humidity problems with blown cellulose?

Dan_15

My question exactly--have not received a satisfactory answer yet.

D107

ny area too humid for blown cellulose?

In John Krigger's book Residential Energy he cites drawbacks of blown cellulose:

--Absorbs much more water than fiberglass, mineral wool, etc. And can retain 50-100% water by weight and lose insulating power if subjected to constantly high relative humidity--over 70%. Becomes problem if water leaks from the outdoors because cellulose wicks water into itself and stores it. This water can carry fire retardants out of the cellulose, causing reduction in fire resistance and corrosion of metal siding and roofing by thte solution of water and fire retardant. (It is possible to use cellulose with non-corrosive fire retardants.)

So living in the NY area,humidity in summer often goes to 80-100%. Am i asking for trouble using cellulose? Anything else for retrofitting old house 4" wall cavities from the outside clapboards?

Joe Brix

Not a fan of cellulose in walls

I think there's too much settlement and it winds up compressing itself so it looses R value.

Cellulose is fine for attics. Humidity should not be a problem with the igh temps. Anyone look into foam injection?

Bob C

How about blown in Fiberglass?????

pminspector_2

blown insulation

ICC calls for a vapor barrier ont he "warm-side" (in winter climates) , a recent call to a supplier of cellulouse in OHIO was made and the reply was no vapor barier is needed, but i haven't got this in print yet...
Perhaps a better question is, why dont you ventilate the moisture to the exterior instead of forceing your insulation to deal with it? The insulation doesn't generate moisture, life process's do, cooking, showering, laundry, animals in the home, including people... & exterior humid air entering without an exit path all contribute to the higher levels of humidity in todays "tight" houses. Out of the fear of higher heating/cooling monthly bills we have inadvertantly created perhaps a more serious problem, one that will ultimatly cost more to repair than the increase in heating costs... its a fine line we walk when we discuss (energy efficiency) insulation and ventilation and the balance between them in todays modern homes, the determining factor can be excess humidity in the home or negative pressure situations in a home that may preclude a monoxide problem, both problems are due the balance of air exchange from exterior to interior.. (either by design or by accident)
One last note ERV devices do not add air to the dwelling they are balanced devices and only transfer.. only a dedicated air supply duct delivering make-up or combustion air comply with code in most cases, Food for thought...

bigugh_4

Humidity?

Here in Utah the summer humidity is around 15%. I have seen copper pipe corrode from the condensation it gets when it covered with cellulose insulation. Fire retardent is usually sodium carbonate (baking soda), and the ATE part is oxygen which adds to the corroision process. I'd find another insulating medium. Chopped fiber glass is at least not looking for water! like cellulose is. Foam has a problem with expansion and if not applied exactaly right will push out the walls, even brick. I have seen that! I just did a section of outside wall insulating. removed the inside walls and insulated and replaced the sheet rock. It was not that bad. good luck

Mike T., Swampeast MO

Well Stated!

And what about us poor suckers in the mid-Mississippi valley where we usually have weeks each year of dewpoints above 75 yet still have fairly (and sometimes quite) cold winters? Plus extended periods of dry weather where every freaking crack opens because the good old sun has driven out moisture?

Foreman

If you blow insulation from the clapbaord side, you will have the worlds largest birdhouse, I blew mine from the inside, ballon construction, was much easier to repair the 1" holes on the plaster, clapboard left undamaged.

Patchogue Phil_30

no settling

Don't know where you get this from. Properly installed cellulose does NOT settle. FACT (to borrow a phrase).

Cellulose r-factor INCREASES when it is dense-packed inside a wall. So then, gravity compressed cellulose would not lose any r-factor.

D107

Cellulose

Alot to think about. From the outside usually they temporarily remove the clapboards so the holes get put in sheathing, plugged with foam after the job and then the clapboards are put back.

I'm going to check with a few more contractors and get back to the Wall with this. In New York, the Energy Star Program is behind this and the polyicinine foam; they even have a video of Richard from This Old House having his victorian house clapboard walls done with cellulose. I don't know how long cellulose has been used this way, if there's been enough testing of it in different climates. While some settling likely occurs, that's probably not the biggest issue.

I'm not an hvac or insulation pro but it seems for new construction the foam is a better sealer and insulator, but on retrofits you'd need a low-expansion foam that you could fill the 4" stud spaces with, without having it bulge laterally and cause damage.

Heard some great ideas so far; the vapor barrier was an interesting question. Applying the cellulose from the inside might be a good idea if the crew could navigate their gas powered equipment indoors.

Thanks,

David

D107

PS re: pm inspector, thanks for the great

post. Seems that homeowners get excited about insulating but don't think of the whole picture. My late father, a mechanical engineer for 50 years couldn't design a 10 cu ft closet without having a vent somewhere. (Grew up in the age of TB.)

From the wall and books i've gotten from the Wall i've been able to slowly start to get a picture of how all the pieces fit together. I guess i'll have to find a way to insulate, ventilate, humidify, dehumidify, cool, heat if it's possible in my old house. Then of course you set all this up and you find that the air you're bringing in as 'fresh' air is full of all the particulates and pollution that's been concerning the air testers of this NY metro area. So then you need great filters for the outside air--also the inside air for the various toxins in the paint, furniture, carpeting, etc.

If i could hook all this up to my treadmill I guess I'll be ahead of the game by the time the bird flu gets here.

David

S Ebels

NOW you're on the right track!

The house has to considered as a system, a whole puzzle made up of individual pieces! Each one affects the others and changes how the entire structure "acts".
Good insulation and sealing go hand in hand, and work together with good ventilation. You are obviously way ahead of the curve based on the fact that you merely brought it up.

As far as cellulose goes, it's good insulation. It does go in wet (new construction) and I make a practice of telling builders to give the stuff a chance to air out before drywalling. This is universally ignored, so walls wind up getting sealed with a fair amount of moisture already present. Not a good thing. The only thing you can do at that point is provide good, mechanical, ventilation to help dry out the house.

In an existing house the product goes in dry and depending on the skill of the insulation installer, some settling may occur. It depends on their equipment and how persistant they are in cramming as much insulation into the wall cavity as they can. Moisture is usually not an issue in this scenario.

Here's a rule of thumb or maybe a "fact of thumb". The better a structure is insulated and sealed, the greater the need for positive ventilation. When I say positive ventilation, I mean something that will actually exchange indoor air for outdoor air as required. It's the only way to keep you and your house healthy.

Dirk Wright

Cellulose Insulation

I have R19 cellulose in my attic on top of original R19 blown fiberglas. I have not noticed any water issues and we live in very humid Virginia. You might want to check out the Cellulose Insulation Manufacturer's Association for some (obviously biased) information:
http://www.cellulose.org/index.html

I like cellulose because it's made from recycled newspaper and is therefore more environmentally friendly than fiberglas. Hpe this helps.

Ron Schroeder

Cellulose does lose R value when it has moisture in it but it loses FAR LESS than fiberglass does with even less moisture. Cellulose doesn't lose as much R value in the cold either. The borax fire retardant also deters bugs. Cellulose is also opaque to radiant heat so it is much better than fiberglass in resisting heat from the attic in the summer. Properly installed, it doesn't settle. I have been using cellulose for over 30 years with great success, most of it here on Long Island where it is so humid that moss grows on pets.

Ron

Dan_15

Ron thats great to hear a long-term success story with cellulose. But what do you think of taking a house that was built in the 1920s without any insulation, vapor barrier or moisture barrier, which has been working fine for 85 years, and suddenly changing its characteristics by stuffing the walls with newspaper? Thats my biggest worry. Here in MA the utilities offer a discount off installation fees up to 50% discount in some cases. The retro-fit industry is real fast and loose and its hard to get an answer about how cellulose holds up long-term in an old house.

Ron Schroeder

As long as the inside (drywall/plaster etc) is tighter than the outside (sheathing/clabords etc.) there shouldn't be a problem. I would put gaskets on the outside wall electrical outlets. Even without an interior vapour barrier, cellulose will out perform fiberglass. Just make sure it is installed to at least 2.5 LB/cu ft. in the walls.

This is the best forum on insulation and energy that I have seen:
http://forums.taunton.com/tp-breaktime/messages/?start=Start+Reading+>>

Ron