Cement Pointing - How much is too much?

[Abecedarian]

Evening all.

I've recently acquired, and moved into, a money pit/restoration project of my own.
Thank you for this forum, it's been useful already but I have a query which I've been unable, so far, to answer.

Upon removing a dated airing cupboard type structure, most of the wall covering behind fell elegantly to the floor in flurry of limey, plastery, festive snowfall.
The lime pointed brickwork which was revealed is pretty ropey. I'll be repairing and repointing it. This is an upstairs bedroom with a chimney breast going through it. I've quickly narrowed the cause to be leaky flashing on the roof....

My main cause for concern - and the reason for the post is, as I continued stripping plaster from the rest of the wall I've uncovered some previous pointing repairs which have been done with cement.
So, I realise that cement pointing is bad, but if it's just patches of earlier repair - I've de-plastered the 2 internal faces of the 2 external walls - is it ok to leave it? Will the wall continue to breathe adequately through the rest of the lime pointing? There are some timbers high up in the brickwork which appear perfectly dry and rot free. One of the walls had been covered in a corrugated bitument type membrane before being gypsum plastered.

The house in question is a solid brick built former rectory dating from 1830. The part I'm dealing with is, we think, an extension added some time after that, the walls in question are 10-12 inches thick.

Any assistance/advice gratefully received.

Cheers,
Paul.

 

[MatthewC]

Hi Paul, welcome to the forum.

The easy answer, in my view, is that it's probably OK and better to leave it than try to remove the patches. If it's done well it will be very difficult to remove and likely to cause damage. I would guess that the decision could depend on the size of the patches and also the state of the wall and pointing outside. I deliberated a long time before doing some ceramic tiling on the wall in my bathroom before coming to the view that it probably did not matter if the wall is usually dry and able to breathe on one side! I would guess that problems would (only?) occur if the wall gets repeatedly wet (like, another leak from the leadwork above).

You mention a bituminous membrance with gypsum over it - that sounds like an entire wall! I wonder how the membrane is attached? In my relatively new flat in London (before I came here in 2010) they had used some sort of bituminous adhesive under the tiles in the bathroom which was impossible to remove (so we tiled over it!!). You certainly don't want to start a job like removing that and find it's impossible to finish properly!

You might want to spend some dark evening reading my blog - click the contact bubble to the right and select the blue circle for the web page.

Matthew

 

[Abecedarian]

Thanks,
I was heading towards the "leaving it alone" strategy, but I'm all for other people's (informed!) opinions.
The bitumen membrane was on the whole of the wall adjacent to the fireplace and looks like it was sold in rolls or sheets, a quick Google search tells me it was popular in the 60s/70s. It came off really easily, in fact, one of the reasons I stripped the wall back to the brick is because it had become loose in a few places. It was simply held in place by approximately 1.2 million nails into the mostly lime mortar.

The external face of the fireplace wall has a tyrolean type sand and cement render with a large crack in it which I'm bracing myself for taking off in the near future. Again, the internal timbers in that wall are dry so no immediate danger I think.

So, immediate plans are tidy up the pointing and repair the brick work inside.
Then give myself a crash course in plastering. I'll start with the bit inside the airing cupboard and take it from there.

Cheers,
Paul.

 

[Flyfisher]

I’d assume that the impact of cement pointing on breathability would be more or less proportional to the amount of it, eg 50% cement pointing would reduce breathability by across the wall by 50%. I’d also guess it would be better if that 50% was spread evenly throughout the wall rather than be solid across, say, the bottom half of the wall.

It sounds as if the wall had previously been ‘tanked’ using that ‘bitumen’ sheet, which would have been far more deleterious to any breathability than the bits of cement pointing. The fact that the wall was dry when that was removed sounds like good news to me and suggests that, even with some cement pointing now exposed, the wall will now be far more breathable than it was before.

As for ‘repairing the brickwork inside’ before plastering, is that really necessary? Unless there are big holes and/or loose bricks I’d have thought that plastering alone would be good enough and any small gaps in the brickwork would be easily filled as well as helping to give a good ‘key’.

It goes without saying, or should do, that fixing the flashing should be a higher priority than whatever you end up doing with the wall.

 

[Abecedarian]

Yes, the next dry day sees me fixing flashing.
Also yes, there are holes and loose bricks.

At the minute that one particular wall is experiencing exceptional breathability, I can positively feel it through the gaps!