Follow Up: Is there a easy way to increase the width of a basement garage door opening?

Asked By: rick on Saturday, January 16, 2010
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Answer Question Previously asked: I have recently purchased a boat which barely fits into my basement. I only have a couple of inches clearance on each side of the boat. I am wondering if there is a way to increase the opening from its present 8 feet to 9 feet without running the risk of damaging my house. Thanks, Ed

Ed, Thanks for the photos and the information. In looking at the photos, it is hard to tell from the inside if possibly the header that is over the garage door frame goes all the way across the top of the entry door. If that is the case it would really help make the job easier and more stable. But I will get to that in a little bit.


Also, it appears from the outside that there is possibly an air conditioner or something covered up, to the right of the garage door. This might prevent you from widening the opening in that direction.


I will include a series of drawings as I explain the procedure.


Before I begin, you need to know that you may need to check with your building department before you begin this work. It will depend on the building codes for your area.


Also, you will probably need a mason to cut the brick and do any iron work, unless you already know how to do that yourself. This is very important because you want to make sure you have the correct support for the brick that will be above the garage door opening. In noticed in your photo that there appears to be a piece of angle iron, used to support the brick over the opening, showing on the left side facing the garage door from the outside. This will have to be either replaced or extended. A good mason will know what to do with this after he takes a look at it. See your exterior photo with my added notes below.


There are three options you have to widen this opening.


If the header of the garage door opening only goes over the garage door you can extend the opening 6” to the right and 6” to the left when looking at it from the inside of the garage

garage opening extended to right and left


If the header of the garage door opening only goes over the garage door, then you can extend the opening 12” to the right when looking at it from the inside of the garage


If the header extends over the garage door and the entry door, then you can extend the opening 12" to the right without having to remove the existing header.

The only exceptions would be if there is anything that might prevent you from extending the opening in either direction. Since I saw the object in your photo that appears to be covered up air conditioner, you may not be able to go in that direction. Also, if there is a wall between the garage door and entry door, you may be limited on going in that direction. For now, I am going to assume that there is no wall.


Before you begin it looks like you may need to move the exterior light if it ends up in the way of the construction. You will also need to remove the garage door, track or any other hardware and remove the jamb and trim.


For support while you are doing this work, you will need to construct a 2 x 4 wall that is around 10’ long depending on the joist spacing above. This will be a temporary wall and the studs will need to be no wider then 12” on center. This wall will be constructed to fit as tight as possible between the concrete floor and the joists.


To get the wall to fit tighter, you can use wood shims between the joists and the top of the wall. You can do this by using a hammer to pound the shims into any spaces you find. The wall itself can be hammered into place with a mini-sledge hammer.


garage opening showing support wall


You will build the wall on the floor and then raise it up, with some help from another person, and install it parallel to the garage door opening as close as possible while allowing your self enough room to work on the garage opening.


The purpose of using the screws is so that you can take it apart when you are done and use the wood for any future project.


The proper steps for all this are as follows.


  1. Determine if you are going to extend the opening in both directions or just to the right.
  2. Have a mason look over the situation so that you have a plan when it is time to get to that part of the work.
  3. Pre-build the new header and have all of the framing material ready prior to removal of the garage door and framing.
  4. Build and install the temporary support wall
  5. Remove the old header and framing unless the existing header extends over the entry door.
  6. Install the new header and studs and jacks. You can use the same method that was already used when the old header and jack were installed. Sometimes there will be more then one stud on each side of the header and more then one jack under the header. The drawings I have done only show one jack and one stud on each side. You will need to adjust the length of the header 3” if you are using two jacks per side. The key is to make sure the rough opening size when you are finished is the right size for the new garage door you will be installing. The manufacture or supplier of the door will have the rough opening dimension and they should be available online or in the installation instructions.
  7. Complete the masonry work, install the trim and then install the new garage door.


Please note if the joist are running parallel with the garage door then you may need to build three 2 x 6 headers that will run across about three of the joists and then install the wall under the headers.


garage opening showing 3 headers and support wall


Please note if the joist are running parallel with the garage door then you may need to build three 2 x 6 headers that will run across about three of the joists and then install the wall under the headers.


Here are some further notes that I added to the two photos you sent me.


The first is the exterior photo. This will show you the cut line if you are extending the opening 12" on the one side next to the entry door. Of course if you are going to extend it 6" on both sides then you would have to make two cuts. As mentioned it appears that there is possibly an air conditioner or other object with a cover on it on the right side as you are facing the garage door that may have to stay there and if that is the case then you could only widen the opening on the entry door side. Also, you may have to relocate the exterior light.


exterior of garage with notes


The next is the interior photo. Remember that the temporary wall is built to support the joists and main floor while you are working on making the changes. This wall needs to be as close as possible while still allowing you to do the work. My assumption is that your concrete floor was poured at a thickness that was up to code. There should be no problem with the floor cracking unless the concrete would be very thin. 


Be careful when removing the garage door and spring. For safety purposes always where safety goggles and if you are not sure how to remove the garage door, consult a garage door manufacturer or supplier for instructions on how to proceed, or hire a garage door company to remove the old door and install the new one.


garage interior with notes


Once again, you may need to check with your local building department for the local codes on doing this work as well as finding out if you would require any type of permit to do this work in your area. Typically, if you are making any kind of structural changes, they require a permit. Unless you are able to leave the original header in place, your building department may consider this structural change.


I hope this helps. Rick


Rick Maselli is Founder and Editor of and Ask Rick


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