What to select for 'Hard To Treat Cavity Wall'?

In the Addendum and Related Party Disclosure section a checkbox of questions appears whenever Cavity Wall is selected as the wall construction type for a property.

This appear in ECMK assessor hub and the Smart Survey App here:

The 3 checkboxes that appear are:

• Property has access issues?
• Property has high exposure
• Property has narrow cavities?

Selecting these boxes will mean that this information will be shown on the EPC certificate - so knowing when to tick them is important.

The reason why these questions are asked, are related to cavity wall insulation and the potential for this being a measure installed at the property.

Convention 9.10 states when access issues, high exposure and narrow cavities should be recorded.

Let's take a look in more detail....

Convention 9.10 states:

An access issue is recorded if there is any façade where it is not possible to pitch a 5 metre ladder considering health and safety requirements. This includes e.g. a narrow passageway, a busy thoroughfare next to a building of more than 2 storeys, a conservatory or large outhouse attached to the property, etc

This could also include any issues related to gaining permission from a neighbouring property to access the area.

If cavity wall insulation was to be installed, ladders or scaffolding may be required so would they be easy to set up on all walls, and allow an installer to treat the property?

If the property has access issues - then this box should be ticked.

A high exposure cavity wall is one that is frequently exposed to wind-driven rain, making it unsuitable for most types of cavity wall insulation because water can penetrate the external brickwork and become trapped in the cavity, leading to dampness and structural problems. 

Homes in high-exposure zones, particularly those in areas like the west coasts of Scotland, England, and Wales, are at a greater risk.

Convention 9.10 states: 

Possible high exposure should be recorded for any dwelling in exposure zones 3 or 4 (see map at end
of these conventions). If in doubt record as possible high exposure.

If the property has high exposure - then this box should be ticked.

The map below shows areas of high exposure in the UK.

Diagram 12 (Approved Document Part C) – UK zones of exposure to driving rain

Source: Thegreenj (2007) CC BY-SA 3.0

On a non invasive survey such as an EPC it will not be possible to ascertain the exact thickness of the cavities to determine if they are narrow.

However we can look at the convention again to determine when this box should be ticked.

Convention 9.10 states:

A narrow cavity is indicated by a stretcher bond brick pattern with wall thickness 220 to 250 mm.

Therefore, if there is a stretcher bond pattern, and the wall thickness is between 220 to 250mm - this box should be ticked.

Now you should hopefully know how and when to tick the relevant boxes that appear for the 'Hard to Treat Cavity Wall' section in your software.