Blown in insulation

[john193]

hi folks. I have a 1964 rancher with little to no insulation in my walls. I noticed wherever there is brick, the walls are hollow. It's 2 by 4 construction with 16 inch centers.

Anyway I recently started looking into blown in cellulose for my walls and I have a contractor coming tomorrow for a quote. Anyone here have any experience with blown in cellulose or questions I should ask during the visit?

Thanks in advance

 

[ihookem]

I had a 2200 sq ft ranch . It would have been 10 yrs old now. I didn't want to pay for foam so I went with blown in. There was not one elecrical box that would leak any air at all, not even with 40 MPH wind gusts. It is worth every penny. The house was just under 4 yrs old and it caught on fire real bad. We tore it down and went with 4" closed cell. I am sure the closed cell is better. The house heats easier with foam. Both houses are the same , on the same lot so it is a fair comparison. One thing I wouldn't do is is put in fiberglass, ever. I am working on a house now and all the outside outlets leak air.

 

[john193]

I have fiberglass on the walls with siding, and I'm even considering having them blown with cellulose (apparently this is doable). Do you recall the price per square foot on the cellulose. A bit of research online led me to an estimate of 1.17 to 1.75 a square foot with labor, but I'm not sure how accurate it was.

My one issue is my kitchen walls have no insulation, but without cutting through the cabinets I don't know how they will fill those...

 

[Highbeam]

I too have a 1963 rambler with R-5 FG batts in the walls. Yeah, that's a 1.5" thick batt stapled to the studs. I was under the impression that they drill the holes on the exterior of the home and blow in the cellulose.

I just put 178 bales of cellulose into my shop attic last weekend. It's fun stuff.

 

[begreen]

There are different densities of blown-in cellulose. The old stuff is low-density. It needs a large hole (1.5"?) and can settle over time. Then there is high-density that is blown in under greater pressure. It only requires about a .75" hole and is not supposed to settle. When you get your estimate ask about this. Also ask how they will check for fireblocks in the wall and whether they will fill above and under them. Same for windows.

 

[john193]

Thanks for the feedback.

The contractor was out yesterday and went over everything with us. He is a friend of my father in law and I don't like picking contractors from the yellow pages.

So they do 2 holes per stud cavity. One a foot from the ceiling and another about 3 feet off the floor, 2 and 1/8 diameter holes. They will dense pack at 3.5 pounds, the natural settling pressure of cellulose is around 2.5. They will fill the wall until cellulose is bulging out of the hole, remove the excess to cover.

I assume the reason for the 2 holes is to compensate for and blocks within the cavity.

Since everywhere I need insulation has brick exterior, all the work will be done from the inside.

Edit, the pressure is per cubic feet.

 

[ihookem]

John, it was 10 yrs ago when I had this done. I think you will really like the cellulose insulation. It will feel like a new house. I think 1.25 -1.75 will come to about 10 bucks per cavity. Just the comfort will be worth it.

 

[woodgeek]

I am also a fan of cellulose...its cheap, green, airseals, easy to retrofit and doesn't outgas.

I am worried about water coming through the bricks (brick walls are permeable)....is there a good roof overhang on the wall in question? Are those walls pointing in the direction of the prevailing wind?

 

[john193]

@woodgeek There is an 18 inch overhang. Behind the brick there appears to be foam board, plywood, 2 by 4 studs finished by 1 inch plaster walls. Would you consider it an issue with this setup as well?

The installer did not express moisture as a point of concern.

 

[woodgeek]

Sounds good. With the deep overhang and the cellulose not touching bare brick I am sure you are aok.

 

[john193]

Yep, won't be touching bare brick. At the density they pack he indicated that it does not provide 100% air imppermiation. probably not a bad idea to allow whatever moisture gets in there to find its way out...

 

[woodgeek]

Agreed. Air permeation is low enough to be really helpful in retrofit, but its still highly vapor permeable (also usually a good thing).

 

[begreen]

Thanks for the feedback.

The contractor was out yesterday and went over everything with us. He is a friend of my father in law and I don't like picking contractors from the yellow pages.

So they do 2 holes per stud cavity. One a foot from the ceiling and another about 3 feet off the floor, 2 and 1/8 diameter holes. They will dense pack at 3.5 pounds, the natural settling pressure of cellulose is around 2.5. They will fill the wall until cellulose is bulging out of the hole, remove the excess to cover.

I assume the reason for the 2 holes is to compensate for and blocks within the cavity.

Since everywhere I need insulation has brick exterior, all the work will be done from the inside.

Edit, the pressure is per cubic feet.

Ask if it is dense packed and at what density.
http://www.buildingenergyvt.com/weatherization-and-insulation/dense-pack-cellulose-insulation/
http://www.applegateinsulation.com/Product-Info/Technical-Pages/329148.aspx
Two holes sometimes is not enough for each stud cavity. They should at least drop a weight on a string in each hole to see if there is additional blockage in the cavity. This could be an old framed in window cavity for example. We had this in our old house.

 

[EatenByLimestone]

I had cellulose blown n this summer. It's a different house! I should have done it years ago.

 

[john193]

Ask if it is dense packed and at what density.
http://www.buildingenergyvt.com/weatherization-and-insulation/dense-pack-cellulose-insulation/
http://www.applegateinsulation.com/Product-Info/Technical-Pages/329148.aspx
Two holes sometimes is not enough for each stud cavity. They should at least drop a weight on a string in each hole to see if there is additional blockage in the cavity. This could be an old framed in window cavity for example. We had this in our old house.

3.5 pounds per cubic feet is the density he quoted.

 

[EatenByLimestone]

A few nights ago I realized that I still haven't turned on a humidifier. I'm just a bit shocked.

I may have cheated on that by switching to a gas stove. I'm sure that releases a good deal of water vapor into the air. Regardless, it's not an appliance sucking electrons that is running.

 

[woodgeek]

Indeed. But just humans breathing and taking showers and cooking releases a lot of vapor too. In an airsealed house, that can easily be enough. I still run a humidifier when 'real winter' is here...maybe from New Years through February.

Cellulose also buffers humidity...it might harmlessly absorb a LOT of water in the summer, and then release it in the winter. It might 'run out' at some point, and then you'll find you need the humidifier. Or not.

Another benefit...my wood floors creak a lot less. They used to have humid warm air on one side, and infiltrating dry air on the other, so they were always 'cycling' their dimensions, even working up nails. Sounded like a shootout walking across the living room. Now they don't do that anymore, just a couple squeaky spots left.

 

[semipro]

I may have cheated on that by switching to a gas stove. I'm sure that releases a good deal of water vapor into the air

I hope you're referring to one meant for cooking not heating.

 

[EatenByLimestone]

Yeah, the one for cooking. I just read back and I wasn't very clear, was I.

 

[semipro]

Yeah, the one for cooking. I just read back and I wasn't very clear, was I.

We had a ventless gas heater for about a week. That thing scared the heck out of me. It served as an ample "humidifier" though.

 

[EatenByLimestone]

My father had one chosen for the cabin. I used it for a year, maybe 2 before I took over the respoonsibility. I took the Century out of storage and put it in. There were awful humidity issues. A weekend running it and the door wouldn't open or close. Part, maybe a lot of the issue, was trying to heat the place up from 10F. The walls were cold and all that moist air hit them. Any that was before factoring in combustion bi-products in the air.

 

[Seasoned Oak]

Iv found Cellulose to be the most cost effective for existing construction. The also make fibreglass for a blow in machine. That just sounds itchy.

 

[Seasoned Oak]

There are different densities of blown-in cellulose. The old stuff is low-density. It needs a large hole (1.5"?) and can settle over time. Then there is high-density that is blown in under greater pressure. It only requires about a .75" hole and is not supposed to settle. When you get your estimate ask about this. Also ask how they will check for fireblocks in the wall and whether they will fill above and under them. Same for windows.

I use a 2" hole and pack the wall cavities tight. IF you user an old worn machine or dont know how to regulate the air mixture, you wont get a good pack and it will settle.