Ezy-Fit System: Internal solid wall insulation gone wrong. Any advice?

[joannaerck]

I had internal wall insulation installed through my energy supplier, funded by a government scheme. I have an Edwardian semi detached house. The system they use is called Ezy Fit (https://www.ezy-fit.co.uk/shop/systems/m-iwi-internal-wall-insulation). The insulation is predominantly made up of 4" thick high density slabs of mineral wool (or on the reveals, Jackoboard) installed directly onto the wall and mechanically fixed into the brick. Then the usual plasterboard and plaster skim.

I was really unhappy with the finish. Almost every wall was out of plumb, not level or not square, far more than tolerance. This was glaringly obvious around the windows and sills where the wall bowed and everything looked completely crooked. I asked for an inspection and the energy supplier agreed it was unacceptable. Builders came back and started removing some of what they'd done, and discovered that, in the month or less since finishing, there was mould all over the walls. They ended up taking everything off which was obviously a huge waste and a massive disruption, because almost the entirety of the walls underneath had developed damp where there was none before. They admitted to a poor and faulty installation causing the insulation to sweat. 

 

This system works by eliminating air gaps, so preparing an even surface, free of missing plaster or holes, is vital. Every potential air gap, such as around the screws should be sealed. However in my case, they hadn't even, for example, taken picture hooks off the wall. The energy supplier used to install the more common SWIP system using wood battens, a vapour barrier and leaving a deliberate air gap, which also allows for a flat and level finish. They no longer use this system (only because the use of wood lowers the fire rating slightly). They wont offer any alternative insulating measures. 

 

My options are to either:

- have it installed again, with more oversight and checks on the work. (It'll be different individuals on the job, but part of the same team).

- have my house returned to how it was. They'll leave a new plaster finish and I get a voucher to go towards redecorating. 

 

However I am worried this insulation just isn't the most appropriate for my property. The old walls require careful preparation for effective installation of this insulation. Undulations and bowing in the walls can't be eliminated. I'm concerned about the quality of the workmanship. I can't be sure there won't be gaps and damp isn't forming again.

 

Is there an effective way of monitoring the insulation for damp, without removing part of it and indefinitely putting off redecorating? If I choose to have it returned to how it was then obviously I do not benefit from any insulation after all of this disruption. Regarding potential compensation, so far I've only been offered £200 for redecorating.

 

Any advice is much appreciated!

[Mr Punter]

With no vapour barrier on the warm side of the insulation there is nothing to stop warm moist air migrating through and condensing on the now colder wall.  Absolutely crap design.

 

BTW I saw in their "system design guide" several references to a "high mortality seal".  I have never heard of this.  Does it kill people?  It certainly has a good go at killing dwellings.

[Redbeard]

I think the 'high mortality seal' only applies in marine environments.

 

Sorry! Sensible reply later!

[Iceverge]

Firstly poorly aligned and plumbed walls are not acceptable. Thats just sloppy but it's easy to see what went wrong ang how it can be cured. 

 

 

Otherwise lets look at the reasons for the condensation. 

Pictures please. Before after and during install. 

1. Details of this sealing around the board edges that is supposed to have happened ( I'm certain it didn't).

2. Detailing around the ceilings and socket outlets too please. 

 

 

 

I'm going to make a diagnosis in the meantime about the mould.  Terrible airtightness is the culprit here, not anything to do with vapour diffusion or vapour control layers etc. It's a red herring. 

Yes vapour does diffuse through materials in an effort to for differing gasses to get to a state of equal vapour pressure ( same as absolute humidity) but the quantity is so miniscule it's not an issue in reality for plasterboard. 

Drafts caused by lack of proper airtightness carry hundreds and often thousands of times more water into the structure which result in condensation.  It's here you need to focus, no matter what kind of structure you have, even an uninsulated wall will suffer from damp internal air making its way inside. 

 

This installed system has no proper tactic to deal with airtightness other than a mastic seal at the perimeter of the boards. This needs to be absolutely immaculately done and will be completely pointless unless you hermetically seal all ceilings, floors, windows, doors, and socket penetrations, it's impractical in reality as it requires adequate knowledge of why it's being done and will cost extra for each follow on trade to take the lever of required care. 

 

For internal insulation you need to move your airtight layer outboard of any penetrations and ensure it's completely continuous throughout the house. This includes taking down ceiling perimeters to ensure there's a continuous airtight layer between both floors and adding a continuous airtight layer to the floors and below the attic. You can use airtight membranes of variable or high vapour permeability, airtight paints or a parge coat.  

 

Adequate mechanical ventilation is very important too to control excess humidity inside the building.  Infact this alone can cover up an awful lot of bad workmanship if done well.  

 

 

I've made a very boring video explaining this in relation to older stone houses in Ireland (where driving rain is also a big issue)  but the principles are the same.

 

 

 

 

 

 

 

 

 

 

 

 

[Redbeard]

Sensible reply as promised. I am really sorry you have had this issue. The manufacturer's info does not seem terribly comprehensive, and how does that 'high mortality seal' (what?!) at perimeters only deal with air-tightness? The instructions for bringing cables through the insulation make no mention of the need for air-tightness, or I may have missed it. Also one of the pictures seems to show (OK, may be my old eyes) a gap between sheets wider than I would wish (i.e. bigger than not a gap at all).

 

There is ref to a condensation risk assessment in exposed areas. There should be one in any case but, as per @Iceverge's post, any 'failure' - quite possible at 100mm - might well attract a recommendation for a VCL from Glaser Method calcs. WUFI or similar may have different views.

 

Edit: Like you, OP, I would be worried about the same firm doing the job again. One might argue that the reality of your installation may have shocked them so much that they will never do a job like that again, but an inescapable fact is that someone signed that off as OK. How confident could you be of 'second time lucky?

 

This is hugely disappointing given that it was presumably done under the auspices of PAS 2035, which came out of the Bonfield Review into public funded retrofit after some spectacularly awful failures. Worrying too.

Edited April 8 by Redbeard
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