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How to Put Blown-In Insulation Under a Flat Roof: DIYer Tips and Tricks

Updated on September 22, 2014
Maren Morgan M-T profile image

Maren is a one-person fixer of "TLC Needed" houses. She explains methods simply to homeowners who are not in the construction trades.

Blown In Insulation for the Roof

A bag of AttiCat brand insulation.
A bag of AttiCat brand insulation. | Source

Flat Roof Insulation

Many of the instructional articles for DIY installation of blown-in insulation apply to large attic spaces in which a person can enter and either stand up or crawl around. Here are tips for homeowners who have un-insulated space under a very low pitched roof. I refer to roof attics which have only 18 inches of space at their highest point and perhaps less than ten inches at most points. This is NOT anything an adult can crawl inside.

If the roof has no insulation, it can lose heat -- regardless of size and pitch of the roof. Here are tricks to getting the insulation into a flat roof.

The "flat" roof to be insulated.
The "flat" roof to be insulated. | Source

Choosing the Insulation Brand

My local big box home improvement store offered two brands of blown-in insulation. My expert friend-helper has worked with one of the brands and described it as being extremely messy and dust-producing. That brand is the less expensive of the two. As I have quite enough challenges in my rehab house, I opted for buying the more expensive, but cleaner, insulation. I have no regrets; the process was relatively painless and my friend was incredibly impressed by the positive difference.

I chose to use the Owens-Corning AttiCat system.

(I do not receive any commission or kickbacks for this recommendation. I am just telling it like it is.)

Of course, you will determine what best meets your needs and budget and it will save you money in the long run to have an insulated (or better insulated) roof.

Overestimate the Number of Insulation Bales Needed

Buy "too many" bales. Overestimate by a little bit how much insulation you think will fit into your flat roof.

Most stores will accept the return of unopened bales and refund your money. However, confirm this with YOUR store before you finalize your purchase. By purchasing a generous number of bales, you will save yourself an extra trip to the store for more bales if you run out. You need to return to the store at the end of the job anyway to return the equipment, so at that time you can return any unused bales.

Renting the Equipment

We rented the blowing machine from the big box store. I am SO lucky to have an experienced friend because he was able to eyeball the equipment. Also, he owns a large vehicle for hauling the blower and the bales of insulation. An SUV or minivan or truck will work. My sub-compact car? Nope.

The blowing machine for the AttiCat system has two pieces plus 2 fifty-foot hoses. It also has a long power cord.


Make sure ALL parts of the rented equipment are given to you.

We were not given the power cord and had to ask for it. In addition, we could see that there was not a clamp to connect the hose to the blower and there was evidence that it had been connected with duct tape. Since we had plenty of duct tape, we were content to take the equipment.

You will probably be asked to put down a refundable deposit against the return of the blower. This was an easy process. The store had a pricing system that if one purchased 10 or more bales of insulation, the machine rental is free. Since my flat roof section is 12 feet by 30 feet (about 4 meters by 10 meters), I anticipated buying less than 10 bales of insulation and therefore paid a machine rental fee which was reasonable.

Also, we took only one of the 50-foot hoses due to the dimensions of the relatively small roof.

Other Equipment to Have on Hand

1. Duct tape !!!

A full roll. Color is not important unless the vibe of the tape hue as you use it (none will ever be seen) is an important karmic aspect for you.

2. Utility knife

This is also know as a box cutter.

3. Dust mask for face

4. Work gloves for both people

5. A one-foot long metal tool such as garden trowel, big screwdriver, or grill hamburger flipper

6. Possibly: one or two sturdy long poles

We were fortunate enough to have bamboo. Also good: broom stick, clothesline pole, old golf club...?

7. Ladder

8. Flashlight

Two poles used to guide the hose into the far reaches of the roof.
Two poles used to guide the hose into the far reaches of the roof. | Source

Read the Instructions!

Read the instructions. I know – it is so annoying. But if the instructions are short and sweet (in my case, the ones on the side of the bag definitely were short), they might make your job easier. For example, the recommended method for how to cut the bale and load it into the blower was different from what my helper had done in the past and the instruction method was definitely easier!

A very tight squeeze exists under a flat roof.
A very tight squeeze exists under a flat roof. | Source

Keep Safe

Although the pink insulation is as non-irritating as they can make it, you still may want to use goggles and a dust mask. The dust mask is especially helpful for the person guiding the end of the hose blowing all the little bits of pink fluff.

Both of you should wear work gloves to prevent skin irritation to your hands.

For the person feeding the bale into the blower machine, you may want to use a tool to help push the insulation into the paddles. I found that sometimes a large chunk would bump around above the paddles and not go down. I used a garden trowel to lightly push such chunks down into the action. Above all, keep your hands safe.

Close-up of the insulation after it has been broken up and air fluffed. (The dirt is from the ground - the actual insulation is pristinely clean.)
Close-up of the insulation after it has been broken up and air fluffed. (The dirt is from the ground - the actual insulation is pristinely clean.) | Source

Pole Work - Reaching All the Spaces

You will have hard-to-reach places because it is a flat roof. Even in my case, with my access point luckily smack-dab in the middle of the roof, I needed to get the end of the floppy flexible hose 18 feet away from the attic hole. Do this by fashioning a pole guide for the blowing hose.

Use plenty of duct tape to fasten the end of the hose to the end of a pole. You may need to create an extended pole, as we did, by using great amounts of duct tape to secure a second pole to the back end of the first one. This made it much easier for the person guiding the blowing end of the hose to reach all areas of the roof.

Diagram of Poles Guiding the Blowing of Insulation

A picture worth 2 ,000 words.  How to connect poles and blower hose using duct tape.
A picture worth 2 ,000 words. How to connect poles and blower hose using duct tape. | Source

Worthwhile Project

I cannot wait to enjoy my lower heating bills due to adding insulation. I always knew it was needed, but I did not imagine that I could do it myself. You can, too! Please let me know in the comment section how your experience was.

Photos and text copyright 2014 Maren E. Morgan.


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    • Maren Morgan M-T profile image

      Maren Elizabeth Morgan 3 years ago from Pennsylvania

      Alicia - aww, shucks. Thank you. I DIY mainly from necessity, and I do like creating things. Have a super day!

    • AliciaC profile image

      Linda Crampton 3 years ago from British Columbia, Canada

      This is great information, Maren Morgan. You complete DIY projects that I would normally never think of attempting myself. Your clear and useful instructions are a great resource, however. They are so encouraging that I might try some of your projects one day!