Repairing a Large Crack in Plaster


Plaster walls in older homes often fall prey to cracks and other unflattering defects such as, uneven texture and pitting. Not only does it render a shabby, dilapidated look to your home, the crack could widen over time and leave your wall plaster vulnerable. Even If you simply fill the cracks with joint compound or spackling, more than often they are prone to telegraph back through. In order to solve this dilemma, self-adhesive fibreglass mesh drywall tape can be applied over the crack for reinforcement.

You may think that patching large holes and cracks in plaster is a piece of cake, until you are faced with the conundrum of matching your walls. The aesthetic appeal is one of the trickiest parts to get right. You don’t have to fret much in case of smooth walls, but for textured walls, you need to accommodate the artistic places as well. However, before getting down into the nitty gritty details, you need to think about patching up the cracks:

N.B: A metal bottle opener is pretty handy to get the job done quickly. Even if you don’t have one, go get one before starting!

1) Neatly undercut the crack using the bottle opener to foster suitable conditions for new plaster. This helps the plaster to bond as the undercutting creates a diminutive lip just underneath the surface of the plaster. Brush or blow out any debris or dust, and moisten the crack slightly using a sponge.

2) Next, use a putty knife to apply patching plaster to the crack, filling it halfway. Wait until the plaster crater is firm enough to support a thumbprint, and then use a nail tip to give the next layer something to cling on to. Let it dry completely.

3)  After the plaster has dried up, dampen the set plaster lightly and stuff another layer into the crack, leaving a 3mm to 6mm valley from the surface.

4) In order to blend the area into the surrounding wall, allow the patching plaster to dry completely before slathering the visible finishing plaster over the crack. The finishing plaster should fill the crack completely. Use a knife with a straight edge to bring the plaster level with the wall. To garner a smooth, even finish, dip the straight edge in water. For textured walls, it is a great idea to employ the edge of a smaller putty knife. You can even cut a cardboard to the dimensions where the crack is the widest. The trick is to drag the surface only across the crack to smooth out the plaster, steering as far away from textured surface as you can!

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