Blown-In Insulation

[Fletch]

My house was built in 1979, has blown-in insulation, but not very much of it (comes even with the 2x6 joists in the attic). We're looking at substantially increasing the amount up there, probably this spring. The local home improvement stores both offer free blower rental with the purchase of insulation, so I'm planning to do it myself.

There are a few can lights, all in insulation-approved housings, so that's not an issue. My main questions:

1) The bathroom fans vent into the attic space. At the least, I expect to have to run ducts out of them and up higher to keep them venting into air rather than into insulation. Should I just go ahead and knock a hole in the roof and make a roof vent for these, or is it OK to keep venting into the attic, given that the amount of air space will be substantially reduced?

2) I noticed that the eaves don't seem to be insulated... is that something I need to specifically avoid doing?

3) Also, out by the edges it looks like they tried to keep the insulation from touching the roof itself. Is that something I need to watch for as well? I remember seeing a contractor on HGTV saying something about how there needs to be room for airflow near the roof, but didn't quite catch his whole point, so that's what I'm trying to determine.

4) It's conceivable that I may want to run some more wires in the future for home theater stuff, but now the insulation will be a foot or so above the rafters. Do I just buy some extra and refill the spaces I smush down, or is there a trick that I can use for such things?

Any tips or suggestions you might have would be appreciated.

 

[gmviso]

Bathroom fans should never exhaust into the attic space because of the moisture in the fan exhause. Regardless of what else you do get those suckers vented either out the gables or the roof.

 

[snorko]

tHE REASON INSULLATION IS NOT RUN TO THE VERY OUTER EDGES IS TO KEEP THE SOFFIT VENTS FREE

Crap, I am not going to retype that.

 

[Digital_photog]

Eves need to be vented and blocked so the insulation doesn't go out into them. You need ventilation at the even and ridge to keep condensation out.

 

[Digital_photog]

tHE REASON INSULLATION IS NOT RUN TO THE VERY OUTER EDGES IS TO KEEP THE SOFFIT VENTS FREE

Crap, I am not going to retype that.

You need to close the eves off and install vents. you can make your own or get them from lumber yards. You don't want a non-insulated area along the whole perimeter of the house.

 

[snorko]

On this line of thought, does anyone know what the typical labor for this is? I know how many bags I would need, and it is enough to get the machine free. However, I do not want to do it.

 

[Digital_photog]

On this line of thought, does anyone know what the typical labor for this is? I know how many bags I would need, and it is enough to get the machine free. However, I do not want to do it.

I haven't contracted any jobs for a while. Check with a local insulation contractor and see what it costs. They usually have wholesale accounts and it may not be a lot extra. Blowing insulation is a dirty job. You will need a good respirator.

 

[snorko]

Blowing insulation is a dirty job. You will need a good respirator.

Hence I am happy to pay someone

 

[Fletch]

On this line of thought, does anyone know what the typical labor for this is? I know how many bags I would need, and it is enough to get the machine free. However, I do not want to do it.

The quote they gave me was basically twice the cost of the insulation. So figure as much labor as materials.

 

[eldirector]

1) The bathroom fans vent into the attic space. At the least, I expect to have to run ducts out of them and up higher to keep them venting into air rather than into insulation. Should I just go ahead and knock a hole in the roof and make a roof vent for these, or is it OK to keep venting into the attic, given that the amount of air space will be substantially reduced?
Mine are all vented into the attic as well (built about '79), and that was per code at the time. Ideally, extend them to an external vent. Otherwise, try to keep the ends off of the insulation, so you don't get it wet with condensate.

2) I noticed that the eaves don't seem to be insulated... is that something I need to specifically avoid doing?
No need to insulate there - you are just insulating the outside from the outside. Make sure the vents are COMPLETELY free (no insulation even near them).

3) Also, out by the edges it looks like they tried to keep the insulation from touching the roof itself. Is that something I need to watch for as well? I remember seeing a contractor on HGTV saying something about how there needs to be room for airflow near the roof, but didn't quite catch his whole point, so that's what I'm trying to determine.
You don't want moisture buildup between the roof and insulation. Leave a bit of an air gap (likely why the eaves are not filled in).

4) It's conceivable that I may want to run some more wires in the future for home theater stuff, but now the insulation will be a foot or so above the rafters. Do I just buy some extra and refill the spaces I smush down, or is there a trick that I can use for such things?
I have used a leaf rake to "fluff" insulation after mushing it down.

Any tips or suggestions you might have would be appreciated.

Get the cellulose stuff - insulates well and itches less. Cover EVERYTHING you don't want to get insulation on (long sleeves, buttoned collars, hat, etc...) and get a good mask. Goggles are nice, too.

Put the machine outdoors, and run the hose through a soffit vent.

I blew insulation into my detached garage last year, and it is an easy job. Dirty, but easy. Did 25x25 in under an hour. FIL ran the machine, and I crawled around. One trick: I taped a broom handle to the hose to extend my reach. That let me work from the center a bit easier.

 

[LEaSH]

If your blown in stuff is level with the 2"x6", might use pink rolled up stuff to run over the top. Perpendicular to the direction of the joists.

 

[littletommy]

Most home stores rent the machines for DIYers. I haven't priced insulation in a while, but, if your willing, you might save a few bucks.

 

[bradp]

The Owens Corning Attic Cat from Home Depot is the best I've used blows nice and has a great R value as well as doesn't settle like Cellulose (Lowes now carries Johns Manville and so does Menards. The rental for the blower is cheaper from HD too. I have done about 20 houses this year (more than normal) you need to put baffles on the eaves to block the insulation from going out to the eaves and allow ventilation to the attic as well.

Labor to do insulation is about $.85/ft for R44