Opinions on best way to drop a ceiling

[Thorfun]

Just now, pocster said:

Yes !

But with nice simple hammer in bolts and wire …

so it's still imparting a downward force on the beams above

[Thorfun]

1 minute ago, pocster said:

What’s the cost estimate for your ceiling ? Timber , pb , skim , paint ?

Your area slightly larger than mine I believe 

it's a small room about 5m x 3m so the costs for the MF ceiling is not that high on top of what i would pay for not dropping it.

[Pocster]

2 minutes ago, Thorfun said:

so it's still imparting a downward force on the beams above

Yes . Buts it’s f all . Wire is roughly every 2metres . Frame weighs f all . Tiles are lightweight and their load is spread over the frame and other wires .

[Pocster]

1 minute ago, Thorfun said:

it's a small room about 5m x 3m so the costs for the MF ceiling is not that high on top of what i would pay for not dropping it.

Thought you were doing the whole basement with a drop ceiling ?? - why just this 1 room ?

[Thorfun]

3 minutes ago, pocster said:

Thought you were doing the whole basement with a drop ceiling ?? - why just this 1 room ?

this is the TV room on the ground floor. basement comes much later. need to get the main house finished first. don't want to end up a lifer like you. 😉

[Thorfun]

6 minutes ago, pocster said:

Yes . Buts it’s f all . Wire is roughly every 2metres . Frame weighs f all . Tiles are lightweight and their load is spread over the frame and other wires .

are the tiles rated to take the weight of ceiling speakers?

 

the frame is probably the same weight as the MF ceiling tbh. i doubt there's much in it. so the plasterboard will be the main difference

Edited May 24, 2023 by Thorfun

[Thorfun]

i will try and phone Gyproc and see if they can give loading figures for the GL system.

[Pocster]

4 minutes ago, Thorfun said:

are the tiles rated to take the weight of ceiling speakers?

 

the frame is probably the same weight as the MF ceiling tbh. i doubt there's much in it. so the plasterboard will be the main difference

Don’t know . I , like you , will stick a speaker in and find out . If it’s an issue I’ll bolt some kind of timber support off my beam n block . For a “ tv room” I really wouldn’t worry about how the ceiling looks . Decent lights , nice speakers - who is really going to care or comment ? . Saves you tons of headache and gives you access to everything.

Edited May 24, 2023 by pocster

[Dave Jones]

24 minutes ago, Thorfun said:

so, for the dropped ceiling i guess i could look at completely decoupling the false ceiling but then that would add extra load on the TF and might cause those calculations to fail?

 

but i'm also asking for the rest of the downstairs as all the posi-joists are designed with the 200N/m² load on the bottom chord. so, from the way the guy was talking (although i think there might've been a bit of understandable arse covering going on) i wouldn't be able to double board anywhere.

 

ask them, its yet another drawback of this expensive build type...

 

would only be a days work to get it done, very simple. could even get some more pozi's to hang.

[Thorfun]

2 minutes ago, Dave Jones said:

ask them

this is an issue when the TF company no longer exists. i do have the SE calculations for the frame but would have to engage an SE to double check and that would cost money i don't have. so a decoupled timber ceiling will be my last resort to be honest.

[Thorfun]

7 minutes ago, pocster said:

who is really going to care or comment ?

SWMBO

[Pocster]

Just now, Thorfun said:

this is an issue when the TF company no longer exists. i do have the SE calculations for the frame but would have to engage an SE to double check and that would cost money i don't have. so a decoupled timber ceiling will be my last resort to be honest.

Shhhhhhhh . Framed tile system SE costs = 0 ( that’s less than 25 quid 😉 )

[Pocster]

1 minute ago, Thorfun said:

SWMBO

Yeah . Perfect answer . You’re doomed 

[Thorfun]

right, more maths required as BG technical support had finished for the day when i tried calling.

 

according to this data sheet the GL1 channels are 0.37kg/lm. i've calculated that i will need 18lm of the stuff. the room is 16.32m² and the GL1 channels will be spaced at 400mm centres.

 

anyone know how to calculate the downward force imposed on the bottom chord of the posi-joists per meter squared?

[Thorfun]

5 minutes ago, Thorfun said:

right, more maths required as BG technical support had finished for the day when i tried calling.

 

according to this data sheet the GL1 channels are 0.37kg/lm. i've calculated that i will need 18lm of the stuff. the room is 16.32m² and the GL1 channels will be spaced at 400mm centres.

 

anyone know how to calculate the downward force imposed on the bottom chord of the posi-joists per meter squared?

does this maths seem correct?

 

18lm x 0.37kg = 6.66kg / 16.32m² = 0.41kg/m²

 

if so, that's nothing! and so with those maths the MF ceiling won't add any extra load i just need to figure out if i can double board with 12.5mm PB and not exceed the 200N/m² maximum load of the bottom chord.

 

maybe i should post this in boffins corner so all the boffins see it? otherwise it's just me and @pocster bumbling through as usual.

[Pocster]

@SteamyTea is sad - this is one for him 

[TonyT]

50 minutes ago, pocster said:

Don’t know . I , like you , will stick a speaker in and find out . If it’s an issue I’ll bolt some kind of timber support off my beam n block . For a “ tv room” I really wouldn’t worry about how the ceiling looks . Decent lights , nice speakers - who is really going to care or comment ? . Saves you tons of headache and gives you access to everything.

Hang the speaker with a gripple hanger or something to take the weight

[TonyT]

1 hour ago, pocster said:

Yes !

But with nice simple hammer in bolts and wire …

Arghh.  No shadow gap!

a travesty🤪

[SteamyTea]

Just run it though a beam calculator and see what the deflection is.

[Thorfun]

23 minutes ago, SteamyTea said:

Just run it though a beam calculator and see what the deflection is.

The guy from the posi place said that the joist could fail if the load exceeds 200N/m² . That sounds scary. I might have been able to find the calculations used by the TF company though so will send that off to them and see what they say. 
 

it’s a shame Flight Timber went belly up for all those that lost money with them and also as they were always really quick to respond to queries like this. I don’t have that resource anymore and so I’m left to my own devices. 
 

im not sure what the beam calculator will show as I don’t believe it’s deflection that’s the issue here as the top chord load is 2060N/m² and we’re designed for 8mm deflection. But that’s the top chord. The bottom chord is designed for only 200N/m²

[Thorfun]

this is from the document showing the joist design I managed to find.

[Thorfun]

 

and this. anyone able to make heads or tails of it?

[Thorfun]

actually there are a lot more calculations that I posted above. here's a pdf for the joists in question.

 

joist_calcs.pdf

 

it's all Greek to me. I'm hoping someone can tell me what it all means!

[SteamyTea]

17 minutes ago, Thorfun said:

it's all Greek to me. I'm hoping someone can tell me what it all means!

One for @Gus Potter I think.

 

Had a quick look, Cord 1 and 1 (top and bottom) have similar dead loads at 210 and 200 N.m^-2, so that is 410 N.m^-2 for flooring and ceiling.

The there is the imposed load, which I think is point loading, at 1500 N.m^-2, which is 159 kg.m^-2.

My knowledge is lacking in that I do not know for definite what the imposed load it.  Seems from a very quick internet search that they are considered equal to impact loads.

 

https://eng.libretexts.org/Bookshelves/Civil_Engineering/Structural_Analysis_(Udoeyo)/01%3A_Chapters/1.02%3A_Structural_Loads_and_Loading_System

Edited May 24, 2023 by SteamyTea

[Thorfun]

1 hour ago, SteamyTea said:

One for @Gus Potter I think.

 

Had a quick look, Cord 1 and 1 (top and bottom) have similar dead loads at 210 and 200 N.m^-2, so that is 410 N.m^-2 for flooring and ceiling.

The there is the imposed load, which I think is point loading, at 1500 N.m^-2, which is 159 kg.m^-2.

My knowledge is lacking in that I do not know for definite what the imposed load it.  Seems from a very quick internet search that they are considered equal to impact loads.

 

https://eng.libretexts.org/Bookshelves/Civil_Engineering/Structural_Analysis_(Udoeyo)/01%3A_Chapters/1.02%3A_Structural_Loads_and_Loading_System

Thank you. I had a quick read of the link and will look into it in more detail tomorrow.