New Opening in Existing CMU Wall - Headers

[Revv]

Hey Guys,

Yesterday I asked about jambs for a new opening in an existing CMU wall and it brought several different methods that were used, so thought I would also ask about headers and see what is being used for headers on new openings in existing exterior CMU Walls, and do you do anything for your sill on windows?


Thanks!

 

[JedClampett]

I usually shore the CMU some distance above the opening, for a length of the opening plus, maybe 32 inches. Then I install a W8 lintel and pack in grout or mortar for solid contact. I've also seen a couple of C8's through bolted above the opening. That's a lot uglier, but much, much easier.
As far as the sill, that's an architectural and weatherproofing detail.
I'd look at the NCMA TEK notes. I don't think they have any details for cutting openings, but they have scads of details for the final installation of windows.

 

[driftLimiter]

Similar to the double C8 that @JedClampett mentioned, you can use two angles that are coped at the ends to get a more compact arrangement.

When we have seismic there can be substantial out of plane bending and anchorage component that needs to be included.
If placing the steel headers on the face of the wall, I carry them a distance beyond the new opening. Determine the distance using #of required bolts, out-of-plane strength of existing wall (bending and axial included). That approach might not work for heavy loads, large walls/openings, so in these cases I look to use a steel jamb that goes to the next level up and anchors into the diaphragm take the axial and out of plane bending. If you are working with existing wall for seismic, then I try to size the jamb post to have a similar displacement out of plane to that of the existing wall expected during and eq.

 

[Roukkia]

drift - why cope the ends of the angles? why not install the angle into the bed joint so then it is a bearing connection to the masonry?

 

[WinelandV]

Roukkia,

I would venture that chiseling out the mortar in the existing wall is not something most contractors would have put in their quote.

Please note that is a "v" (as in Violin) not a "y".

 

[dik]

How large an opening? big? or small? and is the wall loaded?

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

-Dik

 

[driftLimiter]

@Roukkia Like I said I typically see large Out of plane loading on the header and I there are two reasons I don't like that detail. 1) Compromise vertical section for out of plane loads, and 2) No positive anchorage of the header for out of plane loads either.