Underfloor insulation & help checking measurements

sooby, Feb 22, 4:15pm
Hi guys,

My wife and I have decided we??
siobhan41, Feb 22, 5:08pm
Any reason for choosing polystyrene over the other products? .
Looking at a similar decision at the moment.
sooby, Feb 22, 5:17pm
I chose polyester, which is like a material, not Polystyrene sheet because a friend installed polystrene and it was messy, harder to handle & cut by saw, had to be separated from electrical wires, has a lower R value (the higher the R value the more it insulates). Also, polystyrene has to have no gaps around it or it loosing its effectiveness, this is hard to achieve around drainage pipes & other complicated junctions, whereas polyester just bends around and contours to any odd shape.
goldywing, Feb 23, 3:25pm
sounds good to me.If you divide the length of the house x the sheet length will give you however many panels long .X's that by however many joist spacings you have .eg. if one run uses 6 panels and you need to do 8 runs then you will need 48 panels.Divide that by however many panels in a pack and you should be pretty close.
sooby, Feb 23, 5:07pm
Cheers goldywing
ingies, Feb 23, 5:30pm
I used greenstuff insulation, was easy to use and you buy it in a roll, they have 2 diff sizes so buy the right size for your joists and staple it in place. Was easy to do
asue, Feb 23, 5:32pm
Why not just get what you think you need. The place you are buying from should be able to help you get the right amount. If too short just pop back an get the right amount or check if you can get a refund for over supply; or list the surplus on here when done.
sooby, Feb 23, 9:07pm
Good plan - except I know my maths is terrible! I can't trust my own measurements, that's why I posted here to get a second opinion from someone with more smarts!
nzjay, Feb 23, 9:16pm
And be aware that if there is any dampness rising in the ground under the house, you should deal with that first, usually with Polythene taped sheets.
Any dampness collecting in the polyester will lower its effectiveness.
asue, Feb 23, 9:25pm
Also another cheats way is to get an insulation company in to do a quote and see what they list with what you will need and go from there. A bit naughty I know but you could be surprised as it may be easier to get a job done and if you get a subsidy? Insulation is the best money you could spend.
golfaholic2, Feb 23, 11:03pm
Demo yard probably sells wall batts at half the cost of new ones . I'd be tacking them up under the floor .
Save yaself hundreds and be considerably warmer
sooby, Feb 24, 12:31am
cheers guys for all the advice, however I had already considered those points - the only thing I'd like now is someone to confirm if my measurements are correct or not
famrhy, May 23, 12:40am
hey there mate, i install insulation for a living using polyester and all other types. If your home is 81m2 you'll only need 4 bales of Autex Greenstuff R1.5 @ 600mm . Each bale Contains 20m2 . I guarantee this will be enough. :) I would Suggest ( Because you live In Taupo ) that you go for R1.8 its a slightly thicker product.

Here is how much it will cost forAutex Greenstuff R1.5 @ 600mm sourced from the insulation warehouse website

Greenstuf Polyester Underfloor Insulation Roll Form $11.50 or $10.00/sqm (R1.5, 600mm wide, 20sqm/bale)
Qty: 4 Price: $760.00


4 items Subtotal: $760.00

Hope this helps mate , please feel free if you have anymore questions :)