Insulating over fibro

House has plastic/vinyl cladding over fibro, so house is either cold or hot. I would like to remove vinyl cladding, use a sheet type insulation over the fibro and then use weatherboard as cladding. Is there a product that would do this or is it really not doable

Question by:
Les Langford's picture
Les Langford

Hi Les,

I put your question to the National Technical Development Manager at CSR Lightweight Systems, Angus Kell. Here's his advice:

The use of plastic / vinyl cladding was often used to ‘improve the look’ of flat sheet cladding products, they typically are not self-supporting so they were fixed over the ‘fibro’, which is typically asbestos cement sheeting and therefore has significant risk associated with the works. Prior to working near or with asbestos the reader should investigate safe working methods which are freely available.

So there are two (2) possible options:
1. Remove the cladding and asbestos cement sheeting – this then allows an opening of the timber frame and would allow the installation of insulation within the cavity. Depending on where they are located and the climatic conditions they could wrap the building in a breather membrane and clad with usual options.
2. Remove the cladding and leave the asbestos cement sheeting – in this case you could apply a rigid insulation such as PIR over the cladding and then install the breather membrane and cladding. This has some practical considerations such as the cladding needs to be supported through to the timber frame and with the PIR in place is difficult to achieve.

Whilst Option 1 sounds more complex and possibly more expensive it would be the preferred option, for a number of reasons:
- Removal of the asbestos (in an approved manner) ensures you have a healthier home,
- Standard insulations are cheaper than PIR so the additional cost of removing the asbestos should partially be saved by using more affordable materials,
- The external cladding is easier to install,
- Without the build-up of the PIR you will have less effect on windows, doors, etc which if existing have a fixed thickness.

Hope this helps.

Regards,

Angus Kell | National Technical Development Manager | CSR Lightweight Systems
Gyprock™ Plasterboard & Cemintel™ Fibre Cement Systems

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