How to repair render over cement sheeting?

[vas90]

We have some render that has been placed on top of some cerement sheeting.
Would like to restore the render and give it a lick of pain, what would be the best way to do so?

[MitchellMc]

Hi @vas90,

It looks like the crack has formed along the joint between the sheet and the trim added to the front face. The trim appears to have pulled away, creating the crack. The first step is ensuring that the trim is secured correctly. There appear to be nails holding it in position that might have backed out. If you can, I would suggest using screws to hold the trim in position and close this gap. 

Once you've ensured the trim is secured, you can follow this helpful step-by-step guide: How to repair a rendered wall. 

Please let me know if you have any questions.

Mitchell

[vas90]

Hi @MitchellMc 

Bottom part is held by a screw already, not sure if another is required or not. The hardware has a little play towards the top part of the panel.

Would you suggest installing another screw prior to repairing the render?

[JacobZ]

Hi @vas90,

Yes, you should install another screw to stop the movement in the panel.

There is likely timber or metal behind the location of this screw, so you should be able to put a fibre cement screw directly above this one to better secure the top half of the sheet and eliminate the movement in the sheet which would have caused the cracking.

Any movement in the sheet can cause cracking, so if there are other locations where there is movement, they should be fixed off to ensure there is no movement. You can use a stud finder to locate material behind the sheets to screw into. Check out How to use a stud finder for some guidance.

Let me know what you think and if you have any further questions, please don't hesitate to ask.

Jacob

[vas90]

Hi,

I’ve finally started the repairs on this. I began by removing the top part of the old render and adding more screws on both the top and front. After rendering and sanding a couple of times, I’ve noticed that after a few days of drying, the cracking starts again.

I’ve secured it as much as possible—do you have any suggestions on how to prevent the cracking? My concern is reaching the painting stage only to have the same issue reoccur.

Thanks!

[JacobZ]

Hi @vas90,

The more significant cracking seems to be in the area directly above this screw.

Was this screw added before or after you applied the render?

I ask because cracking in rigid materials such as render happens when movement happens. Adding an additional screw after rendering can create enough movement and tension to crack a thin coat of render.

You mentioned that there is play at the top of the fibre cement sheet. Realistically, if there is play in this one location, then there is likely play along the full length of the sheet.

I'd suggest you add additional screws above every screw that runs along the bottom of the sheet.

This will ensure there is no movement at the top of the sheet which will crack the render.

Once these screws are added, you can apply a thin coat of render over the existing one to cover any cracks.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[vas90]

Screws added before the render.

[JacobZ]

Hi @vas90,

If that is the case then you'll probably find that the movement is happening in the areas without the additional screw, but because the sheet is experiencing tension in the spot with the screw, then the cracking is appearing there.

My advice to add additional screws along the full length of the top edge of the sheet stays the same. Removing all movement in the sheet is going to be necessary to stop future cracking.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob