How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

How difficult is it to change a window to french doors or a sliding glass door?

Thursday, September 13, 2018

What kind of wall do you have? Your type of wall construction is the primary factor in how difficult it will be to put a door at a current window location. The two most common types of walls are wood stud frame and concrete block. Wood is much easier to remodel.

    Here is a list of variables that will affect how sensible it is to add a door, how difficult, and the cost of the project:

1) Will the new door be pleasing visually as part of the exterior elevation of the house? Sometimes an added door makes sense from the inside, but looks odd from the outside, and detracts from the value of the home instead of adding to it. You may need to do some additional reworking of the details and trim of the exterior wall around the new door to make it fit in.

2) Windows provide ventilation and doors do not. Will the reduction of ventilation for the room be acceptable?

3) Is there sufficient roof overhang to protect the door from weather? A door will not survive for long under a two-foot overhang that would be adequate for a window. You may need to provide additional roof overhang or an awning.

4) Can you find a door, or pair of doors, that fits the width of the existing window? Exterior doors today are sold prehung, with the door frame already installed around the door and hinges in place, so you can take the total width of the prehung door with frame—plus an additional allowance for shimming it into place—to find a door that fits the opening. 

5) A wood stud wall with an exterior siding material (such as plywood panels or horizontal siding of vinyl, wood, or fiber cement) is the easiest construction type for cutting a window down to the floor and installing a door. There is a wood beam over the window, called a header, that transfers the weight of the wall and roof system above it to the sides of the opening, where there are double-studs for support. If you can leave all of that in place, it will save you money.

6) You can also install a door that is smaller than the opening, with a side light or panel on one or both sides, or simply use a wide trim detail on the sides.

7) Installing a door bigger than the the existing opening involves cutting out the existing header and side studs—while supporting the roof structure above it with screw-jacks—and installing a completely new structural framework around the opening. Much more expensive.

8) Putting a door into a window location in a concrete block wall requires cutting out the block below the window with a concrete saw. Installing a door wider than the existing window is a much more difficult project that involves removing the existing concrete header and installing a new one, while also supporting the roof structure above it with screw jacks. Also much more expensive.

9) How far is it to the ground at the outside? You will need to provide a landing at a minimum, and possibly several steps or a stair. 

10) There is likely an electrical conduit or cable running horizontally somewhere below the window, connecting receptacles around the room. It will have to be rerouted by an electrician. 

11) All exterior doors for entry to a home are required by the building code to have two switches on the interior of the wall near the door: one turns on an exterior light so you can safely see where you are walking as you exit, and the second one turns on an interior light so you don’t stumble over furniture in the dark as you enter the room. They must be included as part of the new door installation.

12) If you have a security system, the new door will have to be wired into the system by the alarm company.

13) A building permit and inspection is required for a window to door conversion. If you live in a neighborhood with a mandatory homeowner’s association, you may also have to submit a plan for the project for their approval.

   Still gung-ho about adding a door to your home after all these considerations? Good! It can be an excellent home improvement project if carefully planned in advance, and done by a skilled building contractor. 

    Also, see our blog post What are the pros and cons of concrete block versus wood frame construction?

 • • • • • • • • • • • • • • • • • • • • • • • • • •  

Here’s links to a collection of our other blog posts about REMODELING:

What are the problems to look for when buying a homeowner remodeled house?

Does it make sense to buy an older mobile home and remodel it? 

Can I leave a gas water heater in place when remodeling a garage into a family room or bedroom?

How can I tell the difference between a renovation project house and a tear-down? 

Do I need a building permit for a backyard shed?

What are the most common problems when a homeowner encloses a porch without a building permit?  

How can I tell the difference between a fixer-upper with potential and a money pit?

Should I buy a fixer-upper?  

• How do I find a good contractor?

• What home improvements require a permit? 

    Visit our DOORS AND WINDOWS and REMODELING pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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