Cheap and easy way to insulate underfloor of weatherboard house

[TimD]

Hi,

   I have an old weatherboard house and would like to get under the house and install insulation under the floor.

I have very little headroom (less than 1m) under the house so I think struggling with stiff boards is not an option. 

So I am looking for a simple and cheap method to do this. It does not have to be super insulation - just enough to take the edge off somewhat and something I can buy in-store. 

Also, hints on what tools I would need would be greatly appreciated too,

Many Thanks

[TimD]

Hi All,

    A quick update. After several weekends,  I have now completed my insulation!

A few lessons learned :- 

• Don't underestimate the amount of material needed - I had to double my order. Also staples - will need more than you think. I used GI Building Sciences 1.35m x 22.5m x 4mm Reflecta Cell Floor Insulation. The good thing about this was its like material, easy to cut and flexible and easy to staple. It was special order, but took less than a week to arrive
• It will take longer than expected!  Don't try and do it in one go. The space under my house was very limited - in some places less than 0.5m - so a lot of crawling on my back for hours at a time
• Watch out for electric cables - there are more cables under your house than you expect and of course be very careful
• Buy a battery electric stapler. I did hesitate at first thinking it was extravagant for one job, but there is no way I could have done it with a manual stapler. I used the Ryobi 18V ONE+ Cordless Stapler  and Arrow 10mm T50 staples. It did jam a few times at the start but later not at all. Maybe it was my technique  
• Remember goggles and mask - a lot of dust under the house
• Remember ear protection - the electric stapler is not particularly loud, but you are in an enclosed space stapling for hours and could cause damage
• Wear a cap or other head protection. You will bump your head!

Other tools:

• Sharp knife and metal ruler to cut the insulation before going under the house
• Scissors to cut around pipes, cables etc.
• Tape to join/seal the pieces - don't allow gaps for the draft to get in
• Tape measure - measure between each joist - I was surprised just how much the gaps between them varied from joist to joist - some were also not parallel (old house)
• Marker pen to mark the size of each strip. The  more you can plan before going under the house the better
• Chalk to label between joists and their sizes
• Torch and headlamp so you can see clearly any obstacles  especially cables hiding in corners and along joists. Check, then check again
• Box to take all the tools you need at the start of the job so you don't have to keep crawling back out from under the house. Use tool, put back in box, not on the ground. I lost 2 pairs of scissors by not doing that (found them again)
• Use an old yoga mat to lie on - lots of rocks and rubble under the house
• Old clothes you don't mind ruining
• Probably most important - Bath salts. These are for a long soak after a day of crawling around in dust, dirt, rocks and cob webs 😀

Thanks everyone who contributed to my post and special thanks to the moderator @MitchellMc who provided the list of suggested products. Without tips and suggestions from everyone, I probably would not have had the confidence to embark on this little project,

Thanks again

Tim 

[MitchellMc]

It's fabulous to hear that your project was a success @TimD! We really appreciate the time you've taken to thoroughly explain the steps you took and the equipment needed. They will be extremely beneficial to the next member considering a similar project. 

I now look forward to your feedback on the difference the insulation has made. I suspect we might need to wait a little while for that update.

Many thanks for sharing your success.

Mitchell

[Jason]

Just wanted to add my thanks for coming back and sharing your experiences and lessons learned @TimD. I'm sure Bunnings Workshop members will find this extremely helpful when tackling a similar job in the future.

Thanks again,

Jason

[Sally8]

I have read this thread and think the advice in it is great.  I too have an old house with a timber floor and a ~600mm crawl space underneath and I am trying to resolve an issue.  I am just not sure which product to use and would love some advice.  The ground underneath is bare earth which does get slightly damp in high rain, the floorboards are hardwood.  Inside the room(s) it is very cold in winter and damp.  The pillows on the bed are often damp and the ceiling has mould and the clothes in the wardrobes get mouldy too.  Would I be better off using the foil or insulation bats (Earthwool) and if so what rating?  Sound proofing is not an issue.  Many thanks in advance for any advice.

[StevieB]

Welcome to the Bunnings Workshop community @Sally8 and thanks for reaching out with your question. It's great to see you jump straight in and contribute to this discussion. 

Let me tag @TimD and @JDE who may be able to offer suggestions. Our resident D.I.Y. expert @EricL will also be happy to help when he's back on the site on Friday.

Stevie

[TimD]

Hi @Sally8,

   I can't advise on which would be the better option for you. Our house too has bare earth underneath. If it rains the first 20cm or so of the soil is damp but once under the house proper the earth is very dry. Yes, if we are having a rainy period the house feels a little damp but luckily we don't have mould. The big thing for me was that the foil was very easy to install. It is very flexible, easy to cut (knife) and easy to install with a staple gun.

I imagine (though an expert could better advise) the bats would give you better insulation than the foil.

Since we installed it, we have definitely felt the foil has helped quite a bit. I wouldn't call it cosy, but we no longer have the bitter cold we used to have, we use the heater less and we no longer need it on full blast. 

Hope this helps,

Tim

[Sally8]

Thanks Tim!  Regards Sally

[Jason]

Important note for our New Zealand readers:

The New Zealand Ministry of Business, Innovation and Employment (MBIE) issued a ban on the use of foil insulation in July 2016. The ban applies to the installation and/or repair of foil insulation in residential buildings. More information is available here: Foil insulation ban | Building Performance.

Thanks,

Jason