How to fix corner brick wall crack?

Question

Hi Team,

Need some assistance to select the right product.

As you can see from the pictures, the two structures (living room and garage) were built at different times on separate foundations. A vertical separation crack running through an interior corner of a wall, visible both inside living room (beige wall) and outside (brick corner where the two brick types meet)

Over time they settle at different rates, pulling apart at the junction. This appears to be a control/expansion joint between two separate brick structures (house vs. garage).

Can you advise the right products to help the cracks interior and the garage.

Thank you.

MitchellMc · Answer

You're welcome, @mohd_awd.

The difficulty here is that it's hard to provide definitive repair advice when there is the potential for ongoing movement between the two structures.

What we know so far is that the non-flexible plaster has cracked because the wall has moved. If, after opening up the crack, you determine it is only affecting the plaster, then a traditional repair would typically involve removing any loose material, applying joint tape, and then replastering the area with a topping compound before sanding, priming and painting.

However, if there is still active movement occurring, that type of repair is likely to fail again in the future. That's really the key concern here. If the structures continue to move independently, cosmetic repairs may only be temporary.

The same applies to the cornice. Under normal circumstances, you could fill small gaps with a gap filler or cornice cement and repaint. However, where movement is involved, a flexible, paintable sealant is often a better choice as it can accommodate some expansion and contraction without immediately cracking. Here's a helpful guide: How to repair a cracked cornice.

On the exterior brickwork side, filling the joint with Sikaflex 11FC is a relatively straightforward cosmetic repair. If the movement exceeds the sealant's capabilities and it fails, it can simply be removed and replaced. The interior plaster corner is more challenging, as filling large cracks and gaps with flexible sealant is generally not ideal, and there is only so much movement that plaster repairs can tolerate before they crack again.

Before investing too much time in cosmetic repairs, I'd still encourage you to determine whether the movement has stabilised.

Mitchell

mohd_awd · Answer

Thanks Mitchell for sharing the right product.

Regarding the interior wall, please see below further photos, the crack seem to aligning with the brick wall -  wide at the top and narrows as you go down. It looks like a plaster crack, I will attempt to open and clean the crack, if it happens to be plaster crack, what is the right filler for it? I'd like to know the steps to follow please.

Also, for the same interior room, the cornice confirms the movement, please reccomend the right product to fill the gaps with the wall.

Thank you.

MitchellMc · Answer

For this application, I'd recommend using Sikaflex 11FC @mohd_awd, as it's a flexible, paintable polyurethane sealant designed to accommodate movement in cracks and joints like this.

Before applying the sealant, remove any loose or deteriorated material from the crack and clean the area thoroughly. If there are deeper sections of the gap, insert a suitable foam backer rod first. This helps reduce the amount of sealant required and allows the Sikaflex to perform correctly as a flexible joint.

You can then apply Sikaflex 11FC to both the exterior and interior sides of the crack. Since it's paintable, it can be finished to blend in with the surrounding wall surfaces.

On the interior corner, it's a little difficult to determine exactly what's occurring from the photos. The cracking may only be in the plaster, but it could also indicate movement that's affecting the corner bead or wall lining. You may need to carefully cut the corner open to investigate further and determine whether the crack extends deeper into the wall structure before deciding on the best repair method.

As mentioned previously, given the apparent movement between the two structures, it's still worth considering a structural assessment if the crack is continuing to widen or reappears after repair.

Mitchell