How to fix cracks developed between two walls

Ash-Say on 04/12/2016 - 19:44
Last edited 04/12/2016 - 20:04

A large crack has developed between two rendered walls of pergola. The left side of wall is made of blueboard while the right is made from brick. See https://files.ozbargain.com.au/upload/82858/44595/pregola1.j… and https://files.ozbargain.com.au/upload/82858/44596/pregola2.j…. This crack is on interior side and the similar crack has developed on the exterior wall.

When these cracks were in early stage, I filled it with Acrylic sealant however it only lasted 3-4 months and the cracks have started developing again.

I organised structural inspection and the structural engineer advised that this pergola was an extension and there was probably building movement and this crack was pretty common particularly when the rendered walls were made of two different materials.

You can appreciate this crack is just expanding. I called one of the renders today and he suggested I didn't put acrylic sealant properly and he will use sealant again but seal it tightly however I am afraid it will break again. I told him to use corner bead and render on the top but he advised it won't last and suggested to stick with acrylic sealant.

I am quite stressed about this crack…Does anyone here have any suggestion to fix it permanently?

TDLR: How to fix a crack permanently developed between blueboard and brick rendered wall?

Home & Garden

Comments

  • pasey25 on 04/12/2016 - 20:02
    +1

    *pergola

    Honestly I'd put a piece of quad or other moulding in the corner to hide the inevitable gap.

    It not quite as nice as a flush corner but it's not too bad and will last.

    • Ash-Say on 04/12/2016 - 20:05

      I am looking for a permanent fix. I am afraid your suggested repair will not last longer.

      • pasey25 on 04/12/2016 - 20:11
        +2

        It will definitely last longer.

        The only permanent fix available is to tie the Blueboard into the brick wall. Since that means probably pulling down the existing wall and largely starting again I doubt you'll want to do that

        • Ash-Say on 04/12/2016 - 20:12

          Can you elaborate on Quad and moulding - How to apply it?

        • pasey25 on 04/12/2016 - 20:20
          +2

          @Tipu:

          Something like this or something from this range placed in the corner glued to the brick and not the Blueboard. Painted same colour.

          Choose the profile that you like best

          http://www.porta.com.au/products/productdetails/quad/meranti

        • Ash-Say on 04/12/2016 - 20:49

          @pasey25: Thanks for sharing the link. I understand it will only hide the crack. Will it also assist to prevent future expansion of crack?

        • pasey25 on 04/12/2016 - 20:54
          +3

          @Tipu:

          No, as I said above, the only way to stop movement between the two walls is to tie them together which isn't palatable I wouldn't have thought

      • onlyletters on 05/12/2016 - 10:43

        Use flexible silicone that can be painted.

  • JimB on 05/12/2016 - 10:18

    Getting that blueboard and brickwall join not to move is impossible without knocking it down and starting again.

    Personally, I wouldn't render blueboard. Not only will it crack between the brick/blueboard join, it will also crack on blueboard/blueboard joins.

    One cheap way to reduce the visibility of the crack is to install a thick bead of polyurethane sealant such as sikaflex, what they used for brick expansion joints.

    I'd either install a timber feature wall, or something like this, http://www.jameshardie.com.au/products/external-cladding/scy… where you are not going to notice a small crack where it meets the bricks.

  • Ash-Say on 06/12/2016 - 21:08

    I have received the following advice from structural engineer. I am confused what he is trying to say here?

    The best joint finishing products where movement is likely are the acrylic based products. They will come premixed in drums. The sheets to be resealed using a primer, then a patch and reinforcing bandage along the joint then a smooth sandable patch for final finishing on joint and nailhole. After sanding the patched areas are reprimed and a flat acrylic based colored render coat is rolled on.

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