Why is my render so grainy?

[BenH1989]

Hi all,

New house owner here which also means complete DIY novice!

Obviously with the new coronavirus lockdown it means there’s some time to do DIY.

Above our bay windows is a border which needs filling in due to neglect and some (fixed) water leak.

I bought some one coat render from B&Q about a month ago and decided today to mix and use it to patch repair.

I don’t have a mixer so I used my trowel to mix and mix for a good while.

However the render has come out very grainy. Is this supposed to be the case? When I see videos online their render looks so smooth. What has happened here? The grain is extremely strong. Like you cannot compact them anymore which makes me think the mixing wasn’t the culprit.

Any help or advice would be appreciated

Thanks in advance

 

[noseall]

You are patching along side a hard surface, so there is nowhere for those grains to go. They are just sitting atop the existing render. Render is grainy and needs depth so overlaying onto a surface that is hard is a no-no. You need to contain the repair patching to the deep parts only and have a neat abutment form patch to existing.

You can't feather in like you can with say a fine plaster skim.

 

[^woody^]

Did you brush it?

 

[23vc]

Did you rub it with a poly float/sponge? If you’d have run a steel trowel over afterwards it after it might have closed/smoothed the surface more. Seen worse tho, rendering’s hard!

 

[BenH1989]

You are patching along side a hard surface, so there is nowhere for those grains to go. They are just sitting atop the existing render. Render is grainy and needs depth so overlaying onto a surface that is hard is a no-no. You need to contain the repair patching to the deep parts only and have a neat abutment form patch to existing.

You can't feather in like you can with say a fine plaster skim.

Some areas had extremely deep holes, I’d say at least 50mm and still the same consistency.

Did you brush it?

Did you rub it with a poly float/sponge? If you’d have run a steel trowel over afterwards it after it might have closed/smoothed the surface more. Seen worse tho, rendering’s hard!

Yes I used a sponge afterwards. Didn’t change a thing. Is there anything finer than render to help smooth the masonry feature on the exterior?

 

[^woody^]

Yes I used a sponge afterwards.

That would be a reason for the surface appearance

 

[BenH1989]

That would be a reason for the surface appearance

Hi woody. Unfortunately not. I used the sponge to hopefully change the appearance but made no difference whatsoever

 

[BenH1989]

I just tried sanding it and it just turns to dust.

What is best to use on this? I just want a smooth surface to paint onto.

 

[23vc]

Exterior filler probably your best bet unless you want to hack off and reattempt the render before it’s rock hard