Framing an opening for an attic ladder
I would like to add a telescoping ladder to access my attic. Currently the only real access I have is through a return air vent, but that is less than optimal. The house is a 1930 flat roof rowhouse, so the ceiling joists just support the ceiling and don't play a role in supporting the roof. The are ceiling joists are true 2x6 spanning 15'. The main reason for the access is to allow me to get up there and install additional insulation, rework some of the ductwork and update some of the electrical. The highest section of the attic is about 4'6" and I would consider some light storage there.
The Werner Televator seems perfect for my application, requiring a rough opening of just 22"x22". Given that our joists are 16" OC, I am going to have to cut one ceiling joist regardless of whether I install the ladder parallel or perpendicular to the joists.
The manual included with the ladder calls for a double header to be installed at the cut locations (page 27). Is this sufficient? I was under the impression it was necessary to double up the joists on either side.
Also, can I use the attic for light storage? I've looked at some of the ceiling joist span tables online and I know that for most modern dimensional lumber 2x6 is not sufficient for a 15' span with no load, but my joists are 75 year old true 2x6s. Can I get away with a couple of boxes of Christmas decorations and some camping gear?
I guess this apply here?
"Section R502.10 Framing of openings in floor framing.
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)."
So, what does it mean by "trimmer joist bearing"? Is that where the joist connects to the rim joist? If so, what happens in situations where the header span is less than 4 feet, but the distance from trimmer joist bearing exceeds 3 feet?
I had a project like this... we doubled all around..
Plaster & wood lath ceiling.... Lots of care to not alllow plaster damage. NO call backs ... except to remodel bath and convert windows to oversized french doors w/ sidelights,,, LV to pool in the back yard.
Brick exterior...Historic district... Client was Landscape Archt.
"So, what does it mean by "trimmer joist bearing"? Is that where the joist connects to the rim joist?" ------- NO, it is where the side joists bear on the closest wall below to the opening for the stair. If so, what happens in situations where the header span is less than 4 feet, but the distance from trimmer joist bearing exceeds 3 feet? -------- If farther than 3' to the farthest header joist of the opening, you need to double the side trimmers only.
If you are past 3' away, definitely double everything as the span rating for true (older) 2x6 joists- Doug/fir, 16"o.c.' is only 14'5" with a 20# load today is 14'1". 1884-1904 edition, page 742: http://books.google.com/books?id=DWs...olumns&f=false
Your 2x6's at 16"o.c. are rated for 20# per sq.ft. The material dead load is: wood- 2.28# plaster- 10.72# cellulose insulation per inch= .14# x 12" = 2.26# 2.28 + 10.72 + 2.26 = 15.26# total load
Be safe, Gary
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