Identifying root cause of water ingress from outer to inner leaf - cavity wall

Metric Tensor wrote: »

Finding it hard to figure out what angle I'm looking at there! Do you have any a little more zoomed out for context!

Apologies - didn't have much time - as had to get back to work. Will post a zoomed out pic tomorrow.

Effectively, that exposed wall tie is at the very edge (above) of the rectangular opening that was cut out. Shows wall tie disappearing into the section of bonded bead infill. I have not exposed it all - will wait for the engineer - but the piece that can be seen has mortar snots on it.

PMBC wrote: »

Dyu have a moisture meter; presumably your engineer will.

Yup, I don't but he will.

PMBC wrote: »

Seems to me that the plaster is not impervious and the mortar snots are the path for water transmission.

I don't want to get ahead of myself but I'm hoping that I already have enough to prove beyond doubt the reason for water ingress.
If Homebond have a responsibility to reinstate, how would you feel about the other walls if it was your house? There's no signs of cracks or internal dampness related to either the back or front walls of the house (it's a semi-d)...although those 2 facades don't take the full brunt of the weather in the same way as the gable wall). Is there any potential that there will be such issues down the road?

A proper inspection has not been carried out on the openings yet. However, the location of the openings was determined purely with the water ingress in mind. I doubt that we will be able to unearth the reason for the horizontal cracks (and proof of same). I guess the only way that can be done is if I open out a section along one of those cracks?

What sort of remedial works would be necessary if for example there was a structural issue due to either improper positioning/application of wall ties or wall tie corrosion? Would it be foolish to assume that the other two walls would not be similarly affected?

Following on from that initial pic, these should give it context as they're zoomed out =>

opening showing exposed wall tie.
Overview of opening.


A second opening was also made;

Second opening
There's a wall tie hanging off the end of that segment of block. There doesn't appear to be any mortar 'snot' on it - but then I don't know if it would have come loose as the outer leaf section was being removed. Then again, the expectation is not that there would be snots on every single tie.

I thought that the area immediately around that first wall tie was wet. However, it seems if I stick a finger through that bead anywhere, the infill is wet.

Metric Tensor wrote:

Remedial wall ties are pretty common and can be installed by drilling in from the outside. The bigger question is how many existing ties do you have to remove snots from.

How will they know where remedial wall ties are needed and where they're not needed? I know the points where the cracks appear may be a no brainer (if its determined that's the actual problem). However, is there a possibility that other points of failure would open at some future point - at which point, I'm s**t out of luck - as I would have to remedy that at my own expense?
How can they determine which ties have snots on them and which have not? Could this be done if the infill was removed?

Metric Tensor wrote:

I think there's two choices with the other walls:
1. Leave well enough alone.
2. Check some of the ties.
I think if you can get some sort of commitment from HB re discovery of wall tie issues in the front walk in future I'd go for 1. But I'm fairly certain there isn't a hope of getting any commitment!

I agree that it's unlikely that they would agree to an arrangement where there wasn't a final settlement - which means that leaving well enough alone is out - so I guess I'll have to open up a couple of sections and check the ties. I suppose I could try with a camera like PMBC suggested but isn't that going to be quite difficult given that the bead is bonded?

Metric Tensor wrote: »

3. Although the wall might not be "correct" throughout all you can do short of taking down the whole wall is identify the areas that are bad now and deal with them. There is the chance of further failure in future but I don't see anything you can do about it now short of Calahonda's rain screen idea

I want to try and avoid being left on the hook due to celtic tiger building practices/lack of oversight. Bought at peak prices with a guarantee on a certain standard so would want to get this resolved completely now (as I'll be on my own hereafter). I'd imagine Calahonda's rain screen would deal with any undetected mortar snots and any lack of integrity of the existing finish. That just leaves any possible structural aspect to deal with (i.e. the root cause of the horizontal cracks and how that can be dealt with - and any potential cracks that have as yet to emerge).

Metric Tensor wrote: »

4. Have Homebond commented?

Hoping to have both engineers on site this coming week.

Metric Tensor wrote: »

5. Even if the other side of the bead is wet it may not be wet all the way through. The assumed flow path of water through beads should mean that it gets drier towards the inside with increasing thickness.

I guess we can determine that by raking back the bead gradually and checking. Cavity seems to be 90-100mm.

Metric Tensor wrote: »

6. Are there insulation restraint clips or some other plastic item on the wall ties? It looks a bit like there are but I would not expect to see them.

There seems to be some sort of black plastic clip in place. Is that to hold the tie in place as the wall is being built - course by course? (it would have been up against the outer leaf).

PMBC wrote: »

I don't have a great view of that pic - or else its the eyesight going - but it looks to me like an insulation restraint - that's when insulation was just half cavity width.

Apologies - I'd like to provide a clearer pic - but don't want to rake back the bead OR accidentally dislodge the mortar snot on the tie - until such time as both engineers are on site and can see it for themselves.
So that restraint would only be useful where rigid insulation was used?

[font=Verdana, sans-serif]Ok, so the update on this is that the other party have finally made a full professional assessment (up until now, they insisted that it was my obligation to prove the precise cause of the water ingress) albeit that I m not privy to the outcome of that assessment (guy under contract so will be reporting back to Homebond). [/font]

[font=Verdana, sans-serif]Removed the bonded bead from the two openings. They had been covered for 14 days - and there had been zero rainfall during this time - blue sky and sunshine. I verified with both engineers that the sections of bonded bead which we cut out were very wet and they acknowledged same.[/font]

[font=Verdana, sans-serif]The area around the wall tie that appeared to have a mortar snot on it was exposed and with that, it was confirmed that the snot extended the full length of the tie from outer leaf surface to inner leaf surface.[/font]

[font=Verdana, sans-serif]My own engineer also expressed the opinion that the angle / bend on the wall ties that we viewed were in such a way as that they were likely to draw water/moisture inwards rather than the other way round.[/font]

[font=Verdana, sans-serif]That's the scenario on the water ingress. It remains to be seen what position Homebond will take on that but I think I have plenty to go on should this have to go further.[/font]


[font=Verdana, sans-serif]With regard to the actual reason for the long lengths and series of horizontal cracks present, I don t seem to be arriving at a definitive finding on that. One theory that was put forward was that the plastering was not all done on the one day and may have been done in sections which *might* lend itself as an explanation as to why horizontal cracks appear at various heights.[/font]



[font=Verdana, sans-serif]Does that last potential explanation sound in any way plausible to any of you? This appears on practically every gable wall in the estate (approx. 30 houses) so would this be likely to happen as a practice throughout? Sounds more plausible to me that maybe it could happen where scaffold wasn t available for some units at the time but not every single house (development was done in 2 stages with the second stage being a couple of months behind the first). IF this was the practice of the plastering crew, then surely the locality should be littered with this type of workmanship? [/font]

Metric Tensor wrote: »

A stop and restart in applying the render would definitely be a possible cause for a horizontal crack...but I would expect that to give a single crack almost the entire width of the gable.I personally don't think the multiple, partial-width close cracks that you have would be an indicator of that. They hardly plastered it in 5 attempts!

Those cracks are probably that little bit longer than the initial pic I provided (that pic was submitted in my original application - which would probably be 9+ months ago at this stage. I will take a fresh pic for comparison and post it up tomorrow.
One thing I also brought to their attention yesterday is the existence (on the back wall of the property) now of a consistent hairline crack - again horizontal - between the top window lintels on the first floor - running from window to window - and a second similar crack running at the same point from one of those windows right through to the window in the neighbouring property (its a semi-d). Until now, the focus has been almost entirely on the gable wall.

Metric Tensor wrote: »

as would a stop and start in blocklaying

I guess I understand how this works with render but how would that come about with blocklaying? Differing consistencies in the mortar beds between the blocks?

Metric Tensor wrote: »

Was the bead wet all the way through?

The bead was wet towards the inner leaf end. However, I have to qualify that by saying that the openings had been made 14 days ago. Whilst I had them loosely covered with plywood, they were getting ventilated. When I checked this upon opening the other week, the moisture seemed evident also on the bead surface next to the outer leaf.

Metric Tensor wrote: »

Any rust on the tie?

By the time I got the opportunity to have a proper examination of the wall ties, it was late last night and in bad light. I'll check again but they seemed to be fine in that regard. I guess they're only 10 years in situ so it would be unusual for them to rust through already??

I *think* I can find someone who worked on the development at all stages. Will try and locate him over the course of the weekend and ask him re. how it was rendered/blocked (in fact how they were all rendered / blocked as this manifests itself on practically every gable wall in the estate to some degree or other).

I have to wait for them to come back with their assessment or viewpoint. However, I'd like to reach some firm conclusions myself as to the nature of that cracking. Not sure what the next check/test should be?


PIC's
Section of the bonded bead infill to a depth of 4"
Overview of wall opening with the bead removed and inner leaf exposed

Don't even have to leave the house for that - practically all gables show exactly the same pattern (in a development of around 30 houses). Some have painted over but horizontal cracks still visible. I've never got into a conversation with anyone about this but I suspect nobody has investigated further - other than to fill and paint over. Mine is the most exposed gable in the development - for that reason, the defect(s) with mine are developing much faster - and also resulting in the water ingress - which I'd imagine probably hasn't happened with any other house (but it will of course - in time).

BryanF wrote: »

A Very serious balls, all I can say is best of luck, and perhap start engaging a very serious solicitor..

Need to get all my engineering related ducks in a row first - and I think I've achieved that in terms of proving liability with regard to water ingress. Just have to tease out specifically the structural aspect of what's at play.
Furthermore, they have to be given the opportunity to do the right thing...on which we should hear more shortly - at least for one aspect of the saga.

If they don't own up to their responsibilities at that point, then I have no alternative but to pursue this further (I always knew this was going to be an uphill battle - so had resolved to dig the heels in from the very outset....with the expectation that this was going to be one long and very drawn out process).

madmac187 wrote: »

Have you put up a straight edge against the building to see how plumb it is?

Struggling to get my mits on something that would act as a suitable straight edge. I ran a plumb line from the cill of the bathroom window on the gable wall down to ground level. Cill ledge was 60mm out from rendered finish. Set the end of the plumb line 60mm out from rendered finish at the bottom secured with a block.

Even though line was taut, I find it very difficult to take an accurate reading - but when I hold the spirit level, at worst, the bubble may be veering towards or on the line (out of centre - indicating that the wall *might* be leaning outwards as it goes up).

I not sure first of all if this is accurate and second of all even if it is, is it so much so that it's significant or insignificant. Perhaps I'd fare better with one of those in-line 'bubble' levels?