water ingress through concrete block wall

[Daniel3103]

Hello,
I'm posting here to ask for advice about a rainwater leak into my bungalow. Rainwater is leaking through the external wall into my bedroom. I've already tried to fix the leak twice, and each time the fix has worked for a while, but the leak keeps coming back. I'm not sure what to do now.
The leak that I see happens when rain falls. The water comes from the top of the window recess inside my bedroom and falls down onto the floor. I'm pretty sure the leak is through the wall not the roof (because there are cracks in the external wall, whose location outside matches the ones inside where the water drops from; because I get the leak when the water falls at an angle onto the wall but not onto the roof; and because I can't see any leak in the loft space). The wall is a double wall made of concrete blocks, with a cavity in between, and the outside is rendered. As mentioned, there are visible cracks and holes in the rendering. I have patched those cracks and holes with cement on two occasions, and each time it has sorted the problem for a while, but the leak keeps coming back. I need to try another way to fix it now, I can think of two possible approaches but I'm not sure whether either of them would work well so I'm opening up the discussion.
The first approach I'm thinking of would be to get a professional to patch the outside wall. Would this have to involve removing the rendering to treat the wall underneath, and if so what would the professional need to do? What type of tradesman or builder would I need to contact? Could I leave this part of the wall without rendering for a few years? (I'm asking this last question because the whole bungalow is a renovation project, inside and outside, a lot needs to be done including the whole rendering but I'm trying to do one thing at a time and the rendering is not the top priority; I'd rather not put new rendering on until I get to this point, but I still need the leak fixed now because the dripping noise is keeping me awake at night.)
The other approach I'm thinking of would be to stick a sheet of waterproof material on this part of the outside wall, as a temporary fix for a few years before I renovate properly. Are suitable sheets available? Would I be able to stick one myself or would I need a professional? Would the noise of the rain falling onto the sheet keep me awake too, as this is outside my bedroom window?
So, would either of my approaches potentially work, or would you do something else? Is there something else I need to know?
Thanks for your advice.

 

[Big Jimbo]

How old is the place ? You may have no cavity tray above your window. Your cracked render is letting in water, pooling on the top of whatever lintle is above your window, working it's way through the inner blockwork and entering your bingalow. Pictures from inside and outside would really help.

[ProDave]

Patching a crack rarely works. you need to strip the render and re render a decent section of the wall. If anything for now patch it with a waterproof sealant, not cement.

 

Photos of the cracks may help.  Is it at the ends of the window? if so it's probably differential expansion of the lintel Vs the bricks / blocks.

[scottishjohn]

drill a  couple of hole from outside inthe wall recess and use expanding builders foam ?

 patching will never mtahch the coulur of what you have now and as @ProDave say it never wotks 

tap outside of render with small hammer -in various places --if it sounds hollow ,then it is not stuck to wall

 

Edited November 16, 2019 by scottishjohn

[Mr Punter]

It is quite odd because there is not usually much wall above a window in a bungalow - just a course of blockwork then the roof overhang - unless it is a gable wall?

[Russell griffiths]

Have you got a picture

i bet you have a broken tile somewhere, the water is running down and pooling behind the facia area as there will be no anti sag method in  place so water is dripping onto the top of the wall and getting in the cavity

then it’s like others have said no weep holes to let water out so it runs to the inside and drips off the top of the window.