Attic insulation primer

I'm trying to get a plan together to start re-insulating my old house. The current insulation is a hodgepodge of materials, techniques, and placement of insulation. It's really quite ridiculous. The rats and mice have made a mess of it as well. I have a few preliminary questions that will help me during the learning process:

1. Given that there is very little usable insulation anywhere in the house, if I start by just insulating the floor in the attic (ceiling of the living spaces) will this be a significant overall improvement given that the walls have poor insulation and the floor has none?

2. What would be the best DIY option for ceiling insulation? Is it acceptable to put the blow-in insulation in place with just a rake or something?

3. Do I need to be concerned about covering electrical features with blow-in insulation?

4. What are some strategies for adding attic insulation, while preserving access to spots that I would like to continue to inspect or work on?

The floor is the last place I would worry about until you have other areas done. There will be little reward for your time, effort and money.

Attic
Kind of insulation you have now? If you have had critters it should likely be removed. That would allow you to inspect wiring and other damage.
If over the years there has been ice dams there might be framing that should at least be looked at.
Is there a vapour barrier, poly under the insulation?
We need to make sure you have adequate venting at both the soffet anf the peak.
Holes drill for wiring in the top of the walls need to be sealed with a fire rated caulk of foam
Pot lights that are not rated for insulation will need an insulated box built over them.
Even if you don't have vapour barrier, light boxes need to be covered with poly and seal in place with accustic sealer.
Air shoots need to be stapled the roof sheeting into the soffet area to allow airflow of the exterior wall
The space between the air shouts and the top of the exterior wall is closed with batt insulation, thatkeep the loose insulation from flowing into the soffet area.
Hows that for a start?

Blown in works best.
Only wiring that should not be covered is knob and tube.
No such thing as "air shouts" but there is baffles. There installed in the rafter bays to allow air flow from the soffit vents to the roof vents. Only need them where the roof meets the walls.
In your area there should be R50 at least and that's 12" of insulation.
Insulating the rim joist in the basement or crawl space with 2" foam and spray foam to fill any gaps. will be a big help.
Never once seen anyone seal up can lights with plastic, sure way to melt the plastic and may start a fire.

joecaption said:

Blown in works best.
Only wiring that should not be covered is knob and tube.
No such thing as "air shouts" but there is baffles. There installed in the rafter bays to allow air flow from the soffit vents to the roof vents. Only need them where the roof meets the walls.
In your area there should be R50 at least and that's 12" of insulation.
Insulating the rim joist in the basement or crawl space with 2" foam and spray foam to fill any gaps. will be a big help.
Never once seen anyone seal up can lights with plastic, sure way to melt the plastic and may start a fire.

Click to expand...

Cover the boxes and build a box around un rated can lights.
air chutes------------- sorry

Thanks for the info! I'll post back with some more questions, there's even more I don't know than I didn't know before!

It's when you don't know what you don't know that get's you into trouble

Donald Rumsfeld couldn't have said it better himself......

nealtw said:

The floor is the last place I would worry about until you have other areas done. There will be little reward for your time, effort and money.

Attic
Kind of insulation you have now? If you have had critters it should likely be removed. That would allow you to inspect wiring and other damage.
If over the years there has been ice dams there might be framing that should at least be looked at.
Is there a vapour barrier, poly under the insulation?
We need to make sure you have adequate venting at both the soffet anf the peak.
Holes drill for wiring in the top of the walls need to be sealed with a fire rated caulk of foam
Pot lights that are not rated for insulation will need an insulated box built over them.
Even if you don't have vapour barrier, light boxes need to be covered with poly and seal in place with accustic sealer.
Air shoots need to be stapled the roof sheeting into the soffet area to allow airflow of the exterior wall
The space between the air shouts and the top of the exterior wall is closed with batt insulation, thatkeep the loose insulation from flowing into the soffet area.
Hows that for a start?

Click to expand...

On one end of the attic they used some blow-in material on the floor of the attic which is a filthy mess and should be replaced. In the other 2/3 of the attic they were in the process of installing 2 inch thick foam board to underside of the roof and had no insulation on the floor. It seems that this is a bad idea as I would prefer to have good insulation on the floor of the attic and probably none in the roof. I was thinking of removing everything and just insulating the attic floor.

Where I live is pretty mild and there is rarely significant snow or ice (but plenty of rain).

What is a pot light?

Can you help me with some terminology: soffet and peak? One thing the house does have is lots of roof vents!

Any photos or how-to's on the light boxes with poly and accoustic sealer?

Foam against the roof deck is mixing 2 different systems so if you want to insulate the floor area, I would take the foam down. I would remove insulation that is dirty or chewed up. But then I would selvage any that still looked usable. A shop vac works good for cleaning things up as they make less dust for to breath.

Pot lights or can light are installed in the ceiling below and extend into the attic, dosn't sound like you have any.

Any ceiling light or fixture like a fan or evem smoke detectors have a box on the ceiling side, there are gaps around these boxes that allow moist air from the house to leak into the attic.
In new houses they insall a pastic cover over the boxes to seal it up so a picture wouldn't help much. The idea is to just wrap that in plastic as best you can. You can seal the edges to wood or dry wall or other plastic with accustic sealer___ comes in a tube and you use a caulking gun to squeese it out. Rubber glooves are in order with this stuff. It is black and guee and never really never dries.
There is a formula for the number vents near the peak that you can find on line, or someone here might help with that.
You also need soffet vents, soffet is the area under the overhang where the rafters hang over the sides of the house.

I assume you are just in planning stage. So let's just get a good understanding of this stuff for now.

[ame]https://www.youtube.com/watch?v=iEwsvoPMq1c[/ame]
http://www.todayshomeowner.com/adding-soffit-vents/
[ame]https://www.youtube.com/watch?v=PXr8Lg1kMM8[/ame]