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How to retro-fit underfloor insulation with Earthwool batts?

I wanted to retro fit insulation batts under our house, which is leveled up on tilts. I have read all posts here on this subject and chosen earthwool batts. Now I have a couple of questions:

1. There are some cables and electrical lines running under our house (see picture). Should I leave some space around them? Should I engage an electrician to check them out for safety? What about water and sewage pipes?

2. The space width is generally 320-380 mm. With batts at 430 mm, they can be tucked in but there is a thin strip on the edge that is compressed (see pic, left side of the batt). Would you recommend cutting it to maybe 400-ish?

Thank you in advance!

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Comments

EricL

Hello @Tensy

Thanks for sharing your question about installing insulation. I propose drawing a map of where the electrical cables are and where you are likely to encounter them. Next, I suggest engaging the services of an electrician and asking them if it is safe to install the insulation in these areas or if they should be the ones to do it where the cables are exposed.

In regards to the water and sewer pipes, there should be no issues in installing insulation around them. As to the narrow spot, I don't think it's necessary to cut the insulation unless it really can't fit.

If you have any other questions we can help with, please let us know.

Eric

Tensy

https://www.workshop.bunnings.com.au/discussion/comment/37147#Comment_37147

Thank you Eric! That’s useful to know and I will engage an electrician.

One additional question: how should I dispose the off-bits of the batts?

MitchellMc

Hi @Tensy,

It would be best to check with your local council for a suitable location that accepts construction waste, such as insulation batts. This will typically be a recycling centre or local tip.

Mitchell

Tensy

A following up question regarding expanding foam:

in the very depth of the underfloor space it is too narrow to work, so I have decided to use some expanding foam to do the job. I bought a bottle of Bostik Fill It expanda foam.

However, I discovered that when I’m lying down on the ground, trying to apply the foam onto the underside of floorboards above my head, the foam just drips down and falls to the dirt floor.
Is there any way to apply it or make it stick and stay…?

@EricL @MitchellMc

EricL

https://www.workshop.bunnings.com.au/discussion/comment/37205#Comment_37205

Hi @Tensy

I suggest placing some cardboard between the timber joist and keeping them in place using tape or stappling them to the timber surface. When you spray into the gap the cardboard will hold the foam in place as it expands and once the foam cures you can either remove the cardboard or leave it there to make sure that the foam is held in place.

If you have any other questions we can help with, please let us know.

Eric

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