Insulation for new house build

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#1465179 7-Jan-2016 14:26

mattwnz: I was speaking to a builder/ developer who builds eco houses, and he advised against PVC from his own experience. He said they just don't stack up compared to the new aluminum profiles you can now get. Also questions over low term durability with the NZ conditions. Also many people don't like the look of PVC, they have a bit of a stigma to them. They are used a lot in the UK, and don't look great when retrofitted into terraces . I would suggest visiting some house that have had them in for the last 10 years to see how they are performing, and how the owners find them. With aluminum, they are a known quantity, and durable/low maintenance. I have some anodized ones that were install 12 years ago, and they look as good as new.

That's what many people say, but there's never anything to back it up, and it's not what the research I've found suggests. I already have french doors, another door, and a bathroom window in PVC, the oldest only a few years old but seems as good as new.

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#1465180 7-Jan-2016 14:26

We are living in a house at the moment with polished concrete floors. (Not our house, comes with the wifes job). We are on Waiheke Island, the house faces directly north.

I'd never build a house with them.

Our floor is not heated, in winter it does get a fair bit of direct sun (if I open the louvres above the north facing euro stackers), in summer, it gets no sun (the eave is just big enough so that summer sun does not enter).
In winter, the floors are cold. In summer, they are cold. I cannot sit and watch TV with socks/bare feet and have my feet on the floor (any time of year). Also, concrete floors are very unforgiving. They do look good though, and are easy to clean/keep clean.

Be careful in specifying polished concrete/tiles, at the very least, install the pipes for underfloor heating so you can install later. My 2c.

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#1465189 7-Jan-2016 14:45

Interesting comments guys, thanks!! Regarding the concrete being cold, I'm not sure how it could be - once it's cured properly, it should stay a pretty constant temperature due to it being insulated from the ground - most people's recollections of concrete floors are based on commercial buildings like warehouses or garages, where there's no insulation at all and the concrete literally sucks the cold out of the ground and radiates it around the room.

And if it does get cold, we'll just wear shoes or slippers etc, which we'd probably do anyway, as it will be winter, and exposed or vinyl-covered concrete is pretty hard on feet/legs. It's mostly an aesthetic thing to be honest, and it's only the foyer/living room/kitchen/scullery - the lounge and the bedrooms, hallways are carpeted.

Forgot to mention, we're also having two Velux's in the living space that will add extra morning sun onto the slab

Main bathroom and ensuite will be tiled with underfloor heating, toilet will just be tiled, and laundry will likely have a vinyl (Karndean or similar).

@billgates - thanks, have been following your thread with interest, what was the deciding factor with your brand of insulation? And did you end up getting the Hansgrohe tapware from that German website?

@trig42 - How old is the house though? Even in the north, I'd imagine a slab would be cold with no insulation underneath. Re: underfloor heating, one of our soon-to-be neighbours has built and put this in - he's spent the thick end of $40k on the heating system, and has $700 a month power bills. Worst-case scenario, we'd just carpet over the slab, so there's a definite Plan B. And the living room area of this space will be defined with a big floor rug anyway, so when actually sitting, there will be cover underfoot.

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#1465195 7-Jan-2016 14:50

The house is about 5 years old. I have no idea what is under the slab, but it would not surprise me if it were not insulated. This house was built as Owners Accommodation for a Lodge. It was done to a budget. It is 'nice' - fully tiled bathrooms, marble benches, nice appliances, fully double glazed - but you can tell it was built to a price (I call the house style over substance). All I know is that I would never have a polished concrete floor throughout a house I built (this house, apart from the tiled bathrooms, is all Polished concrete).

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#1465197 7-Jan-2016 14:53

trig42: The house is about 5 years old. I have no idea what is under the slab, but it would not surprise me if it were not insulated. This house was built as Owners Accommodation for a Lodge. It was done to a budget. It is 'nice' - fully tiled bathrooms, marble benches, nice appliances, fully double glazed - but you can tell it was built to a price (I call the house style over substance). All I know is that I would never have a polished concrete floor throughout a house I built (this house, apart from the tiled bathrooms, is all Polished concrete).

Cool, thanks for the feedback, appreciate your position completely. Building is a very personal/subjective thing :-)

trig42

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#1465198 7-Jan-2016 14:59

Yeah, totally.
I like the look of the floors, and the ease of cleaning/maintenance. Just the temperature is what (now) puts me off. Lots of people do it though, so maybe this is just a bad example. Also, with rugs, you won't notice it (I only notice when sitting watching TV - it chills me from the feet upward :p)

All the best with your build anyway - be sure to post pics of your home networking setup - all geeks have to have a fully stacked comms cupboard :)

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#1465209 7-Jan-2016 15:02

Suggest underfloor heating is required in all tiled areas, including the toilet. Perhaps especially the toilets.

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#1465213 7-Jan-2016 15:09

timmmay: Suggest underfloor heating is required in all tiled areas, including the toilet. Perhaps especially the toilets.

Yeah, still on the fence about this - you tend to spend more time in the bathroom than the toilet, and underfloor heating in the bathroom is a no-brainer for helping with drying towels and dealing with humidity, especially in Dunedin over winter! The counter argument is that the toilet space is a small area to install/heat, and perhaps you'd have it on just enough to remove the chill. Again though, the slab underneath will be insulated, so I don't anticipate them getting freezing cold.

I'll probably end up doing it in all honesty - it'd only be about 2.5 m2 of flooring element.

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#1465215 7-Jan-2016 15:11

trig42: Yeah, totally.
I like the look of the floors, and the ease of cleaning/maintenance. Just the temperature is what (now) puts me off. Lots of people do it though, so maybe this is just a bad example. Also, with rugs, you won't notice it (I only notice when sitting watching TV - it chills me from the feet upward :p)

All the best with your build anyway - be sure to post pics of your home networking setup - all geeks have to have a fully stacked comms cupboard :)

Thanks @trig42 - I've already started another thread on my networking/comms :-)

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#1465216 7-Jan-2016 15:14

nofam: Interesting comments guys, thanks!! Regarding the concrete being cold, I'm not sure how it could be - once it's cured properly, it should stay a pretty constant temperature due to it being insulated from the ground - most people's recollections of concrete floors are based on commercial buildings like warehouses or garages, where there's no insulation at all and the concrete literally sucks the cold out of the ground and radiates it around the room.

And if it does get cold, we'll just wear shoes or slippers etc, which we'd probably do anyway, as it will be winter, and exposed or vinyl-covered concrete is pretty hard on feet/legs. It's mostly an aesthetic thing to be honest, and it's only the foyer/living room/kitchen/scullery - the lounge and the bedrooms, hallways are carpeted.

Forgot to mention, we're also having two Velux's in the living space that will add extra morning sun onto the slab

Main bathroom and ensuite will be tiled with underfloor heating, toilet will just be tiled, and laundry will likely have a vinyl (Karndean or similar).

@billgates - thanks, have been following your thread with interest, what was the deciding factor with your brand of insulation? And did you end up getting the Hansgrohe tapware from that German website?

@trig42 - How old is the house though? Even in the north, I'd imagine a slab would be cold with no insulation underneath. Re: underfloor heating, one of our soon-to-be neighbours has built and put this in - he's spent the thick end of $40k on the heating system, and has $700 a month power bills. Worst-case scenario, we'd just carpet over the slab, so there's a definite Plan B. And the living room area of this space will be defined with a big floor rug anyway, so when actually sitting, there will be cover underfoot.

I have a honed concrete floor,with insulation under it, and it is cold to walk on. You would need rugs. It is designed to be passively heated by the sun, and in those areas it is usually warmer. I would get hot water pipes installing for future underfloor heating, becuase it is reasonably cheap to do it at the pour stage, even if there are never used for heating, it provides future proofing, and an advantage when selling. Make sure though that you have it broken up into a good number of zones
Electric coil heating under a bathroom floor is expensive to run.

You also need to be careful with skylights, as they can overheat rooms in summer.

Where you have got concrete being passively heated, you should make the slab thicker, so they can store more heat, and provides more thermal mass into the building, which helps to moderate the temperature.

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#1465245 7-Jan-2016 16:04

joker97: I never understand this thermal mass concrete slab thing.

A huge bottomless heat sucker in the winter that is impossible to counter.

A giant oven roasting slab in the summer that is impossible to cool.

Some of the low-e dual glazed glass now blocks heat energy entering the house at certain angles as you can see here (for Americans seasons but you get the idea)the sun is at different positions based on the season so its possible to block heat energy in summer but still allow it in winter similar to the way large eaves or verandahs work on - old houses were very good at keeping excess heat out of the house.

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#1465247 7-Jan-2016 16:08

joker97: One would be assuming the sun is heating the concrete slab in the winter ... or is it a giant heat sink and sucks all the heat up in the winter?

And summer roast ... yikes.

Passive design is done so in summer there should be overhangs on the roof/windows, to block summer sun from entering through the windows. So sun only heats the slab in winter when the heat is needed.

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#1465272 7-Jan-2016 16:51

mattwnz:
joker97: One would be assuming the sun is heating the concrete slab in the winter ... or is it a giant heat sink and sucks all the heat up in the winter?

And summer roast ... yikes.

Passive design is done so in summer there should be overhangs on the roof/windows, to block summer sun from entering through the windows. So sun only heats the slab in winter when the heat is needed.

So, it is not very useful in summer, such that you have to actively block sun touching it, and that it is there for the winters ...
What if the winter is not very sunny, the house will turn into a freezer?

Disclaimer - i am no architect, civil engineer, geologist, physicist etc, I'm just skeptical

billgates

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#1465281 7-Jan-2016 17:01

nofam:

@billgates - thanks, have been following your thread with interest, what was the deciding factor with your brand of insulation? And did you end up getting the Hansgrohe tapware from that German website?

In the end I settled on Knauf due to positive reviews from overseas forums and value for $$$ I am getting. The builder can get it even cheaper incl install through Carters that what I got quoted by the only distributor/installer for it in Waikato. Polyster is good as well but expensive. If installed right, Knauf will last for many many years.

Not doing overseas purchasing of plumbing material due to the connection sizes of plumbing screw threads being different. You most likely can buy an adapter but I don't want to go through the hassle with the plumber if they throw a tantrum about overseas product (DIY is no issue). Reading the Australian forums, over there you also need a WELS certification for the hardware before plumber will install it (DIY is no issue). So I went with Methven which is just as good quality and the builder gets a nice discount on it.

Do whatever you want to do man.

timmmay

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#1465310 7-Jan-2016 18:23

nofam:
timmmay: Suggest underfloor heating is required in all tiled areas, including the toilet. Perhaps especially the toilets.

Yeah, still on the fence about this - you tend to spend more time in the bathroom than the toilet, and underfloor heating in the bathroom is a no-brainer for helping with drying towels and dealing with humidity, especially in Dunedin over winter! The counter argument is that the toilet space is a small area to install/heat, and perhaps you'd have it on just enough to remove the chill. Again though, the slab underneath will be insulated, so I don't anticipate them getting freezing cold.

I'll probably end up doing it in all honesty - it'd only be about 2.5 m2 of flooring element.

For drying towels get the biggest heated towel rail you can fit in your space. We got the biggest one they make in a good brand, works well.

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