Insulation advice for a first time renovator « Alternative Technology Assn Forums

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Insulation advice for a first time renovator

(16 posts) (7 voices)

Started 11 years ago by Bernardo
Latest reply from robmal04

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Bernardo
Member

Hi, I'm about to embark on renovation of a single storey double brick cottage in Sydney's east. A design and construct firm will add a second storey.

At this stage, the second storey will have Hardie fibre cement Newport "weatherboard" external cladding on three sides and brick veneer on the street facade, for local council "aesthetic" reasons. Roof will be Colorbond zincalume.

Windows will be uPVC double-glazed. Upstairs rooms will have ceiling fans and there will be three openable skylights.

I'm keen to avoid a "hot box" upstairs, minimise noise penetration between floors, as well as from street and neighbours, and generally keep energy bills down.

I've asked the designer for better than usual insulation and he has suggested the following:

Zincalume roof over R1.5 foil backed fibreglass insulation blanket;

R2.0 fibreglass insulation batts in upstairs stud walls;

R4.0 fibreglass insulation batts in upstairs ceiling;

R2.0 rockwool acoustic insulation batts between downstairs ceiling and upstairs floor.

We are on a hill and well shaded from western sun. We have good northern exposure at the rear of the property and are overshadowed by a two storey building to our east.

Any thoughts on the insulation set-up proposed above?

Might I be better off going for some combined acoustic/thermal insulation in upstairs stud walls?

Would insulation as specified by designer likely be more than adequate given the performance of double-glazed uPVC windows?

Could lack of insulation in the double brick downstairs undermine the work done by insulation upstairs?

Thanks in anticipation, B

Posted Monday 3 Jan 2011 @ 11:28:50 am from IP #
dave lawrence
Member

a few suggestions

for improved noise attenuation between floors check :
http://www.gyprock.com.au/oursolutions/homeowner/displaysolution/noisesolutions.aspx

do you mean colourbond roof, most council wont allow zincalume in built up areas due to glare factor ?

make sure glazing is maximised to north and minimised to east / west .

also ensure suitable eaves .. i recommend 900 mm for sydney , but i know this depends on your setbacks.

Ensure stairwell can be closed off to stop heat loss in winter .

Also ensure stairwell is correctly positioned , in my opinion one of the most challenging parts of first floor additions is where to place the stairwell.

if adding plumbing , try to design for short pipe runs.

hope that helps.

Posted Monday 3 Jan 2011 @ 7:30:18 pm from IP #
Bernardo
Member

Many thanks, Dave. That acoustic Gyprock looks promising.

Re roofing, I did ask for Colorbond but the quote specifies "prefinished corrugated zincalume roof sheeting". What's the difference, apart from council anxieties?

cheers, B

Posted Tuesday 4 Jan 2011 @ 1:32:50 am from IP #
dave lawrence
Member

zincalume has no colouring , colourbond does .
maybe "prefinished corrugated zincalume roof sheeting
refers to colourbond, but i have never seen it described thus .

Posted Tuesday 4 Jan 2011 @ 2:15:05 am from IP #
Russell Moore
Member

Considering your location, I would be making full use of your natural airconditioner, ie, the Pacific Ocean.

To cool the house attempt to encourage cross breezes as much as possible, pity about the house to the east as this will diminish the sea breeze effect.

Good breezes can still be had from the NE and SE though. Windows placed to scoop these breezes into the house are possible with vertical casement windows.

Posted Tuesday 4 Jan 2011 @ 4:06:50 am from IP #
Bernardo
Member

Thanks Dave. We've been given a colour chart for the roofing so it must be Colorbond.

Thanks Russell. All but one bedroom upstairs will have two windows and there will be openable skylights as well so I'm hoping those Pacific breezes will do their cooling job.

Posted Tuesday 4 Jan 2011 @ 5:22:20 am from IP #
Bernardo
Member

PS, Anyone venture an opinion about whether those R values look about right?

Posted Tuesday 4 Jan 2011 @ 5:30:49 am from IP #
dave lawrence
Member

r values are indicative . if installed correctly you may achieve the ratings claimed.
mostly they are not installed correctly .
especially when installed around penetrations, pipes etc .
I am a fan of double stud framing for that reason with outer frame housing insulation and inner frame housing pipework , cabling etc .

Posted Tuesday 4 Jan 2011 @ 7:47:32 am from IP #
Bernardo
Member

Thanks Dave. Any handy online material explaining how insulation is properly installed? Having no expertise myself, I'm reliant on the skill and care of the design and construction company doing the reno.

BL

Posted Tuesday 4 Jan 2011 @ 8:34:41 am from IP #
dave lawrence
Member

when in doubt read the instructions supplied with product.
a curiously ignored phenomenon in building is reading the instructions !!!!
read this :
http://www.yourhome.gov.au/
it is very comprehensive and objective

Posted Tuesday 4 Jan 2011 @ 8:53:14 am from IP #
Frateco
Member

Dave, I thought insulation bats only got to R3.5? Bernardo, a major factor with batts is that they are not compressed or they won't achieve anywhere near their R value. A mistake commonly made in Qld is to have 70mm stud framing and then use R3.0 batts that are 100mm thick. It does not work. There's installation guides on Bradford Insulation site.

Posted Monday 10 Jan 2011 @ 1:57:14 pm from IP #
Foilboard
Member

Hi Bernardo. The advice given to you by the architect is quite comprehensive. As an option I think you should also have a look at the reflective blankets from Kingspan-Aircell Insulation as I believe they would work quite well and are very cost effective. If you plan on having downlights and have an issues with asthma I recommend looking at a polyester batt instead of generic fibreglass as well.

In an ideal situation it would be best to create a thermal break around your home. Rigid based cladding or reflective panels such as Foilboard would eliminate any risk of thermal leakage thus creating a more comfortable internal temperature.

I am not a fan of any bulk insulation in walls as it has a tendancy to sag overtime, and are often poorly installed.

Hope this helps.

Posted Monday 10 Jan 2011 @ 10:23:21 pm from IP #
dave lawrence
Member

I am not a fan of any bulk insulation in walls as it has a tendancy to sag overtime, and are often poorly installed.

I agree with above statement.
also any moisture in bulk insulation radically decreases performance of the product, as the water vapour has displaced the trapped air .

Posted Monday 10 Jan 2011 @ 10:52:25 pm from IP #
Eco
Member

Poor installation is not a reason not to use a product. It is a reason to change installation practice and the supervision of that installation.

If it sags then a solution may be to use polyester batts and staple it up.

Dave - I am interested in the last statement. Do you have a study to back up that bulk insulation picks up moisture in situ overtime (are some materials affected more that others) or is it an onsite observation.

Posted Monday 10 Jan 2011 @ 11:14:59 pm from IP #
dave lawrence
Member

"Poor installation is not a reason not to use a product. It is a reason to change installation practice and the supervision of that installation."
I agree entirely but would stress that the onus is on you the owner to ensure that happens .. easier said than done

RE study to back up claim above about moisture in batts , I have read in the past and from my own observations I believe that statement but I have NO EMPIRICAL EVIDENCE to prove it .

Posted Tuesday 11 Jan 2011 @ 6:11:53 am from IP #
robmal04
Member

I agree with all the comments and suggestions, I wish I had this info before I had done some extensions. I would also recommend the yourhome website for a lot of expert and well written information. Quick point on a metal a roof, a small point on the colour, the darker it is the more heat it absorbs, we are currently painting an old roof and are going for the lighter colour for that reason, but still selecting a colour that fits the house and suburb. Metal roof is nice be can get very noisy in heavy rain. I am unsure if you will be having a large roof space in the extension our extension doesn't and is very noisy in heavy rain. A place I am doing up which is a flat metal roof I am lifting the sheets and rolling out Bradford Anticon blanket which is fibreglass batts with foil backing. As the batt is against the iron it reduces the direct noise has an R factor if about 2 (u can get higher) and assists with condensation. I live in Adelaide so unsure how this applies to your location, but don't forget about setting up air flows thru the roof, have vents in the shaded side of the house and exit point on the warmer side to create natural cooling air flow.
Hope it all goes well, Rob

Posted Tuesday 11 Jan 2011 @ 10:00:36 pm from IP #

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