Convert Attic to Bedroom

One of the most compelling reasons to remodel a home is to gain additional living space. Many couples buy their family home shortly after marrying and end up with a home that’s too small for their growing family. This leaves them with two options: sell their home and buy another or find a way to make more room in the home they have.

In most cases, it actually makes more sense to add space, than it does to buy a new home. Even after 10 years, only about 30% of the loan principal is paid, so unless property values increase significantly, selling a home after owning it for 10 years isn’t financially rewarding. Most of the profits will go towards paying the real estate company and the closing costs, leaving the family starting over, investment wise.

Basements and attics are the easiest places to find additional space in a home, assuming that the home has them and that they are actually usable. There are parts of the country where homes are built without basements, because the water table is so high, that basements flood constantly. Older homes may not be built with enough headroom in the attic to add in a room. But if there is enough attic space, then this can be one of the easiest ways of gaining a room in a home.

One of the nice things about converging available attic space into additional living space is that it has a pretty good return on investment. Typically, the home’s value is raised by 60% of the cost of the project. But that’s based on having a contractor do the work, not on the homeowner doing it themselves. If the homeowner does the work themselves, the increase in their home’s value will be more than their cash investment in the project.

Can it be Done?

To determine whether an attic can be added to a home, start by looking at how the roof is built. If trusses were used, it’s unlikely there will be enough space to add in a room, unless the trusses were designed with that in mind. But if the home was built with rafters, there should be plenty of space.

While it is theoretically possible to restructure a roof that has been built with truss, turning it into a raftered roof, it’s not easy. Before even attempting it, it’s necessary to get a structural engineer involved in the process, to determine what needs to be done. That will obviously up the cost of the project.

To determine if there’s enough space for a room in the attic, use the Rule of 7s. That is, most building codes require that at least half of the finished room have a ceiling height of at least 7 feet, that this area be a minimum of 7 feet wide and provide a minimum of 70 square feet of area with this 7 foot ceiling. If it has that, then it should be possible to add a room which will meet code.

If the attic doesn’t supply the necessary space to match the Rule of 7s, don’t despair. Additional headroom can easily be added to any attic, by adding on a dormer or two.

The next consideration is whether the ceiling joists for the room below are big enough to be used as floor joists. Once again, whether the roof is of truss construction or rafter construction is paramount. With trusses, the bottom stringer (the ceiling joist) is usually only a 2”x 4”. That can’t be used as a floor joist. For other joist sizes, the maximum span between supports is as follows:

Lumber SizeOn 16” CentersOn 24” Centers
2”x 6”9’ – 1”7’ – 11”
2”x 8”12’ – 0”10’ – 2”
2”x 10”15’ – 2”12’ – 5”
2” x 12”17’ – 7”14’ – 4”

Finally, there’s the issue of a staircase to the attic. It’s not unheard of for a home to have a staircase up to an unfinished attic, especially in older homes. But it is extremely rare in newer ones. About the only staircase that new homes might have into the attic is a pull-down attic ladder. That’s not enough to use the space up there as a room. A real staircase will need to be built. That means finding space for that staircase, probably by adding it in over the staircase from the first floor to the second, if it is a two-story home.

Planning the Project

As mentioned earlier, building a room in the attic might require the services of a structural engineer. It might also be a good idea to consult with an architect for figuring out how to fit everything together. In that case, the architect will probably be the one to make contact with the structural engineer and get their advice.

It might be necessary to pull a building permit to do the project, especially if there is going to be any structural work, like putting in floor joists, adding wiring or adding in a bathroom. That varies from place to place, so it will need to be checked on locally.

The other thing to consider is whether the existing home’s services can handle the addition of a room in the attic. Generally speaking, there isn’t much of a problem with adding in another electrical circuit and it might be possible to tie it into a room below. The bigger problem is the additional volume of air to be heated and air conditioned. The home’s existing system may not be large enough to heat and cool another room, necessitating the addition of another unit, even if that is a window unit or mini-split.

If a bathroom is to be added, it is best to install it above the bathroom or kitchen below. That way, the water and drain lines can connect with the shortest possible run, saving on money. But the configuration of the new bathroom might have to be adjusted, so that the drain lines align with what’s below.

Hiring a contractor to do all this would probably cost somewhere between $40,000 and $50,000. However, if the homeowner does the work themselves, they can save a considerable amount. The average cost for a few of the big ticket items comes out to:

  • $1,100 for ducts and vents
  • $4,000 if a new HVAC system needs to be added
  • $1,800 for materials to build a dormer
  • $2,000 to $3,000 to have stairs built
  • $500 for electrical wiring
  • $2,000 to $10,000 for construction materials, depending on size and how fancy the décor

It only makes sense to get the most bang for the buck, when going through the trouble of turning an attic into usable living space. That means making use of the space behind the knee walls, perhaps turning it into storage space. After all, the attic won’t still be the family’s dumping grounds for things they don’t know where else to put, so that extra storage space will be welcome.

Doing the Actual Conversion

There’s a lot to do, in order to convert the typical attic into usable living space, so don’t expect the project to go quickly. Fortunately, most of the work being done will be out of the way of the family, so it shouldn’t affect their lives too much. However, some pats, like tying in plumbing and building the stairs might inconvenience the family, making it important to plan those parts of the project carefully.

The first thing to do is clean out the attic, removing everything that has accumulated there through the years. It might be a good time to sort through those things as well, getting rid of anything that there’s no reason to keep.

Build the Stairs

The first and most obvious thing to get in place is the stairs up to the attic. While they could be done at any time during the project, starting off with them will make it easier to get up into the attic and especially to get materials up there. The addition of a door, either at the top or bottom will both help provide for some privacy, as well as helping with temperature control of the attic space.

The Floor

If the existing ceiling/floor joists need to be upgraded, this is the time to do it, before building anything else. These new joists can be “sistered” onto the side of the existing joists, as the insulation between the attic and the floor below it isn’t as important as it was before. For that matter, it might be necessary to remove some of that insulation, if it is covering up the tops of the floor joists.

Cover the entire area with ¾” construction grade plywood as a subfloor. The building code allows the use of OSB instead of plywood, as their strength is similar. However, OSB is more susceptible to water damage, so it might make more sense to avoid it in the attic.

Dormers & Skylights

If any major structural work is going to be done, such as adding in a dormer or skylight, now’s the time to do it, while there is the maximum available floor space in the attic area. Besides, doing it before anything else is done reduces the chances of water damage, if it decides to rain while there is a hole in the roof.

If for any reason the hole in the roof needs to be left there overnight or even longer, it should be covered with a tarp. But that tarp shouldn’t just cover the hole in the roof. Rather, it should go up to the roof peak and over it, keeping water from seeping in under the tarp. Spread it out at least a couple of feet to each side of the hole as well. Since nails can easily pull through the tarp, it’s a good idea to use furring strips or drywalls shims, nailing through them and allowing them to clamp the tarp down.

attic, bedroom
Attic bedroom, Tomline

Frame in Walls

Most attic conversions include the addition of some walls, whether the area is being divided into more than one room, perhaps leaving some area for storage or knee walls are going to be added, separating the eaves from the living space. In either case, the wall framing is necessary for installing electrical, plumbing and HVAC ducts.

Wiring, Rough Plumbing, HVAC

Rough wiring and rough plumbing are easier to put in before the walls are finished. At the same time, the walls at least need to be framed in, as these items are normally hidden within the walls. If you are going to have professionals do this work, they’re going to need that framework to hold their wires and pipes.

The biggest thing during this phase of the project is ductwork for the HVAC system and installing a new air handling unit, if it is required. Typically the HVAC unit will be installed in a part of the roof that is not being used, such as in the eaves. That means that the design of the attic room must take into account leaving enough space for the installation of the air handling unit, if a new one will be installed.


Homes are typically built with the attic insulation on the floor, with no insulation on the bottom side of the roof itself. This means that the attic room will end up being insulated from the rest of the house, a major part of why a new air handling unit might be needed. It also helps to keep any noise from the attic room from traveling down to the rooms below.

The flip side of that is that the attic room is not automatically insulated. It will be necessary to insulate the gable ends, the knee walls and the underside of the roof. While most people would do this with fiberglass batts, it might be a good idea to consider using spray in insulation, as it provides a greater insulation density and eliminates the gaps in the insulation normally associated with using insulation batts.


Finally, after all that, the fun part begins, finishing out the new room to turn it into the living space desired. This part will probably take as long as everything before it. That’s actually pretty typical in construction.

Finish starts out with the installation and finishing of drywall. If the stair had not been installed yet, this would require cutting the sheets of drywall in half, lengthwise, just to get them into the attic. But with stairs in place, it should be possible to get full sheets up the stairs. Some help might make the job easier.

The next thing is the flooring. While the insulation between the attic and the rooms below will do a lot to dampen any sound traveling between the floors, heavy footsteps can be annoying to those below. So it might be a good idea to carpet the attic room, rather than using any sort of hardwood flooring or laminate.

Of the whole project, the fun part is finish out the woodwork. Depending on the budget and personal style of the homeowner, this could include using beadboard panels, board and batten on the walls, or even tongue and groove paneling. Some fancy baseboard and casing will go a long way towards making the room look attractive.

This is also the time to work on any build-ins, such as cabinets or shelves built into the knee walls. This is the place for using one’s imagination, finding ways of turning every bit of space into something usable. Properly done, the build-ins will not only make the living space more attractive, but more usable as well.

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