topic Re: custom roof help needed in Modeling

custom roof help needed

Anonymous — Tue, 23 May 2023 12:56:51 GMT

Hi can any help me build a custom roof , i need to create a sloping floor for a theatre and cant for the life of me work it out , any help greatly appreciated.

Re: custom roof help needed

Dwight — Tue, 11 May 2010 12:25:58 GMT

Investigate the Complex Profile

Eric Bobrow's fantastic article, yet again

Re: custom roof help needed

Anonymous — Wed, 12 May 2010 15:55:54 GMT

Dwight's right (as usual).

Use profiled walls to do the stepping. This allows them to curve (as most theater seating does).

Attached is a screen shot from an early schematic model I happen to be working on right now.

Re: custom roof help needed

Erika Epstein — Wed, 12 May 2010 16:22:47 GMT

Matthew,
Very nice model.
What is an SOG?

Re: custom roof help needed

Anonymous — Thu, 13 May 2010 01:07:20 GMT

Erika wrote:
Matthew,
Very nice model.
What is an SOG?

Thanks. Of course it's very preliminary. It'll be much better when SD is finished in a couple of weeks.

SOG = slab on grade

Re: custom roof help needed

Dwight — Tue, 25 May 2010 17:30:50 GMT

Matthew wrote:
Erika wrote:
Matthew,
Very nice model.
What is an SOG?
Thanks. Of course it's very preliminary. It'll be much better when SD is finished in a couple of weeks.

SOG = slab on grade

SOG = Sonovagitch

Re: custom roof help needed

Anonymous — Wed, 21 Jul 2010 02:34:53 GMT

Hello Matthew,
I am curious about something.
In your image you call out a sloped SOG.
I wonder how steep a slope is practical
for concrete work. I have not sloped form work
more than maybe five degrees and wonder
how steep the form work can be before the concrete
just keeps slumping and cannot be held in place
until it kicks off. I am contemplating a sloped frost wall
with a sloped top surface and wonder how much of a slope
I can get away with.
Thanks,
Peter Devlin

Re: custom roof help needed

Gerald Hoffman — Thu, 22 Jul 2010 21:31:08 GMT

Peter, I have done a sloped conc roof slab at 6/12 pitch. The crew managed to pour it OK. I am not sure what special techniques they used if any. Picture is too big to post so here is a link. There are 2 pictures there and in one of them I have put a light oval around the sloped slab in case you couldn't find it.

http://picasaweb.google.ca/lh/sredir?uname=gerald.hoffman&target=PHOTO&id=5496842324775204370&aid=5496841530401436305&authkey=Gv1sRgCPX59om9sJOBmQE&feat=email

Cheers,

Re: custom roof help needed

Anonymous — Thu, 22 Jul 2010 21:43:56 GMT

Hello Gerald,
Thanks for posting back.
A 6 in 12 pitch is fairly steep considering
that water and concrete flow down hill.
I'm sure the crew had to use some special
techniques. Why did you think this was possible
and thus specified this in the plans ?
Thanks,
Peter Devlin

Re: custom roof help needed

Gerald Hoffman — Thu, 22 Jul 2010 22:38:08 GMT

Peter,

I had actually specified this to be framed with wood but the Structural Eng wouldn't go for it in this area so it got changed to concrete. I had seen concrete applied to the top of CMU gable end walls in the Caribbean. They top off the wall with concrete to fill in the notches along the top of the staggered blocks as well as an additional 8" deep bond beam above that all sloped. Some of the roofs were at least 9/12 or so so I just assumed it would be OK for my 6/12 roof.

Maybe its better sometimes when you don't know if it can be done or not. It worked out OK. I could ask the crew what they did if you would like the information.

Re: custom roof help needed

Anonymous — Thu, 22 Jul 2010 23:17:04 GMT

Hello Gerald,
Thanks for your reply.
If it is not a trouble, I would like to know
how the crew did this. Thank you.
Peter Devlin.
P.S. What happened to rumplestilskin in a tub ?

Re: custom roof help needed

Anonymous — Fri, 23 Jul 2010 22:45:11 GMT

Peter wrote:
In your image you call out a sloped SOG.
I wonder how steep a slope is practical
for concrete work. I have not sloped form work
more than maybe five degrees and wonder
how steep the form work can be before the concrete
just keeps slumping and cannot be held in place
until it kicks off.

I'm not sure of the limits to sloping concrete. In the theater we aren't going much over 1 in 12. We're actually topping over an existing sloping slab. The project is in schematic design phase so I'm not too concerned about means and methods.

I used to work with Terra Dome who place monolithic concrete over a curved fiberglass custom form. Depending on the structural requirements I imagine that you can adjust the slump and maybe add accelerants to minimize flow.

You might want to check with engineers, contractors, concrete manufacturers and testing agencies for more reliable advice.

Re: custom roof help needed

Anonymous — Fri, 23 Jul 2010 23:16:02 GMT

Hello Matthew,
Thanks for posting back.
I know a man at the American Concrete Institute.
I think I will give him a call. Thanks for the suggestion.
Peter Devlin

Re: custom roof help needed

Anonymous — Mon, 26 Jul 2010 18:23:00 GMT

I talked to a man at the Portland Cement Institute
about how sloped concrete is done and he told me
the following. Basically, it is the water content of
the mix. At significant slopes the the mix must be very
dry (2" slump or less) making the concrete quite stiff .
If the concrete is four or five thousand psi it does not
have to be consolidated though it is not as strong as
if it were consolidated. He told me that slopes of
75° or more can achieved.
Thank you,
Peter Devlin

Re: custom roof help needed

Anonymous — Tue, 27 Jul 2010 17:28:27 GMT

I used to work construction on water diversion projects. We poured concrete at 70-80 degrees (90 being vertical). You just need a lot of reinforcing to hold the mud and a very dry mix.

Think swimming pools.

Re: custom roof help needed

Gerald Hoffman — Wed, 28 Jul 2010 02:29:52 GMT

Peter,

I finally got in touch with the concrete fellow that did the roof section that I was talking about. He said he used a slightly dryer mix but also was able to cover the top over with 2X6's and worked up the slope closing the concrete in as he poured uphill. In this case the upper surface of the concrete would not be exposed so it didn't matter if it didn't look perfect.

Cheers,

Re: custom roof help needed

Anonymous — Wed, 28 Jul 2010 15:42:18 GMT

Hello Gerald,
Thanks for the research and posting back.
As you can see I did some research myself
and posted some information about this issue.
Thanks,
Peter Devlin