How to repair different plaster cracks?

[johnk]

Hi all,

Have 4 types of cracks that I am wanting to repair in my home all in plaster whilst I paint my house. The house is 25 years old and these cracks have just slowly expanded over the years and have never been repaired as such, so quite good for 25 years.

1. Hairline cracks in ceiling - these are extremely fine but run for a number of meters - was thinking to either run the edge of a paint scrapper inside the crack to expand it and fill with Uni Pro Multi Purpose - then simply paint and not even bother using an undercoat as I am painting the entire ceiling and walls. Alternative was to use tube of acrylic gap filler and simply use my finger to fill in and paint over.

2. Corner tape edge has peeled off in one of the corners -  was going to use mesh tape and then several thin layers of Uni Pro Multi Purposed Filler to evenly spread this out - 2 -3 multi purpose filler coats sanded in between - and then simply paint over with the same paint I will use for the walls and ceiling

3. Some larger cracks over my timber venetian blind areas - I can see some mesh tape there - was going to sand, add some additional mesh tape and fill in with  Uni Pro Multi Purposed Filler to evenly spread this out - 2 -3 coats sanded - and then simply paint over. Was also considering to not add any mesh tape but simply run the edge of a sharp plaster blade to expand and then simply fill in and sand.

4. Some cracks where the wall meets the ceiling and there is timber trim - was simply going to use a tube of acrylic gap filler

and a caulking gun to fill this in.

Pics attached and look forward to any advice!

Thank you.

John.Corner tape peeiling offHairline Ceiling crackLarger crack over blindsCracks where ceiling meets wall 

[EricL]

Hello @johnk 

Thanks for sharing your question about the interior cracks in your plaster. You would get better results with the Uni Pro Multi Purpose filler on your ceiling as it will cure to a plaster like consistency and will not sink or settle. Whereas the acrylic gap filler might sag or move while it cures. For the corner edge you might need more filler, and I suggest using Gyprock CSR 2.25kg Less Mess Multi-Purpose Joint Compound specially if you are removing the old mesh tape in the corner. You can use the joint compound on the large cracks near the blinds and your idea of using an acrylic gap filler for the wall and ceiling will work just fine.

Here is a link to our best advice: How do you repair ceiling cracks?

Here is a handy step-by-step guide: How to repair a cracked cornice

I also suggest having a look at this discussion - How to repair cracks on the wall, celling and cornice? by @mmd22.

If you have any other questions we can help with, please let us know.

Eric

[johnk]

Thanks Eric,

does the Gyprock multi-purpose-joint-compound then an additional compound on top of it as a finishing compound?

Also with the ceiling crack, is my idea to make the crack bigger with the edge of a plaster tool the right approach before filling in?

Ta.

John.

[EricL]

Hi @johnk 

Technically the multi-purpose joint compound will add a layer to finishing compound, but the properties of the multi-purpose compound allow you to get a fine finish on its surface when sanded properly. In regards to making the crack bigger, it is a sound step as it removes all the loose parts of the crack and allows more of the filling product to enter the crack and thereby allowing it to grab onto the sides of the crack.

If you need further assistance, please let us know.

Eric

[johnk]

Thanks Eric,

What about the option of a quick setting compound so I can fill, sand and paint within a few hours? Any recommendations?

[MitchellMc]

Hi @johnk,

The Poly 100g Rapid Interior Filler is a great multi-purpose fast-setting filler. Painting over can be completed in 30 minutes, so you should be able to sand quite soon after application, depending on the temperature and humidity.

Mitchell

[johnk]

So a bit of an update. 

Wall repairs proceeded well although I found the rapid set plaster difficult to work with as it’s very plastic and soft. 

After 2 coats of Taubmans Easy Cost paint the issue I have that the ceiling looks quite blotchy in appearance and despite sanding it very smooth somewhat rough. Wondering if I needed to have diluted the paint as it was warm and humid upstairs when I applied this? Will try and post some pics but wonder now if I should fine sand and apply a final 3rd coat but that is diluted with water as this paint seems quite porous.

Advice would be appreciated.

[MitchellMc]

Some images would be beneficial in providing advice @johnk. Provided the filler was sanded smooth, there shouldn't be any blotchiness after coating, nor should there be any reason to dilute it.

Keen to assist further.

Mitchell

[johnk]

hi @MitchellMc,

See the images attached. This is why I am thinking of a light re-sand with 220 grit and also applying a final coat when it is a lot cooler to avoid the paint going really sticky when I apply it. I am also considering adding  something like Floetrol to the paint which is a paint conditioner that help with paint spread and better flow.

I suspect that I did not get the same effect on the walls as they were cooler and the ceiling in these photos is on the second level which can get very warm.

[MitchellMc]

How much of the ceiling did you cover with the Poly 100g Rapid Interior Filler, @johnk? Typically, it is used for smaller repairs, and to skim-coat a whole ceiling, you'd use a topping compound.

The ceiling has quite a rough and gritty texture. Was that introduced by the Rapid filler, or was it rough to begin with?

Mitchell