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  1. #1
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    Default looking for advice on insulation.

    20170924_130229.jpg

    Just wanted to say that this forum is great, and that I appreciated the help I got last time when my heater broke down.

    So I live in the western suburbs of Melbourne, my house is brick veneer.
    I had a vehicle drive into one of the bedrooms. Most of the repairs are nearly done.
    I just need to do the insulation, need some advice on what to use. Studs are roughly 95mm deep.
    To the right of the pic is the brick veneer. How do I go insulating against the exposed brick?
    Also all the plaster is off, so should I insulate the adjoining walls?

    I could only upload the one pic.

    Thanks for your help.

  2. #2
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    You need to keep batts from touching the brickwork and maintain the normal approx. 50mm gap between the bricks and batts.

    Do this with nylon string or fishing line. Two vertical runs from the top plate to the bottom plate, between each stud. Loop around the noggins and staple in place. You can also add reflective foil or building wrap inside each stud and noggin area. The foil or wrap must be highly breathable.

    I also do a horizontal run between the studs to be sure the bats or foil doesn't push out and touch the brickwork.

    Yes to insulating ajoining walls.

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    An alternative than can give good results is Foilboard. If you cut the foam board to fit inside the studs flush with the external face you get good results if you add another layer flush with the internal face then you get very good results or you could face the entire internal wall with it under the plaster
    "A big boy did it and ran away"

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  4. #4
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    Foilboard needs a specific gap on both sides to reach its stated R value so not ideal to have it up against the plaster.

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    If you go with batts the earthwool 2.5 wall batts are good for this as they are stiff and don't slump down.

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    Quote Originally Posted by joynz View Post
    Foilboard needs a specific gap on both sides to reach its stated R value so not ideal to have it up against the plaster.
    Not true if using 2 layers of FoilBoard with the gap between them, as it is the gap in the cavity that makes them work. both options are shown on the FoilBoard site [ or were] with the different R values for each scenario, Foil and foam backed plaster sheet is a standard building product in the UK after all. It's simply another option as it also works extremely well for sound damping used like that, the thicker the FoilBoard the better then too
    What you get is plaster/foilboard/airspace/foilboard/gap/ brick veneer
    "A big boy did it and ran away"

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  7. #7
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    Thanks for the quick replies.

    I'm leaning towards using the earthwool.

    In the wall cavities are there any regulations in relation to packing the insulation with the 240v power?

    Also what R value batts should I be using for the ceiling?

    What brand or type of building wrap or foil is highly breathable?

    And at some point in time I would like to add insulation to tile roof, ie between the trusses, what would you recommend as I would like to start this from this room as the ceiling is exposed?

    Thanks again.

  8. #8
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    Quote Originally Posted by redvl2002 View Post
    Thanks for the quick replies.



    In the wall cavities are there any regulations in relation to packing the insulation with the 240v power?
    It will de-rate the wiring but the sparkie should work that out.

  9. #9
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    For ceiling I suggest R4 or R5. The thicker the better. Any less than 4 is a waste of time.

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    Quote Originally Posted by redvl2002 View Post
    Thanks for the quick replies.

    I'm leaning towards using the earthwool.

    In the wall cavities are there any regulations in relation to packing the insulation with the 240v power?

    Also what R value batts should I be using for the ceiling?

    What brand or type of building wrap or foil is highly breathable?

    And at some point in time I would like to add insulation to tile roof, ie between the trusses, what would you recommend as I would like to start this from this room as the ceiling is exposed?

    Thanks again.
    Cut a hollow in the insulation around light switches. No need to cut huge holes for this though. From memory, a 5 per cent gap in insulation creates a 30 percent loss in energy. Cut snugly around pipework so the insulation isn’t compressed.

    If if you have downlights, you can use the insulated 'cones' that minimize the gaps and heat loss.

    Proctor Wrap.

  11. #11
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    Default looking for advice on insulation.

    Quote Originally Posted by mudbrick View Post
    If you go with batts the earthwool 2.5 wall batts are good for this as they are stiff and don't slump down.
    Quote Originally Posted by mudbrick View Post
    For ceiling I suggest R4 or R5. The thicker the better. Any less than 4 is a waste of time.
    This is good advice, did this at our place. Inside doesnít get over 23, before insulating it would regularly hit 30+... we also had to go R 2.5 under floor as well.

    Earthwool is great, easy to cut and fit. You need the specific wall batts though as itís denser.
    I had a life, but my job ate it...

  12. #12
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    Quote Originally Posted by Godzilla73 View Post
    Inside doesn’t get over 23
    Couldn't handle that, last few days kept upstairs at 28, downstairs for sleeping. Why are 2 storey homes built with bedrooms upstairs when these rooms need to be cooler

  13. #13
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    Default looking for advice on insulation.

    Quote Originally Posted by phild01 View Post
    Couldn't handle that, last few days kept upstairs at 28, downstairs for sleeping. Why are 2 storey homes built with bedrooms upstairs when these rooms need to be cooler
    Two story houses are perfect for temperate and subpolar climates... neither of which Australia has ever had much of.
    Joined RF in 2006...Resigned in 2020.

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    Quote Originally Posted by mudbrick View Post
    For ceiling I suggest R4 or R5. The thicker the better. Any less than 4 is a waste of time.
    Law of diminishing returns, and it depends on the details of how the house is constructed. Buying R5 in Sydney when R3 is specified will never return your extra cost, and with certainty it is not a waste of time to use less than r4

    BASIX and BCA are up to date now and have appropriate minimums for the various climates in Australia. You might want to increase insulation in Western sydney in a hope with small windows or good window coverings which has had poor solar design and a family that use the air conditioner nearly religiously (Sumer and winter) Then an extra R2 may well return.

    but it really isn’t a blanket (excuse pun) situation.

    you can do the maths on R values, but you don’t get value for the extra until the existing thickness is over run, and that doesn’t happen very often.

    Correct answer is, it depends

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    Quote Originally Posted by SilentButDeadly View Post
    Two story houses are perfect for temperate and subpolar climates... neither of which Australia has ever had much of.
    Ok, dumb question SBD, I am making the presumption that it’s single storey versus double here - but how does an upper storey get hotter than a single storey?

    Heat gain should be the same for any room under the roof space, and any convection possibly concentrates heat upstairs, but a single window open should fix that

  16. #16
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    Default looking for advice on insulation.

    Quote Originally Posted by pharmaboy2 View Post
    Ok, dumb question SBD, I am making the presumption that itís single storey versus double here - but how does an upper storey get hotter than a single storey?

    Heat gain should be the same for any room under the roof space, and any convection possibly concentrates heat upstairs, but a single window open should fix that
    Yeah the issue is convection and most traditional two story home designs take advantage of it by using the heat generated downstairs to keep upstairs warm. Which is rarely required here in Oz. Our take on two story homes these days is very different with double height rooms and massive voids in mcmansions. And it can easily be managed by opening a window. But much of the housing stock is so poorly designed that even that will make no difference to airflow... especially in two story conversions.

    I like two story houses but way too many are poorly designed for their surroundings and their climate zone. And the traditional European double storey box has little place here at all...
    Joined RF in 2006...Resigned in 2020.

  17. #17
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    I extended my house with lower level bedrooms. The year round comfort is so superior to any two storey home I have been in.

  18. #18
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    Quote Originally Posted by pharmaboy2 View Post
    Law of diminishing returns, and it depends on the details of how the house is constructed. Buying R5 in Sydney when R3 is specified will never return your extra cost, and with certainty it is not a waste of time to use less than r4

    BASIX and BCA are up to date now and have appropriate minimums for the various climates in Australia. You might want to increase insulation in Western sydney in a hope with small windows or good window coverings which has had poor solar design and a family that use the air conditioner nearly religiously (Sumer and winter) Then an extra R2 may well return.

    but it really isn’t a blanket (excuse pun) situation.

    you can do the maths on R values, but you don’t get value for the extra until the existing thickness is over run, and that doesn’t happen very often.

    Correct answer is, it depends
    Last point is correct - it depends!

    Minimum standard are NEVER best practice, just the worst you are allowed to install and stay legal!

    The issue is not simply return in investment on energy savings - the issue is occupant comfort at a reasonable cost. And that can be increased all year round in Australia climates by increasing by around +R-2 ie if the standard says R4 in the ceiling then go to R-6, if it is a cold climate and the standard says R-5 then go to R-7.

    But given bulk insulation is often quite cheap and on this forum many will FYI then there is no reason not to go a bit further.

    In cold old Canberra (cool temperate zone) for example I have R-13 in my roof on a poorly oriented 1970s BV house. As it happens the latest increases in gas prices has made all the traditional energy cost calculations out of date. Extra insulation can be offset more by costs savings, but good insulation well over minimum standards will just make for much greater occupant comfort - at modest cost.
    Advice from me on this forum is general and for guidance based on information given by the member posing the question. Not to be used in place of professional advice from people appropriately qualified in the relevant field. All structural work must be approved and constructed to the BCA or other relevant standards by suitably licensed persons. The person doing the work and reading my advice accepts responsibility for ensuring the work done accords with the applicable law.

  19. #19
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    Thanks for all the responses.
    Would it be advisable: as sarking is usually placed under the tile when building, but could I retrofit and fix between the rafters, thus creating a barrier between the roof tiles and the earthwool insulation that would be laid on top of ceiling plaster.
    Would this work?

  20. #20
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    Hi, you can retrofit sarking, but the only advantage is radiated heat from the back of the tile. In the case of tile that isn’t very much at all - nature of the material, and in Melbourne I wouldn’t bother, just rely on insulation thickness to slow heat transfer down. Dark roofs are an even money bet in the Melbourne climate, so by extension I wouldn’t be concerned much about heat load, and more about heat loss (the biggest energy user for melbournians)

  21. #21
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    Quote Originally Posted by Bloss View Post
    Last point is correct - it depends!

    Minimum standard are NEVER best practice, just the worst you are allowed to install and stay legal!

    The issue is not simply return in investment on energy savings - the issue is occupant comfort at a reasonable cost. And that can be increased all year round in Australia climates by increasing by around +R-2 ie if the standard says R4 in the ceiling then go to R-6, if it is a cold climate and the standard says R-5 then go to R-7.

    But given bulk insulation is often quite cheap and on this forum many will FYI then there is no reason not to go a bit further.

    In cold old Canberra (cool temperate zone) for example I have R-13 in my roof on a poorly oriented 1970s BV house. As it happens the latest increases in gas prices has made all the traditional energy cost calculations out of date. Extra insulation can be offset more by costs savings, but good insulation well over minimum standards will just make for much greater occupant comfort - at modest cost.

    Generalisations much? Of course a standard can be best practice.

    your general rule assumes that if x is good then x +2 must be better. It’s just not logical. If one wife is good, is 2 wives better?

    Its extremely unlikely you have r-13 in your roof. R3.5 batts are 175mm thick, if you have R-13, then your insulation is over 600mm thick! - it would be impossible to walk around up there.

    The reason I think it’s gone a little far, especially the opinion part, is that insulation works on a linear basis, so it slows heat conduction/convection by holding the air still, so it heats up/cools down in incremental layers. For that to happen to the point of overwhelming you need either very large temperature differentials or long periods of time. What this actually means is that your extra 4 inches of insulation makes zero difference for 355 days of the year, and helps during the 2 cold snaps and one multi day heatwave you may experience in Melbourne.

    this is a very important point tothe cost effectiveness. You are not gaining any benefit from the extra insulation day to day because the std does it’s job for 95% of the weather - you only get benefit when it’s overwhelmed and heat is transferring out or inwards.

    Anyways, it’s a diminishing return problem in heat let alone cost. Here is a US graph of the effect in Portland Oregon , Louisville Kentucky type climate. To adjust R values to Australian R values, divide by 5.6. So R10 in this graph is the equivalent of R1.8 wall in Australia for example. What counts is how the thicker you go, the less advantage you get from it before you have factored in cost

    d091889f-2f85-4de8-9efe-ca9a9aa24527.jpeg

  22. #22
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    is there an R value to thickness chart? or ceteris paribus it is linear?
    freedom of expression freedom from consequences...

  23. #23
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    Quote Originally Posted by DavoSyd View Post
    is there an R value to thickness chart? or ceteris paribus it is linear?
    R value is assigned by material, so yes if R3.5 is 100mm thick, then R7 is 200mm thick for that material. Ie you can add them together , 2 layers is r7. Well in theory, because when you put r3.5 on top of r3.5 most materials will actually compress a little under self weight and the total R value will decline slightly from both thickness and conductivity (I think). That’s why Rockwool should be better over the long term because it resists compressing over time better than glass

    No to a chart, but should be manufacturers specs

  24. #24
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    OK so almost additive...

    You'd want to be getting cheap materials rates if you using 4 layers of R3!

  25. #25
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    A mate of mine got a truckload of glasswool for a case of beer! And I mean a truckload, but he only lives in a townhouse
    So of course he insulated his ceiling with R5 but still had half a truckload left so added a second layer, Yep 5+5 total near R10!
    Now he says he can walk around the place in t shirt and shorts all year round!

  26. #26
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    Quote Originally Posted by mudbrick View Post
    A mate of mine got a truckload of glasswool for a case of beer! And I mean a truckload, but he only lives in a townhouse
    So of course he insulated his ceiling with R5 but still had half a truckload left so added a second layer, Yep 5+5 total near R10!
    Now he says he can walk around the place in t shirt and shorts all year round!
    Well how is the rest of the house no floor stumps to deal with and how are the walls?
    have kingspan R5 on the walls and Bradford gold bats R4 on gthe ceiling soon i have my 6.5 kingspan reflective sarking installed with new ridge caps working and sal and painted tiles.
    I also retrofit R 2.5 undefloor HD polyester bats


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    Quote Originally Posted by phild01 View Post
    Couldn't handle that, last few days kept upstairs at 28, downstairs for sleeping. Why are 2 storey homes built with bedrooms upstairs when these rooms need to be cooler
    Probably because these rooms are warmer in winter

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    Hello Bloss...have been reading some of your posts....and you seem very well experienced.
    here i have a ceiling (cement sheeting on timber beams 9hardwood) and above NO INSULATION and then a cement sheeting roof. (super six)
    i want to make the room below cool....as in the summer it is very very hot. and at the ceiling unbelieveable. i have had lots of ideas. Foil board to gyprock with batts above. But some people say that the air above the insulation will be so hot it will heat the bats or styrofoam and the temp will remain all night ...so that the next day one will start with a high temp and only get hotter ...thus heating the air below. (or the gyprock below). i really am confused. (if possible I would like to keep the open beam look to some extent...but not absolutely necessary. Cool room is most important. as it is my office (bought the house this way...didn't know it was so hot and that there was no insulation above)
    thanks
    Raelph

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