Air sealing and insulation

[kennyp2339]

Last night I was a little board and since the weather was cool and damp I elected to stay inside and relax.
I went on youtube and was watching a few videos on building sheds and I came across a Dr.energy video with air sealing, proper insulation installation for attics.
This guy offered the best information, how to advice I've seen in a while. Yes this was more of a 20min promotional video for his business but I walked away with more knowledge, anyone considering adding insulation to there homes should watch his video's first so you can get a general idea of what involved to do it properly, and what to ask a contractor when he / she is giving an estimate.
To insulated an attic space, air sealing is key, this will require total existing insulation removal. start off fresh, then with low density foam you spray beads, much like caulk in a shower door or tile everywhere there's a leak. So all of your top plates, drywall seams, drill holes for electrical wires, registers for heating / ac get sprayed. For houses with hi hat lights you can get roxal boots that go over the hi hat and then sprayed / sealed shut.
Once all the air sealing has been completed then you insulate, it recommended that you use a blown in insulation. For those that need spots in the attic for storage you put foam sheets in that chases that you are covering with boards.
The idea for all of this work is to reduce air seepage / movement, since air is what moves the cold. If you slow the air leaking from the top then the natural stack effect will slow down and you will have less cold filling air at the bottom of your house.
There were move videos on packing hi density foam into wall with existing insulation using a machine and drilling holes in the walls from the outside, insulating basements with natural rock walls, block walls, and pour cement walls.

 

[DickRussell]

Good reading on air sealing can be found at this site:
http://www.greenbuildingadvisor.com/blogs/dept/musings/how-do-everything

In particular, under the general topic "Air Sealing," see this one:http://www.greenbuildingadvisor.com/blogs/dept/musings/air-sealing-attic

Be careful about air sealing and adding insulation around "Hi hats"/Can lights/recessed lighting fixtures. Even the ones labeled IC/AT (Insulation Contact/Air-Tight) have limitations, and temperature rise within one can go over the temperature rating of wiring into them and of foam insulation covers you may want to install over them. There was an article in Fine Homebuilding magazine on this: http://www.finehomebuilding.com/2015/01/07/air-sealing-can-lights-safely. That link doesn't let you read the whole article without signing in, but you may be able to find it in your local library.

 

[Don2222]

Interesting, air sealing is important but blown-in insulation is usually ground up newspaper treated with chemicals such as rat poison to make it fire resistant until the chemicals wear off and the insulation settles and loses some of it's R-Value. Although the blown-in is quick and easy to install. I had 2x4s in the floor of the attic so I ripped some of 2x4s into 2x2s then nailed the 2x2s on edge forming 2x6s so I could put R19 insulation instead of R13 insulation Fiberglass Batts in.
I could not go any higher than 2x2s because the existing electrical wiring could not be lifted any higher. That would mean extensive electrical re-wiring.
Under the fiberglass, I first installed Reflectix foil which makes the house about 10 degrees cooler in the summer! Saves a lot in air condition costs!
See some of my pics in this good post
https://www.hearth.com/talk/threads...lation-project-need-advice.68821/#post-865965

 

[cableman]

I was able to lift my existing insulation, air seal all top plates/wires/ceiling boxes and exhaust fan fixtures, then lay down another r38. Made a big difference, some of the top plate gaps were almost an inch!

I also pulled all my exterior electrical outlets through out the house, siliconed wire coming into box then caulked box to sheetrock.

I pulled front and back soffits, air sealed and r30 insulated

Air sealed my basement sill also. Man i used alot of cans of great stuff! The pro gun is great too, wish i had that for the attic job

 

[Highbeam]

some of the top plate gaps were almost an inch!

This has always baffled me. Where is this gap? In my part of the country we sheetrock the ceiling to the wall top plate and then sheetrock the walls up to the ceiling and that joint gets mud and tape. There is no "gap" at all. The only way interior air can leak up into the attic from a wall is if the sheetrock isn't attached at the bottom, or leaky wall penetrations, PLUS another hole in the top plate at like a wire penetration.

What are you sealing along the wall top plates?

 

[cableman]

This has always baffled me. Where is this gap? In my part of the country we sheetrock the ceiling to the wall top plate and then sheetrock the walls up to the ceiling and that joint gets mud and tape. There is no "gap" at all. The only way interior air can leak up into the attic from a wall is if the sheetrock isn't attached at the bottom, or leaky wall penetrations, PLUS another hole in the top plate at like a wire penetration.

What are you sealing along the wall top plates?

More so in the corners and i have a 45deg bathroom door. I believe the rest is just 40 years of 2x4 shrinkage! Some areas were a 16th and others more.

 

[Highbeam]

More so in the corners and i have a 45deg bathroom door. I believe the rest is just 40 years of 2x4 shrinkage! Some areas were a 16th and others more.

My 2x4s are 54 years old and the sheetrock is still firmly nailed to the top plates, and bottom plates. So from the attic you were able to see into the room below or into the wall cavity? Still seems weird.

 

[cableman]

My 2x4s are 54 years old and the sheetrock is still firmly nailed to the top plates, and bottom plates. So from the attic you were able to see into the room below or into the wall cavity? Still seems weird.

Yup. I cant remeber and i forgot to take picks but im almost thinking they rocked walls 1st, i felt like it was easy to see the wall rock or maybe the ceiling rock was short.

Still, even if it was tight a bead of silicone on the top sill b4 wall rock was hung would have been needed to truly air seal it.

 

[Highbeam]

Still, even if it was tight a bead of silicone on the top sill b4 wall rock was hung would have been needed to truly air seal it.

I see what you did and have seen others do it but I worry they are wasting their time. I would expect that when you looked down along the side of that 2x4 top plate from the attic you saw a 5/8" deep gap but if you looked into the gap you would have seen mud and/or the top of the wall sheetrock at the bottom fastened tight to the side of top plate. If the sheetrock is no longer attached to the top plate and you can actually see in behind the wall sheetrock then yikes!

 

[cableman]

I see what you did and have seen others do it but I worry they are wasting their time. I would expect that when you looked down along the side of that 2x4 top plate from the attic you saw a 5/8" deep gap but if you looked into the gap you would have seen mud and/or the top of the wall sheetrock at the bottom fastened tight to the side of top plate. If the sheetrock is no longer attached to the top plate and you can actually see in behind the wall sheetrock then yikes!

I saw light from outlets i had open!

Im a diy guy that over thinks and over does everything, but if i was building my own house the top plate in an attic would be spray foamed. If its not air will leak into the bays and come out outlets or sill plates unless the rock is siliconed to it.
These days an energy efficient built home seals and silicones all these areas, it just makes sense.
Wood will shrink and detach itself from the mud also.
Perfect example is my basement sill, when built they mortered sill against foundation on the inside, wood shrunk and seperated from mortor causing air leaks all over! Great stuff to the rescue.