Cement without aggregates- advice

AmateurBodger · 21 Feb 2021

Hi,
I’ve made what I now realise was an amateur mistake and used PolyCell Quick Set Cement without sand to patch up an outside wall.
The wall itself has penetrating damp that comes from shoddy work on a neighbours recent extension (terraced housing), so when it rains the wall looks saturated right away from top to bottom. Moss is starting to grow on the wall, paintwork on the bottom half is flaking away and the wall is becoming ‘bobbly’ for want of a better phrase. I have a couple of questions:
1. Apart from looking shoddy and possibly not lasting too well, is there any immediate reason to get a professional in to remove the cement and replace with mortar?
2. Is there any downside at all to treating the wall with waterproof sealer to make the bricks waterproof? Is there any risk that this will ‘lock damp in’ as opposed to the other way around?
Any advice or help would be really appreciated. Thanks!

williamglossop · 22 Feb 2021

What is Polyfila cement?

AmateurBodger · 22 Feb 2021

Sorry - it's 'PolyCell Quick Set Cement': Polycell Quick Set Cement Polyfilla, 2 kg - Grey: Amazon.co.uk: DIY & Tools
OP updated to avoid any confusion.
It's a quick mix cement - so far as I know there's nothing major that differentiates it from any other standard cement, though packaging suggests it can be used alone to repair masonry.

williamglossop · 22 Feb 2021

And you've smeared it on your exterior walls - like render? Just making sure I've understood

AmateurBodger · 22 Feb 2021

Hi William,
Its not all over the wall, but I’ve used it to fill a series of holes or cracks near the top of the outside wall, just below where the wall reaches the roof. In terms of overall area of the wall covered it’s small and as an average it would be approximately 1 brick in height used for the width of the wall. On 1 occasion I have covered an entire brick and the mortar on both sides of it because it had moved. I have added a photo which might help.

williamglossop · 22 Feb 2021

No photo.....

williamglossop · 22 Feb 2021

Either way, you should repoint any areas where the mortar between the bricks is loose or missing with a suitable strength mortar. 4 sand to 1 cement is typical, but you can use more sand if needed. After that, once the brickwork is sound, you can buy various products to seal the exterior face of the brick work. Although I've not used it, Storm Dry seems to do very well. With regards sealing damp in, that won't really be a problem......... particularly with the storm dry product as its breathable, and hence will allow water vapour to pass through it.

AmateurBodger · 22 Feb 2021

AmateurBodger · 22 Feb 2021

Sorry- thought it had been posted but it had just been uploaded my side!
Great- makes sense. it sounds like what I’ve done isn’t ideal because I should’ve used mortar to re-point properly.
given that it’s already happened, I’m currently thinking I’ll leave it there for the medium term and as it starts to crumble away do a better job with sand.
Sounds like the waterproofing for bricks will work just fine and allow excess water in the bricks to pass through.
Thanks for all your help!

^woody^ · 22 Feb 2021

stuart45 · 22 Feb 2021

That's a neat looking repair. Well done. Change your name to Pro Bodger.

AmateurBodger · 22 Feb 2021

Haha!

I know it looks pretty bad, but unfortunately I learned a lot of lessons immediately after seeing it dry and reflecting on the handy-work! The key thing is whether it's worth removing everything and starting again or not (apart from it looking horrible, which might be enough of a driver to do it in itself in time when I have the willpower to face it again).

From what I understand, I should've used proper mortar for sure and been neater, but that this may well help prevent water from getting into the wall and causing further damage in the short and medium term. If I've got any of that wrong then please shout!

Mark.

JohnD · 22 Feb 2021

if you have a water problem, find the source of water and correct it.

I guess you mean that water is falling off the edge of the roof.

is there a rainwater pipe discharging onto that part of the roof? Why doesn't the water just run down the slope and into the gutter?

Before you bodged it, was there any space between the edge tiles and the top of the brickwork?

Who does the wall belong to, and who owns the shed that has been built on top of the roof?

JohnD · 22 Feb 2021

AmateurBodger said:
It's a quick mix cement - so far as I know there's nothing major that differentiates it from any other standard cement, though packaging suggests it can be used alone to repair masonry.

It appears to be Prompt Cement or "Ciment Fondu" and I can't see any advantage in this case. Some grades are intended for repairing firebacks or other hot things, and some are intended for repairing wet conditions like drains or sea defences.

OPC has retarders added to delay setting so it is easier to handle with less waste. Your stuff is intended to set very fast.

AmateurBodger · 22 Feb 2021

Hi John,

It's a party (shared) wall, but it forms the edge of our neighbours house rather than our own (it just goes out from the back of our house). Our neighbours fully own the extension 'shed' built above the wall.

I'm pretty confident that any damage would've been done when they had their extension done, but I can't prove that as fact and I'd be relying on them to be kind if I gave them a call.

There was (and still is in places) space between the wall and the roof tiles which is unfilled (0.5-1cm). I've not messed with that much - it was part of the neighbours' extension work. There was a huge gap at the far end of the photo just behind the guttering where you could put your hand in behind the gutter and below the tiles. I have messed with that and tried to fill it.

In terms of the source of the water - it's hard to know because there's nothing visible on our side of the wall except apparent saturation and 'bobbling' of the wall at the bottom. Water appears to flow directly down the top of the roof and there's no obvious runoff. What I do know is that our neighbour was having an internal leak around the 'hand size hole' which I believe is now better, but the wall still gets saturated.

Yes there is a run off gutter that flows over the top of this section of roof and lots of moss growing on our neighbours house behind it.

Hope that makes sense!

diynot

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Cement without aggregates- advice

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