How to design a loft conversion

Updated February 21, 2017

Create a loft conversion by utilising unfinished attic space above your home or business. You can convert attic space over a garage as well. If you need more square footage to create a bedroom, bonus area, in-law guest room or office space, loft space can be ideal. The cost of a loft conversion should be less than building an addition under a new roof, since there will be an existing roof area and floor area already in place.

Measure the enclosable floor space and headroom you will have to work with. Make sketches that will include a bathroom, if possible. Use graph paper to design the loft by allowing one square of graph paper to represent six inches of real space. Check out all headroom. Make sure you have adequate walking space in all rooms of the loft that will incorporate slanted ceilings as part of wall space.

Consult with a plumber and an electrician for routing water lines and drains, plus all ductwork for heating and air, before you finalise a basic floor plan. Figure out where the attic stairs will come into the area from the floor below. Allow space in your design for a staircase at least 42 inches wide, so that furniture can be moved into the area easily.

Plan walls and floor space around placement of loft windows. Design windows for light, but incorporate them as an escape route in case of fire. Place windows at the ends of the building, if possible, since dormer windows are costlier and more difficult to construct. Use at least one sliding door with roof deck area if you have room. Engage an expert carpenter to advise you on window installation as you plan your design, since your city may have strict building codes for loft areas.

Plan how you will frame the interior of your loft space. Don't overlook using every square inch wisely by designing storage units back under low-lying eaves, for example. Design a wall unit for storage, books or media players so you can use minimal furniture and keep the area neat. Do plan to include a bathroom in any loft, even if must borrow space for a commode and small vanity from closet space. Include creative touches in your design such as window seats and skylights.

Design the loft to be well insulated, since heavy insulation will save a lot on your energy bill. Plan room for this insulation by framing ceiling and exterior wall areas with 12-inch boards to accommodate thicker insulation.


Never start a loft conversion until you check with your local building authorities. You will most likely be required to obtain a building permit. You may also be required to build an escape window or two of very specific dimensions under local codes.

Things You'll Need

  • Measuring tools
  • Sketch pad
  • Graph paper
  • Plumber consultant
  • Electrician
  • Carpenter
  • Local building code checklist
  • Building permit
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About the Author

Judi Light Hopson is a national columnist for McClatchy Newspapers. She is founder of Hopson Global Education and Training and co-author of the college textbook, Burnout to Balance: EMS Stress. She holds a degree in psychology from East Tennessee State University, and has been a professional writer for 25 years.