How To Install Folding Attic Stairs

A note from NH...  Thanks to STIRA Folding Attic Stairs for allowing us to reprint this article on installing attic stairs. 
We have made some slight editing and formatting changes for better readability and added a few notes of our own.

Regardless of the brand of folding stairs you choose, the installation procedure will be very similar.  However, specifics such as the size of the "rough opening" or fastening locations may vary. Always refer to the manufacturer's directions for your stairs.

After reading this article, you will know for sure whether this a project you would like to tackle!

Before you install your attic stairs...

Though installing your own folding attic stairs may seem daunting, don't worry... it's not as a big job as it may seem at first glance. Unlike many "DIY" products, you need not worry about assembly, we've taken care of that at the factory. All you need do is cut or enlarge the opening and fit the stairs. Stira Folding Attic Stairs are designed to be a completely integrated unit ready for fitting.

Fitting the Stira Folding Attic Stairs should take no more than two hours (though significant framing changes in the ceiling may add hours to this).  Here are a few things you should bear in mind before you start.

1. Check the attic for constraints to enlarging the opening, such as pipes, wires etc.

2. Bear in mind that the Stira Folding Attic Stairs will arc about 14" (35cm) beyond the opening as it folds and unfolds. (NH:  Measure carefully... this may cause clearance problems if installed in closets or small rooms.)

3. If the opening is in a bathroom, consider a new opening in the hall or landing.

4. Make sure you order the correct Stira Folding Attic Stairs size to suit your ceiling height.

5. Place an old sheet on the floor to protect your carpet or wooden floor.

6. If your attic contains trusses instead of "2 by" joists, be careful!!  The consequences of cutting trusses can be severe loss of roof strength or other possibly dangerous structural issues.  If you are unsure how trusses work, don't do any cutting before consulting a builder or building inspector.

Necessary tools...

Enlarging the existing opening...

The first thing to do is strip away the existing trim.

When you remove the old trapdoor you will see that there is a small lath around the opening on which the trapdoor sits. This should be removed so what you are left with is bare rafter.

Now you need to mark out the length of the opening. You can do this with a pencil. Just mark the length of the opening onto the plasterboard.

Important! The Stira Folding Attic Stairs will arc about 14" beyond the end of the opening as it is unfolding, so you should keep this in mind when locating the stairs.

Measure the frame of the Stira Folding Attic Stairs and cut the opening 1/2" (12mm) longer.

You can cut the actual plasterboard one of two ways. The old fashioned way is to use a utility knife to start the cut on the underside of the ceiling, once you have the cut started you can use an ordinary carpenter's or drywall saw. If you have a Jigsaw this makes the matter easier but definitely dustier!

Once the plasterboard is cut away to the desired size you can now cut the rafter.

Depending on how the rafters are running you may need to use a bridging piece to create the rectangular opening needed to fit the Stira Folding Attic Stairs.  Make the opening as square as possible to help in proper fitting later.

Once the opening is complete we can move to the actual fitting.

Installing the Stira Folding Attic Stairs

The best way to actually fit the Stira Folding Attic Stairs is to lower it into the opening from above. At this stage you can fit the door handle before you raise the Stira Folding Attic Stairs into the attic.

Once you have the stairs in the attic, you need to screw two pieces of lumber to the underside of the ceiling at either end of the opening. Any piece of waste lumber will do, you could use the old trim you removed earlier.

It's important that the boards do not extend more that 1/2" into the opening. This is so the frame will rest on the laths in it's approximately final position, but the trapdoor will be free to open to test it's function prior to final attachment.

Once the temporary laths are in place you can lower the Stira Folding Attic Stairs  into the opening.

Securing the frame

Make sure the stair frame is square by measuring across it, corner to opposite corner. Using a carpenter's square is unreliable because the sides of the frame (where the stair springs attach) may be slightly bowed till they are secured with screws.

Do not install the stairs too tightly within the opening!!

THIS IS IMPORTANT!!  If you cannot move the stair frame into a square position, you may have made the rough opening a little too tight.  You may need to enlarge the opening slightly to allow the outer frame to move that little bit. For example, if the inner frame is hitting the outer frame on the left hand corner then you need to move the outer frame forward on the left hand side.

The simplest way to do this is to drive a small wedge between the frame and the joist on the left hand side at the hinge end of the frame. (Notice that the Stira has very heavy frame construction. Many other brands use much lighter "1x" wood, so using a wedge is NOT recommended.  You may permanently damage the frame.)

Secure the frame to the joists with 3" or 3 1/2" screws at the locations indicated in the instructions.

Once the frame is secured you can remove the temporary laths and fit the trim. It's best to start at the front end of the opening with the trapdoor closed. Leave about 1/4" gap between the trim and the actual trapdoor all around to prevent binding.

Cutting to length

Cutting to length is crucial to the proper sitting of the stairs on the floor. Its important to bear in mind that you should check both sides of the stairs, don't assume that the floor is level. Open the Stira Folding Attic Stairs and unfold it and fold the bottom section back out of the way and rest it on the floor. (See graphic below left)

Now using a straight piece of timber, place it on the face of one of the side stringers of the stairs and extend it to the floor maintaining the angle of the stairs. Mark the piece of timber where it intersects the stairs at the wraparound hinge.

You should check the other stringer separately, as the measurement may not be the same. You can now transfer this measurement onto the bottom section and mark the cut line.

Now saw off the excess and sand the ends. Just double check that you have the angle marked the right way around, in other words the angle of cut will be the same as the angle of the step.

Problem. After I've made the cut to the two side stringers and there is a large gap between the top and middle section of the stairs when I climb the stairs (graphic above right).

If you notice a gap between the top and middle sections of the stairs this means the bottom stringer has been cut to the wrong length. You will need to recheck your measurements, as you may need to take a little more off the bottom section. But you should check the operating instructions first to make sure you are using the Stira Folding Attic Stairs correctly.

Congratulations!  You should now have a fully-fitted Stira Folding Attic Stairs!

Thanks again to STIRA Folding Attic Stairs for allowing us to reprint this article on installing attic stairs.