routed into the upper face of the decking and gypsum sheathing applied directly over the decking with shingles over that. IT's entirely possible it could be built that way. A clue might be had in observing the gables and eaves to look at their alignment with the interior ceiling.
 

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