IWI and driving rain n UK: we have the same issues and will get worst with the new weather patterns

Calahonda52

https://www.bbc.com/news/articles/cxwwr7vyrj0o

From Linked in

The BBC's breakfast programme this morning highlighted the challenges faced by some homeowners who had installed cavity wall insulation, leading to significant levels of deteriroating dampness. The published article can be found at  .

Today I dug out my 1997 copy of BRE's Good Repair Guide 26. Interestingly, it said:

"As long as the wall condition and building details are suitable for filling, the building is in an area where there is little risk of driving rain and the walls are under 12 m high....the decision to insulate the cavity is complex and will need the advice of a specialist."

I also found my copy of the Energy Savings Trust's 2007 Guide for Specifiers and Advisors. Not surprisingly, it says on page 3, that "suitability depends mainly on the local exposure to driving rain and the condition of the existing construction". Likewise the recommended procedure on page 5 involves checking exposure although page 6 very clearly states that "beads and mineral wool can be used in any exposure up to 12m in height, provided the installation is to the appropriate BBA or BSi....". There's an earlier 2003 version but I will spare you that for now.

Back in 2017, BRE published a report for Constructing Excellence in Wales. This highlighted very significant concerns about the effectiveness of such systems in surveyed properties, leading to just the kind of issues identified today by the BBC.

In 2017 the NI government also commissioned research. This found thatthere were very serious problems in 1.1% of their stock, and compliance issues in a further 24.2%. A wide range of contributory issues was identified.

Here is the BRE map of the UK showing wind-driven rain, which in turn is based on the methodology set out in BS 8104. It's fairly obvious from this that much of Scotland suffers very badly in terms of exposure. It's therefore also pretty obvious that there might be some challenges for those wishing to install such systems.

My recollection is that claims management companies first started doing the rounds in or around 2018, and by the following year the Department for Business and Energy was certainly providing advice to consumers on how to sense-check any such approach. In any event new installations had dropped to a trickle by that time.

As we face increasing pressure to retrofit properties, people will inevitably start looking again at cavity wall systems. There are, as today's article shows, real challenges. It's important that we get it right this time and that proper professional advice is sought from qualified architects and surveyors on a "whole house" approach.

Let's not just leave it to the installers this time.https://lnkd.in/eZ97iyT5

Lumen

Isn't this mostly an issue with exposed brick-built houses?

Ireland doesn't have much brick, particularly in exposed areas, right? Bricks out!

Calahonda52

https://www.boards.ie/discussion/comment/122204856#Comment_122204856

Poorly rendered block suffers from the same, with the move to a scud + final coat

Lumen

https://www.boards.ie/discussion/comment/122204904#Comment_122204904

Yeah, but render can be fixed. I suppose on the upside brick will breathe the moisture out if given a chance to.

That BBC story is interesting/grim. Taking out the insulation hasn't stopped the mould. No mention of ventilation. If she can't afford to heat the place it's possible that it's relying on purge ventilation which she's not doing.

Calahonda52

More grim

{ The driving rain/wind is also an issue with EWI when using the acrylic crap}

"The impact of compromised insulation on building energy performance"
Journal: Energy and Buildings
Big thanks to my co-authors Gianmarco Amedeo and Oliver Kinnane.

The paper is free to download for the next 50 days using this link:


▪ Context
The energy renovation of buildings is a key part of many national decarbonisation strategies and is going to ramp up further in Europe following the latest EPBD. This makes sense. But a performance gap between how a building is designed and how it actually performs in practice exists. This is obviously not good and lots of research has investigated how user behavior is causing this gap. It can. But the significance of this user-related rationale is inconclusive according to a recent review paper ().

▪This research
Far less research has been published on the technical performance gap rationale: under-performing boilers, heat pumps, insulation systems etc. This paper investigates why, and by how much, insulation can underperform in practice. Specifically, we look at two common culprits for insulation under-performance: 1) wet insulation and 2) air flow around the insulation (thermal bypass). Using thermal modelling, and computational fluid dynamics, we found that both scenarios can increase heat loss by more than 100% in highly insulated walls. The potential impact of thermal bypass in extreme scenarios is especially concerning, and could increase the heat loss by more than 300%. 

▪Significance
The degree to which the envelope's insulation is compromised obviously plays a part, and quantifying this exactly is difficult. However, these significant deviations from the designed performance align with the academic literature on envelope under-performance in practice (See first image attached to this post). 

Insulating our building makes sense. Insulating our buildings properly makes even more sense. 


Shout out to a  who highlighted the risk of thermal bypass in typical Irish construction typologies almost two decades ago (), to Jan Lecompte who published experimental work on thermal looping in 1990 (the year I was born!) as well as Terry McFadden who wrote about the impact of wet insulation, two years prior to that. All cited in the paper. Despite the early warning signs it seems we still need to pay attention. And for that, there is some really good practical guidance from Eurima on how to avoid these risks here. https://lnkd.in/dnuKJQHVJoseph Little

10-10-20

https://www.boards.ie/discussion/comment/122204856#Comment_122204856

Historically, wasn't it a combination of brick and also completely unsuitable cellulose blown insulation in the UK? Then the bricks and mortar at the base of the wall would then start to blow out due to frost action, and you'd end up with a wall starting to undercut itself. And then common remediation by applying a waterproofer to the outside of the brick was then further trapping moisture. A complete mess.

10-10-20

https://www.boards.ie/discussion/2058353973/iwi-and-driving-rain-n-uk-we-have-the-same-issues-and-will-get-worst-with-the-new-weather-patterns

Reading that BBC article you can see why IWI needs to be a whole-house approach and, much and all why we hate it, why large gaping vents are a significant part and parcel (on paper) of the overall system.

jackboy

Would cheap cladding on the most exposed walls eliminate this driving rain issue?

Calahonda52

https://www.boards.ie/discussion/comment/122212379#Comment_122212379

If it acts as a rain shield and protects the EWI then yes, I prefer cement board, with ventilation behind it