Wall insulation

The upstairs bedrooms in my house are half in the ground floor roof space. I just measured the temperature of the inside surface of the gyprock and it's up to 40 deg C for the sections of wall that are below the level of the tiled roof, and that's with the rooms being airconditioned. As you'd guess, there is no insulation in the walls.

So, time to insulate. I have good access...I can stand up vertically in the ceiling space where the walls are. What should I be using...glass batts, or is there something else I should consider. Also, what rating? I was thinking R4?

I was gonna say yes to glass batts but frankly D3 has the better and cheaper answer.

again coolroom panels. or offcuts Ebay is a good start type coolroom and not cool room(s) youll get the yuppies version of their dining room conversion

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decrepit said..
I don't think R4 will be enough to really do the job.
I also like the idea of cool room walls

Agree, just check their fire rating.

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psychojoe said..
The Bradford gold batts sit nicely when placed. The elcheapos will have you choking on fibres for a week, and itchy. I finally insulated and put blinds on my sunroom, don't need the aircon any more, unless the mother in law visits. Might sell the aircon. Sounds like you need some sarking and/or anticon as well.

The sarking is fairly new and in good condition (2nd story was built only 10 years ago.) Odd thing is that the ceilings and bedroom walls above the rooftile level are insulated really well...always cool to touch. They just neglected to insulate the wall sections that are inside the roof space, and those roof tiles are dark and angled perfectly to capture the afternoon western sun. Solar cells placed there would probably do a dual function of shading that section of roof.

Looks like I'm limited to R3 anyway for walls, since anything higher is much thicker than the depth of the wall frame.

Damn, was just up in the roof now and found a rat has been chewing at the aircon ducting.

I'll have to check what temperature it gets to inside the roof space. Maybe I should get some whirlybirds.

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psychojoe said..

Harrow said..

Maybe I should get some whirlybirds.

Whirlybirds are a dud invention.
There's a guy who makes vented tiles specifically for crossflow ventilation. Lower tile on one side, higher tile on the other, done. Plug them for winter.

Whirlybirds sure make a difference to my house here in Sydney.

Does it make dollars and cents to do the job? The warmth that you gain in winter vs the heat you want to shed in summer might even things out. And how much extra power does your A/C use for summer cooling? It might be only a few dollars worth per year vs hundreds for insulation, new gyprock & paint, plus all that time that could be better used arguing with idiots on the internet

What is it with double-brick in Perth. Why is it so common? Was it just a thing of the times?

I used to live in a fibro house from the 1940s and at least I could/did insulate the walls and it would be pretty comfortable. With double-brick it seems that it sucks the heat out in winter and is sort of okay in summer. Are new houses in Perth still done this way or do they at least have an interior frame to allow some decent insulation?

I feel like I would be better lining all the walls with plasterboard and foam to improve the thermal efficiency.

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Harrow said..

FormulaNova said..
What is it with double-brick in Perth. Why is it so common? Was it just a thing of the times?

I used to live in a fibro house from the 1940s and at least I could/did insulate the walls and it would be pretty comfortable. With double-brick it seems that it sucks the heat out in winter and is sort of okay in summer. Are new houses in Perth still done this way or do they at least have an interior frame to allow some decent insulation?

I feel like I would be better lining all the walls with plasterboard and foam to improve the thermal efficiency.

Aside from the upstairs extension, our place is double-brick, built in 1918 with plenty of fireplaces. I figure back then it was easy to heat a place by burning wood, but not so easy to cool, so double-brick did what was needed at the time.

I recently fixed up a place in the country where it was originally double brick, and as you mention, lots of fireplaces. At least it had 3.6m high ceilings. Yes, 3.6m! But it seemed to do the job of keeping things cool in summer with those high ceilings. It was around the same age, if not a decade or two older.

The add-on to the house was done in timber, with slightly lower ceilings of only 3.2m, but I suspect that its easier to warm those rooms in winter.

A realestate agent in that area was telling me that in the old days you just kept the fires going all the time in winter. Now, you use AC and its a bit harder to keep the place warm.

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decrepit said..

FN you saw our house at Avalon. double brick downstairs, with cavity insulation, reverse brick veneer upstairs.

In summer we could open the place up for the evening sea breeze and cool the house down. In winter we let the sun in through the north facing windows, to heat the place up. Without AC we maintained temps between 18 min in winter and 30C in summer, which occurred after several days of 40+ with overnight mins only getting below 30 for an hour or so before dawn.

Our place was designed to have heaps of thermal mass, you just need to make sure there's enough North facing windows to heat it in winter, and a good enough airflow to cool in summer.

Yes, I remember. Was it designed that way from the start or retrofitted that way? I think you built it right?

In the house I am in, I liked that it had good solar access to the north, but in typical WA fashion, there is a big patio blocking it off. I have dreams of adding on and making a new family room that has the chance of good solar access for winter. I am not sure about thermal mass these days as you need to 'charge' it up and if you don't it stays cold/hot.

I guess it could be worse. The house I rented before had almost no solar access because of the way it was oriented, and then the added a giant room at the back that also had no solar access. It was okay in summer because it had an AC inside, but a loss to try and heat in winter.

I wonder if new builds these days are designed well or just enough to pass the minimum efficiency standards?

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FormulaNova said.. >>> Yes, I remember. Was it designed that way from the start or retrofitted that way? I think you built it right?

In the house I am in, I liked that it had good solar access to the north, but in typical WA fashion, there is a big patio blocking it off. I have dreams of adding on and making a new family room that has the chance of good solar access for winter. I am not sure about thermal mass these days as you need to 'charge' it up and if you don't it stays cold/hot.

I guess it could be worse. The house I rented before had almost no solar access because of the way it was oriented, and then the added a giant room at the back that also had no solar access. It was okay in summer because it had an AC inside, but a loss to try and heat in winter.

I wonder if new builds these days are designed well or just enough to pass the minimum efficiency standards?

Yep we went to a passive solar course first, then designed it accordingly.
We lived in the old shack for a couple of years to get a handle on the micro climate.
That led me a bit astray, the old shack was an oven in summer and a fridge in winter.
The only window that opened to the south, swung the wrong way, shutting the seabreeze out. So I rehung it so it opened into the seabreeze, that made a huge difference, we could open it as soon as the breeze came in, that kept the temp half reasonable.

For the new house I designed the windows to open into the breeze. But the house worked so well, it was always cooler inside until around sunset, by that time the breeze had started to turn SE, so orienting them to the SW was a waste of time.

The only compromise we made was the west facing windows, I just had to have a view of the point!

Because we can't see infrared we under value radiant heat. But getting rid of it can make a huge difference.

It doesn't matter so much what you use but how you do the job you want to fill all gaps and put eve vents in and a werlybirds it makes a big difference!!!!

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sn said..

FormulaNova said..What is it with double-brick in Perth. Why is it so common? Was it just a thing of the times?

The earlier olde schoole double brick houses had ventilation bricks placed regularly about 1 or 2 courses above the foundation level,
Natural convection allowed air to flow into the gap between the walls and out through the roof space, keeping the temp. down and at the same time keeping the wall cavity dry.

More recent double brick houses didn't bother with the expense of using ventilation bricks - the bricklayer just left mortar out every couple of bricks to leave a gap.

Unfortunately - this gap is between the bottom row of bricks, which then gets blocked up by garden beds, dust, weeds etc. and stops the air flow caused by natural convection.
The walls heat up, moisture builds up, termites and bugs have a new home,

That makes sense. I just don't like the construction method after living here for a few years. I think I would prefer an insulation layer between the skins of brick, or better yet, brick veneer so that the interior walls are isolated from the thermal mass of the bricks.

I think double brick might have had its time before AC was common, but I am not sure it is still as good.

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decrepit said..

FormulaNova said.. >> or better yet, brick veneer so that the interior walls are isolated from the thermal mass of the bricks.

I think double brick might have had its time before AC was common, but I am not sure it is still as good.

For good passive solar in the Perth area, you want the thermal mass inside and a well insulated veneer outside.

That will hold the heat generated by north facing windows in Winter, and hold the cool from the cold air at night during the summer.

Yeah, I remember you saying this before and it is inline with current design ideals. I just don't know if it works in practice.

As you say, you need north facing windows to heat up the thermal mass in winter, but you then need to shield this same thermal mass in summer, whether its using some sort of shading or something more active like blinds and curtains. In summer you then need to have a decent airflow through the house to lower the internal temperature. All good if you have a decent seabreeze handy, but otherwise not so good. You may have all this thermal mass, but no easy way to cool it.

In reality though, very few people seem to care about solar orientation and then the design of the house, and I doubt many new estates make allowances for this. I wonder if they even consider this when laying out the streets?

People just throw AC into the house and accept that good insulation should make it okay.

I consider the house I am living in, and I don't think it would work well with passive cooling and heating. The thermal mass inside doesn't get enough airflow through in summer to cool it down much, and then in winter it doesn't heat up enough. I really think it would be much better off to insulate the interior walls, with a layer of something and then plasterboard. That way I could cool or heat the interior volume as required and not worry about whether I have heating on all the time or cooling on all the time.

I see that in much colder parts of the world that they can design passive heating/cooling houses that do very well. They are super insulated, but I don't think they rely on thermal mass much, except maybe at the very end of the house where it faces towards the sun.

I can see how the house I am living in would have been great when they built it. Good solar access, and as long as you open the windows a lot to allow the seabreeze in, it would work well. But now, it is not up to scratch.

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sgo said..
The right eaves on North facing windows will keep the sun out in summer and let it in in winter. Just get the depth of eaves right when you build.
Passive solar design used to work , and still does.

I think a better way of expressing that is 'passive solar design CAN work, and still may'. I guess if implemented correctly, in the right climate, it can work, but there are a lot of "if's" involved.

I thought it was only my expectations of it, but when you go searching you can find people that have come up with the same answer that it might work, but instead it seems better/easier to go with a superinsulated house and heat and cool it mechanically.