When it comes to the refurbishment of non-trad homes a thermal upgrade will always form part of the package. But just what are the options for insulating non traditional properties?
Non-traditional properties were mostly constructed after the end of the second world war as a result of a severe shortage of housing. There was a need to build quickly and also to find an alternative use for factories established to support the war effort which needed to diversify.
Hence, traditional building materials of brick and block were replaced by timber, metal or concrete frames. These also incorporated various cladding or finishing materials and systems.
Properties were built quickly but designed as a short term (often just 20 year) fix. Read more on the history of non traditional construction. That was decades ago though and yet people are still living in these properties today. Homes that are in desperate need of refurbishment.
Insulating Non Traditional Properties
As part of any refurbishment program a thermal upgrade will always be included. This is required to bring a property up to current regulations as a minimum. There are basically three alternative options for insulating non traditional homes. All of which are relevant to both low-rise and high-rise post war properties:
Internal Wall Insulation (IWI)
Internal wall insulation involves, as the name suggests, cladding the internal walls of a property with insulation.
It will often be considered If a property has no cavity or a narrow cavity. There are many drawbacks though:
- Internal wall insulation will result in a reduction of living space.
- IWI does not address cold bridging in all cases and therefore a risk of condensation can remain.
- The main external envelope ends up colder and more vulnerable to freeze thaw issues.
- There’s significant disruption to tenants who will often need to be rehoused during works.
- Whilst IWI will provide a solution to the thermal upgrade of a property it will not change or improve the external façade which, if required, will need to be addressed as a separate measure.
IWI is a good option if the external facade is required to remain untouched for whatever reason.
If a property has a cavity, is structurally sound and external upgrade is not required then this is a viable option. However if there is no cavity, if the cavity is too narrow to fill or if there are any structural issues like failed wall ties then this may not provide the solution.
Cavity wall insulation remains a popular option but its effectiveness is completely dependent on the size of the cavity. Before 1980 cavities were often only between 40 and 60mm compared with today’s which may be up to 165mm. This means cavity insulation often provides little benefit to insulating non traditional properties.
There are other issues too:
- Fully filled cavities may provide an effective bridge that can carry moisture between a wet external and the dry internal leaves.
- If the insulation becomes wet its properties are nullified.
- Wall ties need to be checked for corrosion
- Cavity wall insulation does not change or improve the external façade which will need to be addressed as a separate measure.
External Wall Insulation
An external wall insulation system ticks the majority of refurbishment boxes.
A standard EWI system consists of insulation panels (typically EPS or Mineral Fibre) that are mechanically fixed back to the existing substrate, a base-coat render incorporating a fabric reinforcing mesh and a finish of choice.
The benefits are varied:
- EWI completely wraps the walls with insulation of a type and thickness to achieve targets or current regulations.
- The risk of thermal spikes and internal condensation are eliminated
- The whole structure is kept warm and free from degradation.
- The external facades can be completely transformed through the use of various finishes, colours and texture.
That’s what makes External Wall Insulation the obvious choice for insulating non traditional properties. It effectively insulates, provides minimal disruption to tenants, modernises the appearance and can completely transform communities.
However, as standard EWI system doesn’t provide the answer in every case … let me explain.
The system works as follows:
Insulation panels of a type and thickness specified to achieve current regulations or desired u-value targets, are mechanically fixed back to the existing substrate by way of specialist fixings of a nail or screw variety dependent on the substrate.
Base-coat render (incorporating a fabric reinforcing mesh) is then applied directly to the insulation before a finish of choice is applied – typically render, dash, brick slips or brick effect or a combination of these.
When Standard EWI Doesn’t Work
In effect then, a standard EWI system is only as good as the substrate it’s going to be attached to.
A survey of the existing walls therefore always needs to be carried out prior to the specification or application of a standard external wall insulation system in order to:
- Confirm suitability for application of external wall insulation system.
- Agree scope for any repairs and/or additional works required make the walls suitable to receive the system.
- Satisfy that they are structurally sound and suitable to accept additional loads from the Cladding System.
Whilst a standard system will be OK more often than not, if suitability can’t be confirmed then a more engineered solution may be required … a structural external wall insulation system for example.
Structural External Wall Insulation
The big difference with Structural EWI is that, rather than fixing insulation boards directly into to the outer leaf of the existing substrate as with a standard EWI system, a Structural EWI system comprises of longer insulated panels (up to 3.6m), housed within a galvanized or stainless steel metal “cage” which are designed to span (either vertically or horizontally) between floors or load-bearing columns and are attached directly to the existing structure accordingly.
These panels are joined together with a wire mesh to provide a rigid, continuous envelope around the building with adds real structural integrity. It basically wraps the entire exiting substrate to form a continuous monolithic structural solution … like a corset around the building!
A thick layer of base coat render is then applied to the system which works with the panels to provide a high degree of racking, flexure and spanning. This can be then finished in exactly the same way as any standard EWI system.
Because the panels don’t fix back into the substrate and as instead they fix into the structural framework of the building the condition of the existing substrate or the quality of the concrete is immaterial. It therefore doesn’t matter what the substrate is, what condition it’s in or whether it’s left in situ or removed.
There’s no need to over-engineer a solution and so there are times when a hybrid combination of structural and standard EWI systems may provide the most cost-effective refurbishment solution.
Insulating Non Traditional Properties – Learn More
If you’d like to learn more about the different refurbishment options for insulating non traditional properties or if you have a project which you’d like to discuss we’d be delighted to hear from you. Our friendly, efficient and expert technical department are happy to advise. They will work with you to help establish the right specification. Just pick up the phone or drop us an email and we’ll get straight back to you. Contact Structherm >>>.