Insulation - good deals?

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Fred99

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#150342 19-Jul-2014 11:51

I searched and there are plenty of older threads/posts on insulation. I'm wondering what the most cost effective options are now.
We have about 220m2 floor and ceiling space to insulate. House is 1960s, external walls are now all insulated.
There are existing ceiling batts, but these aren't very thick. I was planning to put a blanket over these. Knauf R3.6 "earthwool" blankets seem to be reasonable value, at a shade over $10/m2 incl GST. We have no downlights to bother about, access is good. Installing blanket form insulation over the lot should be easy.

There is existing foil under the floor joists. I'm ripping it down - while I think it might have had some effect (I wonder though if it's partly placebo effect) it's unsightly and dangerous (potential electrical hazard) and interferes with wifi and mobile phone signals. Joist spacing is about 360mm, access is good - sub-floor basement area is used for storage etc. Plenty of wiring (all PVC) clipped on the side of joists. Expol have a tape to put over wires to prevent plasticiser leaching in to the polystyrene, but there would be a hell of a lot of taping to do - unless when I get the foil down, I find that the wires are clipped toward the bottom of the joists, so will not be in contact with the polystyrene (60mm thick - and positioned up against flooring with no gap. I wionder though if some other form of insulation might be better - given that apart from the close joist spacing - installation should be very easy because of the good access. Retail price of Expol also seems high to me for what it is.

Any suggestions welcome. Online calculators suggest that this would cost about $8k to have installed rather than DIY. That seems to be a ludicrous sum given the ease of access.

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#1091947 19-Jul-2014 12:02

I'd leave the foil there, it's also a vapour barrier. It's only dangerous during installation if it's not done properly. I'd turn off the mains while you're down there if you do take it out, just in case.

Blankets are a good idea, much better than individual pieces. I had loose fill wool in my ceiling, it was a LOT better than nothing, but over a couple of years it compacted down, blew around, and wasn't that useful. I put pink batts over the top and it made a significant difference. I have two layers in some places now, just because I had some spare, it works well. Sounds like "earth wool" is the same as pink batts, fibreglass. Sounds fine.

Fred99

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#1091959 19-Jul-2014 12:21

Some of the foil I've already removed - to access plumbing and data cabling etc. It's a mess - the subfloor area is a basement / garage, used for storage. Poly panels will look much better. Floors are t&g rimu - tightly installed - no air gaps. I'll be removing some carpet and polishing floor boards in living areas - so figure that upgrading the floor insulation will be worthwhile.

timmmay

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#1091963 19-Jul-2014 12:32

Carpet and underlay is around 2cm of insulation, plus it reduces the rate of heat transfer from the foot into the floor. It will probably get colder and feel colder.

Fred99

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#1091965 19-Jul-2014 12:39

timmmay: Carpet and underlay is around 2cm of insulation, plus it reduces the rate of heat transfer from the foot into the floor. It will probably get colder and feel colder.

Which is why I want to upgrade the floor insulation.
I read that some people have problems with floorboards after sub-floor insulation is installed, as the timber dries out and warps a little. I don't anticipate such problems, as the boards are heart rimu, nailed to very solid rimu joists at 15 inch centres, minimum sub-floor space is about 1m through to almost 3m, well ventilated, and dry.

ubernoob

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#1091999 19-Jul-2014 13:51

Have you looked at these. We got our underfloor and roof space done with the subsidy before they brought in the Free for community service card offer

It has made a huge difference to our 1950's, no insulation in the walls, house. We also have T&G heart rimu floors and they have shrunk, will probably need to get them re-sanded and polished

http://www.energywise.govt.nz/funding-available/do-you-qualify-for-funding

http://www.eeca.govt.nz/eeca-programmes-and-funding/programmes/homes/insulation-programme

Handle9

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#1092007 19-Jul-2014 14:23

I've done a DIY polystyrene install and would never do it again. It's more work than other products and if your house moves quite a lot it can fall out.

Polyester is heaps easier, and is more forgiving of non-uniform joist spacing. Unless your joist spacing is perfect then you have to cut every sheet of polystyrene. Polyester you gun staple into place.

The only down side of polyester I've seen is if you've got a dog. Mine used get under the house and have a merry old time ripping it out.

I've bought a fair bit of gear from the insulation warehouse, they're good dudes and have good youtube videos to show you how to install.

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mattwnz

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#1092008 19-Jul-2014 14:28

Cover the poly with fool or building paper. Will also reduce drafts

Fred99

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#1092023 19-Jul-2014 15:07

Thanks for comments. I imagined that with "Expol" brand and similar pre-cut with grooves, then breaking it off to suit joist spacing wouldn't be too much of a problem. I expect that the joist spacing won't be very even, but is about 360mm. Other brands (competition to "Expol") don't seem to have less than 420mm width - so there'd be quite a lot of wastage.
Expol have clips - fix two at opposing corners to each panel installed, to keep them in place. It looks easy - but I guess that's how they want it to look.
I really don't want to cover the insulation with building paper or foil. For a start, that would at least double the work.
If you gun staple polyester - do you staple through it to the floor boards? How many staples? (I can feel a bad dose of RSI coming - as to get a staple in to 50 YO seasoned heart rimu, then you really need to crank up the force on a staple gun).

I think I'll go for the Knauf "Earthwool" blanket for the ceiling. The price seems good compared to alternatives, and though glass fibre, they claim it's much less scratchy/itch to install than their competitor's product (ie Batts).

DarthKermit

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#1092027 19-Jul-2014 15:17

I installed Expol underfloor insulation in 2010. Its R value is 1.4, so it's not going to make a huge difference. It was a prick of a job to install.

Our 1950's house has rough sawn flooring beams that were all unevenly spaced. One panel of Expol is 1200 mm long. On some of the runs I did, the beams were out of parallel by 15 mm over a 1200 mm length!

I used Expol bales in all the different widths that it comes available in (four I think). I had a heap of little off cuts that I continually re-used to fill in funny little gaps and spaces.

At the end, it was a job well done (if I may say so), but I'd prefer to never do it again.

Some essentials for me were:
A long insulated mat to lie on while I was in the crawl space. It kept me warmer and dryer.
A very good light source to see what I was doing.
A decent amount of room in the crawl space to move around in.
A sledge hammer and a block of wood to force some panels into place when I'd cut them a little too wide.

Whatifthespacekeyhadneverbeeninvented?

Fred99

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#1092034 19-Jul-2014 15:44

I'm pretty sure joist spacing won't be very even. I just looked at Knauf Earthwool sub-floor insulation - and that does look easier to install than Expol would be, as well as being available in an R2.2 rating. But there's a problem - panel widths are 480mm minimum, from their install instructions I need 400mm (40mm wider than the ~360mm spacing - to get a secure press-fit). So a lot of cutting - and a lot of wastage. It seems most panels are set up for 450 or 600mm joist spacing.

Cbfd

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#1092057 19-Jul-2014 16:36

I did our house a couple of years ago - same sort of size did the roof with the insulation blanket bradford gold - and the underfloor with pink batts underfloor insulation - cost me $1200 all up and about half a day to install -

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shrub

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#1092060 19-Jul-2014 16:49

Ive just done my roof used that knaf blanket 3.6 its easy to work with and coverage is good. Order online and its way cheaper that bunnings etc.

Fred99

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#1092073 19-Jul-2014 17:22

shrub: Ive just done my roof used that knaf blanket 3.6 its easy to work with and coverage is good. Order online and its way cheaper that bunnings etc.

I just ordered it. I actually found a valid promo code that knocked another $100 off, as well as their special on until 30 July. Yes - much cheaper than Bunnings
I ordered R3.6. There's already about 75mm of existing batts, so overall R value will be in excess of R5 - probably not a bad thing for Chch.

That just cost about $2400.
Now what to do with the floors. I'll do a few calculations, as the knauf sub-floor R2.2 appeals to me, but I'd need to cut each panel down from 480 to 400mm - so 20% waste. Even so - the price isn't as bad as some of the alternatives.

mattwnz

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#1092095 19-Jul-2014 18:01

Make sure it is bio soluable. If I was installing it, I would probably install wool, something like terralana, especially if you saving on installation fees, as I would prefer to work with wool. Wool has other benefits too, including how it deals with moisture but isn't good for installing over downlights. So if you don't have any downlights, then it shouldn't be a problem to use real wool.

Handle9

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#1092097 19-Jul-2014 18:08

Fred99: Thanks for comments. I imagined that with "Expol" brand and similar pre-cut with grooves, then breaking it off to suit joist spacing wouldn't be too much of a problem. I expect that the joist spacing won't be very even, but is about 360mm. Other brands (competition to "Expol") don't seem to have less than 420mm width - so there'd be quite a lot of wastage.
Expol have clips - fix two at opposing corners to each panel installed, to keep them in place. It looks easy - but I guess that's how they want it to look.
I really don't want to cover the insulation with building paper or foil. For a start, that would at least double the work.
If you gun staple polyester - do you staple through it to the floor boards? How many staples? (I can feel a bad dose of RSI coming - as to get a staple in to 50 YO seasoned heart rimu, then you really need to crank up the force on a staple gun).

I think I'll go for the Knauf "Earthwool" blanket for the ceiling. The price seems good compared to alternatives, and though glass fibre, they claim it's much less scratchy/itch to install than their competitor's product (ie Batts).

Have a look at the videos here on how to install. The best way to do polyestser is a total blanket under the joists, stapled to the bottom of the joists. It's also easy to cut as you rip it rather than using scissors etc.

http://insulationwarehouse.co.nz/installation/installation-guides/

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