Attic Stairway Installation Tips - Rough Openings

Do you want to add a stairway to an existing space? A folding or disappearing attic stairway is a great way to get up and down in a limited amount of space. The ceiling opening for these stair systems varies from model to model. However, the common inexpensive folding attic ladder usually fits in a space 22 inches wide by 54 inches long. You can buy true disappearing attic stairs that require an opening of 30 inches wide by 8 feet long. The opening size is a function of the length of the ladder or stairway.

Creating an Opening in a Finished Ceiling

How do you create a rectangular opening for an attic access system? If you have a prefabricated truss roof, it is a breeze. Why? Because you can't cut a truss! You simply will fit the stairway between the trusses. If you have a common framed roof or attic and your ceiling/attic floor joists are 16 inches on center, then we have to do some carpentry. Let's get to work.

When you decide to cut a ceiling joist or attic floor joist, you change the dynamics of the structure to a slight degree. The load which was being carried by that singular, cut joist must be transferred to the joist on either side. To accommodate the added load, you need to add a joist alongside each uncut joist on either side of the cut joist. Adding this joist is not always easy. Electrical wires may pass through the joist system. Floor boards may have to be pulled up. It may even be a challenge to get the floor joist up to the attic!

If in doubt, you can call a structural engineer to get a professional opinion. It may save you some work, especially if there are nearby walls in the close vicinity of the proposed stairway. These walls may easily carry the load or the existing attic floor joists may be oversized.

Creating the Opening

You can't always trust that attic floor joists will be square or parallel/perpendicular with second floor walls. As such, you need to draw on the ceiling below where you want the stairway. Center the rough opening dimensions given to you by the stairway company on the ceiling. The rough opening refers to the opening you create with the rough framing lumber or attic floor joists. It is usually 1/2 inch bigger in width and length than the actual stairway assembly.

Be SURE that you have checked to see where the stairway will end up in the attic. You don't want to walk up the ladder or stairway directly into a wall or other obstacle in the attic.

You also need to be aware of the clearances required by the folding ladders when they unfold. The folding ladders always fold out farther than the rough opening. Put the rough opening too close to a wall and you may not be able to unfold the ladder!

Check the rough opening you have drawn for square. It must be square for the stairway to fit! It is square when the diagonals from opposite corners are equal. Use an accurate framing square to layout the opening and you should be very close.

With the rough opening drawn on the ceiling, proceed to drive a 16 penny nail up into the attic at each corner of the stairway opening. Look in the attic to see where the nails end up. Be sure there are no wires, pipes, ducts etc. in your way. If the area is clogged with utilities, maybe you should re-think the access location.....

If you like the location, use a sawzall or other saw to cut out the opening. Do whatever you can to stay on the line you have drawn. This will help you frame in the opening in the attic.

Frame the opening using the same size floor joists as are currently present in the attic. You may have to double up the joists that carry loads from other joists! Use joist hangers to attach the joists that run into one another at a 90 degree angle. Do not use roofing nails! Use structural joist hanger nails.

Be sure that all of the joists you install are vertical or plumb. Use a framing square or level to make plumb lines. The rough opening at the ceiling must equal the rough opening in the attic.

An attic ladder can be very heavy. You will not be able to hold it in place and attach it by yourself or with a helper holding it. You have to create a little ledge for the stairway to rest on as you attach it to the rough framing members. This ledge must not extend too far beyond the rough opening. If it does, the flush panel will be flush with the ceiling. In most instances, you want the stairway frame flush, not the panel. Check your directions to see. With the frame flush, you can trim out the stairway much like the doorways and windows throughout your home. Look at those and you will see what I mean.

Fastening the Stairway to the Rough Opening

Think of how much the stairway assembly, you, and all the boxes you will carry up into the attic weigh. If you use wimpy finish nails or drywall screws to attach the stairway assembly to the rough opening, you are a FOOL! Read the directions. Most manufacturers require 16 penny nails and/or 1/4 inch lag bolts. Drill holes for these fasteners so you do not crack the frame. Drilling is important. The frame may not crack now, but may at a later date as attic temperatures cook and fry the lumber.

Trimming Folding Ladder Stringers

The biggest challenge may be making accurate cuts on the bottom of folding ladder stringers. It doesn't take a rocket scientist to figure this out. It simply takes patience.

Most folding ladders are in three sections. The bottom section is the one that has to be trimmed to fit. You do this by opening the ladder and folding down the second section. Leave the third section folded back on the second section.

Take a regular steel tape measure. Slide it along the top edge of the stair stringer. Note the measurement at the end of the second stringer, when it finally touches the floor. Do this on both sides. Unfold the ladder's third section. Measure down the stringer from the hinge point. Make a mark. Do this same procedure on the bottom of the ladder as well. The bottom measurement had better be less than the top measurement. If not, you have goofed up some how. If you have anxiety about making the cut, do a test cut on a similar sized piece of scrap lumber. Make sure it is the same width as the stringer. Cut the test piece and place it where the third section would be. If it works, trace its shape onto the stringer!