The life of two scientists, creating a small home, in big mountains

Tag: Attic

The B.L.O.W

This pallet of insulation was delivered before the New Year, and had been sitting in our garage…


…until yesterday!


Yep! We blew!


We intended to do the insulation before the New Year, but Slav has been busy with his work. In top of that, we were just swimming in small tasks in preparation for the blow. Sealing the gaps, taping the pipes, closing the missing portion on ceiling drywall, laying down Ethernet cables for future use, you name it. Most recently, we installed rafter vents as preparation for adding more insulation. It was an incredible tiring and dusty job, but we were so excited to finish it so our insulation could finally go where it should be!

We were so pumped to blow!

We got up early Saturday morning and headed to Home Depot. We ordered our insulation from their website, so even through the product was delivered directly to our door, the store honored the purchase and rent us the cellulose blower for free.



The blower came with 75 feet of hose, which was just enough for reaching the end of our attic.




The process was pretty straightforward and the instruction was posted right on the machine. An on-and-off switch turns on a set of rotating paddles, breaking insulation apart and mixing it with air. The speed of blower can be controlled by a slider on the side, which dictates how much air is pumped into the machine. One person feeds chucks of insulation into the machine from the top, and the other person holding the end of the hose to direct where to pump.


In our case, I fed the insulation and Slav went into the attic. It did take some practice to get used to this machine. First, our machine did not come with a slider, which means we were always blowing on the maximum speed. Since there is no on-and-off switch on the end of the hose, I tried to feed the machine different amount and in different speed while staying on the phone with Slav to get feedback on how things worked on his end.

I did research a bit on the blowing process, and everyone says that it is desirable to break the cellulose into very small bit, since big chucks tends to clog the machine. But in our case, I did not find it matters much, The machine comes with a 3 x 3 grid on top, and as long as the insulation chuck was small enough to fall into the machine, it got broken down by the strong moving paddles nicely.

What mattered the most, in our experience, is the amount of the insulation one feeds each time. I started feeding 1/3 bag a time, which is about 10 pounds. It almost fills the machine, but the blower spilled out insulation like toothpaste. It did not work at all for us. We figured that too much insulation blocked air into the machine, so I started feeding much smaller chucks and it worked much better – the blower started to shoot fine insulation constantly and evenly, as it intended to.


Another problem we had at first, was unwanted spills. Due to the missing slider, insulation kept spilling out from the open slot, so I taped it over. The hose also came off a few times, resulted in a big mess in the garage:



Slav came out of the attic and use a rubber cord to hold the hose in place. We were back in business!


A couple bags insulation in, we had worked out all the wrinkles and the process started picking up the pace. I fed small chucks of insulation constantly, and Slav directed the hose while slowly backing out.


I opened six bags at a time, which should fill 4 rafters. It was very helpful to stay on the phone all the time so we could ensure that we had a good coverage.




The 36 bags quickly disappeared. In a couple hours, we had only 4 bags left and majority of the attic was covered with 11″ additional insulation (R41):


Beautiful, isn’t it?

This is what we had before, only 5 inches of loose fiberglass (R13):


And this was what we have at that point, 16″ all around:


We have tried to blow into the garage wall without much success. So we decided to add the rest four bags into the attic, because why not. Slav went back into the end of the attic to address some uneven spots.

We soon ended up with this:


16″ near the rafter vents and 18″ in the middle.


It gives us R54~R60 insulation value. The effect was immediate – our furnace hardly came on the last two nights and house became much quieter.

The garage is clean again. We could not say that about ourselves though…



We are keeping close eye on the thermostat, and will give you guys an update on how much it saves at the end of this month. Our little ranch feels really fancy now!

Retrofitting Rafter Vents – A Hardcore DIY to End 2017

During my rental years, I was obsessed with buying a house. I was not only looking forward to owning my own place, but also to renovating and creating in it. It sounds crazy because renovation is basically spending money to create work for oneself, but it makes sense if you like tangible tasks and working with your hands. I have to admit, although I knew I’d like renovating, I did not know I’d like it this much. I almost do not mind doing it for living, which is the most one can say before actually doing it for living.


The real test for my love and commitment came a couple weeks prior, after we decided to beef up our attic insulation. It is necessary to say the least, since we have only R19 in our attic in a zone calling for R49 to R60. We also like the idea to make our house run more efficiently, even through the cost of adding insulation takes years to pay off. But it is incredibly challenging to add insulation into our attic, due to the roof trusses system and the 4:12 pitched roof.


Why? Here is the logic – by the way, please do not tell me if I am wrong, because we are already waaay too far into the process and there are 1100 pounds of cellulose insulation currently sitting in our garage. Ha!

Basically, because of the trusses, we have to use blown-in insulation instead of laying down fiberglass batts. And due to the soffit venting system, we need to retrofit rafter vents to ensure adequate air circulation in the attic. If you do not know what rafter vent is, here is a video. It is basically a piece of foam or PVC board that has build-in tunnels, and it is meant to be installed tightly against the top plate of your exterior wall pointing up, so fresh air from the soffit vent can rise along the cold roof, out from the roof ridge vents, and bring moisture out with it. Without rafter vents, loose insulation can block the soffit vents and moisture will be trapped in the attic and cause rot.  

Typically, rafter vents are installed before the ceiling drywall is hung, allowing workers to stand below the roof structure and easily staple the rafter vents onto the plywood subroof. But in our case, we had to retrofit them in, which means crawling into the tight corner where the roof rafters meet the exterior wall, and stapling the the rafter vents to its position.


When I say tight, I mean tiiiight. A regular size guy will not be able to reach the top plate unless he is super flat and has ridiculous long arms. It happens to be that Slav is a regular size guy with regular size arms, which makes me the chosen one to crawl into corner and staple the vents.


As any good husband would do, Slav raked away the loose fiberglass insulation to give me a few feet of clear working space. It was nice for him to do that because moving around 55-year-old fiberglass is incredibly dusty (our camera would not even focus). But he did it so I did not have to crawl through loose fiberglass and plant my face into it, so #husbandoftheyear. And as a good wife and a hardcore DIYer, I crawled into the corner, carrying one rafter vent at a time, and stapled it onto the top plate.


See the nails protruding out of the plywood subroof? I had to keep my head down to prevent them from protruding my dura. At least they are 3-month-old nails, so they do not have rust on them yet.

One down, 33 more to go.



After each rafter vent was stapled down, Slav piled the old insulation against the corner as high as he could without blocking the vents. It makes blowing cellulose easier, but more importantly, piling the fiberglass insulation against the corner allows us to have better insulation in majority of the attic. Here are some nerdy schematics for my argument:

Figure 1. The allowance. We can only add loose insulation up to the top of the rafter vents, which is 16″ from the attic floor. And trust me, we tried to buy rafter vents that are longer than 52″ and really did not find any affordable options. That is because that with modern roof pitch (steeper) and better insulation materials, 52″ on the roof usually gives plenty of rise (height) for effective insulation. But we are dealing with really lower roof pitch, so 52″ on the roof only gives us 16″ rise.

Picture 0

Figure 2. The normal insulation strategy. We already have 8″ fiberglass insulation in the attic, which gives us R19 (R 2.375 per inch).  Adding 8″ cellulose gives us another R30 (R3.7 per inch), brings our attic insulation to the minimal requirement in our zone, R49.


Figure 3. The improved insulation strategy. Packing fiberglass insulation along the exterior perimeters resulted in 5″ fiberglass insulation in most of the attic, which gives us R12. Thinner fiberglass means that we can now add deeper cellulose on top, 13″ to be exact, which brings total insulation value to R60! Of course we would need more cellulose for this to work, that is why we ordered a whole pallet of this stuff.


Interestingly, by ordering more insulation, we actually saved 37%! Here is the breakdown: we got a pallet (36 x 30-pound bags) in order to achieve R60, and we paid $450 (free shipping since we bought from Home Depot website) before tax. If we had bought less, we would have to order the retail type, which are 19-pound single bags at $14.25 per bag, and we would need 50 bags of them to get to R49. This would have costed us over $710 before tax! So paying 37% less for more and better insulation? Deal!


While moving insulation around, we also taped the gaps on ventilation pipes and closed the attic-to-soffit opening with heavy plastic. This plastic functions as a temporary support for the insulation above, allowing us to open the soffit and dry wall it from below.



Let me tell you, retrofitting rafter vents is safely to say the four circle of hell. Maybe because we are too greedy… for more efficiency? I do not know. But four hours later, we crawled out of the attic looking like this:



Anyone knows how to get fiberglass out of jeans?


Just to make the information complete, there are baffles designed for retrofitting you can buy, and it is plausible to cut open from the outside and feed the baffles from the outside (here,  here, and here). We did not want to disturb the newly installed gutter and create more work for ourselves, and all the retrofitting vents are a bit shorter to our need.

So here we are, crossing off most of the things on our insulation to-do list. The last thing we need to do before the blow is to lay down Ethernet cables, which Slav will tackle himself this week:

1. 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 it from the top
4. 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!

We are so pumped to blow!


Attic Insulation – It is Happening!


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.


The Plan

So here is our handy to-do list before beefing up our attic insulation:

1. 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
4. 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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