Questions to those that have actually installed Solar

richjdavies

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Sep 9, 2013
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You don't need to... but it's worth paying someone who has done it before to give your their experience (and do all the work like lining stuff up, understanding light, space, entrance gaps etc. making sure it doesn't fall down!)

You don't have to... but you should!
 

richjdavies

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Sep 9, 2013
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Did you even read what I wrote at that url I gave you?
Please go read what I wrote, I explain in lots of detail.
Apologies was on my phone. Helpful advice. I didn't realise isotherm was for sale generally... but a quick google does indeed show it up! In fact builders has a special on:
5m (x1.2m) of 135mm thick for R440 - which is basically the same price as thinkpink!
So thats 6sqm for R440 = 73/sqm -- I need around 230sqm = 39 (say 40) rolls = R17,600
So next question - where can I get a better price for Isotherm :)
 

Steamy Tom

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I think you were born yesterday ( or just Steamy Dom).

It's like building a house, you need an architect to do the designs and plans to go the next step.

You must be an ANC supporter ...
You clearly have no concept of how that industry works. stop strutting around like Mr big stuff and state your need then if it is so large.

Your argument spirals to insults because you have so little understanding.
 

lsheed_cn

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Sep 14, 2008
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Site shows about 10% more than Builders... Anyone else got a good supplier?
I phoned around, can't remember exactly who I bought from, as it was a couple of years ago already.
I asked Pennypinchers, Builders Whorehouse, Buildit, Buildwell, Buco,etc but I think I went deep Grassy Park to buy, as the local trademen places had the best deals. Would probably have been either Buildwell or Global.

Note - Builders will give further discounts if you are a builder also, so worth looking into having a trade account with them, but they are also the most expensive.

Recommend calling around, as there are specials, especially if you're going to buy a bunch of rolls.

Global
+27 21 706 2566

Buildwell Build It
+27 21 705 3793
 

TheJman

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Jul 16, 2011
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Did you even read what I wrote at that url I gave you?


Answers on a postcard to, "nope, i guess not."

Copy and pasting from myself, I'll put it below. Again, lots more detail where I originally wrote it up here -
https://goingsolar.co.za/2016/01/08/being-efficient-roof-insulation-keep-it-cool-in-summer-and-hot-in-winter/




Isotherm (Plastic based)
My personal choice is to recommend Isotherm for insulation. Its basically plastic, so is harmless to work with, and it won’t degrade like other products. Its really easy to work with too. It doesn’t have issues with water either, so is less of an issue with leaks. DIY’ing a roof install with it is fast and easy too. The rolls are light and it pretty much lays itself out when you unroll it. Once again, remember that our Cape Town R value is 3.7, so a minimum of 135mm is recommended. Again, if you can afford thicker rolls do it.

Think Pink (Fibreglass based)
While this offers marginally higher R values than Isotherm, its a pain to work with.
If you’re getting a professional installer to do it, then this is your choice, if you’re DIY’ing – avoid. Needs face masks, and gloves, and makes working in the ceiling space annoying afterwards as the fibreglass gets into your skin. Downsides – its a little worse than Isotherm with regards to water, but nowhere near as bad as cellulose.
Again, recommended thickness is at least 135mm for Cape Town.

Blown paper/ cellulose
(Just say no)
This is usually the cheapest solution. Usually its blown into the air space with a blower and the benefits are that its extremely fast to install. You need to put down at least 3-4 inches though. There are major downsides – while it offers moderate R values initially, it does tend to settle, and the R values reduce somewhat after a few months. It also has bad issues if there is a leak, as it absorbs the water, and the resulting weight can collapse the ceiling boards. Lots of examples of that on google images.
Lastly it also gets everywhere – you’ll be finding bits floating down for years to come.
Avoid.



Some comments on your reply -
1) Isotherm is not fibreglass, so no itching, and safe to handle.
2) Pumped cellulose is crap, and should be avoided - for a few issues; It settles and is then far less effective. When wet is a hazard. Rodents and birds love it.


Please go read what I wrote, I explain in lots of detail.
Hey man,

Thanks for the information - a concern I've always had with the insulation (probably stupid, but bare with me please) - is that I have downlighters and there is lots and lots of wiring all over the place, what is the risk with the insulation and the wiring / heat from the lights?
 

Quintrix

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Dec 1, 2009
Messages
613
Hey man,

Thanks for the information - a concern I've always had with the insulation (probably stupid, but bare with me please) - is that I have downlighters and there is lots and lots of wiring all over the place, what is the risk with the insulation and the wiring / heat from the lights?
Read up but as far as I can remember you need to leave 100mm space around lights. So no iso over lights
 

Geoff.D

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Read up but as far as I can remember you need to leave 100mm space around lights. So no iso over lights
The real answer, of course, is NOT to use downlights, end of story! The entire idea of insulating the ceiling is to create a heat barrier between the inside of the home and the ceiling cavity. Now, with downlights all over the place and 100 mm dia holes around the fittings, that barrier is "full of holes".

The entire concept of downlights was and still is just stupid.
 

lsheed_cn

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Hey man,

Thanks for the information - a concern I've always had with the insulation (probably stupid, but bare with me please) - is that I have downlighters and there is lots and lots of wiring all over the place, what is the risk with the insulation and the wiring / heat from the lights?
Move to LED lighting for a start, its a lot safer in terms of fire risk, as the power requirements are far lower, and it saves the initial cost of light replacement within the year. Complete no-brainer really!

Cut around the the insulation thats going over the lights and leave a circle in the insulation above them. Usually 10cm diameter or so is enough.
Note - Any transformers should go *above* the insulation!

I also agree with Geoff. D, holes in insulation misses the point, but sometimes you don't have other options..

Addendum - looks like SANS has updated requirements for Western Cape, and now 145mm is the recommended value. Personally, given the very minor difference in r-value, I wouldn't bother if the pricing is higher than for 135mm, especially if you don't have insulation currently.

  • ISOTHERM 145mm is SANS compliant for the Western Cape Region installed r-value 3.77
  • ISOTHERM 135mm is NOT SANS compliant for Western Cape region installed r-value 3.54
 
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Geoff.D

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Thanks for the update. Also to be accurate, the SANS recommendation is a minimum value -- you can go thicker. It also does not mean that the previous rec now means all those homes already installed are now defective, just possibly, less efficient.
 

TheJman

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Move to LED lighting for a start, its a lot safer in terms of fire risk, as the power requirements are far lower, and it saves the initial cost of light replacement within the year. Complete no-brainer really!

Cut around the the insulation thats going over the lights and leave a circle in the insulation above them. Usually 10cm diameter or so is enough.
Note - Any transformers should go *above* the insulation!

I also agree with Geoff. D, holes in insulation misses the point, but sometimes you don't have other options..

Addendum - looks like SANS has updated requirements for Western Cape, and now 145mm is the recommended value. Personally, given the very minor difference in r-value, I wouldn't bother if the pricing is higher than for 135mm, especially if you don't have insulation currently.

  • ISOTHERM 145mm is SANS compliant for the Western Cape Region installed r-value 3.77
  • ISOTHERM 135mm is NOT SANS compliant for Western Cape region installed r-value 3.54
Thanks so much man!!

My roof is a complete mess up there! I kinda want to take a vacuum cleaner to the place before I do anything, and there are so many cables laying all over the place that my concern for fire is huge!
 

lsheed_cn

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Thanks for the update. Also to be accurate, the SANS recommendation is a minimum value -- you can go thicker. It also does not mean that the previous rec now means all those homes already installed are now defective, just possibly, less efficient.
I did mention it before (edited as that was probably a bit passive aggressive before, not my intention!)

Once again, remember that our Cape Town R value is 3.7, so a minimum of 135mm is recommended. Again, if you can afford thicker rolls do it.
Isotherm and the other options all seem to max out at 135mm (everything else) or 145mm (Isotherm), so you'd have to roll additional layers if you wanted more R value. Wouldn't be worth it though, there would be other targets to resolve first - i.e single glazed windows.

I'm quite cognisant of the need for insulation, I'm currently building, and it seems that I need to emphasise the insulation part with the workers here, as they just aren't used to putting it in. Eg XPS board in wall cavities during build etc.
 
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Geoff.D

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Thanks so much man!!

My roof is a complete mess up there! I kinda want to take a vacuum cleaner to the place before I do anything, and there are so many cables laying all over the place that my concern for fire is huge!
Go and get yourself a second-hand vacuum cleaner from Hospice etc for that task. It will be completely wrecked after the exercise. Or, resign yourself to replacing the wife's one afterwards.
Inspect the wiring. Check the connection boxes and make sure they will be above the insulation. Look for cable joints that should not be present and put those in connection boxes. The cables will then be fine IF specced correctly for the purpose they are being used for.

1.5 mm for lights, 2.5 for power sockets and 4mm for heavy appliances like stoves, hobbs etc. Or get an electrician in to do the inspection for you.
 
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