Vertical Cracks Starting At Junction Of Infill Wall And 1st Floor Beams

[YuleMsee]

Masonry infill wall was constructed and 6 months later this cracks that start at the junction of the wall and the soffit of perpendicularly running 1st floor beams have occured, 3 in no. all starting at a beam junction. Wall is natural stone masonry, 200mm thick

1st floor slab has offices with aluminium/gypsum board partions. Could the cause be the sagging of the 1st floor beams?

 

[milkshakelake]

Might be long term deflection of the 1st floor beams, or simply the live load. It looks like that infill wall was never meant to take concentrated gravity loads. Also, non-bearing walls should have a gap for deflection at the top. Without this gap, they unintentionally become load bearing members. CFS or wood partition walls can handle deflection a bit better because they're ductile (though the sheetrock/finish will still get damaged), but masonry is brittle. If it can't carry the load, it will crack.

I'd also verify if it's actually the wall being cracked. If it has furring and sheetrock attached, it might just be the sheetrock, not the wall itself.

 

[KootK]

Like MSL intimated, that's a pretty normal cracking pattern for any brittle material picking up an imposed bearing load. Load spread doing its thing.

 

[YuleMsee]

Follow up question, what would be the best method to fill those cracks after introduction of a flexible fill between the new wall and slab soffit

 

[milkshakelake]

For an infill wall that's not taking a lot of load, I wouldn't even worry about it. First thing for you is to measure the crack. If it's superficial, you won't be able to fix it anyway unless you remove and replace some masonry. Best thing is to use compound or joint sealant to seal the gap and paint over it. If the crack is more substantial, like 1/4", pack it with Type N mortar or non-shrink grout and then paint over it.

For the top of the wall, I'd put some kind of lateral restraint so it's not just a cantilevered wall. There are U-shaped channels that achieve this. Edit: For something already in place, instead of a U-channel, it might be better to attach some angles on each side at like 3'-0" OC or something. This will allow it to vertically deflect but not out of plane.

 

[gte447f]

How are you going to introduce a compressible filler between the top of the wall and the beam soffit? You are going to have to modify/demo the top of the wall to do that. If you are going to be doing that anyway, it should be fairly easy to also fill the crack, if its a decent width, with mortar as milkshake suggests.