Furring Best Practice

[sbrown]

I have a CMU Building - rather large 170,000sf convention center. The exterior walls are 12" cmu with various exterior finishes(diff. wall type for each). So on the inside I'll need to furr out the walls with 2 1/2 mt. studs and gyp. Now I can build this into each wall type. But then I can't tag it separately. Or I can draw it as sep. parallel walls. and join them with the exterior wall.

there are pro's and cons to each approach. I'd like to get a sense what others are doing.

The biggest pro's of sep. furring

1. easy to vary the height of the furring at diff. ceiling conditions.
2. Tag as sep. interior wall type.
3. Easy to switch interior finishes.
4. Easy to isolate as interior wall vs. bearing wall.
5. If model gets too big, ID can be grouped/linked.
6. Ceilings and floor finishes can be based on the furring wall instead of the struct. wall.


The biggest cons
1. Drawing 2 walls,
2. align and lock or make sure when changes occur the walls are updated.
3. Join Geometry with parallel walls.

[gwnelson]

FWIW - I've usually chosen the furring as new walls. More time consuming as you note, but more control.

[twiceroadsfool]

FWIW - I've usually chosen the furring as new walls. More time consuming as you note, but more control.

We do them as seperate walls. Its worth the hassle, all things considered. I DO (however) wish that when two walls were joined, each element HOSTED on one of them gave you the option:

1. Treat joined hosts as one element
2. Treat joined host as seperate (use original host)

For things like door frames that wrap, etc. If theyre Masonry frames its a non issue, but in some other cases it can be a little irritable.

I also think when drawing walls we should be allowed to set it to NOT JOIN at ENDS, WHEN WERE DRAWING it. Go to draw the furring at a corner, and watch it join and mitre in to the outside walls. God, thats annoying, LOL.

But yeah, two walls.

[gwnelson]

And having to create an opening in the furred wall for existing windows instead of being able to double-host.

[sbrown]

Yes, I don't like that when you reach a corner it tries to join. I'm thinking its best to draw the walls away from the shell wall, then align and lock?

[cliff collins]

Just thinking about how finishes will be applied to the "inside face of the outside/furring" walls?

For the envelope/openings it makes sense to build the "two walls" way.

However, now I have my linked ID model and I need to place a thin "finish wall"
over the gyp. furring--but it's in the Shell & Core, so I can not join geometry.

How is everyone handling this?

Seems there are trade-offs in either scenario.

cheers....

[jhs.222310]

how would you get the internal finish wall to wrap properly into openings and reveals cut by doors etc? - alter the model to have the finish in the door/window insertion family?

[twiceroadsfool]

Just thinking about how finishes will be applied to the "inside face of the outside/furring" walls?

For the envelope/openings it makes sense to build the "two walls" way.

However, now I have my linked ID model and I need to place a thin "finish wall"
over the gyp. furring--but it's in the Shell & Core, so I can not join geometry.

How is everyone handling this?

Seems there are trade-offs in either scenario.

cheers....

We dont break up the model that way, so its a non issue for us.

As for existing walls and new furring, join geo still works to cut out existing window openings. I just finished a reno job that way...

[cliff collins]

Aaron,

So you dump all the Interiors into a single model?

We can not do that due to the size/complexity of our projects.

Our current ID model, at DD level of design, compressed and purged, is 106 MB.
The Shell/Core is 85 MB
Then add in Structural and MEP. blah blah blah......

File size dictates, as well as our workflow with Architects and ID staff.

So--with separate models, we put the Finishes in the ID model.

Scott gave a good presentation at AU on this--which gets the discussion going,
but also leaves some things up in the air, like the situation raised in this thread.
Scott had 3 different scenarios, each with advantages/disadvantages.

I'd be interested to hear how others are handling this on large/complex jobs.

cheers........

[sbrown]

I would think your ID model wouldn't need the thin finish. The benefit of the furring is I will make multiple furring walls with diff. finishes. So I would edit the walls in your ID model to include the finishes.

[pwmsmith]

Scott,

I have tried both methods and when its a combined single wall you start drawing and you come to the trash room and it does not have furring so you change walls and start again, and on the other side of the trash room you change back and you come to the stair tower and it does not have furring, so you change wall types and.........(never seems to end.)

On most projects I have gone to the separate wall system.

Pat

[twiceroadsfool]

I would think your ID model wouldn't need the thin finish. The benefit of the furring is I will make multiple furring walls with diff. finishes. So I would edit the walls in your ID model to include the finishes.

I think Cliffs point was he cant Join Geometry the Furring/finish with the Shell wall, to get the openings in to them.

And Cliff-

Just because i said the Int and the Shell are in the same model, doesnt mean im saying its "all in one model."

Structure is always seperate for me, as is MEP. And if 189 MB is too big combined, then id start breaking the model up by geography. Im not saying everyone has to do it that way, but thats the way i would do it. <shrug>

Ive done some pretty large complexes with models broken up by geography, and we had nary a problem that way.

As for "staff workflow..." I mean, i can say i have staff who draw plans and staff who draw details. But im not going to put them in a seperate model because thats how the staff thinks it should go. :)

[SCShell]

Hey Scott,
I have always modeled them as separate walls.
Main Reasons:
The furring's ht. can be controlled separately from the masonry without unlocking etc.
Scheduling and tagging
If and when I need to export to a cost est. program, they will show separately.

Just a few off the top of my head
Steve

[sbrown]

Yes, for the exterior windows and doors, you have to add an opening family. Typically Interiors would be adding trim, so make a generic model -wall hosted trim family with the opening in it that you can add to the walls for all exterior window and door openings. Then align and lock them to the centers of the doors and windows, or manual move as required.