Thread: jointing compounds??

Do you know if the joints were done with paper joint tape or the fibreglass easy tape ?

The easy tape is known for cracking.
Jointing should be done with base coat to joint and flush then a toping coat to finish, the base coat is a setting compound and will be difficult to remove but can be done sometimes.

On the old Renovate Forums the member Rod Dyson was the guru plasterer with excellent tips and advice, his website is still active for reference:
How to plaster, plastering tips, plastering cracks, holes,

Originally Posted by ajm

I read online somewhere that it’s best to remove all plaster and tape around the crack, essentially returning the join to its original form (before plastering). Is that the case? it seems logical to me to do it that way but just thought i would check here. secondly, what jointing compound(s) should i be using?

I’m far from an expert on this topic, but i have done some fixes on cracked joints in my house with good results. So I’ll take a stab at your questions.

I’ve fixed joints both by removing the joint tape and starting from scratch, and also by simply scraping out a narrow channel along the joint (without going through the tape) and then refilling it. The joints I redid from scratch are still invisible, but the scraped joints have cracked again after less than 12 months. So I think you’ll get a better result with the former, particularly if you are removing the mesh tape and replacing with paper tape.

The paper tape is much better at resisting movement / flexing, and therefore better at resisting cracks. It is tricky to apply for a rookie though. If not sufficiently wettened by the compound when applied, it will bubble and peel and you’ll have to rip it off and go again.

The only jointing compounds I have experience with are the Gyprock 45 dry powder mix as a base coat, and Gyprock Gold topping coat. The powder takes a little practice to mix to the right consistency. I found that a consistency somewhere between smooth peanut butter and toothpaste worked best for me. The Gold topping compound is very soft and sands easily, with minimal dust.

If the butt joins are cracked, and paper tape has been used, re-doing the same way will result in another cracked join. I have had this case.
As painful as it is, what I would add to the above is, having scraped the joint out, to cut a square piece out of the butted sheets join, maybe 100mm x 100mm, away from the battens underneath - that's where the cracking may be most obvious - and glue a plaster backing plate across the hole (that is on the inside, not the outside visible surface) using cornice cement or backing cement. Then refill the hole with scrap and re-tape as above. Yes it is a painful process, as is any rework. But I'd rather not do it again!

It depends on whether you have initial settlement or if it is ongoing movement that is causing your issue
You don’t necessarily need to remove all the original coatings but definitely the topping coat and then any removal of base coat is just to help you achieve a visually pleasing joint with less peaking.
If you are going to get ongoing movement you are best to caulk the crack with a flexible filler or express the joint.