Where do breathable solid walls fit into Building Regulations?

In Wales we have a glut of solid walls. Lots of buildings built during the mid and later stages of the nineteenth century to home the workers in the mines and docks. The urban areas of Wales are notably these old terraces that we made from a mix of local and imported stone, brick and the old lime mortar. These houses are so common in Wales that we have forgotten that they are actually classed as Historic Buildings.

Part F (Ventilation) of the Building Regulations classifies Historical Buildings in a number of ways, but the web version crucially includes the definition (see 3.11):

‘buildings of traditional construction with permeable fabric that both aborbs and readily allows the evaporation of moisture’

It recommends that with regard to Historic buildings (3.22 c.) that it might be beneficial to include:

‘making provisions enabling the fabric to breathe to control moisture and potential long term decay problems: see Society for Protection of Ancient Buildings Information Sheet No.4 The need for old buildings to breathe, 1987.’

SPAB have a range of books and publications that all state that buildings should have the correct materials used in their refurbishment (although they don’t go into the use of stone dust rather than sand!)

However this part of the Building Regs refers to ventilation and so most of the advice on how to deal with breathable structures will come down to venting it more so that humidity in the building can be removed. Not by using the inherent nature of the wall to do this for you!

So is there better news elsewhere?

Short answer is no. All the other building regs (and the paper version of F) do not include ‘buildings of traditional construction with permeable fabric that both aborbs and readily allows the evaporation of moisture’ as their definition, they all harks back to Conservation areas, Listed buildings, Historical Interest…

Part C of the building regulations looks at Resistance to contaminants and moisture. By its very title it is not going to be pleasant reading for anyone with an Historic Building. Firstly, there is no mention of breathability in the definition of Historic Buildings. However, there is a slight glint of light at the end of the tunnel, namely:

The need to conserve the special characteristics of such historic buildings needs to be recognised. In such work, the aim should be to improve resistance to contaminants and moisture where it is practically possible, always provided that the work does not prejudice the character of the historic building, or increase the risk of long-term deterioration to the building fabric or fittings. In arriving at an appropriate balance between historic building conservation and improving resistance to contaminants and moisture it would be appropriate to take into account the advice of the local planning authority’s conservation officer.

So if you have a Local Authority Planning Officer who understands breathability and the possible structural damage that can be caused by using non breathable materials etc – see SPAB and others like us, then you might stand a chance.

Any more luck in Part L – Energy Efficiency?

One might hope that the recognition that damp walls are 30% less efficient than dry ones might show its face in Part L, but alas no.

OK, BRE know what they are talking about and they have a new BREEAM Domestic Refurbishment Standard. I have had two looks at this. Firstly a quick overview to see if there were some references to damp (after all we are talking about refurbishment of old buildings here). No category.

A search for damp on the website, brings up some info on Historic Buildings again, but with the definition being more linked to the one without ‘buildings of traditional construction …

Under Compliance Note 4 (Historic Buildings) –Historical buildings typically have high levels of air infiltration
leading to discomfort and heat loss. Historic buildings however also
typically require a higher level of infiltration to remove structural
moisture in the absence of impermeable damp
proofing. The refurbishment should be designed to meet the requirements
of Building Regulations Part F section 3.11–3.16 and reference is made
to the guidance provided in:

  • The guide to building services in historic buildings, CIBSE, 2002
  • BS 7913: Guide to the principles of conservation in historic buildings
  • Building Regulations and Historic Buildings, English Heritage 2004
  • Guide for Practitioners,
    conversion of traditional Buildings, application of the Scottish
    Building standards, Historic Scotland, 2007

One credit is awarded:

Where an assessment is carried out to
establish the current levels of air tightness and structural moisture
prior to the specification of fabric measures and heating systems. The
assessment should establish the appropriate level of ventilation for the
building, based upon:

  • the balance required to
    achieve a healthy, comfortable and draught-free environment whilst
    allowing appropriate building breath-ability in relation to structural
    moisture levels.
  • a minimum requirement of 0.4
    air changes per hour (or 8 litres/second per person) should be assumed.
    This may be greater where the structure needs higher levels of
    ventilation in order to deal with structural moisture levels.
  • ventilation rates are sufficient to allow structural moisture to be dealt with effectively.

Two credits are awarded where:

The first credit is achieved and where the
following testing was also carried out in order to develop the
ventilation/air tightness strategy for the building:

  • pressure testing was carried out before and after refurbishment in accordance with the appropriate standard
  • temperature and humidity is monitored before and after refurbishment

The only other grain of comfort in the new BREEAM comes with:

Under Compliance Note 7 (Design Aims)  – The design aims should be
formed following a discussion and/or a site inspection with reference to
a surveyors report (where available) which highlights any problems with
the existing dwelling (e.g. rising damp, excessive condensation, thermal comfort etc.)

So within BREEAM Domestic Refurbishment there is a mention of damp, but it’s remedy is ventilation and it also relies on surveyors to notice it in the first place. Worrying again for all those believers that damp should be dealt with using materials so that it is a permanent solution.

I think that the system is definitely against the growing number of people who recognise the need for appropriate solutions for our aging stock. The shame is that it will be future generations that will suffer along with the very nature of the buildings that we are trying to improve.