INSULATION
It is worth noting that both EWI and IWI, if improperly designed or installed, have the potential to exacerbate or create damp problems in a wall
Bring on the technology Adding insulating boards to either the internal or external face of the wall has historically treated solid walls. Both options raise significant challenges for landlord, tenant or an owner-occupier for that matter. External wall insulation (EWI) requires a large capital outlay, between £8,000 and £22,000 per home according to the NAI and requires economies of scale to make it viable. EWI has been most often applied to local authority or housing association-owned apartment blocks. For individual homes, the holy grail would be to persuade a whole street to invest in EWI, but the political and economic mechanisms to do that have not been created. Internal wall insulation (IWI) is a more cost-effective option, requiring a capital investment of between £4,000 and £13,000 according to the NAI. But it can be disruptive for householders, and could mean that a landlord must lose a tenant and suffer from a rent-free period, as well as the costs associated with securing a new tenant once the work is done. IWI also reduces the space inside a room and can mean that period features are sacrificed or recreated at some cost.
It is worth noting that both EWI and
IWI, if improperly designed or installed, have the potential to exacerbate or create damp problems in a wall. EWI applied to a wall with rising damp, which remains untreated, will make the problem worse. IWI can cause condensation to form behind the insulation leading to damp and mould. As with any energy efficiency improvement measure, it is always important to take a holistic view of a property and the way it works to avoid causing more problems than are solved. One potential solution is a system approach which combines super-slim aerogel technology and a masonry cream that allows wet walls to dry out while preventing moisture getting in. Because these aerogel materials are
super-insulators they can still have a significant impact when applied in very slim
ADF MARCH 2019
layers. When it comes to selecting the right masonry cream, it’s important to choose one that allows water inside the wall to evaporate out while preventing moisture from outside penetrating inwards. For that Victorian end-of-terrace property cited earlier, the application of the combined slim insulation and masonry cream changes the U-value of the walls from 1.7 W/m2
K when damp and uninsulated to 0.8 W/m2 K when treated.
The application of such a system is good news for the tenants as well as the landlord. They could expect to save nearly 30 per cent on their heating bills every year.
Hudson Lambert is director of Safeguard Europe
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