# Blown in cellulose, need advice!



## mnp13 (Jan 16, 2007)

Is that behind drywall or plaster and lath?


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## Windows on Wash (Aug 30, 2011)

Each home is different in terms how it dries. Without know more about the home, location, and exposure, it will be difficult to say how the home will respond.


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## s10ehhhhh (Nov 16, 2011)

This is behind Plaster and another material which has a thick cardboard texture to it, about 1 inch thick (see the third pic)

i live in Montreal, so the winters get very cold, and sometimes on the worst days I have trouble maintaining 18 degrees celcius, 

The house is heated with electricity

It's a hard choice at the moment, I spend around 2200$ in electricity (which includes the heating obviously) per year, which I dont think is that bad, but when its really cold, it uncorfortable.

I also have gov grands that can give me about 3000$ back, so it would hardly cost me anything to have the job done!

my main concern is the moisture, I dont want to affect the structural integrity of the house, or have any mold, 

can cellulose be blown in this type of wall, is the 1 inch space between the cardboard and the tar paper going to cause a problem?


also another reason I want to do this is to have better soundproofing..


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## Windows on Wash (Aug 30, 2011)

Should be fine. Between the amount of paint on the walls and the asphalt paper, you should have a good enough vapor barrier.

GBR knows this stuff better than I do so I will wait on him to leave feedback.

Dense packing the walls should stop any and all air movement as well as deaden all the noise.


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## Gary in WA (Mar 11, 2009)

I agree with WW, above. That sheathing is structural, called Celotex, or black board when I installed it in the "70's. http://www.inspectapedia.com/structure/Fiberboard_Sheathing.htm Minimal R-value. 



The black paper/felt (vapor retarder) is vapor permeable (lets moisture through) adjusting to its wetness (5-60 perms): http://www.dickseibert.com/martin.pdf



Cellulose is a good choice when SPF is sometime cost-prohibited. No vapor barrier is required by the manufacturer but is required per your location:http://www.cellulose.org/HomeOwners/AirVaporBarriers.php

ftp://ftp.cmhc-schl.gc.ca/chic-ccdh...ngual/Vapour_Permeance_Volume_1_Web_sept5.pdf


There are also vapor barrier paints available. 


Gary


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## s10ehhhhh (Nov 16, 2011)

Hi GBR,

Thanks for your response, you seem very knowledgeable on the subject, can you come do the job for me in montreal haha, there isnt many companies here even willing to blow in cellulose..

but seriously, I have shown these pic to one contractor, he mentioned that if he blows the cellulose from the exterior, that the pressure would most likely rip through the black vapor barrier, essentially sending cellulose in that extra 1 inch of space between the celotex and vapor barrier. if this were to happen could it cause problems?

also to understand better, is it because the climate here can get very cold that I would need a vapor barrier?

Thanks again


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## Windows on Wash (Aug 30, 2011)

Vapor barrier/retarder should be to the warm side of the home in your case.

If dense packing of the cellulose tears that asphalt paper and the cellulose is in direct contact with the exterior sheathing, that will disrupt the drainage plane/rain screen effect.


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## Gary in WA (Mar 11, 2009)

Sounds as if the tar paper is on the studs, then 1" of furring, then plaster. I see the wood planks on the exterior and the angled diagonal blocking in the wall cavity, be sure he insulates these at every corner and maybe every 25'. There should be some weather-resistant barrier under the siding, on top the wood sheathing boards. I'm guessing another layer of tar paper.
I don't see a problem with blowing cellulose in, pushing pieces of tar paper against the plaster board. It would still be effective as a vapor retarder, just in pieces: http://www.greenbuildingadvisor.com...ier-or-vapor-barrier-building-science-podcast Similar to a split umbrella, you would only get wet where there are splits. Actually bad example, but hopefully you get the idea. 

You want *all* cavities filled against convective loops working there; http://joneakes.com/jons-fixit-database/743

http://findarticles.com/p/articles/mi_m0KWZ/is_3_6/ai_n8582994/

Gary


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## s10ehhhhh (Nov 16, 2011)

GBR thanks for your response, You are pretty accurate with your description of the wall, yes those are diaganal blockings (im hoping there is only one blocking between each stud) 

for the exterior there is the wood sheeting, and Ceder grained asbestos siding (according to the description on the photo below) I dont think there is tar paper

so in your overall opinion, the cellulose would be a good idea, whitout too many draw backs? I'm trying to get as many opinions as I can, cause I know theres no turning back once this is done

I found this old blue prints of the house in my basement and thought I would post it, let me know if this can give any more insight


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## Windows on Wash (Aug 30, 2011)

GBR in WA said:


> Sounds as if the tar paper is on the studs, then 1" of furring, then plaster. I see the wood planks on the exterior and the angled diagonal blocking in the wall cavity, be sure he insulates these at every corner and maybe every 25'. There should be some weather-resistant barrier under the siding, on top the wood sheathing boards. I'm guessing another layer of tar paper.
> I don't see a problem with blowing cellulose in, pushing pieces of tar paper against the plaster board. It would still be effective as a vapor retarder, just in pieces: http://www.greenbuildingadvisor.com...ier-or-vapor-barrier-building-science-podcast Similar to a split umbrella, you would only get wet where there are splits. Actually bad example, but hopefully you get the idea.
> 
> You want *all* cavities filled against convective loops working there; http://joneakes.com/jons-fixit-database/743
> ...


+1

That is exactly how it looks from the drawings.

Blow away and make sure he gets on both sides of those bracing blocks as GBR mentioned.


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## s10ehhhhh (Nov 16, 2011)

Hey guys, 

I just came across an article which got me a little worried

what is your opinion on this?

http://www.bobyapp.com/blog/2009/06/myths-about-insulating-old-house-walls

Thanks


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## Windows on Wash (Aug 30, 2011)

The house should be airtight and you should have a minimum of R-50 in the attic to start with.

That being said, it does not negate the benefit of have insulation in your walls and having dense packed cellulose (an air barrier) will do nothing but help the drying potential of that wall by sealing up the bulk vapor movement.


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## Gary in WA (Mar 11, 2009)

The article is correct on most points. I think you are confusing vapor barrier with vapor retarder, very different. http://www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11810
http://www.greenbuildingadvisor.com/blogs/dept/musings/vapor-retarders-and-vapor-barriers

You are fine in your application. 

Gary


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