I have just blocked up an old doorway and there are gaps from the old plaster board to the new one of course, what would be the best render for filling these gaps with taping? Price being a factor here. Thanks in advance :)

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  • What's wrong with just using drywall mud (and letting it cure or dry) before you tape?
    – Huesmann
    Jul 20, 2023 at 13:04
  • Hi Huesmann, do you mean just an undercoat? seems like it might be the best way to go, i did some local price checks and most compounds atm are highly priced, i might end up just using mud from the garden! :D Jul 20, 2023 at 14:42
  • Easy Sand is eleven dollars a bag.... I'd have to have my guy re do it because that's a call back when it cracks or bubbles, because that's too big a gap to not use durabond, and I hate durabond.
    – Mazura
    Aug 19, 2023 at 22:36

1 Answer 1


I believe the answer for filling large gaps like that is something called "concrete fill". I'm not sure where you can purchase it though, as it seems difficult to find in the states.

The product is CGC Synko® Brand Concrete Fill and this is the datasheet for it: https://www.usg.com/content/dam/USG_Marketing_Communications/canada/product_promotional_materials/finished_assets/synko-concrete-fill-datasheet-en-can.pdf

As you can see, it says:

CGC Synko® Brand Concrete Fill is a lightweight, quick-setting, fiberglass reinforced plaster compound. It is formulated to fill deep voids or cracks in interior concrete or masonry walls and ceilings. CGC Synko® Concrete Fill is excellent for filling and leveling cracks and voids between pre-cast concrete panels, columns and concrete masonry. It can also be used to pre-fill or patch plaster or drywall surfaces.

  • Hi Joe thanks for replying, yeah had a quick look at concrete fill and cement fill, seems to be too wet/slurry like to fill horizontal gaps, unless is can be made some what thicker, i have found afilling compound but its pretty pricey, starting to think just expanding foam :D Jul 19, 2023 at 22:46
  • @RazorStorm From what I've seen, it's not really a slurry. It's like extra-thick drywall mud. Also you add your own water so you can adjust how much you put in if needed Jul 20, 2023 at 14:43
  • This stuff seems to be what i want but i cant seem to find it local, i am in europe so it might not exsist here :D Thanks joe, will see if i can locate it Jul 20, 2023 at 14:49

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