How to Install an Attic Bathroom with Perfect Results?

How to Install an Attic Bathroom

Expanding your space is not a very unusual thing. People do so because maybe they are getting married, having kids or simply wanting larger space. One spot that is usually neglected and comes in notice when space expansion is the main concern is attic. Larger scale buildings always come with minimal structure. And so, just like a basement, using the attic for expansion is a great idea.Let’s talk about how to install an attic bathroom.

How to Install an Attic Bathroom – The Steps Involved.

We’ll be discussing a general outline that involves low attic bathroom cost and simple procedures. You’ll need to be sorted with some important things before actually adding bathroom to attic. Let’s start with those…


Here are a few things you should check or prepare for earlier to the actual installation phase.

#Getting a Building Permit.

The first and foremost thing you should do is get a building permit. There should be codes and laws involve depending on your building management team. And you should be following those to add the attic bathroom legally.

#Consider Flooring. Height, Plumbing Requirements.

No matter what attic bathroom ideas you want to follow, there’s a need to think about flooring, height, additional length, and plumbing. In case you want to install a complete bathroom, make sure the floor planning is strong.

For a half bathroom, you may skip bathtub to go only with the toilet and sink. And so, the floor needs to be capable of holding these sturdily. A structural engineer or qualified contractor should help you here.

The spot where your attic has maximum height should be center part of this bathroom. Also, for additional height, it's best to install some skylight or dormer space. You can also opt for installing both.

For plumbing, consider if it’s possible to locate new bathroom right above the existing down kitchen or bathroom. This way you can minimize the plumbing cost. Since the new and old plumbing lines will stay nearby this way.

#In Case of Staircase.

Sometimes people have a sliding attic ladder as the main hatch because it hits their head while opening. In such a case, a staircase is the best option. Just make sure the staircase is enough wide and simple in structure. During construction, you need to carry cabinets, units, and materials.

#Temperature, Noise, Light & Moisture Issues.

Attics usually follow up with outside temperature. And so, there’s nothing too particular here. If you want even temperature throughout the whole year, its best to stick with wall insulation. This will also help in reducing noise. Since that space is quite exposed to echoing.

While for lightings, go with brighter soft colors. This will create the illusion of space. Natural lights will make it more like a skylight. Also, you may want to consider installing a solar attic fan. This is for concerns such as moisture damage. Also, it’s pretty good at energy efficiency during hot summer days.

Materials & Tools Needed to Install Attic Bathroom

  • Vanity and sink
  • Toilet
  • Supplies for plumping.
  • Drainage pipes.
  • Floor covering and subfloor.
  • Drywall that is waterproof.
  • Compound and screws for drywall.
  • Sanding sheets.
  • 2-by-4s.
  • Electric boxes and GFCI outlets.
  • 14- and 12-gauge electric cables.
  • Bathtub(optional)
  • Surround kit for bathtub or shower(optional)

#Starting with Subfloor & Interior Walls.

For this step, you need A/C grade plywood with half or ¾ inches thickness. Use full sheets and lay them across the straight joists. This is the base for your floor covering.

Now time for some bathroom space made of non-load bearing walls. Use studs on the 2-by-4s by maintaining 16 inches spacing on center to build walls. Through these walls, you need to run the wires and pipes next.

Most attics come with a unique triangular structure. And so, short walls are better to use for enclosing. These have a common name, knee walls. It’s time to get the drywall fastened stud assemblies to face drywall screwed stud. Apply drywall compound nicely. Let the compound dry gradually. Finish it by sanding the compound and make it smooth.

#Fixing the Electric Circuits in Bathroom.

There’s, of course, the need for electricity inside an attic bathroom. And to make that happen you need at least two GFCI outlets of 20-amp. Also, you need a ceiling light that could be controlled through one switch.

Usually, most code don’t need exhaust fans in the bathroom. You can go with a halfway opening window. It should be at least 3 feet square or more than that. In case of difficulty with installing openable attic bathroom windows, it’s best to stick with a fan.


This is by far the most difficult and trickiest part of attic bathroom installation. Somebody who has experience in DIYs may find it simpler though. Usually extending a lower floor water supply line is the best way. Planning and installing drainage and venting is difficult though.

Some of you may believe stacking an attic bathroom over your existing down bathroom or kitchen will need only vertical linear plumbing. However, that’s not necessarily true all the time.

If you chose to cut attic drains into the lower bathroom’s line directly, this may lead to some drainage problems. Since there’s a chance of hampered venting. There can be a need for cutting the drain on lower floor.

Some case involves ensuring proper venting by continuing whole way down to the basement or crawlspace. This is why you should consider contacting a licensed plumber or expert on attic bathroom plumbing.

#The Shower/Bathtub & Surround Installation.

If you want me to talk about the simplest and fastest method of installing attic baths, then I’ll surely recommend prefabricated shower/bathtub. Not to mention wall surround units that provide super ease here.

Tiles may be a bit too heavy for weight concern up there. And so, pre-fabricated units of acrylic or fiberglass are a better and lighter option than the tiled units.

There’s no need to install lower level cement boards if you have a direct-to-stud wall surround kit. The same goes for eliminating water-resistant drywall. 

The surround needs caulking and screwing directly to wall forming open studs. There are single, three- and five-pieces wall surround kits available.The three- and five-piece picks are better at accessing attic bathroom.

#Floor Covering Installation.

You should stick with installing lightweight floor covering because of the mass concerns related to an attic bathroom. The best choices available are sheet vinyl, luxury vinyl plank, and vinyl tile. These are less in weight compared to porcelain and ceramic tile. Also, these are better for saving bucks no matter if you choose a DIY or professional installation path.

#Vanity, Sink & Toilet Installation.

During the plumbing rough in you should have stub-outs. These are meant for installing the vanity and sink into bathroom.

You need to set a silicone ring on the toilet closet flange’s top part. Using wax is also possible. Next, carefully put the toilet on this top part of closet flange.

There should be hardware included that you need to use for screwing everything in place securely. Don’t go for over tightening nay screws. This may risk into cracking. Next, you need to connect it with the water supply lines. And the setup should be complete.


And that’s how to install an attic bathroom into your home. By adding a bathroom in the attic bedroom, you are making it more demanding for resale. And so, installinga same-level-bathroom is one of the best decisions you’ve taken.

Good Luck on Getting an Excellent Result by The End of Installation.

Stephen Colbert

Stephen Colbert is a specialist in avionics technology. He has been involved in avionics technology since 1993. He spent more than 15 years writing about high tech gadgets. Numerous publications have interviewed him. He is very passionate about sharing his knowledge.

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