Insulating an existing wall is more difficult than insulating an attic because you need to modify the exterior and interior wall. It would cost a lot of money to remove the wall covering in order to insulate your existing wall.
That’s why the blow insulation method is a perfect choice because it is less expensive and creates less mess during installation. Generally there are 6 steps on how to blow insulation in walls :
Here’s how to blow in insulation in walls
- First, you need to put each stud and one of the horizontal blocks that exist near or at the center of the wall’s height with a stud finder. Then use blue masking tape to mark each horizontal blocks and stud center. A horizontal block is placed halfway between the top and bottom of a wall cavity in some homes. Some of the blocks are arranged in a diagonal row.
- Secondly, make a hole into the top of the wall cavity, approximately 6 inches below the ceiling, with a hole saw and drill. Create the hole in the center between each set of studs. Do not throw away the wall-covering pieces that were removed by the hole saw. You can reuse them to fix the holes once the project is finished.
- If your wall has diagonal or horizontal blocking, make a second penetration an inch or two underneath the block. Make the hole in the center between each set of studs. The insulation hole must be made at regular intervals, filling one cavity at a time.

- After that, by using a vacuum, you need to remove the old insulation.
- This is where you start using the blow insulation machine. You can get the machine by renting them. Insert the blower hose into the first hole and direct the nozzle deep into the cavity of the wall. To make a seal, wrap a rag around the hose where it touches the wall. Have a partner to turn on the blower while you hang on to the hose. As the cavity fills, pull the hose back. How much to blow insulation walls is when you sense resistance and can no longer put insulation. Ask your partner to stop the machine.
- And for the final step, you need to replace the drywall cuttings and patching and painting over the holes on your wall.
How Much is the Cost to Blow Insulation in Walls
If we talk about the cost on how to blow insulation in walls, the answer may vary. It will depend on how big is the area of the wall that needs to be insulated, what material you use, and how you do the insulation. Generally, the cost per square foot ranges from $0.64 to $1.19.
If you do it yourself, your estimate for a 500 square foot area will range from $145 to $200. Add $150 to $300 for manpower for a professional job, and roughly it will cost $300 to $500 for 6 hours of work.