New Opening in Existing CMU Exterior Wall, What do you do for your jambs? 1

[Revv]

Hey Guys,

So basically I am cutting a new small window into an existing CMU Wall, how do you usually account for your jambs in this situation? Only about a 12-15' wall and 4' wide window so not very heavy loads.

Thanks!

 

[DaveAtkins]

My hunch is it will be OK. Is the wall reinforced? If so, the nearby reinforcing should be able to pick up the additional wind load from the window jamb.

You need to do the calculations. If it doesn't work, you can break open the face of the CMU and add rebar. Or bolt a steel member to the inside of the CMU.

DaveAtkins

 

[JedClampett]

If the walls (or jamb area) aren't solidly grouted, I add the reinforcing and solidly grout the jambs as DaveAtkins said.
[ul]
[li]Is it difficult? Hell yes![/li]
[li]But what are the contractors going to complain about? The Weather?[/li]
[/ul]

 

[driftLimiter]

I agree with JedClampett here. If the walls are grouted then I extend the new header system past the opening by a length that Is reasonable to distribute the load. Another option I have done is to bolt channels to the face of the wall and use that as a jamb.

 

[LTBGeek]

We ask for the contractor to grout the jambs solid, but we don't typically ask for them to be reinforced if they aren't already.

 

[Standard American]

We always call out (1) #5 in the first two cells adjacent to the new opening on each side to be drilled and epoxied into the footing and tie beam/bond beam then grout those cells. I'm in a high wind area so maybe you only need (1) grouted cell for out of plane load.

 

[driftLimiter]

How are you guys proposing to install vertical reinforcement in the jamb for a window cut out of an existing wall? I can visualize using a form edge to grout the jamb, but what about anchoring the rebar? I have never done this in an existing setting. Are you suggesting to hog out the wall wider than the opening so you can build a new jamb altogether?

 

[Standard American]

You just saw cut the face shell on one side of the wall. Drill and epoxy your dowels in, splice your new bars on your dowels then form it up and pour it.

 

[GC_Hopi]

Yep, standard practice for strengthening unreinforced masonry walls. You dont have to cut a full height slot if the contractor is good they can use a intermittent slots. Like cleanout in high lift grouting.

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