Desperately Seeking External Solid Wall Insulation in Lambeth

Last Autumn I finally got around to looking into getting external Solid Wall Insulation (SWI) on the gable end of my Edwardian semi.  The memory of freezing in blankets, hats and gloves in last year’s big chill with the heating full on, but only getting to about 15-16˚C max, was fresh and raw in my mind.   I had also recently met a lovely lady from Sto – the solid wall insulation product experts – who seemed confident that doing just the one, side wall would be workable and make a huge difference to our thermal comfort and heating bills.

Apart from being slightly less frostbitten in my home this winter, my other motivation was to test out the mechanism by which SWI was installed.  I want to experience the process, from the initial interactions with the council through to how the installation process impacted on the householder, as it is a much more involved process than, say, installing Cavity Wall insulation.  I also promote it widely to owners of solid walled homes in my work, but don’t have direct experience of it and how it performs, which is a gap in my ‘toolkit’ that needs filling.

Mass roll out of external SWI is an essential element of the Green Deal – actually getting to these 6-8 million ‘Hard-to-Treat’ homes and making a marked difference to their efficiency and fuel bills is at its core and vital to its sucess.  So far installation numbers for SWI are in the thousands per year, mainly because it is an expensive and, in the eyes of householders, a complicated product to install.   This installation rate needs to increase by a factor of about 10 quickly, as in this decade, if the Green Deal is going to deliver the carbon savings it is hoping for in the timescale required.

Lorraine from Sto, and Jason from P3 Projection coatings, who would be doing the install, visited for a technical survey and measure up in November and from the practical side of things, it was going to be challenging (mainly due to a narrow side alleyway which made the scaffolding tricky) but doable.  Hooray, first hurdle overcome. Tick that box.   They went away to work up a cost for the project and my task was to contact the council to ensure there were no issues with installing SWI on my house.

This is where the complications start.  Just before Christmas I received a response to my initial enquiry to Lambeth Planning Dept asking whether there would be any issues to me putting SWI on my gable wall.  I’m not in a conservation area and neither is my 1905 Edwardian semi of any listed status; so, hopefully no issues there.  However, the Planning Dept at Lambeth have come up with an alternative ‘issue’, one that is rather difficult to take seriously.

Basically the council has decreed (unofficially of course, I’d need to apply officially to get this officially ‘in writing’) that because the external SWI would be over around 100mm in depth (that’s just 10cms folks, on just one wall of the house) it does not come under ‘permitted development rights’ and hence is not permitted without first going through the planning permission process.  Planning permission that cost £100s, if not over a thousand pounds, and takes up to 12 weeks, with no guarantee of success.   Apparently any addition that is over 100mm is seen as an ‘Expansion of a dwelling’ – now this is faintly ridiculous; how can a cladding which sole purpose is to increase the thermal efficiency of an old leaky home, be considered as an ‘expansion’ of a home in any sensible way?

I reproduce the text from the council:

“My colleagues in planning are of the view that the application of an insulating material and a render skim would normally result in the ‘enlargement’ of the property. The extent of enlargement would be dependent on the thickness of the insulating material and the render. We have had very few proposals for the external rendering of properties and from my limited understanding the render thickness normally ranges from 100mm upward.

The national planning regulations allow for single family dwelling houses to have ‘permitted development rights’ which allow some work to be undertaken without the need for planning approval. The regulations make reference to the ‘enlargement’ of a property and present circumstances where enlargement would be ‘permitted development’ and other circumstances where it would not. I have reproduced the text below for your consideration:”

Naturally, I will be contesting this rather ‘jobsworthy’ view and also attempting to get responses from other councils on what their views on this issue are.  Will SWI become another ‘postcode lottery’ I wonder?  If this is a widespread view amongst local councils, it could have a devastating effect on the ambitions of the Green Deal to finally crack the nut  that would help ‘Hard to Treat’ homes come up to a decent standard in terms of thermal efficiency.

The BBC is potentially interested in this story, so if anyone reading this has had a similar response to from their council on this issue, please get in touch with me.

7 comments… add one
  • Richard January 10, 2012, 8:34 am

    Hi Paula
    Have you looked at CLG's "Permitted Development for Householders – Technical Guidance"? I think Lambeth may well be going over the top. I'll forward a copy to you. It's a turgid read (I know – I often have to dive into it as chair of our PC's planning committee!), but may be worth the effort.

  • Henry Unwin February 5, 2012, 10:56 am

    What an interesting read the technical guidance makes( – pages 9-31)!
    I have no idea if any of the below will help, it has left me rather confused!
    I have been speaking to the planning officials at Northamptonshire County Council who seem to think there is no need for planning permission unless the building is on article 1(5) land:
    ·         A listed building
    ·         In a National Park
    ·         In a Conservation Area
    ·         In an Area of Outstanding Natural Beauty
    ·         (Or of “townscape merit”)
    It may be the case that building regulation approval is required but that is a much simpler (and cheaper) process.
    It seems there are lots of contradictory statements depending on where you look. The main requirement is that the materials used looks the same as those of the original house (even though no one will be able to see your side wall!)
    Conditions (page 29)
    A.3 Development is permitted by Class A subject to the following conditions:
    (a) the materials used in any exterior work (other than materials used in the construction of a conservatory) shall be of a similar appearance to those used in the construction of the exterior of the existing dwellinghouse

  • Peter Barber October 1, 2012, 9:23 am

    Hi Paula This must be very frustrating. In my job working within London for a large EWI system manufacturer  I have heard of some local authorities having concerns over the change in appearance, particularly with regard to conservation areas. Indeed at a recent seminar I conducted with a local authority, their surveying department had invited  a member of their planning team along for them to get a better understanding of EWI systems. Our marketing dpeartment is aware of the planning issues regarding EWI and it is something  that we are keen to address. In many case we have worked hard with contractors and specifiers to produce samples or to even prepare sample panels on buildings to show planning officers, how an EWI system will look. We make sure that planners are aware that there are many render finishes available,including dry dash,synthetic ,textured scraped or mineral. On particular projects we have helped produce EWI systems with ashlars or architectural details to mimic tradtional facades or have used brick slips on insulation.We can now even produce "brick effect render". However this issue  appears to be solely down to thickness of the system. Has the planning departement advised you as to what thickness or build up would not cause an issue? As a systems manaufacturer we are always looking for thinner insulation solutions. Is the specification proposal based on the use of a PIR or PHS insulation board? This may save you a few precious mm over an EPS or Mineral fibre based system. I hope this helps.   Kind Regards Peter Barber London specification manager (London)   Saint Gobain Weber

    • Paula October 1, 2012, 9:30 am

      hi Peter

      Thanks for your comment.  It is my feeling, although not confirmed, that the issue seems to be that the whole system – insulation, board, render – will be over100mm in total and that is the issue!  Although I might be wrong here!  I need to go back to the original full response and check.

      Will let you know


  • Peter Barber October 1, 2012, 4:17 pm

    If the original proposal was based on EPS or mineral woool, the use of a PHS (Phenolic) insulation may allow you to go down to as little as 60mm. Do you recall what the target u value was? If you have details of the existing wall construction and the target u value I could ask our technical department to do a u value calcualtion for you.  
    Kind Regards Peter

    • Paula October 1, 2012, 4:27 pm

      Hi Peter

      I think it was phenolic, but on discussions, to get the reduction in u value required, the whole ensemble, as it were, would add up to be around the 100 mm mark.  Hence the problem!


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