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pwa 05-29-2011 08:32 AM

attic insulation in old house
Hi to all,I bought a house in the northwest built in 1930 and have been checking out the insulation.The attic has a vented room built inside of it for storage and beyond that is open.The open area has 4 suffit vents.The rafters are on 24" centers and filled with what looks like vermiculite and wood chips and then covered with loose fill fiberglass insulation.The loose fill averages about 12" deep.The vent have cardboard ramps to keep them clear.Can I increase the loose fill or add batts?Can you have too much insulation?Do I need to get rid of the vermiculite and start over?

Katz 05-30-2011 06:02 AM

Do you need to get in the attic on a regular basis?
I remember one of my contractor friends saying you can have too much. A 1930's house, have you gone around and weatherproofed / sealed everything yet?
If not, I would do that first.

pwa 05-30-2011 07:28 AM

Yes I do go into the attic,and the house is sealed up well.The former was a real DIY person.I am learning to be a DIY person.What seemed real out of a date and makes me question its effectiveness is the vermiculite and would chips between the joices,Whats up with that?

HomeInsulation 05-30-2011 07:52 AM

Vermiculite Warning - May Contain Asbestos
Hey pwa,

I'll do everything I can to help you save money on your energy bills and make your home more comfortable. But the first thing you need to know is...

Vermiculite Insulation probably contains ASBESTOS.

Especially if you're home is in the Northwest and was built in the 1930's. Most of the vermiculite insulation in the U.S. came from a mine in Libby, Montana which produced 70 percent of it from 1919 to 1990. It was sold under the brand name Zonolite.

You may be able to find some old bags laying around in the attic. But I would just assume it contains asbestos.

fabrk8r 05-30-2011 07:57 AM

Before you go any further with your project do a google search for vermiculite insulation and read up on it.

I don't want to alarm you unnecessarily, but your house is the right age to have vermiculite which came from the Montana mines which were contaminated with asbestos.

I advise you not to disturb the insulation until you have it tested, especially if you have children in the home.

My suggestion would be to cover the existing vermiculite with fiberglass without disturbing it.

HomeInsulation posted my thoughts while I was typing!

HomeInsulation 05-30-2011 12:51 PM

EPA Vermiculite - Asbestos Website
Here's a link to the EPA's website on Vermiculite Insulation and Asbestos.

I hope this helps...

pwa 05-30-2011 03:25 PM

WOW, now that I got the &*$# scared out of me, I will get on it and check the links out.Since the vermiclite is covered with loose fill fiberglass is removal a must?

pwa 05-30-2011 03:36 PM

Ok I checked out the link and I am not so freaked out.It would be nice to know if I could go into my attic without a worry.I have been doing work up there thats how I found the vermiculite.Would be great if I could back some and have it checked out.Anybody know a place that could do it. Thanks for the info

Gary in WA 05-30-2011 10:29 PM

Check locally for asb. testing.

Where are you located? Is the attic air-sealed?


pwa 05-31-2011 06:00 PM

Im in Grangeville Idaho.I am intending on leaving it in place but I sure am glad I know its there.The previus owners lived here for 50+ years and the women is still alive so I cant be to big of a problem.I dont know what you mean by air sealed.Would it be effective to fiberglass bats on fibeglass loose fill to raise R value? Thanks for all the response.

HomeInsulation 06-02-2011 02:15 PM

Attic Air Sealing and Insulation Choices
hey pwa,

You'll be able to work in your attic if you wear the proper mask. (I use a 3M 6000 series half mask approved for asbestos removal.) Try not to work up there on extremely hot'll sweat a lot and your mask will shift around leaving gaps around your mouth. Wait til night time or cooler weather..

Even still, I would limit the amount of activity and plan on blowing insulation to prevent the amount of movement necessary to accomplish your r-value goals. Blowing insulation is a 2 man job, so you'll need to have a buddy help you out loading the insulation into the blower.

You can use the rental machine that comes free with the insulation. You can get it at the Home Depot or Lowes around here in NJ. You'll have to choose between blown fiberglass and blown cellulose. I like the recycled nature of cellulose, so I usually take that path, but blown fiberglass does a fine job.

Air sealing is the process of installing caulk, expanding foam, sheet metal, foam board and gaskets to prevent air from flowing through the walls, floors and ceilings in your home.

35% of your heat and air conditioning is lost through holes, gaps and cracks left in your home by the electricians, plumbers, HVAC installers and framers. No amount of fiberglass insulation will stop air from being sucked out of your house by the winter winds, but air sealing will...

The main problem you have is that in order to properly air seal your attic floor, you need to remove the insulation...

If you want to dramatically lower your energy bills and make your home a lot more comfortable, this is the way to go. It's also the most expensive route. But the heating oil $4/gallon it might pay off in a few years. After all, most of the heat in your home rises and escapes through your attic.

There are less expensive ways to dramatically lower your energy bills, but I'm running out of time right now...

pwa 06-02-2011 07:47 PM

Thanks for all the great advice.I do have a couple more questions.Can I lay fiberglass bats on the loose fill without compressing it?The floor in my attic has roll out fiberglass between my living space cieling and attic floor(dont know how much but I can see it) This is where you walk and on the sides where the roof drops 1X12s were placed on edge to keep the loss fill in.Can I have to much insulation here.I am thinking as long as ventilation is not blocked you cant have to much insulation.

Gary in WA 06-03-2011 01:48 PM

You will lose about R-2 or 3 per inch of compression;

Find your Zone on the map or closest city below map:

Compare Zone for R-requirements:

Air sealing: Good:



The installed density is important with loose-fill:

Be sure the cost doesn’t out-weigh the value:

Follow local minimum Codes.


DavidNielsen 06-06-2011 09:18 PM

The best attic insulation for an old house
Blown-in cellulose attic insulation costs about the same and seems to have many advantages over fiberglass. Yet, 75% of the market is fiberglass. Cellulose repels rodents and many insect including termites. Rodents love fiberglass. It has a higher R-Value per inch, which matters in a lot of tight spaces common to many attics. It is non-toxic whereas fiberglass "outgasses" HFAs & HCFCs. Fiberglass generally contains formaldehyde to which 20% of the America population has an allergy.

So, why is fiberglass 75% of the market ? Maybe it is because most people like Pink more than gray. In any case, I suggest you take a good look at cellulose.

fabrk8r 06-07-2011 06:37 AM


Originally Posted by DavidNielsen (Post 662408)
So, why is fiberglass 75% of the market ? Maybe it is because most people like Pink more than gray. I

I would like to add that anyone who has ever had to touch fiberglass, like I do on a daily basis, will much prefer cellulose.

I start itching just thinking about fiberglass. :eek:

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