With winter settling in, we are keeping a close eye on our energy consumption. With below freezing temperature every night, our electricity and gas bill increased about 20% last month. We do have to heat the entire basement this month for our guest, so overall our little ranch still performed better than we thought it would be (thanks to our brand new furnace, new roof, and all the insulation Slav has done on the exterior). However, we knew that we could further improve our energy efficiency by adding insulation into our attic.
How much do we need?
According to our house inspection, our attic currently has 8″ fiberglass insulation, which gives us insulation value of R-19. The recommended roof insulation value for Denver homes is R49-R60, which means that we are significantly lacking attic insulation. This might be due to the different building codes when our house was built in 1960s. It could also because the height of our attic. As you could see from the picture below when we replace our subroof, the 8″ fiberglass has already filled the space at the low points. There is only about a few inches height for additional insulation along each side.
To take a better look ourselves, Slav and I took a trip to out attic together. It was my first time being inside the attic, so it was pretty exciting to me.
In general, the attic and the insulation are in better shape than we expected. We have a solid 8″ loose filled fiberglass insulation throughout, even 10″ to a foot at some places. There is no mold, rot, or any additional damage we could see. And there is no trace of any animals.
We both wear respirators and goggles that seal against our skin. They helped a lot when we crawled around to even out some thin spots.
Inspect the vents
While we are up in the attic, we spent some time inspected the duct and pipes going through the attic. Because our kitchen and bathroom are all centrally located, all our vents are clustered in a small area in the middle of the house. As you could see from the picture above, from left to right, we have the old water heater vent (which is no longer in use since we installed a new tankless water heater), the main floor bathroom vent, a sewer vent (the copper pipe), and the kitchen fan. All the pipes comes up from the dry wall ceiling below, and any gaps between dry wall and pipes need to sealed to prevent heat loss.
Picking the Right Insulation Material
In order to insulation our attic as much as possible, we set out to find blown-in material that gives us the most R value per inch height. We settled on the all borate-treated blown-in cellulose from Green Fiber. The reason for choosing blow-in cellulose is four-fold: we have to use blown-in because how our roof trusses are built, and we want to use cellulose to cover the old fiberglass for health concerns. Cellulose also offers the highest fire retardation rating, and has better pest and moist control compared to fiberglass. The particular type of Green Fiber product we chose has the best fire-rating, noise reduction, moisture control, and does not contain any ammonium sulfate. Ammonium sulfate is often added as a fire retarder if the cellulose is not borate-treated, and it is extremely corrosive to almost all metal when combined with moisture. Since we have bath fans, kitchen vent, and electrical conduit in the attic, the all-borate mix just makes it safer.
According to this insulation calculator, we need 26 bag of this type of Green Fiber product to beef us our attic insulation to R49 and 36 bags for R60. We decided to order a pallet of 36 bags, and spare a few bags to insulate the northern wall in our garage. This wall separates our garage and the main floor kitchen, and therefore has a lot of heat loss and poor fire rating. Blowing the Green Fiber cellulose between the 2″ x 4″ studs will give this wall almost R15 insulation, which is comparable to batt insulation and much easier for retrofitting.
There is a Xcel Energy rebate for adding insulation in Colorado, which grants 30% rebate off the purchase. But there is a catch – the insulation has to be installed by licensed contractors. Since we are doing it ourselves, we cannot claim this rebate. But if you are hiring it out, do not forget to claim your rebate!
The DIY preparation list
Blown-in insulation is a good DIY-project. It is relatively cheap, fast, requires team work, and offers instant gratification. With our pallet purchase, we can get free rental for a blowing machine from Home Depot for a day. We also scheduled the insulation to be delivered to our door for free, saved us the effort of strapping on a 5′ x 5′ x 8′ pallet on our trailer and unload.
Aside from the machine and material, we also need to install rafter vents in between the rafters. They will not only prevent loose insulation to fall into the soffit and block the vents, but also create channels for any moisture to vent out from roof ridge vents when we pile up loose insulation into the attic. Most of the rafter vents sold in local stores are made in styrofoam, which breaks easily during handling and installation. Since we are retrofitting an old attic with 4:12 roof pitch, we decided to pay a little more for PVC rafter vents. The ones we will be installing is 51″ long, which offers more than 16″ height from the attic floor. So it can vent above our estimated total 16″ loose insulation without clogging the build-in tunnels or soffit went.
An Surprising Discovery
Good things happen to hard-working people, I firmly believe that. Crawling around the attic floor in 8″ fiberglass paid off handsomely – we found that our kitchen soffit is completely hollow inside!
Do you know what it means? That means that the only reason the kitchen soffit is there, is for the upper cabinet to be mounted at a lower height. It also means that we can remove the soffit completely and build cabinets up! The best part of renovating this house so far has been demos – carpet (here and here), walls, and ceilings. And now I get to simplify the kitchen and adding more storage by demo the soffit? This just become the task I am most-looking forward to in the kitchen!
A couple months earlier, we did drill a couple holes into the soffit and use our awesome little endoscope to probe what was in it. When we saw fiberglass, it really confused us. We also could not figure out what else might be hidden in the soffit. And now we know – it is just insulation falling down from the attic!
To make the future demo process easier, we decided to close the soffit up from the attic. It will create a floor to support the insulation. Before we nail down a piece of board, we decided to scoop up the insulation in the soffit and put them back to the attic. We did not have to do that, but I am so glad we did – because we found this!
Below the existing insulation, the kitchen fan vent is completely detached. There is no tape and the alignment is waaay off. The pipes were replaced by our roofer back to September, so obviously they did not do it right. Oh well. We overall liked our new roof and think the roofers did a good job installing it. But this particular part is a bit disappointing.
There is nothing tape and the Great Stuff cannot fix.
So here is our handy to-do list before beefing up our attic insulation:
Order the insulation material
2. Seal air gaps, realign and tape-secure the kitchen vent
3. Scoop the insulation out of the kitchen soffit and close the top
Even out the existing insulation
5. Lay down ethernet cables for future use
6. Install rafter vents
7. Prepare the garage wall for blown-in
8. Book the machine and it will be the Blow day!
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