Attic stairs

RJA · 12-17-2010, 12:48 PM

I want to install an attic stair in my hallway. I've looked through pretty much all the diy sites to find that I need to build up an entry hole. I will need to cut at least one ceiling joist for the hole. One site called for an additional stringer to be added to the uncut joists and to double up the perpendicular boards as well, also adding joist hanger in each corner. My question is how long should the new stringer along the uncut joist run? I was thinking at least to the walls on either side of the opening with a foot or two over hang. My home is 55 years old so no engineered truss system.

Nick DIY · 12-17-2010, 03:08 PM

Check your code, but this is how I would build this (see attached)
Joist hangers all the way around and all joists to the walls.

dadflynn · 12-17-2010, 03:39 PM

Quote:

Originally Posted by RJA

I want to install an attic stair in my hallway. I've looked through pretty much all the diy sites to find that I need to build up an entry hole. I will need to cut at least one ceiling joist for the hole. One site called for an additional stringer to be added to the uncut joists and to double up the perpendicular boards as well, also adding joist hanger in each corner. My question is how long should the new stringer along the uncut joist run? I was thinking at least to the walls on either side of the opening with a foot or two over hang. My home is 55 years old so no engineered truss system.

I don't really think you have to go that far. In a perfect world that is the proper way to build it. The units are only about 4' long and it isn't really necessary. You need to cut out one joist and box out the opening. Just use the same size joist material to form the box. I did this in a wide hallway many years ago and there is no problem. You don't need joist hangers either provided you can get at the back of the side joists so you can run in some 3" screws. The new metal stairs the use pneumatic tubes rather than springs are nice. I just replaced my old wooden unit with one of these and was very happy with it. Both Lowes and Home Depot carry them. Both are made by the ladder companies, Werner & Louisville.

DexterII · 12-17-2010, 04:08 PM

Quote:

Originally Posted by dadflynn

I don't really think you have to go that far. In a perfect world that is the proper way to build it. The units are only about 4' long and it isn't really necessary. You need to cut out one joist and box out the opening. Just use the same size joist material to form the box. I did this in a wide hallway many years ago and there is no problem. You don't need joist hangers either provided you can get at the back of the side joists so you can run in some 3" screws. The new metal stairs the use pneumatic tubes rather than springs are nice. I just replaced my old wooden unit with one of these and was very happy with it. Both Lowes and Home Depot carry them. Both are made by the ladder companies, Werner & Louisville.

"That (Nick's way) is the proper way to build it.

Nick DIY · 12-17-2010, 04:20 PM

Quote:

Originally Posted by dadflynn

I don't really think you have to go that far.

I'm going to try (this weekend) to get you some pictures of the hole that they cut for my chimney, where they did just as you described. Nowhere near 4', and failed - badly.

When it comes to the structural integrity of a house and the small amount of extra cash it would cost, this is not where I would cut corners...

**Gary in WA** · 12-17-2010, 07:05 PM

Build it to least minimum Code:

R502.10 Framing of openings. Openings in floor framing shall be framed with a header and trimmer joists. When the header joist span does not exceed 4 feet (1219 mm), the header joist may be a single member the same size as the floor joist. Single trimmer joists may be used to carry a single header joist that is located within 3 feet (914 mm) of the trimmer joist bearing. When the header joist span exceeds 4 feet (1219 mm), the trimmer joists and the header joist shall be doubled and of sufficient cross section to support the floor joists framing into the header. Approved hangers shall be used for the header joist to trimmer joist connections when the header joist span exceeds 6 feet (1829 mm). Tail joists over 12 feet (3658 mm) long shall be supported at the header by framing anchors or on ledger strips not less than 2 inches by 2 inches (51 mm by 51 mm). From 2009 IRC: http://publicecodes.citation.com/ico...002_par031.htm

Most are 22-1/2” x 48” OR 54” to fir between 2’on center ceiling joists.

Gary

RJA · 12-19-2010, 12:00 AM

Thanks for the helpful posts, please put up the pics of the chimney project