Under Floor Insulation in Canberra?

cranky 25 June 2009 34

Renovated Chateau Cranky a couple of years ago, incorporating insulation (batts) in all walls and roof areas. The certifier was fullsome in his praise of the installers work.

The place has always since seemed to require more heating and cooling than I would have expected from the insulation installed.

We do have some uncurtained glass, so in an attempt to track down heat loss/gain, I used one of those infrared temperature measuring guns. I was suprised to find that virtually all surfaces were similar temperature, but that the floor was several degrees cooler.

The floor is wood, 19mm thick floorboards, layed on top of the existing 19mm pine floor. I would expect 38mm of wood to be a fairly good insulator, but this appears not to be the case.

How does one increase the insulating abilities of a wooden floor? Access underneath is relatively easy.


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34 Responses to Under Floor Insulation in Canberra?
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The cat did it The cat did it 9:59 am 26 Jun 09

old canberran said :

Was it a white one or the more expensive brown waterproof type?

It was brown, but not waterproof- brown because the Reid Night Cart used to empty its tank on us every morning, just as we were going to sleep after working all night at the Westridge ….

Seriously, much of Canberra’s old housing was dreadfully cold- but the ones I feel really sorry for were the workers living in tents.

old canberran old canberran 1:56 am 26 Jun 09

I think the answer to the original question is good quality woollen carpet. A nice warm house and polished floors just don’t go together.
Our house in Watson started off with polished floors and when we could afford carpet the heat improvement was very noticeable.

ant ant 10:48 pm 25 Jun 09

old canberran said :

Canberrans are getting soft. I was brought up in a 1920’s style guvvy house in Braddon and the only heating was an open fire in the lounge room which you had to stand on top of to get warm. My bedroom had linoleum on the floorboards, wooden frame windows and the house had 9 foot ceilings and carpet in most rooms. It was double brick without insulation in the roof. At 7.30am I used to ride my bike 5 miles across Canberra to school. Some days it was impossible to have a shower in the mornings because of frozen pipes.

My oath! I live in a wooden house, and it’s mostly insulated, however the floor is the weak point. The only heating is the sun, and a stupid slow-combustion stove that works if someone’s here to get it going (never easy) around 4pm. If you get home at 7pm, give up. Thank god for fleece (which they didn’t have in the 20s). I’m wearing several rugs now.

I have my shower after coming home from work, as the house is warmer then than in the morning, and the pump seems happier too. I’ve wrapped newspaper around the pipes (which are plastic) and they haven’t frozen in some years now, but I’m taking no chances. I love these modern hot water systems and not those dreadful chip heaters, ye gods.

My father used to pedal his bike across the valley to Manuka to the pictures, before they put a lake there.

Your tale reminds me of my last instructing stint in Utah, where on Sundays I had to ride my bike 3 miles in driving snow (usually) befoe dawn, to get to the ski bus as the town buses didn’t run on Sundays. God that was cold and if it was snowing, you were SOAKED by the time you hit Fort Union. On those days I packed a change of clothes in my pack. Miserable. One day, the local TV channel filmed my bike attached to a tree with a foot of snow on the saddle for the evening news.

DrKarl DrKarl 10:39 pm 25 Jun 09

Clear Comfit window insulation, I used a similar product in Canada in Alberta where it gets to -40C it works, there was insulation in the walls roof and the basement. The house was snug and warm with central heating. Have to have the heating on all the time otherwise frozen water pipes bust, and outer parts of your body get frost bite and fall off. You want to see the drunken bums on the street for proof.

GB GB 9:38 pm 25 Jun 09

We got a guy to install batts under our old wooden floor – they are the R2.0 batts but he said in an underfloor situation you’d be lucky for them to rate R1.5 in practice. He just poked them in and stapled open plastic mesh over to hold them. This is an uncarpeted floor, and its old so there are some big gaps between the floorboards.

Inside, I also took off the skirting and draughtproofed the edges (especially the external edges) with space invader and no more gaps. This is important in old houses, where the flooring of each room stops at the walls, rather than having a continuos, fairly draughtproof floor continue under the internal walls.

These two things made a heap of difference in winter — and only a slight temperature increase on summer nights. I guess those gaps in the floor were useful for something…

There seems to be a fair bit of uncertainty about whether you should completely seal under the insulation, especially if you use a foil – it can cause a moisture trap.

See here for a fairly recent research summary (2005) – not all relevant to Canberra.

We’re thinking of doing this under another part of the house, which is similar to yours — 19mm new cypress pine over some old cypress pine, and some bare.

Let us know how you go!

Nosey Nosey 8:56 pm 25 Jun 09

Call Brad FREER from Eco-Insulation.

He and his team just replaced my roof insulation and I couldn’t be happier (unless I did the floors too).

Brad told me that you lose 20% of heat through the ceiling, evaporative ducts(closing them in winter is a good tip),downlights and tastics, 20% through windows, 20% through the floor, 20% through walls and the last 20% through small gaps under doors and other little gaps that might be there.

Insulation in any of these areas simply lowers the amount of heat you lose.

Simply closing the evap ducts made a big difference.

You can call him on 0431116000.

I am not friends of Brad. I only know him through his insulation company replacing batts in my ceiling.

I thought his honest service justified a free plug.

old canberran old canberran 8:29 pm 25 Jun 09

The cat did it said :

Luxury!! we used to live in paper bag in middle of Molonglo River …

Was it a white one or the more expensive brown waterproof type?

andy pandy andy pandy 6:20 pm 25 Jun 09

they use the more rigid batts that go in walls. When I did it I used packing tape stapled to the joists to hold in place (check the distance between your joists as this will determine the batt you use). Go to Just rite they can tell you all you need . I would also suggest you might want to pay someone to do it (it isn’t hard but it is close to the crappiest job I have ever had to do)

Snarky Snarky 5:49 pm 25 Jun 09

#24 Canberrans are getting soft.

(grin) My grandparents lived in a *very* old farmhouse at Binalong for about 15 years in the early ’70’s. Wattle and daub for about a third, corrugated iron walls for the rest. Dirt floor for the very oldest part (not really lived in anymore) and timber flooring for the rest, except the “bathroom”, which really the outside laundry with a slat door and concrete slab and a clawfoot bath. Tin roof, plaster ceiling, no insulation of any kind. We visited a couple of times a year from our home on the pleasantly warm north coast of NSW. My god winters were awful at that place! The fire was a freeze or fry arrangement whereby you could set your clothes alight in front standing too close while ice formed on your back. Dunno how they managed to survive it!

The cat did it The cat did it 5:47 pm 25 Jun 09

Luxury!! we used to live in paper bag in middle of Molonglo River …

old canberran old canberran 5:16 pm 25 Jun 09

Canberrans are getting soft. I was brought up in a 1920’s style guvvy house in Braddon and the only heating was an open fire in the lounge room which you had to stand on top of to get warm. My bedroom had linoleum on the floorboards, wooden frame windows and the house had 9 foot ceilings and carpet in most rooms. It was double brick without insulation in the roof. At 7.30am I used to ride my bike 5 miles across Canberra to school. Some days it was impossible to have a shower in the mornings because of frozen pipes.

bugmenot bugmenot 4:06 pm 25 Jun 09

I’ve installed under-floor insulation a few times now (over a couple of different houses). The easiest method I have come across is R2.0 batts (for a floor, you’ll likely need the 430mm wide batts) held up with shade cloth & staples.

The shade cloth can vary dramatically in price, so shop around to find what’s cheapest. It is massively easier to work with than a wire-based product for holding up the batts.

The batts are easy enough to install and will hold themselves up between the joists as a snug fit. Complete a large area (say an entire room or two) and then come back with the shade cloth. If you have a compressor and an air stapler, even better, else a standard heavy-duty stapler will do the job.

Make sure you trim the batts to fit into tight spaces. A properly fitted batt should not need to be stuffed into a space, but should remain full and fluffy for maximum insulative qualities.

In the places I have done, R2.0 batts are the correct size. An R2.5 batt will need to be compressed substantially (reducing effectiveness) to the point you could have saved money and just bought R2.0s. R2.0 batts are also going to be easier to manage under the floor.

Also, take the bag of batts under the floor with you and then open them. You really don’t want to be going back and forth bringing batts under the floor.

HTH

Snarky Snarky 3:14 pm 25 Jun 09

I put wall batts (R2.5) under the floors of our extension, and held them in place with big sheets of third-grade-quality plywood acquired v. cheaply from a mill. Did this rather than the chicken-wire thing because drafts under the floor area still circulate up in between the batts and remove heat. With teh plywood it’s all sealed up. Underfloor insulation does make a substantial difference to heat retention!

mossrocket mossrocket 3:06 pm 25 Jun 09

from their website (hey aircell – how about some royalties for this free plug!!):

According to the Australian Greenhouse Office up to 20% of heat, and subsequently energy, can be lost through the floors during winter. AIR-CELL® Insulation is the ideal solution to underfloor insulation producing higher thermal resistance than a 100mm concrete slab when installed beneath a timber or metal-framed floor structure.

Installed as a vapour barrier and insulation medium in one application, AIR-CELL® Insulation stops cold air drafts and re-radiates the heat that would otherwise be lost, back into the building while providing a resistance to conductional heat loss as well.

And because it is easy to install, AIR-CELL® can also be applied to existing homes with suspended floors.

mossrocket mossrocket 3:04 pm 25 Jun 09

i nailed aircell insulation under my floor – it’s made a big difference

http://www.air-cell.com.au/

caf caf 2:52 pm 25 Jun 09

There’s a downside to putting batts under your timber floors – they’ll hide early evidence of termite activity from the pest inspector (you are getting regular termite inspections, right?).

Hells_Bells74 Hells_Bells74 2:23 pm 25 Jun 09

MWest said :

The only time timber floors are warm is when they are on fire, which is far from ideal.

Funny though!

MWest MWest 2:18 pm 25 Jun 09

The only time timber floors are warm is when they are on fire, which is far from ideal.

ant ant 2:10 pm 25 Jun 09

I’m having this issue too, wooden flooring up on quite high piers. Rest of the house is insulated to jiggery, double glazing, north-facing (it’ll be warm this evening, sun’s out) but lack of insulation on the floors means the cold creeps through eventually. The main technique I’ve seen in houses like mine is the bats held in place by wire (mesh is best). Simple technique.

I get draughts through my power points when the wind is blowing from the east.

AG Canberra AG Canberra 1:34 pm 25 Jun 09

Floors will almost always be cold in Canberra – that’s why most of us don’t have polished floorboards in our bedrooms – too blood cold!

The best thing you can do is heat the place properly, seal up all draughts and use efficient insulation where required.

We are currently having our ceiling insulation replaced (Thanks K Rudd. Everyone should get this done – it’s free!) and I asked about the floor insulation. The guys said it takes many many years to recoup your costs putting batts under the floor. They advised using floor rugs in winter and packing them away in summer when you want to walk on cool timber.

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