How to Make a Two Car Garage Into a Four Car

Changing a two-car garage into a four-car garage must be done with care in order to add value to a home. The addition should not look obvious, or it can detract from the market value of the property. Making the expansion work well will require designing a roof line that harmonizes with the home's architecture. Once the roof area is planned, it's much easier to create the floor plan layout, walls and flooring of the added space. Matching exterior colors for walls and shingles is important as well.

A typical two-car garage requires detailed planning to make it a four-car structure.
  1. Gain ideas for expanding a garage by reviewing home design books. Examine various roof lines to see how to extend a roof line horizontally, build an A-frame roof to extend at a right angle from a typical ranch roof, or create a hip roof for the new part of the garage space. Keep in mind that a hip roof means the roof will have four sloping sides. Design the added garage area to look right in proportion to the rest of the house from many angles.

  2. Measure the allowable yard space for two additional garage stalls. Use these measurements to sketch a new addition that will extend the garage on one side, for example. Consider building an L-shaped addition with two additional roll-up garage doors accessible from a different driving direction. Plan to drive two more cars into the garage from the side or back of the house versus front curbside, for example.

  3. Construct a new foundation by digging a footing area to hold concrete. Use 2-by-10-inch lumber for building the footings. Lay two rows of cinder blocks, on top of the footings, to hold cinder block walls for the new addition. Leave an opening for car drive-in space when laying the two rows of cinder blocks. Lay metal gridwork in the floor area before having concrete poured for the floor area.

  4. Create the walls and roof areas. Lay cinder block walls and leave window openings. Build a framework for the roof area that will allow a central standing wall to be removed. Use metal support posts to sustain the new roof rafters and shift weight the removed wall once held. Add bricks to the exterior walls. Create overhangs and soffit areas, and add all gutters and downspouts. Cover the roof with 1/2-inch plywood and asphalt shingles.

  5. Add windows and doors. Install new windows that match those of the rest of the garage. Include a walk-out door, since a garage of this size will need an exit door for several reasons. Keep in mind that bringing tools, supplies or car items through a walk-out door will be handy. But install the door in case of fire as well. Use an electric screwdriver to install metal tracking for roll-up doors in the new garage stalls. Hang the new garage doors.

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