DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (
-   Building & Construction (
-   -   Old home insulation woes (

nowwhatnapster 10-26-2008 05:43 PM

Old home insulation woes
Hey all, new to the forum, I decided to take a peek at the insulation in my home. Need some advice. With the rising costs of heating oil I'm sure I'm not the first person to bring up this topic.

Here's the situation in my attic (sorry if i use any structural terms incorrectly):
  • Home built in 1948.
  • Mostly Rock wool insulation (Paper backed), half of which is upside down (vapor barrier on top) (attic is not heated or atleast not supposed to be).
  • Almost all of the insulation extends to the edge of the roof with no space for air movement. (where the truss and rafters meet)
  • The rock wool is also severly flattend Anywhere from .5~3" thick, between rafters that are 6" high.
  • Some unfaced pink fiberglass has been added ontop over one of the bedrooms, also in pretty bad shape, about 4~6.5" thickness total (including the rockwool).
  • About 10~15% of the attic is uninsulated. Due to the pitch of the roof and arched living room ceiling, you would have to crawl through a fairly small opening to get insulation into that part, I'm willing to do this as I am 5'6 and 135lb.
  • There is a closed window on one gable, and a screened open vent on the otherside. (Bathroom vents into this one, really nothing preventing it from blowing right back into the attic)
So... there you have it, quite a mess IMO.

My girlfriend started living with me and she sneezes constantly when at my home. I'm thinking their is a good amount of mold due to the poor airflow in the attic and the upside down insulation.

Here is my plan, please advise me if you would do something different.
  • Remove all upsidedown insulation (mold concerns)
  • Remove insulation near edges (to improve airflow)
  • Remove correctly installed but severly damaged rock wool insulation where necissary. (tempted to just get rid of it all since im ditching half of it already)
  • Install R19 faced fiberglass, with R30 crosswise over it.
  • Replace window in gable with a vent.
  • Add a fan with a heat sensor and moisture sensor to the existing vent.
Not sure if adding a damper to the vents would be helpfull or not.

And just so you know I bought a 3m6800 full face gas mask and P100 particulate filters. I'm also going to pick up some disposeable coveralls.

Thanks for your advice in advance.

If you need pictures let me know and ill take some.

wombosi 10-26-2008 06:00 PM

Sounds like a pretty studley pran, man. I'd get rid of all that old cruft in there and go new fiberglass, or blow in cellulose.

If you have the money spray it with icynene and that will take care of your mold/vapor problems.

Is the main attic large enough to walk around in?

davitk 10-26-2008 06:53 PM

Respirator, disposable coveralls, hood and booties. Pull all the old crap out, find and seal penetrations (wires, top plates, plumbing, vents, chimneys etc) against air leakage with expanding foam, then blow in cellulose. You usually can rent a machine where you buy the material.

Venting can be tricky in an older house, be sure to get eve and roof vents right. And install a proper bath vent to the exterior with a damper.

Wildie 10-26-2008 07:43 PM

My house was built in '48 also. In my case, somebody had placed fibre glass between the ceiling joists already.
Total R value was probably 12.

I had R20 installed on top of this, for a total of R32.

I'm of the impression that gable venting should not be used anymore.
Soffit venting used in conjunction with a ridge vent or mushroom vents are best and gable venting interferes with the flow.

One thing that I found was that rubber insulated wiring conductors was used and the rubber has started to disintegrate.
If you have rubber insulated Romex wiring, I would recommend that you would replace all the wiring while the insulation has been removed.
Especially, if its ungrounded, as mine was.

nowwhatnapster 10-26-2008 09:26 PM

Thanks for the fast replies all.

schmolze: Not really, the attic is about 5 feet at the peak. Have to be bent over if you want to stand. Less painfull to crawl. The living room which is in the center of the house, has a cathedral ceiling, so you have to climb over it to get to the other side of the attic.

davitk/Wildie: I see what you mean about the ridge vent and the airflow. I've debated it. I agree I think that would probobly be the best solution. Maybe in spring/summer next year I'll try tackling that. I got a circular saw, and extra shingles in my basement. Right now, I'm thinking as a temporary solution to promote air circulation is by installing a gable fan. If you dont think the new insulation will get damaged by one winter then I wont bother with the fan and just install the ridge vent when spring comes.

Wildie: The wiring in my house, with the exception of a few additions is all that metal stuff, that bends like a drinking straw, dont know what its called. I know its in need of replacing. I recall the electritians saying that the rubber on the wires inside is brittle and cracks when bent. Not sure I have the skills to tackle that, I'd have to do a little research first. I might hold off on the second layer of insulation untill I get the wiring squared away. Was thinking of adding some recessed lighting anyways.

As for the type of insulation I'll probobly stick with the fiberglass batts and replace all the old stuff. Mainly because I know how to work with it. I would like to get my hands on some of that wool or cotton insulation, but its too damn expensive, I'll stick with the respirator and mask.

Wildie 10-27-2008 01:18 PM


Originally Posted by nowwhatnapster (Post 177243)
Thanks for the fast replies all.

Wildie: The wiring in my house, with the exception of a few additions is all that metal stuff, that bends like a drinking straw, dont know what its called. I know its in need of replacing. I recall the electritians saying that the rubber on the wires inside is brittle and cracks when bent. Not sure I have the skills to tackle that, I'd have to do a little research first. I might hold off on the second layer of insulation untill I get the wiring squared away. Was thinking of adding some recessed lighting anyways.

Its known as BX cable( armorsheathed). In my area its used for commercial use, usually. Its not required for res use, but it is permissable.

nowwhatnapster 10-28-2008 01:01 AM

Cellulose good, no soffit vents bad...
Ahh BX cable. I'm gonna leave it as is, thats another project.

So I re-read all your advice and did a little more research on cellulose insulation. I think I have to agree with you that the cellulose has more benefits than fiberglass. Less hazardous to your health, higher recycled content, higher r value.

I also spent a little more time examing my home, it appears the house has No soffit vents whatsoever. It was definitly boarded shut...Guess it doesnt matter that the insulation was crammed up against it.

I should probobly make the soffit vents a priority before I go installing fresh insulation in, even if i dont have a ridge vent yet... What do you think?

davitk 10-28-2008 05:55 AM

Does your house have eves?

nowwhatnapster 10-28-2008 08:54 AM

Not that I can tell. Here is a pic of what it looks like all the way around my house.

hope you like my mspaint skills.

There is no visible gap between the wood siding and the roof, just a painted board between each rafter.

Wildie 10-28-2008 12:02 PM

Rather than have a fascia and soffit it appears from your sketch that the rafter bay uses a block on the top of the wall rim plate.
I assume that the rafter 'lookouts' are left open.
Rather than attempting to make an opening in the bay block, perhaps it would be simpler to remove the block completely.
Then to keep insects and other pests out, cover the rafter lookout with vented vinyl soffit material.

davitk 10-28-2008 09:40 PM

1 Attachment(s)
I'm not quite sure how to handle the exterior as we don't build like that around here, but don't completely open the rafter bay lest the wind blow through the insulation, robbing it of its R-value. Here is a pic of correctly installed "proper vents" or "insulation chutes"; notice the space under and around them is sealed.

nowwhatnapster 10-29-2008 02:30 AM

Wilde: Yes the lookouts are open and an aluminum gutter sits in front of them.

davitk: I will be picking up some of those baffles this weekend, and I'll make sure to blow in insulation underneath them similar to your picture.

Correct me if I'm wrong but isn't there some kinda ratio for determining the size of the ventilation? Maybe that's more of a concern for the ridge vent. ? Like x sq.ft of ventilation per x sq.ft of attic space? Maybe I'm over thinking it.

Also: I took some measurements of the attic, comes out to about 1100 sq ft. So I will need about 30 bags ($210) of this stuff to achieve R-19 6".

Do I need to be concerned about the weight of this stuff if i were to add up to R-49? Those bags are like 80lb's if I read correctly. Dont want the plaster ceilings to cave in.

davitk 10-29-2008 08:54 PM

I would vent every rafter space as a prophylactic to ice damming, not worrying so much at this point about balancing the soffit/ridge vent areas. You want to keep that roof cool along the entire lower edge so the snow does not melt and refreeze, and also so there will be no stagnant areas for moisture to condense.

As far as overloading the ceiling, as long as you don't have lath and plaster (from the age of your house I would guess drywall or fiberboard skim coated with plaster) you should be OK, unless you are blowing it into a cavity and dense packing it; if you're spraying in an open attic it comes out of the hose light and fluffy.

nowwhatnapster 11-01-2008 06:12 PM

davitk: Yea its gonna be the dry light and fluffy kind. So nothing to worry about then. Also, I will plan on installing eve vents in all the eaves that can accept them.

Any Ideas on vapor barriers for the cellulose? Yes/No? I heard if you have enough airflow in the attic they are not necessary. Or is it just good measure to put one in anyways.

davitk 11-02-2008 06:20 PM

If you can install a vapor barrier, do so. However, I can't imagine how to go about retrofitting one, unless you vacuum all the old insulation out and spray closed-cell polyurethane , topped with your cellulose. The stuff works great but is pricey.

All times are GMT -5. The time now is 11:23 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Search Engine Friendly URLs by vBSEO 3.6.1