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Water Ingress/Damp

Discussion in 'Damp And Damp Proofing Discussions' started by borderfox100, May 20, 2017.

  1. borderfox100

    borderfox100 New Member

    I've been having some issues with water ingress through this wall. It's been acknowledged by the structural insurer that the one coat render was inadequate for an exposed site. Furthermore, full fill bonded bead insulation is being used in the 4" cavity. It's resulted in efflorescence on the surface of the internal wall inside the house.

    As an aside, anyone like to comment on the horizontal nature of the cracking? People have mentioned to me that it must be wall tie failure but the build is only 11 years old - and stainless steel ties used. Others suggested settlement/subsidence (it's built on a raft foundation) but any engineers I've had on site have ruled this out. The insurers engineers reckon the plastering was done in 'lifts' i.e. sections by scaffolding height. Didn't sound logical to me (given some of those lines are very close together) but I asked a guy who worked on the development and he said walls were plastered in one hit - not in sections. These lines are present on the gable walls of EVERY house in the development.
    Could it be that it was the blockwork that went up in sections and the mortar consistency differed with each section? Then again, how would this explain this being the pattern on every house in the development? The cracks seem to be at the very same points in each case (generally speaking).

    Anyway, on to my next query. In order to determine the nature of the problem, I had to do a bit of invasive probing. Section removed from the outside wall and cavity insulation removed. The bonded bead full fill EPS insulation was wet to the touch. My engineer is of the belief that it's compromised. i.e. rather than it repelling water, it's conducting water - and carrying it across into to the inner leaf wall.

    I also checked the floor screed inside - at the point where it adjoins the internal side of that wall. See the water mark up to 0.5m in from the edge? That led me to check the dpm/dpc internally - PIC. There's no sign of the damp proof membrane coming up and wrapping up around the edge of the floor insulation and the screed (between those elements and the block wall).

    I then checked the cavity from the outside - removing the EPS bead right down to the bottom of the cavity. Here's what I found PIC. Just for clarity, what you're looking at in that photo is..

    Top of photo = inner leaf blockwork wall
    Bottom of photo = outer leaf blockwork wall

    The Black item you see is the membrane, presumably the dpc rather than the dpm (?) but right above it is a major glob of mortar that almost bridges the cavity in it's entirety.

    What I'm Trying to Achieve...

    This is all being worked though with a structural insurer. They're not prepared to do the work themselves and are offering a cash settlement. Therefore, I have to get all my ducks in a row and make sure that EVERY defect is addressed as part of that settlement. They've priced their offer on the basis of re-rendering (3 coats plus 'webercote' finish) They will remove the cavity infill - clean off wall ties with high pressure lance and replace with certified EPS insulation material (or at least they have priced on that basis).

    My other concern is the floor screed - and in tandem with that, what I found at the base of the cavity and the fact that there was no lining of membrane internally between the screed/insulation and the blockwork. No matter how well rendered, a certain amount of water will get through a blockwork wall. If it finds it's way down to that cavity base, is there not the potential for water to transfer through on TOP of the membrane - and be carried all the way through to the floor screed inside?

    What works would be required in this instance to 'clean' the cavity floor and any idea of cost of same?

    Lest anyone thinks this is overkill, I've spent 2 years arguing with insurers who were not prepared to pay out a single penny - despite the fact that the house inside and out is ruined with dampness. With that, I want to see to it that they live up to their obligations and cover the cost to allow me to reinstate to a position whereby this can never happen again.
  2. flynnyman

    flynnyman Private Member

    Maybe a very weak mix of morter on the block work or the frost got it? Either way I would take a section off to see what's going on, it's coming off anyway coz it's shocking also what newton were the blocks? Was a mesh incorporated? Was a primer used depending on the blocks? looks like the plaster goes all the way to the floor this would cause cold bridging and the mould around your floor.
    • Like Like x 1
  3. borderfox100

    borderfox100 New Member

    "Maybe a very weak mix of mortar on the block work or the frost got it? Either way I would take a section off to see what's going on, it's coming off anyway coz it's shocking also what newton were the blocks?"

    Yes, I guess I'll have to remove a section from where one of those cracks are. I've already opened two complete sections through the outer leaf wall - completely - 2 rectangular openings.

    "Was a mesh incorporated?2

    No mesh.

    "Was a primer used depending on the blocks? looks like the plaster goes all the way to the floor this would cause cold bridging and the mould around your floor."

    No idea - I bought off the plans - house is in an estate - built 2005.

    I've been doing some excavating of my own inside. I seem to have found either the dpm or dpc.


    Isn't there something at odds here regardless of which of these it is?

    - If its the DPC - then surely it shouldn't be below floor screed/floor insulation level?

    - If its the DPM - then it doesn't seem to be connected to any other membrane going inwards? That seems to be the end of the membrane.

    Can anyone offer an opinion on this?
  4. borderfox100

    borderfox100 New Member

    I got a plasterer/builder on site. He's thinking in terms of the mortar also - as you suggested flynnyman. He's thinking that they may have used too much plasticiser or fairy liquid (if there was no plasticiser around)!

    I'm taking his (and your) advice. Going to take a core sample through one of the cracks - and send it off to a lab for analysis.

    Anyone up to speed on the nature of mortar testing? I assume they can figure out the sand/cement ratio. Can they determine the strength of the mortar? I've queries in with a couple of labs - waiting on them to get back to me.
  5. zombie

    zombie Private Member

    Has your nhbc guarantee expired?
  6. borderfox100

    borderfox100 New Member

    @zombie : No, I'm claiming against the structural insurer. However, they have opted for cash settlement - so I have to be very careful and insure that the scope of works which their offer is based upon is accurate.
    They're suggesting it's just a case of poor plastering....no admission re. blockwork/mortar, etc. Naturally, if they pay out for re-rendering and I go and plaster, I need to do so knowing that I'm not covering up a bigger problem that will come back in a few years to bite me in the ass!
  7. Ajax123

    Ajax123 Member

    I deffinitely think the cracks need investigation. Is the ground on which the hiuses are built made up ground. Is it heavy clay that is now drying out. Is it settling. My advide would be dont just concentrate on the cracks and the render as the problem could be in the foundations and subsurface. If you find the render is cracked moisture could be getting in via the cracks.
  8. zombie

    zombie Private Member

    So have nhbc accesses been out and done a survey themselves?
  9. borderfox100

    borderfox100 New Member

    @Ajax123 : Houses were built on raft foundations. It's now 12 years since they were built (i got claim in just before 10 year deadline and have been fighting with the insurer ever since).
    The site was raised - but nobody I've had look at it seems to think this is the issue at play. I hope it's not that in any event as there's an exclusion clause in the insurance policy for subsidence.

    As regards moisture getting in - that's a definite (whether it be via the cracks or simply due to a pathetically thin one coat render (and poor workmanship to boot).

    I'm going to get a core sample taken out - centred on one of the cracks - so I get a complete sample of block from above/below the mortar bed - and the mortar itself.

    @zombie : Yes, the insurer have surveyed - but as you can imagine, their job is to minimise $ exposure. The initial report one of their junior engineers produced and I was only privy to part of it (the other part would have been more interesting :) ). Just so there's no confusion, I'm in Ireland so whilst we are generally talking about the same thing (structural insurance), it's run a bit differently over here...although the insurer in question is involved in both the UK market and Irish market.
    • Like Like x 1
  10. zombie

    zombie Private Member


    Have you considered paying to have a site survey from an Structural Engineer/Architect.

    With them using there professional guidance for best remadie and then submit that as a plan of works?
  11. borderfox100

    borderfox100 New Member

    @zombie : Yes, of course. I've done that already and there's a difference of opinion in terms of the scope of works that's required (between what my engineer suggested and what their engineer suggested). However, I've fallen short of lab testing and certain types of destructive/invasive investigation. There are already 2 openings made in the gable wall and a small excavation internally in the floor screed. I've contemplated lab testing of blocks, mortar bed and plaster previously. However, as you'll appreciate, there is no end to the amount of testing that could be done and the amount of costs i could rack up with this.

    Notwithstanding that, I think there's enough merit in what has been uncovered so far to justify taking a core out along one of the cracks and sending it off to the lab.

    There's every reason (regrettably) to believe that this will go legal - so I have to get my evidence/proof in order to demonstrate that what I'm asking for is reasonable. Furthermore, as they now want to make a payment and wash their hands of it (i.e. I have no come back in such a scenario if further damages occur or are discovered during the remediation process), I have to double and triple check every aspect of this as best I can. That's what's leading to my query here - just in case one of you flag something that I have missed, etc.
  12. zombie

    zombie Private Member

    Fair play mate...can tell your a savy fella and very articulate so can see that your trying to be thorough and I don't blame you pal.

    Its way over my building experience sadly... I think your best bet on here is @imago he's a builder with a wealth of knowledge and project management etc.

    Good luck with at all be interesting to here how it's resolved!

    @imago ?????
  13. Dropsalot

    Dropsalot Private Member

    I have recently spoken to builder who is going to build a small development within 20m of the entrance to a disused (1960's) coal mine !
    I predict that the future holds another thread like this one....

    Btw good luck to the op, hope you get a favourable resolution.
  14. malc

    malc Private Member

    a raft foundation is a very expensive foundation which is designed to float up and down. it must be a very poor quality plot of land to require this foundation. most builders would not develop this land as the build would cost more then the property is worth.

    the only photo i could get up was of the cracking on the cable end. this is thermal cracking, with poor maintenance of the decoration .

    Bdec have produced an exterior paint that will cover these cracks as long as you do not attempt to fill the cracks.
    • Useful Useful x 1

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