A couple of weeks ago we informed you that a revised version of Approved Document F had been released for consultation. This release included a new section on existing buildings which we had been patiently waiting for almost a year.

My initial reaction to the document was positive, but then I read the document in more detail and saw an amendment that had been included in one of the earlier sections of the document. Needless to say I was dumbfounded by this alteration…

Lime render cannot replace ventilation in a building

As an industry we are very much aware of lime renders, as a product it has been promoted as an alternative traditional method of damp control for a long time, but one thing it most certainly can not do is replace ventilation in a building. Lime has many pros and cons, but how could it possibly be promoted as a possible solution for the provision of reasonable indoor air quality?

Older buildings were not better ventilated because they had lime render – they were better ventilated as they had open chimney breasts, draft windows etc. But we must now appreciate that most of these buildings are not the same as when they were first built. They have been altered and modified to suit a modern lifestyle.

I think most understand that the passage of air movement through most types of wall construction in UK dwellings is a relatively small and slow process. Disagree? Perhaps try a little experiment – put your lips against the wall and see how long it is until you pass out!

This comment is a little flippant, but surely the choice of render is rather irrelevant and what is more significant is the sub straight it is applied to. If a lime render was applied to a granite stone wall what impact would that have on the buildings provision for ventilation within a building? ABSOLUTELY NONE.

Ventilation is about more than moisture control

Furthermore ventilation is about much more than moisture control. One of the main reasons for the review of Approved Document F was to pave the way for better indoor air quality and prevent the accumulation of air pollutants, especially as we strive to make our buildings more airtight and carbon friendly. The approach being advocated here does not provide a solution for providing better indoor air quality.

What is even more scary is the fact that this is included within the proposal for an Approved Document. This is a loophole that will undoubtedly get exploited. I appreciate that retrofitting ventilation can be problematic in historic buildings – especially when giving consideration to the external aesthetics, but that’s why you look for an experienced and competent contractor who could work with you to come up with the best solutions.

I’m not trying to be ‘anti-lime’ here…

I am obviously very disappointed by the potential inclusion of this within the standard. I am not anti-lime, which I’m sure some people will say as a response, but just aware of its limitations – and what it can not do is be used as an excuse to get around the provision of good indoor air quality.

I expect many of you will be equally bewildered by these comments and I would encourage everyone to respond accordingly on the consultation:

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