Thread: Roof Insulation - keep loose stuff or replace with batts?

Welcome Brett,

I think you will find a very helpful community here. I know I have found most of my help from the vast range of people doing so many things to their houses on here. There are many options and opinions, and the research on here is definitely worth the read.

Originally Posted by Shubes

So do I keep this stuff and just even it all back out, or am I better off replacing it with batts? (Much easier to work with).

I've heard both types are good, some people have even said the blow-in stuff can insulate better if left to cover the wooden beams too, rather than just placing batts in between the beams.

Many thanks,
Brett.

Well Brett, it happens that both kinds are effective, so you have choices. First of all, blown insulation tends to settle and compress itself over time, so it is not unusual to find only a thin layer in older homes--it was once much thicker.

Rather than remove what's there, I would just fill the spaces with more loose insulation up to the top of the joists. Then, if you really want to insulate, lay some batts perpendicular to the joists over the top of the fibre insulation. If you do this, be sure to choose the batts that have NO paper on either side, because you do not want condensation problems.

Hi Pete! Thanks for the welcome (and thanks for sending me the link to this site, it is fantastic).

Bob - I like your idea of using the blown stuff and making sure it's up to the level of the joists, and then maybe adding some batts later on to finish the job. That would be some very effective insulation I think!

Cheers again, the comments are much appreciated.

"Rather than remove what's there, I would just fill the spaces with more loose insulation up to the top of the joists. Then, if you really want to insulate, lay some batts perpendicular to the joists over the top of the fibre insulation."

What he said is an option, but even just leaving the loose fill in place and covering it with your new batts as they are usually installed within the joists is fine. I have done it on a number of houses and it works very well.

The advantage of additional loose fill and batts across would be the additional sealing of any airgaps - even small gaps reduce the efficiency of insulation.

But that would be significant extra cost and not all that much benefit IMHO.

Make sure you go for highest R you can afford - ie: R3.5 minimum but R5 if you can.

Thanks for the comments Bloss.... sounds good. I'll start researching and pricing up some batts.... R5 sounds excellent, I'll see what the price is like.

A very rough rule of thumb with loose fill insulation is that you get about R1 per inch. We were under-insulated so I just added batts over the loose rockwool.

The calculations that suggest an "ideal" insulation level of R3.5 for Melbourne were done before the recent energy price increases, and I think the trend will continue. Think interms of R5, or even R6.

Wind in the roof can "snow bank" loose insulation. Just rake it level.

Cheers

Be certain that it is not asbestos based before moving it about. In Canberra and the NSW coast east of Canberra we had the famous Mr Fluffy who pumped asbestos insulation into hundreds of houses.

Graeme - thank you for that very useful info re: one R rating per inch. I was also thinking of going way past R3.5 - R5 sounds like a good target. That should help the heating bills over Winter.

mat - Hmmmm very interesting. I never actually realised there was asbestos based roof insulation, that's a real worry. Is it easily identifiable??? Mr Fluffy needs his ass kicked!

There certainly is asbestos roof insulation. It's loose fill - so no panic if you have batts. Note however that most loose fill is NOT asbestos - it's rockwool, shredded newspaper or less commonly one of a few other materials including fibreglass.

How to identify it? Assuming you're not absolutely sure what the loose fill is (product / brand name or the actual material) then you'll need someone who knows what they're doing.

DO NOT remove some yourself. Get a licensed asbestos removalist to come and identify it for you. You will have to pay for this even if it's not asbestos (insurance etc costs these guys a fortune so don't expect any of their time to be free - got to make $ to pay all the overheads) but it's money very well spent in my opinion.

Ask how much you will be chaged before you get them to come to your home. Get several quotes if it seems to high.

If the removalist tells you that it is asbestos then get them to put a sample in a sealed bag that you get analysed. The analysis should cost around $70 if you take it to the lab. I suggest using a 35mm film canister (the plastic bit the film comes in) and putting that in a snap lock sandwich bag. Then put that bag into another sealed bag (first rule of asbestos disposal - always double bag it). A decent lab should dispose of the sample for you and not give it back since it is a dangerous material (and you don't want it back anyway).

Only reason for you getting the analysis is to make sure they're telling the truth and not simply trying to get some $ out of you for removal. Actual removal of the asbestos will be $$$ so make sure it really is asbestos before going ahead.

You'd be amazed at just how common asbestos is in Australia. Everything from roof tiles to electrical cables to heater gaskets has been made with it in the past. Even bakealite (spelling?) plastic was often "fibre" (asbestos fibre) reinforced as was the tar wrapping on underground pipelines and even concrete. Several thousand products contained it - even some of the old ice chests. And of course there's always "fibro" - that's an asbestos and cement mixture.

Thanks for that detailed answer Smurf.

I have had a good look previously at the loose fill currently in the roof - it just looks like shredded up green / yellowy material (mainly green) - like the typical fibreglass batt type material. Is this any indication it may be safe, or does the asbestos stuff still look the same? That's a good idea getting a sample tested.

I guess this is part of the fun when playing with old houses!

Unfortunately you can't tell by just looking. But in Melbourne it is highly unlikely to be asbestos. There was only one major installer using absestos loose fill and for the most part he worked in the ACT and region and did some on the NSW south coast. He imported his stuff from South Africa over about 10 years in the 70s and 80s.

Testing is the only sure way to know. Most asbestos in the uses described by Smurf are not dangerous so long as they remain undisturbed ie: the fibres are retained within the cementitious or other material they are bound up with. If you cut, drill, sand or otherwise create dust then it becomes extermely dangerous stiff.

As the loose fill insulation was pure asbestos fibres it is highly dangerous at all times - so $75 or so to get test is worth it. As Smurf said though arrange it yourself, but take the usual precautions with masks etc and double bagging.

I never enter a roof space without a mask and mostly wear good protective clothing that I remove and wash afterwards. Roofs are full of dust of various types and glass fibres and dust generally are not good for human airways.

Plenty of web info on asbestos - some of the best on insulation is on the ACT site as it had the most houses done with loose fill.

See:http://www.asbestos.act.gov.au/

and the Vic govt site is at:

http://hnb.dhs.vic.gov.au/dsonline/d...os_in_the_home

Originally Posted by Smurf

I suggest using a 35mm film canister (the plastic bit the film comes in) and putting that in a snap lock sandwich bag..

What's "film"?

Pretty much gone the way of asbestos.