# Forum Home Renovation Rendering  Cracks in render

## Tonyc

Hi, we had our brick house rendered about 9 months ago and a fine crack has now appeared on one wall. The crack is in a straight line down the wal.  When I had a closer look at where the crack is, I found out that it is where the expansion joint is.  
Love to hear to your suggestions on what I can do about this problem, as it is not a good look ?

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## rrobor

Personally I would run an angle grinder down the crack, then fill the cut with something that will expand and contract, then paint that to match. First I thought they made a mistake rendering over the joint but then I couldnt find a way to get a descent surface  without doing that. So I believe the angle grinder is the way.

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## Tonyc

Hi, thanks for the advice, any suggestions on the best filler to use ?

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## ScroozAdmin

Rendering over a movement joint is asking for it, polysulphide sealant is the the norm for expansion joints, theres one or two part, the one part comes in a silicone type cartridge and is more user friendly for small jobs, you'll probably need to ring around to find some but brands such as Sika would be a good place to start digging, goes in like silicone but cures to a tough rubber seal which is overpaintable. Plan B, hide it with a dummy rainwater pipe or aerial cable etc.

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## Tonyc

Hi Thanks for that, just to get it clear in my mind where to go from here if we stay with plan A.  
Are we saying that we still run the angle grinder down the crack then fill the cut the Sika type product you referred to? Sorry to ask so many questions but do not want to turn one problem into two because I have misunderstood your advice.

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## rrobor

Ill tell you a trick I do. I can never match the mortar of the brickwork of my house so I dont try.  Any time I get some old mortar I save it in a bucket and store it under the house. If I need to brick something up and have to match the mortar, I get some out of the bucket and pound it till its sand. Then I do my bricks and whilst the mortar is wet I rub this sand into it. For me, If you have any spare render ,  pound it up.  Then cut your slot with the angle grinder, carefully fill it with silicone. (Tape both sides with blue masking tape) then push render dust into the wet silicone. You will get a line, but the line will be as if it should be there, not an oops.

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## ScroozAdmin

> Hi Thanks for that, just to get it clear in my mind where to go from here if we stay with plan A.  
> Are we saying that we still run the angle grinder down the crack then fill the cut the Sika type product you referred to? Sorry to ask so many questions but do not want to turn one problem into two because I have misunderstood your advice.

  yes you'd need to cut a decent slot say 5-10mm wide ideally, professional sealant applicators might also be worth a call for advice, this type of thing is there bread and butter and this stuff can be tricky to apply.

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## cherub65

No need to silicone if you dont mind the appearance of a cut.
Render-er would have just used a trowel to cut expansion when render was soft, (if he'd remembered :Doh: ) So you would have same look if you just cut and paint it.
Get a mate to hold a straight edge and use a small grinder.

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