Best way to fix a blotchy exterior wall?

I completely agree with 24/7 homecare although I would use an SBR render bond rather than pva , little bit more expensive but worth the extra and made specifically for the job.

there is no easy way to do this, the whole of the existing render would have to come off as render cannot be patched up without the patch being seen through the paint when decorated no matter how good the new render is feathered in, if you want your wall to look like an old rendered wall then get it patched up if not get the whole wall done to make it look like new

Hi, Ok your blotchy wall is blown if you tap the lumps the render will fall off.Depends how bad and how many lumps there are as to the best way to deal with this. Find a lump and with a small hammer knock the middle out and work in a small section at a time until you come to some solid render.If there does not seem to be any solid render then i would think the whole lot would need to come off. If you do hit solid you can repair the render by first pva the brick work make up the render add bonding mix to it and put a key coat on first [scored] then a top coat to give a smoth finish. GOOD LUCK

First off what do you mean by lumps? Is it a textured finish. Or are the lumps the size of your fist or bigger. First thing to do is find out if the render is loose. I have come across loads of rendering jobs that look crap but when you try to hack off it's as hard as iron. Best bet get a good plasterer around to take a look & give you a quote. But if you do have a go at repairing yourself don't use P.V.A it's not ment for external use and in most cases the reason render fails in the first place. Hope this helps But if it doesn't at least it was free:-)