Repairing lose render around windows + gaps

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matm

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Hi,

I have been having issues with damp around the corners of our windows and after a lot of investigation the issue has been found! The windows where not sealed with silicone against the sills when they where put in. This means water goes along the sill and into the walls.

I decided to check out the rest of the windows in the house and all windows have very lose render / pebble dashing in the bottom corners of the windows. Its very sandy and crumbly render. I decided to have a look and inspect the windows. As expected all the windows seem to be missing the silcone and allowing water to get in.

Im asking for some advice on the best way to repair this.

My idea is to remove the lose render from around the window (as I have started to do already)

+ remove any old foam.
+ silcone the windows
+ fill all gaps with new expanding foam
+ ??? Im not sure on the next steps after this. Can I just apply new pebble dash rendering? over these areas? What is the correct way to do this?

One window just had very soft sand and cement behind the pebble dash rendering which I could almost dig out with my fingers!

I have attached some photos of the corners of the windows. Two where I have remove the corner render and two upstairs windows and a ground floor side window where I have not removed the render yet...

All windows show signs of damp getting in around the corners.

Downstairs windows with corners removed

IMG_20200404_170020.jpg IMG_20200404_170036.jpg IMG_20200404_170042.jpg IMG_20200404_171018.jpg

Upstairs windows
IMG_20200405_123121.jpg IMG_20200405_123108.jpg IMG_20200405_123018.jpg

Downstairs side window
IMG_20200405_155519.jpg IMG_20200405_155512.jpg IMG_20200405_155500.jpg

Thanks
Matthew
 
Last edited:
Any advice? I would like to give this a go while the weather is still nice and as a project while on lockdown :)
 
Hi Matm, were do we start. Having looked at your photo’s your windows look to be mismeasured . The frame line for the openers are clearly to close to the render line. What they should of done is fit 20mm addons to each side of the frames then the render line wouldn’t be covering the frame. If your happy giving this a go, I would chop out the existing pebble dash, fill the gap between frames and render with febfoam. Once this has set you have the option of various finishes such as plastic trim or pebbledash. Hope this helps.
 
Hi Johnny thanks for the reply.

Yes im happy to give this a go. Im happy it sounds like im on the right track :)

Im going to chop back all the lose render from the corners and follow it along the sides until it feels solid again. Then fill all the gaps with foam + silicone the windows where needed.

The bit im unsure of is the rendering part.....

How should I go over the foam? How many coats or layers? What should I use?

Would something like this be ok?
https://www.screwfix.com/p/cementone-waterproof-cement-grey-10kg/58196
+ a bag of spar dash

How do I get the colour of the render to match the existing colour?

Thanks for the help :)
 
When you take the render back I’d be interested to know how the windows are secured in. You can use any expanding foam to fill the void between the frames and the brick line. When dry cut this back so you can then move on to rerendering your windows. Make sure you silicone seal to help with the damp problem.i would be against finishing the windows as they are and the main reason for that is the amount of space you will have around the frame. As you can see from your photo’s the render is on the frames so every time you open and shut the windows they move and so does the render. Cut them back and use plastic trim to enhance the frame line.
 
That makes total sense, about the render cracking over time with the window being opened and closed!. Just looked at photos online and other houses around mine and they all seem to be done the same. render going onto the frame!

is there ready mix scratch coat and ready mix top coats that I can buy or would I have to mix it all up myself? (do I still need to do a scratch coast and top coat for these small fixes?)
 
I’m sorry I have very little knowledge of ready mix or premix render. Personally I would have a smooth rendered finish around the windows and a white plastic trim finish.
 
Just removed a bit more of the render to have a closer look.

It appears to be just a thin layer with no foam at all in gaps! Just a small bit of foam in bottom corners.

Just taken some photos

IMG_20200409_134637.jpg IMG_20200409_134656.jpg IMG_20200409_134649.jpg IMG_20200409_135111.jpg IMG_20200409_135124.jpg

Im happy with either a smooth or dash finish, just would like to know the product to get and the steps to take as this would be my first time doing this sort of repair.

If I get it all foamed and siliconed will that provide enough of a seal to get the render sorted out over the next couple of days? Thinking of doing the foaming and silicone now and then get the render sorted out on the weekend.

In regards to the trim. would it be parallel with the wall and frame to bridge the gap or more like a right angle with the frame and then render up to that to make a right angle? Is there any particular type of trim I need for this? Trying to track down the parts.
 
The good news there screwed in. Yes fill all around the windows with expanding foam let it dry and trim it flush . You can then set about the render.i will forward a photo of a job we finished off like I’ve suggested it’s easier.
 
Very nice and neat Foxhole!
There doesn't seem to be any silicone between the trim and the render. Would have thought it would need some?

Just need to know what materials I need to do the render repair and I can get started :D
 
Trim is glued to blockwork with dual purpose adhesive/sealant .Black silicon between frame and trim .
 
Started the repair today on one window as a test

Took back all the render around the edges and removed the trim at the top. The trim had nothing behind it and there where many gaps so another place for water to get in.

Render removed with trim still in place
IMG_20200410_150713.jpg

All foamed
IMG_20200411_145223.jpg

Once all the foam is cut back will use some silicone to seal up the edges.

I'm planing on using a bag of this to do the render repair
https://www.trade-point.co.uk/departments/tarmac-one-coat-ready-mixed-render-25kg-bag/1501080_TP.prd
It should be good enough for the small areas?

+ a bag of spar
 
Another update from me...

I have stripped back another window, resealed the edges with silicone and foam the gaps back up. Once the foam dried I sanded it all down flush.

I have removed most of the old "repair" around the windows back to the original scratch coat it.

Before I do the new render I just want to double check a few things

Do I definitely need 2 coats for this smallish job around the windows? Is it ok to remove the old pebble dash layer and just do one coat over the foam and side?

Is it ok to leave the old scratch coat there? its feels solid?

This is the left side with the foam and most of the old render removed.

IMG_20200421_152551.jpg IMG_20200421_152558.jpg IMG_20200421_152852.jpg IMG_20200421_152606.jpg

This is the right side that I need to finish and foam up. The gap is a lot smaller :)

IMG_20200421_152618.jpg

I have decided to mix up the render myself. We are going to repoint the patio so might as well get all the bits to mix up the render as well.

From all my reading im planning on 1 cement 3 sharp sand + 3 in 1 everbuild?
and if I need to do another coat it should be weaker. Either a thinner layer or 1 cement 4 sand.
+ canterbury spar to match up with the old spar

Thanks for the help

Matt
 
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