Modular CMU Construction - Rough Opening Size For Double Door 2

[JoelTXCive]

Remember...the only dumb questions are the ones not asked...

If I'm doing a double 6-0 by 7-0 steel door in a CMU wall, then what would my rough opening dimensions be?

I know the rough opening height would be 7-4, but what about the width?

The next modular width is 6-8, but that seems too wide for the jambs? Maybe a double 6-0 is not truly 6ft wide? Don't they need room for the jambs and possible t-astrigal?

Thank you in advance!

-Joel

 

[masonrygeek]

The easiest way to remember modular masonry is that if the "foot" value is odd, then the "inch" value must be 4" (eg. 7'-4"). If the foot value is even, then the inch part must be 0" or 8" (e.g. 8'-0"). Although you can find out about modular dimensioning of concrete block here:

https://ncma.org/resource/modular-layout-of-concrete-masonry/,

BIA has some better charts:

https://www.gobrick.com/docs/defaul...ng-and-estimating-brick-masonry.pdf?sfvrsn=0.

 

[GC_Hopi]

Here what a door supplier told me.
 7’-0” Door in Masonry Wall – 4” Heads & 2” Jambs
 8’-0” Door in Masonry Wall – 2” Heads & 2” Jambs
 All Doors in Gypsum Stud Walls – 2” Heads & 2” Jambs

 

[JoelTXCive]

Thank you, those are good responses.

I'm comfortable with the modular layout. My question is what would the rough opening be for a DBL 6-0 door, which I think is a somewhat common size.

I just received a mechanical sheet with that size door called out, so I need to know if I should tell the mech engineer that they really need a DBL 5-8 (really two 2-10's), or if they can stay with the DBL 6-0.

 

[XR250]

Perhaps it does not need to be modular? It is nothing for a mason to cut the blocks as needed. I'd put it in the GC's court.

 

[JLNJ]

Six-oh doors will require some cutting of block (2" frames). No big deal.

 

[dik]

Are the jambs 2" or 1-1/2"?

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[GC_Hopi]

IMHO, it is worth informing the mech engineer that a modular door would be lower cost and have a better install. Here is a documentation from NCMA Link

 

[jayrod12]

Except if the door ends up needing to be custom ordered the costs of that versus a nice modular opening are likely a wash versus an off the shelf door and cut masonry for a random opening.

I've stopped trying to get architects on board with modular opening sizes, or modular lengths of stairwell walls. I just let them do their thing. The good ones pay attention, most don't.

 

[masonrygeek]

Jayrod, don't give up! If you let them slide on this, then they'll start doing other things that annoy engineers. There is a cost to cut block and to install them and it may include more jobsite wsste, more dust (hopefully not), etc.

 

[jayrod12]

Oh I agree with all the benefits of modular design. I'm just tired of wasting air telling them how beneficial it is only for them to say "It didn't fit the layout/vision." Owner's don't care because the couple of bucks here or there to cut block to suit their desired layout isn't enough to make it worth it. Sad really, but it's the reality I face.

 

[GC_Hopi]

Well at least it is documented and if is comes back to you as a field issue you can point to the email and charge the architect for the rework/wasted time responding to an RFI. I know engineers dont like to do this but I think it should be the standard since as masonrygeek said there is a cost and maybe that will open the architect's eyes.

 

[dik]

Joel... a BPS for the neat thread...

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[WinelandV]

Not specific to doors in CMU, but an architect sent me the following document that he found for minimum rough openings.

From his email, he did note that the contractors that he works with will go with an 88" tall opening for CMU walls.