I am looking at trying to insulate under our floor. We have an 80s weatherboard, totally uninsulated house with masses of glass. Slowly slowly my husband is taking the roofing sheets off and insulating under them. Part of the house has subfloor access (max height is only about 75cm, but I can get in and shuffle around on my back under our main public/family space. I am horrified to see the wooden floorboards in the hall are not even set on particleboard. The living room has a carpet at least. My plan is to seal up as many gaps around the edges as I can and then put insulation in between joists. I am thinking about expol (seems easiest to install in cramped conditions) or bradford optima. Feel like if doing it should make it as effective as possible. Any thoughts or ideas or experiences gladly received.
Subfloor insulation advice
(13 posts) (9 voices)-
solar_star
MemberI've got some packs of expol sat under the house waiting to install. have put some up. make sure you measure carefully between the joists as it comes in different widths and you want it to be a fairly tight fit not just drop out again.
I spoke to the expol people at one of the homeshows and they confirmed that you need to use the tape you can buy between the expol and any wiring because otherwise the casing of the wiring reacts with the expol. The tape looks like stiff paper tape.
Posted Monday 30 Aug 2010 @ 11:19:30 am from IP # -
ghostgum
MemberI hope your husband is also putting RFL under the roof sheets before he replaces them. That greatly improves summer temperatures in the house.
There is some technical information on subfloor insulation of wooden floors at
http://www.timber.org.au/resources/Insulation%20Solutions%20for%20Suspended%20Timber%20Floor%20Systems.pdfI've used concertina foil batts.
I know someone who use bulk batts (I'd use polyester) held up with the packing band tape stapled to the underneath of the joists.
Another person held up the batts using RFL.Nothing wrong with tongue and groove floorboards. They are probably more robust than my particle board flooring.
My experience is that it doesn't reduce your heating bill much (this winter after adding the subfloor insulation I've used more gas than last winter), but it does make the floor feel warmer. It is particularly good under the floor which gets the northern sun, keeping more of the heat in the house and making the sub floor area noticeably colder.
Posted Monday 30 Aug 2010 @ 11:21:04 am from IP # -
acd
Memberthanks for that info. Yes hubby is putting RFL in as well. The 2 rooms so far completed are considerably better, more especially noticeable in winter.
Is the idea of little animals living in the batts under the floor just an urban myth? Is there any real advantage to the bradford optima compared to using any batts?
Im not sure I can face batts and RFL - maybe Im just a bit clumsy but I found it difficult to nail up the RFL onto inside of rafters in the one small area of attic space we have, and the thought of trying to attach it above my head in a tight space seems too hard. In a way Im not even trying to reduce the heating bill, I would like to be able to keep the temp more constant. At the moment the heating is set at 18C. We wear jumpers, thats fine, but as soon as the heating turns off (at 10pm) the temp plummets to a couple of degrees above outside temp.Posted Monday 30 Aug 2010 @ 11:57:13 am from IP # -
GBD
MemberOne assumes your in a colder area of Australia?
How cold? ie what town area etc?As per above, you will get far greater gains by enhancing the walls and windows.
Something like 10 to 15% is lost through the floors,
and 30 to 40% through walls and non curtained windows.But if you're still thinking under the floors is next then do it.
As for rodents - yes they can live in the underfloor insulation, (they can also live in the ceiling) and yes they do exist in suburbia - all be it probably not as frequently as in rural areas.
How to hold the batts up - a staple gun or a nail gun makes life easier in tight close spaces.
Trust this helps.
Posted Monday 30 Aug 2010 @ 1:21:33 pm from IP # -
ghostgum
MemberWe used a staple gun to attach the concertina foil batts. It's easy to use. You just lie on your back or side under the house and work with your arms straight up. After an hour your arms and neck start to hurt, so you need to do it in stages. We have pine floo joists, so the staple go in easily. Not sure how stapling would go on old hardword floor joists.
I read somewhere that there was one or a very small number of occurences of animals making nests in under floor batts. If you haven't got a mouse or rat problem, then you probably won't have a problem with pests in the batts.
Posted Monday 30 Aug 2010 @ 9:00:07 pm from IP # -
actually it depends what you are stapling into i.e. the joists ... why not try with a manual staple gun now ... the concertina batts are not the issue it is the floor joists.
Posted Tuesday 31 Aug 2010 @ 12:20:19 am from IP # -
I stapled into the joists using an electric staple gun. You can get a cheapie for $40 or so. So far I have used it to retrofit sarking to the underside of the rafters in the garage and also to staple up R1.5 poly batts to about 30% of our floors. The stapler is holding up well though having the drag the cord around under the house is less convenient than a cordless manual stapler.
As per Ghostgum's note, we used packing strapping material recycled from my work and the odd skip bin around teh place. The material seems well suited to the task and looks a lot neater than my first attempts with lighweight netting.Posted Tuesday 31 Aug 2010 @ 2:57:49 am from IP # -
solar_star
MemberIts obvious I know but be careful not to staple through any electric cables which may be nailed to the joists.
I'm sure there are all sorts of rules about where the cables are meant to be attached but judging by the underside of my house they may not be followed too carefully. sometimes they are on the bottom of the joist sometimes they are on the side of the joist. Danger is when you are in a tight space that you might be stapling at arms length where you don't have a good sight line.
My tip for this kind of safety related issue is to have a systematic sequence of actions 1) check an area for location of cables - using touch and a mirror on a stick and torch as necessary 2) only work with enough material to cover the area where you have checked. repeat.
Having worked under the house putting insulation on water pipes I found it was better to just crawl out and take a break than press on when I really shouldn't have.
Posted Tuesday 31 Aug 2010 @ 3:21:29 am from IP # -
jaccp
MemberI'm currently fitting Greenstuff polyester batts under our floor. It comes in big rolls and can be torn by hand rather than cut. Was planning to cover with foil but as there'll be no air gap between batt and foil there'd not much point and it's hard to do foil with cables/water pipes etc. It's 430mm wide and tension fits between joists. Manufacturers recommend stapling bottom side of batt into joist but we've used twine and stapled under joist to make it easier/quicker. I'm also planning to close up baseboards to reduce airflow under house (but allow just enough ventilation).
Not a pleasant job wriggling around under there and I had the power off when I was stapling.Posted Tuesday 7 Sep 2010 @ 12:39:41 am from IP # -
Foilboard
MemberThere are many products on the market for underfloor applications and it is important to consider the right type for your particular application.
Typical bulk insulation, in my opinion, is highly susceptable to vermin and drawing moisture which in turn will cause sagging and thermal leakage across the entire area. If installed with a waterproof lining to the underside it will work quite well however it can be quite labour intensive.
Products that are rigid like such as the Expol are a much better alternative to bulk insulation.
Then you have materials like the Foilboard(r) or Aircell that are either installed to the underside (creating a thermal break), or high inbetween the joists creating still airspaces that are highly effective.
Essentially, by eliminating any airflow underneath will dramatically reduce the cold floor over winter.
Posted Thursday 14 Oct 2010 @ 1:05:03 am from IP #
