How should I install underfloor insulation?

[Repairattempts]

Hi,

I am looking at installing underfloor insulation but don't know where to go in terms of choosing products. I have 450mm joists. Can waterproof wall insulation be used for underfloor insulation? Or do I need to use underfloor specific products? Is there that much of a difference?

Thanks!

[MitchellMc]

Welcome to the Bunnings Workshop community @Repairattempts. It's wonderful to have you join us and many thanks for your question about underfloor insulation.

I do apologise for the delay in my reply.

If you are talking about fibreglass insulation then floor or wall are very similar. The underfloor comes with a coating to prevent wind blowing through it. This is most important if the underside is not enclosed, like a subfloor to a house. Will underneath the insulation be exposed to the elements at all? If it's enclosed with plasterboard then you could go and use the slightly more budget-friendly wall insulation.

Please let me know fi you have any questions.

Mitchell

[Repairattempts]

Hi Mitchell,

Thanks for your advice! The underfloor is surrounded by a couple of wooden panels with aeration gaps so relatively enclosed but certainly not like a solid brick or plasterboard panel. Do you think that this would be sufficient blockage to use wall insulation?

Thank you!!

[MitchellMc]

I believe so, @Repairattempts. The other option might be to use wall batts and staple sarking across the bottom of the joists. That might not work out any cheaper than the floor batts, though.

Mitchell