underfloor insulation

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#569613 16-Jan-2012 19:59

anyone knows a good insulating company in dunedin?

Handle9

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#569614 16-Jan-2012 20:05

I've done polystyrene myself on my last house and wouldn't do it again. I had a 50s house with different widths in between the joists. This meant that each piece of poly had to be cut to different widths. Also if your house moves at all then the polystyrene can fall out if you don't staple little plastic supports under it.

If I did it again I'd use a polyester blanket that is stapled to the joists or a double layer foil which you also staple. It's much quicker to install and performs better than polystyrene as it doesn't leave gaps in the insulation where the joists are. Just my 2c worth.

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#570034 17-Jan-2012 16:45

I seem to recall when we did this Govt paid up to a 1/3 or about $1300 depending on factors. Either way, quotes are free as is the subsidy advice and our contractor did all the running around and paperwork for us, we just had to choose a supplier and pay at the supplier, the contractor gets his bit from the govt at the time.

I got the ceiling done by a contractor (also have 50/60's house). The contractor supplied a quote and gave me the work order to choose my supplier of material. I went to Placemakers and got myself a DIY Know How card, then bought the material. The govt paid the 1/3 and we got 10% of the value of the order back in vouchers a few weeks later. As far as I know, this still works this way. Nice to get $200 of vouchers in the mail after laying out $2k a few weeks before.

I did the underfloor myself with Expol and it works well. You have to use a polystyrene cutter if you want no mess at all or a sharp UNserated knife as a good second prize. Serations will sheer the polystyrene and create a mess. Believe it or not serated blades are useless after a few hundred meters of polystyrene, so if you go this way, plan to buy a few knives and throw them out afterwad (or sharpen them yourself if you know how).

The underfloor is only effective if the space is dry, so as mentioned, plastic over the dirt will dramatically reduce the moisture in the cavity.

Now, onto something I found out the hard way - your floorboards will shrink. This is normal because effectively, you are making the air around the wood dry and the moisture is escaping. No big deal, all that happens is the gaps between the floorboards get a millimeter or two bigger. What happens though is that for a week or so, the house is filled with very loud cracking sounds as the boards pull apart. I have good advice not to repair this as the boards will expand in winter again as the moisture content pics up. Dont fill the gaps till the boards have been through a few seasons and 'settled'.

We also got the walls Airfoamed which was not cheap, but was the singlemost effective thing ever.

I strongly advise you get a free quote form the EnergyWise contractor. It's free and sets the stage/standard for what you may be in for. When he gets there, get him to explain the job, so that way, if you want to do it yourself, you have an idea of the scope and tools required - his experience weighs more than your knowledge (unless you are a building contractor reading this).

Uneven spaces between joists was not an issue as each Expol piece has to be cut anyway and as they are supposed to be tight and they are flexible/maleable, you can cut up to 10mm too big and squish in the blocks. If you cut too small or have lots of big offcuts, dont throw them out till the job is finished, You can use the offcuts to fill up the odd gaps between the joists and the walls or where you have small opportunities between meeting blocks etc. The blocks dont fall out if they are made too big and forced in - I am confident that if your house has been there for 50+years there would be signs it moves (like massive cracks in the gib or leaking windows frames, otherwise, the blocks shouldnt fall out. When the job is done, go around with a can of Gorilla expanding foam and fill in the cracks as well as forcing a small squirt between each block, the foam expands and adheres to the floorboards and the Expol, acting as a glue. I say use Gorilla as it's seems to be the only expanding foam product that can be used in an upright position, enabling easy application to a surface that is restricted and above your work area. The blocks muct be tight in place or the expanding foam will dislodge the block, then dry at an awkward and unprofessional angle. Gorilla foam is effectively expanded and dry in a few minutes, so if you have a block that moves, just hold it in place for a few minutes while the foam dries.

Also, if you use something like Expol and find it pricey, you can do one room at a time, say each month and slowly get there before Winter.

Good luck and let me know if I can expand on any one point.

timmmay

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#570053 17-Jan-2012 17:23

I'm surprised you listed airfoam as the most effective thing ever. I have it done, and I found ceiling insulation far more effective. I'm not even sure I noticed a practical difference with wall insulation.

The other downside of airfoam is they drill heaps of holes in the weatherboard and roughly bog and print them. You need to properly sand, prime, and paint them yourself. With my old house, with oily old wood, the wood leaked oils for 6 months before we could paint them.

Aside: given how bad my overall paint job is, and how old the oily wood is, we're just going to replace the cladding with something modern and low maintenance rather than try to paint them. It's just easier. Paint keeps bubbling and pealing off my house as it was never primed or sealed.

gundar

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#570116 17-Jan-2012 20:12

A common misnomer is that home insulation is designed to keep things warm. The different types of insulation have properties that make them suitable for more than that purpose.

Our house had no insulation, not even builders paper was found on the two or three holes I've made; through the Gib, I could see Huntly brick and mortar. The Airfoam obviously was most effective here for this specific situation (you did start out by looking what you already paid for with the house, right?). Airfoam is also an excellent sound insulator and because it lays against the wall, it not only slows sound travelling through the wall, it also stops the vibrations inherent in a 50 year old house made from mostly dry wood and some loose nails.

We had an internal wall filled with Airfoam in order to create a barrier between the master bedroom and the nursery (we have twins). It was good money spent. Before, I could very clearly hear words through what was in fact two sheets of Gib and some sparse framing. Now, I have to go into that room to hear anything more than incoherent muffles.

The Expol has made a very big difference to the contact tempreature* of the lounge floor as well as how much wood the burner goes through each fire and each Winter.

*I dont know if such a phrase exists, but I think it should be the sudden tempreature difference experienced at first touch of an object, until a few seconds later, the gap closes through heat conduction.

But, I still think everybody should get an expert in for a free quote before any ideas are set in stone. Even if they just let you know what is already there, for sure.

timmmay

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#570123 17-Jan-2012 20:17

Thanks gundar, interesting read and good points :)

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#570125 17-Jan-2012 20:18

timmmay: I'm surprised you listed airfoam as the most effective thing ever. I have it done, and I found ceiling insulation far more effective. I'm not even sure I noticed a practical difference with wall insulation.

The other downside of airfoam is they drill heaps of holes in the weatherboard and roughly bog and print them. You need to properly sand, prime, and paint them yourself. With my old house, with oily old wood, the wood leaked oils for 6 months before we could paint them.

Aside: given how bad my overall paint job is, and how old the oily wood is, we're just going to replace the cladding with something modern and low maintenance rather than try to paint them. It's just easier. Paint keeps bubbling and pealing off my house as it was never primed or sealed.

in which order did you do them? most of the heat escapes through the roof. hence if you airfoamed first you will notice no difference whatsover, and then in comes the roof insulation and you get the combined effect of the roof and airfoam together and sensed an amazing change.

if you did it the other way round, then i accept your anecdote

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#570130 17-Jan-2012 20:40

My order was:
- Ceiling (blown wool R3.0 apparently but I don't believe that)
- Under floor (4cm thick blanket, couldn't get to whole house but 75% coverage)
- Wall
- Retrofit double glazing
- Ceiling (pink batts R2.6 over top of wool, but still with gaps)
- Replace downlights

Wool made a big difference over nothing, the biggest probably. Next biggest was F2.6 pink batts. Floor made a big difference to smell and dampness, not sure about heat. Replacing downlights, not sure. Wall, ditto, not sure what difference it made. Double glazing helped HEAPS with condensation, not sure about heat. Overall i'm sure wall, floor, and glazing made a significant difference.

I think I have to finish the ceiling properly, eliminate all gaps.

Next i'm taking the kitchen fire placeout, it's never used and has a huge hole heat goes straight out. Then double doors that leak air. Then a heat pump in the kitchen.

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#570136 17-Jan-2012 20:58

SaltyNZ: Wiring is rated for a certain current according to temperature, with the assumption that it radiates into the roof space. Putting a nice layer of thermal insulation on top of it causes it to overheat.

Continuing the warnings here..

Similar problems may occur if polystyrene is installed in contact with electrical cables - a chemical reaction occurs between the polystyrene insulation and the outer insulation of the cable which causes the cable insulation to break down over time. This warning is provided in the safety warnings for the product, more details online.

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#570145 17-Jan-2012 21:20

I did a 70's house which had enough variation in joist widths to require a lot of custom cutting. A very sharp knife is your best friend and dangerous. I imagine a commercial installer would rip through at a rapid pace breaking along the concertina perforations by hand and as long as it sticks in the gap its a win. Doing it myself I went for too tight rather than too loose, and that took some effort to compress and insert the material + a right sized block of wood and hammer to ensure they went tight against the floor.

If your floor is tongue and groove and you have some air movement up through the floor you will notice a massive difference. If you already have carpet and underlay over it, not so much difference but you will notice it.

Whatever the floor, the key thing is stopping any air movement. Air insulation value is 1R per inch, so if you can stop the air moving in a six inch cavity you are getting R6 in theory. If it is a particle board floor all the better for that. For this reason, I would consider wool backed or polyester backed foil, but only if you can do an excellent job of sealing the cavity. Have not read the manual on that, just my HO there.

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#570171 17-Jan-2012 21:50

Hi Shaopu,
I live just arount the corner in new windsor.
We had expol put in the floor of our 1966 house and made zero difference to the floor temp but it did stop drafts in the floor, if there was a gust of wind from the west dust flew out of the cracks.
Expol has some serious design flaws and if not installed correctly ( like ours ) it is next to useless, I contacted Expol about 5 years ago and they said they were changing the design to something simalar to what I descripbed but never happened.
We also had CSR gold out into our roof and again it made no difference but we did get a governmet grant and cost us nothing.
Eco insulation did our ceilings, they also do floors. http://www.ecoinsulation.co.nz/ I can not reccomend them highly enough.
We used a different company to do the expol and they are no longer around ( thank goodness ).
Regards
John

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#570198 17-Jan-2012 22:43

gundar: A common misnomer is that home insulation is designed to keep things warm. The different types of insulation have properties that make them suitable for more than that purpose.

<snip>

We had an internal wall filled with Airfoam in order to create a barrier between the master bedroom and the nursery (we have twins). It was good money spent. Before, I could very clearly hear words through what was in fact two sheets of Gib and some sparse framing. Now, I have to go into that room to hear anything more than incoherent muffles.

<snip>

I sure wish i had done all the internal walls with insulation while they were open. I only did the walls which seperate the lounge/kitchen from the bedrooms. The extra soundproofing between each bedroom would have been a welcome addition in a house with kids...!

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gundar

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#570200 17-Jan-2012 22:45

Then get Airfoam to fill the walls! They left the walls smooth but needing a paint. The fill is done from one side, so thats only one side to repaint.

I dont work for them BTW.

Batman

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#570224 18-Jan-2012 03:16

what do you guys think about pellet fire?

timmmay

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#570258 18-Jan-2012 09:21

Pellets have a decent reputation. A fireplace though needs a big gap in insulation around the chimney, so when the fire's not on the heat goes straight out it. Also, cleaning and maintenance is annoying.

There's no way i'd buy any kind of fire these days, i'm taking mine out and getting a second heat pump when I get around to it.

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