Im looking at putting underfloor insulation in my home. Just after a bit of feedback on what a good insulation to go with for DIY purposes. Cost, ease of insulation and effectiveness.
Thanks
johotech,
May 8, 6:45am
You can't have all three. Pick any two. but effectiveness has to be one of them, or you're wasting your time.
1vanvan1,
May 8, 6:51am
Either or really. Effectiveness is obviously the main concern. Ease of insulation would be next followed by cost.
Im more trying to gauge what product people have and what the think.
Ive read a bit about Expol and people think its a waste of time.
skin1235,
May 8, 7:08am
even the best systems use the static airgap as the insulating factor, then the heat tranfer rate of the introduced product
so if you can devise a method of trapping the air against the floor, and excluding any other air getting in to that area, plus use a barrier system that does not convey the temp in that area to ambient outside air too quickly, you have solved the problem
2 separate layers of silage cover does a good job, especially if you allow the second sheet to 'bag' a little between attachment it may not meet with the approval of those attempting to sell you a halfpie stopgap measure for squillions and an upgrade to better for squillions more, but up in the bach ( which also has sizal just under the boards on top of the joists ) a double layer of silage cover has created room temp floors all day and night, it never cools down
cost, diddly ease, not too bad once you suss how to fold it ready for use, and the method to install, ( light battens and an air stapler ) effect, unknown officially ( although a lot of councils now insist on poly on the dirt surface under houses to stop damp rising ) personal experience, it works, and works well
I've installed it in a number of homes and been very happy with the results. I like it because it's easy to handle, doesn't irritate you, staples to the joists which I found easier to do than using batts and the strapping system.
I'm a firm believer that if you're coming from no underfloor insulation, then pretty much anything is going to be an improvement. Of course, it needs to be done properly, but really it isn't rocket science you just follow the instructions.
tweake,
May 8, 9:16am
nice cheap way. however i see one problem. if you use anything that doesn't breathe or let moisture through it, it can hold moisture in the floor. fine if its stays dry, but once it gets wet it will stay wet. building paper is better, any moisture/condensation can be drawn away.
1vanvan1,
May 8, 9:26am
We currently have a foil type black paper stuff which hangs down in a arch. House was built in the 80s. What is this stuff? Is it insulation at all?
johotech,
May 8, 9:44am
Not really. It was put under a lot of floors in those days as a moisture barrier. Some of the flooring used in the 80's wasn't waterproof and more like MDF than the flooring we use now.
jonners2013,
May 8, 7:42pm
I honestly couldn't tell you what that is. I've seen it a few times but never known for sure. If it's hanging down and generally in poor condition then it's probably not doing anything useful anyway so I'd be ripping it out and replacing with decent new insulation.
I think for memory the cost of the insulation for my place was something like $800. I installed it all myself. Quotes for supply and install was in the region of $2400. Typical 1950s 115 square metre bungalow.
lythande1,
May 8, 7:58pm
Why? Hot air rises, cold air falls. Insulate your walls and ceiling, draw your curtains at night.
tweake,
May 9, 5:40am
heat goes from hot to cold in any direction. as you in direct contact to the floor, it makes things a lot nicer for a small temp difference.
bluecat1529,
May 9, 10:56am
What jonners said. Easy to fit, clean, and not horrendously expensive. I have fitted several types over the years and only use Greenstuf now
ingies,
May 9, 11:49am
I have used the greenstuff, as well as a polystyrene product. Sold the polystyrene product on trademe as it was much harder to install, and with the airgaps I couldn't see how it would be an effective insulator. I ended up putting in a double layer of the greenstuff in and am happy with the results.
jonners2013,
May 9, 7:41pm
The polystyrene does work well but because it's less flexible it is less forgiving to install. In my old house the floor joists are not a consistent width apart, so it was going to be a pain to be cutting each piece of polystyrene to fit.
I suspect that in a new house with good underfloor access, the polystyrene is probably easier to install.
tweake,
Jan 13, 11:06pm
i think the best way to use polystyrene is to fasten it under the joists. use it as a 2nd layer, ie fill between joist with greenstuff then polystyrene over the joists. just not sure about how moisture moves through it.
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