7 tips for a successful insulation retrofit

23 September 2020 Kingspan Insulation UK

Refurbishment projects have a habit of throwing up unexpected challenges or difficulties and insulation retrofits are no different. Whilst you can never account for everything before you start stripping back the plaster, these tips should help you to deal with common challenges you may encounter to ensure a successful installation.

1.    Check the condition of the property

Before you order any insulation, it is important to carry out a thorough inspection of the property for any issues which need to be addressed. This inspection should cover the entire property, not simply the area you are looking to install insulation, as failure in one part of the building can easily impact other areas.

Start by looking carefully for any signs of damp within the property. Rising damp can typically be identified by patches of cold or wet plaster around the base of ground floor walls along with flaking paintwork and rotting or warped skirting boards. Penetrating damp and condensation issues usually appear as isolated patches of cold plaster, condensation or mould build up in areas of the house. 

If damp is discovered, the cause must be addressed, damage repaired, and the area dried before any insulation can be fitted.  

Even when damp isn’t present, it is important to assess the property for issues which may lead to problems in the future. These may include:
•    missing pointing;
•    moss growth;
•    condition of existing drainage, guttering and downpipes
•    loose or cracked tiles;
•    presence of asbestos;
•    gaps around service penetrations (such as electrics and gas), windows and doors; 
movement or bulging in walls.

It is crucial that all of these issues are properly addressed before work starts as, once the insulation layer is fitted, it may be harder to access the area and any remedial work may mean having to remove and replace the insulation layer at considerable cost.

2.    Assess the ventilation

When insulation is fitted properly, it will also act as a barrier against air loss and draughts. For this reason, it is important to consider whether additional ventilation will be needed within the property and to develop a clear ventilation strategy.

Start by ensuring that existing ventilation channels such as air bricks and eaves are clean and free from obstructions. Pay particular attention to humid areas such as kitchens and bathrooms which are likely to require extraction fans.

If you are planning major work then it is a good idea to get an air-leakage test and an assessment of the existing ventilation provision carried out to better understand the current provisions and whether that might be sufficient after work is complete. 

3.    Take a ‘Whole House Approach’

To ensure energy efficiency measures (including insulation installations) function effectively and provide best value, it is important that they are implemented as part of a cohesive longer term improvement plan for the property. This should consider both the best improvements for the property, and a clear schedule for their implementation.

The new publicly available specification, PAS 2035, clearly defines this Whole House Approach including new roles and responsibilities. It will be compulsory for all TrustMark registered installers to follow this process from the start of July 2021, so it is important to familiarise yourself with its process. You can find out more about PAS 2035 in this blog.


4.    Choose insulation products carefully and don’t mix and match

The materials you fit can have a major impact on the finished property, so it is important to select them carefully and ensure that they are appropriate. In cases where there is significant external noise, for example, the owner may want to consider sound proofing. Often, however, retaining living space or headroom will be the priority and this will mean selecting materials with lower thermal conductivities (also known as lambda values). The lower the lambda value, the more effective the material is at preventing heat loss, meaning a slimmer thickness is required.

To help identify the most suitable solution, it is a good idea to make use of services such as our U-value calculator. This can help you to quickly identify an insulation solution which is suitable for your application in a thickness which will ensure you reach your desired U-value.

Different materials have different properties and putting the right material in the right place with the right thickness can affect the risk of interstitial condensation forming within a construction . Thermal insulants should be selected by matching their performance characteristics to the specific requirements of their application. Designers should take into account that different insulants offer different degrees of resistance to the transfer of both heat and moisture. When thermal insulation is provided in more than one layer, their relative physical characteristics should be carefully evaluated and the risk of interstitial condensation assessed.

Keep in mind that materials which look very similar on the shelf can have very different performance. For this reason, it is important to ensure the product you fit is suitable for the application and that you use the same product across the entire construction. 

5.    Get a condensation risk analysis 

When selecting insulation, it is important to get a full condensation risk analysis. This analysis looks at a number of factors. These include the building’s construction, its location and the likely relative humidity inside to determine the risk of condensation occurring either on the surface of the new layer (surface condensation) or inside the layer (interstitial condensation). We can provide a full condensation risk analysis as part of our U-value calculation process, helping to prevent issues with damp as part of your ventilation strategy.

6.    Pre-plan junctions carefully

Accuracy of detailing around junctions such as between floors and walls, at joists and around windows and doors is critical to the overall success of the refurbishment. Gaps in the insulation layer will create thermal bridges which can allow significant heat loss and potentially lead to condensation issues. For this reason, it is important to carefully plan work around junctions before you start, rather than trying to make it up as you go. This additional planning should ensure a problem free installation whilst ensuring that the whole layer performs effectively. 

7.    Take your time and focus on accuracy

Similarly, when it comes to the installation, take time to ensure everything fits tightly and securely. Bear in mind that junctions in older properties are rarely square and that gaps between joists are unlikely to be identical, so all insulation should be measured and cut to fit the specific area. It is also important to carefully follow the manufacturer instructions, including advice on the number, type and position of fixings and any requirements for ventilation or breather membranes.

Kingspan Insulation Ltd

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