# Blown-in insulation in walls



## Wildie (Jul 23, 2008)

lisak9393 said:


> Hello - I'm new to DIY chatroom and am a homeowner trying to save money do things myself. I wish to rent an insulation blower and blow either fiberglass or cellulose into the walls. I also need to insulate a dirt crawl space. If anyone has ideas about insulation blower rentals, let me know.


 I hired an insulation contractor to blow cellulose into my house walls! Its not an easy chore, and there are many pitfalls! In my case, the house was empty, so the holes were drilled from the inside! They may be drilled from the outside, but as my house has aluminum siding, it would have looked like it was shot up with a machine gun! Brick can be drilled through the mortar and plugged without affecting the appearance! My house is a bungalo style and not that large. Even so, it took the contractor and his helper four full days to do the job! And this did not include filling the holes! Your house may have 'fire stops' in the wall cavities! If so, it will be necessary to drill one set of holes near the ceiling. And another set under the four foot level. And of course above the lintels and under the windows! I'm an original DIY person, but I contracted this out and was glad that I did!


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## lisak9393 (Jan 22, 2009)

*Thanks for the heads up*

Hi there - could you tell me who you hired (I'm in the south bay) or who'd you'd recommend? My house is 1200 sq feet - what did it cost you for this service? I'm also thinking of insulating the crawl space/under the house - do you think that the walls or crawl space makes more difference? (my crawl space just has dirt below - house built in 1956, tract home in Sunnyvale).


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## angus242 (May 1, 2008)

Are your walls already insulated? May seem like a silly question but if they are, you cannot blow in new insulation.
Otherwise, I don't think it's all that hard of a DIY project. While I am a contractor, I don't normally do large scale insulation projects. I recently had a home owner request cellulose insulation in a small bathroom I was remodeling. Because the wall was only 5'x8', I rented the insulation blower from Home Depot. I did have the advantage of a gutted wall so it was a bit easier to see what was happening. After doing the little bathroom wall, I thought the process was so easy, I went back and got 20 more bags of cellulose and brought the blower to my own house. I tore out my daughter's exterior-facing wall, removed the fiberglass batts and blew cellulose into her wall. I then removed the cheapo fiberglass blown in stuff in the attic above her room and blew in 16" of new cellulose.
The entire project took me less than 1/2 a day at my own house. Of course, I did have to re-drywall her wall again but it was well worth it. Her room is now about 5° warmer than it was previously. 
Some things about the cellulose:
If you have uninsulated walls, you'd need to drill about a 2" access hole in each stud cavity. A stud finder would probably be helpful locating each stud. Don't assume they're all 16"OC. I did have a few stray 8" cavities.
You need to rent the bigger or more powerful blower to do the walls. You also need the nozzle attachment. It's cone shaped and helps taper the hose so you can blow into the small hole in the wall. Just remove the nozzle to blow into an attic.
It is a MESSY process. They tell you to keep the blower unit outside for a reason. Also, don't assume you can keep the cellulose from blowing around the interior. You can't. I just blocked off the room and used a towel for the bottom of the door. I covered all the furniture with a large drop cloth and sealed the HVAC return vent. Containing the mess was pretty simple. I just waited about 1/2 hour after finishing to let the dust settle. Vacuum and then a quick mop (hardwood floors) and I was cleaned up.
I really thought the process was pretty easy. Maybe I just expected a big pain in my rear job but it wasn't. I suppose the hardest part for you would be to make sure you're filling each cavity since you can't actually see the insulation going in. You can hear the machine start struggling to blow once each bay was filled but I still had to go back and touch up a few spots that I missed even after I thought they were full. Good thing is there's no way you can install too much.
Rental of the blower was free if you purchased 20+ bags. The blower itself is HEAVY. 100 lbs+.

Hope that helps some.


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## lisak9393 (Jan 22, 2009)

*Blown in insulation*

Thanks for your response. I don't have insulation in the walls. Can it be blown into interior walls too for sound proofing? Also, where did you rent the equipment? Do you recommend cellulose over fiberglass? I also have a crawl space which is covered with dirt. Do you think I should put insulation underneath my house above the crawl space? Would that help with the temperature of the house?


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## angus242 (May 1, 2008)

I definitely recommend cellulose over fiberglass. Cellulose is treated with borate as a fire retardant. Also, critters don't like the borate; acts as a animal deterrent! Cellulose is an excellent sound deadening material.
I mentioned I rented the blower at Home Depot. They have 2 models. The larger is what you'd need to blow into walls. 
I'm not an insulation expert so I cannot give sound advice for your crawl. I do know that you should do something to control the moisture on the dirt. Hopefully someone with more knowledge will be able to chime in about that.


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## Wildie (Jul 23, 2008)

The earth is a pretty good insulator, the outside walls are where the heat is lost! For my crawl space, I insulated the walls with Roxul insulation. It doesn't wick moisture and is fire rated! Its held in place with wire pins! These pins have a perforated base plate. A dab of construction adhesive is placed on the wall, then the pin is pressed into it! 24 hours later, you can hang the insulation and the vapor barrier! The dirt floor of the crawl space should be covered with 6 mil plastic also! I'm in Canada, so my labor costs would be different that those of the US!


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## lisak9393 (Jan 22, 2009)

*Clarification about your email*

Hi Wildie - was your email in reference to insulating crawl space or wall insulation? I have open crawl space, vented (dirt groundcover) and hardwood floors - so it'd help with the floor temp, anyway, to insulate (4' gap between post and beam under the house). Not sure whether the insulation you mentioned works in that case. Is it blow in, or batting? I need to both insulate the walls and the underside of the subfloor.


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## Mike in Arkansas (Dec 29, 2008)

I think what Wilde was saying was he insulated the walls of his foundation around his crawl space.


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## Wildie (Jul 23, 2008)

lisak9393 said:


> Hi Wildie - was your email in reference to insulating crawl space or wall insulation? I have open crawl space, vented (dirt groundcover) and hardwood floors - so it'd help with the floor temp, anyway, to insulate (4' gap between post and beam under the house). Not sure whether the insulation you mentioned works in that case. Is it blow in, or batting? I need to both insulate the walls and the underside of the subfloor.


 I used cellulose blown into the wall cavities on the main floor! In the crawl space, I used bat insulation on the crawl space walls, as they were accessible! The bats are held in place with 'pins' that are designed to hold bat insulation in place!


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## HomeSealed (Jan 3, 2008)

lisak9393 said:


> Hi Wildie - was your email in reference to insulating crawl space or wall insulation? I have open crawl space, vented (dirt groundcover) and hardwood floors - so it'd help with the floor temp, anyway, to insulate (4' gap between post and beam under the house). Not sure whether the insulation you mentioned works in that case. Is it blow in, or batting? I need to both insulate the walls and the underside of the subfloor.


Do some research on crawlspace insulation. The new line of thinking is to seal and insulate the entire crawlspace and NOT to insulate the floor of the home from it. Also, I'm not a huge fan of blown-in insulation as it tends to settle over time among other problems, however if it is your best option, just rent a blower from one of the big box stores.


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## angus242 (May 1, 2008)

HomeSealed said:


> I'm not a huge fan of blown-in insulation as it tends to settle over time among other problems,


Can you elaborate on this statement? Everything I've read and been told is to the contrary with newer cellulose. I actually had a lengthy conversation with a rep from GreenFiber that states many of the old issues such as settling, fire resistance and mold inhibiting have been addressed with the current products offered now.


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## joasis (May 28, 2006)

The old cellulose would indeed settle...the material we use now is denser, and if sprayed in an open wall condition, glue set. No, it does not settle, and it is miles ahead of fiberglass. 

The best option in a home with no wall insulation is to bare the walls, insulate right, and rock...great time to update the electrical wiring as well....because a home built without insulation probably means old wiring also. This does cot cost as much as you would guess, and sheet rock is a DIY friendly project.


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## wr00010 (Jul 6, 2009)

Hi, I have exactly the same scenario as the user lisak9393.
- 1958 home in the SF South Bay, with no in-wall insulation.
- Crawlspace has no insulation from underneath, it is immediately above the dirt.
- Most of the house has wooden floor.

Looking for answers to the following:
1. How much difference, in degrees of temperature, would each of these -- cellulose foam insulation in the wall and crawlspace insulation (with insulation bats) -- make? 

Wondering if one or the other is significantly better and hence which one should I do if I were to do only one?

2. What is the cost of cellulose insulation, including:
- insulation material
- equipment rental
- cost of repairs (filling the holes etc.)
- And labor, if I were to opt to get this professionally done

Is there any rough guide on per square foot cost
- for DIY (only material + rental)
- or done by contractor (material + labor)
BTW, my house is roughtly 1200 square foot. As for the exterior wall surface requiring the insulation, it would be about 800 to 1000 sq. ft of wall area.

3. Should I venture out into this, it "seems" relatively easy (though a bit messy, possibly). What about electrial connections/wires -- do I need to worry about those in any way when blowing the insulation there? I am not very hand, btw.

4. A question about a different alternative altogether.
My house exterior is not stucco currently. It has the vertical wood panels, about 18 inches apart, over a wood surface. 

What I am wondering is this: should I have the bat or foam insulation on the current exterior wall, and then have the wall surface created on top with stucco exterior? The idea is that, while I'm spending money on the insulation, might as well spend a bit more but also get a brand-new finished and newer style exterior created. (and if I were to go for that option, I may be able to get away with a cheaper bat-type insulation?)

Any help/feedback is greatly appreciated. Thanks in advance!

-WR


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## Yoyizit (Jul 11, 2008)

wr00010 said:


> - 1958 home in the SF South Bay
> BTW, my house is roughtly 1200 square foot.


With 600 Heating Degree Days in January and losing 7000 BTU per HDD through your house envelope this upgrade might never pay for itself, depending on what you pay per 100,000 BTU for fuel or elec..

I wanted to do the same to my house but that is just too many holes in the walls.


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