How to Maximize the Impact of Insulation | Ask This Old House
Ask This Old House general contractor Tom Silva gives some basic tips about insulating an attic
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Tom demonstrated a variety of different insulation types that can be used in an attic.
Cost: $100 and Up
Skill Level: Beginner
Tools:
Insulation blower
Shopping List:
Unfaced fiberglass insulation OR
Cellulose insulation OR
Rigid foam insulation
_” plywood
Steps:
1. An easy way to improve the insulation in a home is by insulating the attic floor.
2. Fiberglass insulation can be unrolled and placed into floor joists. Be sure to install unfaced insulation. Faced insulation has a vapor barrier that can hold on to moisture and cause mold in the attic floor and the ceiling below.
3. It’s possible to rent an insulation blower and buy cellulose insulation to blow into the floor joists. In this case, blow the insulation so that it falls higher than the floor joists to allow for settlement.
4. If the attic floor is covered, add a layer of rigid foam and then add _” plywood on top of that.
Resources:
The fiberglass insulation Tom showed is manufactured by Owens Corning (https://www.owenscorning.com/) . It comes in a variety of different R-values depending on where you are in the country and how much insulation you need, and it can come either faced or unfaced. Tom recommends getting unfaced insulation, but if it’s only available faced, the label can be peeled off and used.
Tom also discusses using cellulose insulation or using rigid foam insulation over floor boards to allow for storage and added insulation in an attic.
All of these can be found at a home center.
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How to Maximize the Impact of Insulation | Ask This Old House
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1st comment!!!!!!!!
Great videos. Quick question. How do you edit your shows on television like do u use Adobe Premiere or…
This had to be the tenth video of the same thing being said.
It's that how they make videos now? By rinse and repeat?
Hiiiii !!!,!
So glad I hit the bell; these guys (and gals) are always teaching me something. Sometimes, though, they end up costing me more money, even though the episodes are free: now my wife wants a plunge pool, and the kids are in on it too!
Where would you use 'faced' fiberglass then?
I love this show and i dont even Live in a house
What about the new types of insulation like, recycled jeans, foam board and rockwool insulation?
4:03 – OK this part was hard to follow – so if I want to convert part of my attic to usable storage space but properly insulated, I can put down unfaced fiberglass between the floor studs and then plywood on top? And in the case of a pre-installed floor, am I following this right that rigid foam would go on top of the pre existing floor, and then another layer of floor board on top? Could you also do insulation between the floor studs, a rigid foam layer, then flooring on top for even better results (less air leaks)?
MY house was built in 1910- no insulation at all. 40years ago i added 3inches then 5years ago i added 9 inches to the ceiling floor. Cant remember if either layer had a vapor barrier. Is this what your saying- neither layer should have a vapor barrier?
So what is the paper on the fiberglass for? a) stop dirt from going down the insulation. Insulation what is it? It is a way to stop air from moving. So you want lots och air standing still. b) The second thing the paper is for? Stop winds from digging down in to in the insulation. So paper always goes on top and no need for it to be perfect.
Heat and moist. Every house shall have a plastic barrier som moist don't go up in to the attic. Over that the insulation goes. Ventilation of moist inside of the house is not done thru the attic.
If you have poor insulation heat escapes. But there is a problem if you have too much. What why? In the winter some heat needs to heat the air in the attic. So that it can start circulation and dry the air from moist. If not you get a cold and moist attic. That does so mold starts to grow. You can install a mechanical ventilator that starts when needed.
Tommy is my yankee hero!
Ventilation question. It was mentioned about a (1) soffit with a ridge and (2) gable vents. Is gable vents with a ridge acceptable?
You can also use ridged foam on the roof joist/rafters. It will keep the heat in the rafter space and out of the main attic. https://www.owenscorning.com/insulation/residential/products/attics?customer=residential
A carpenter’s Barbie doll housr
I'm cringing from watching them handle fiberglass insulation with no gloves.
No rockwool?!
I dont need isulation, were I live the average temperature is 27 degrees.
Nice tutorial but I might suggest that you also include building code compliance. One error that you may consider correcting is “adding insulation in the attic space in lieu of the uninsulated exterior walls”. Here’s the issue: the idea that heat rises and therefore adding a pile of insulation in the attic is a solution, really isn’t true. Heat does rise however it will travel to wherever its colder and take the path of least resistance to get there.So, if the exterior walls are cooler than the ceiling, the heat will tend to move through the fenestrations, cracks and uninsulated walls, it is only slowed down going through the attic insulation. Obviously there are a bunch of other related issues that attribute to heat loss. Hope I was helpful. By the way, nice Washington State license plate in the background!
Energy Efficient Home Builder & ICC Building Inspector
At the end when talking about ridged foam Tommy said put a 1/4 ply on top of the the foam and he said something like ignition barrier? Is that what it's called or did I hear that wrong.
It seems you guys always only consider the simplest situations. "Easy access to an attic" well come along to mine. 4/12 with 2×4 trusses 16" o.c.. Go ahead crawl around spreading insulation while not stepping through the ceiling sheetrock. Let me know how you slither through the diagonal bracing. When you are done with that we can talk about trying to insulate above the bottom chord and then where you are going to put your feet. Maybe how you are going to get out to the wall plate when it tapers down like it does? No insulation blowers available in this area. When you have stuffed it full of R30 insulation think about how you are ever going to access it again (there are attic blower motors, bathroom fans and ducting etc. etc. that need maintenance). I would guess it has been one long time since any of you ventured into the real world? Doug
can you repair a metal roof from the underside? what if you have a metal roof with a steep pitch? what about waterproofing seams? metal roofing please!
Won't rigid foam in the attic floor create a vapor barrier and block moisture, thus promoting mold???
this show is still on? havent watched since Steve Thomas left
There seems to be two camps of thought on this. The traditional roof/wall/floor air ventilation- and total house air sealing… which…if moisture did get in, would be a total nightmare! I can see both sides of the argument, bit I'm at a a loss….!?
Say I want to add plywood. That won’t mess up the air flow or the insulation property? I live in south Florida so it’s moist and hot
How many layers of insulation can be put in attic? Thank you
Thanks for the important tip! I was about to do it all wrong.
If the moist warm air is making it to the insulation then you have some more work to do. You need to remove all of the insulation, seal any air leaks, and put the insulation back. What I did was I started on on end of the attic. Removed the insulation from a couple of the areas between the joists, select everything inside those areas and then put new insulation in filling the cavity to the height of the joist. Then I moved on to more areas until I finished the whole attic. At the outside edge between every rafter I installed a rafter vent. At this point I had an R value of 22. I then went back to where I started and did a 2nd layer of R22 at a 90 degree angle to the 1st layer. Now I had a properly vented attic with a R44 value. It did take a while since I could only spend about an hour up there because the lack of air flow made it very hot in the summer. For the attic access hatch I used 4 inch ridged insulation glued together up to the thickness of the other insulation. Which was about 15 inches. My thermal camera now shows a very even temperature ceiling including the attic hatch. A noticeable drop in heating and cooling and a more even temperature in the house. The furnace and AC turn on less frequently.
So when do you use “faced” insulation?
So, spray foam… got it
Great video guys….getting ready for an insulation remodel project on my channel…building a studio in my shed!