Measure the ceiling, the attic opening you have (or can cut between the joists) and the floor in front of it. You get the folding attic ladders that fit, from Louisville’s and Werner’s own installation tables, and the room each needs to unfold.
Your attic ladder
A 22½ × 54″ attic ladder fits9 models for a ceiling of 8′ · the least room: Werner’s W2208, 64″ to swing and 54″ to land
Quick answer: most folding attic ladders need a 22½ × 54″ rough opening; wider ones take 25–25½″ or 30″, and a 12-foot ceiling takes a 63″-long opening. Under an 8-foot ceiling, 9 models from Louisville and Werner fit a 22½ × 54″ opening; the one needing the least room is Werner’s W2208, 64″ of floor to swing, landing 54″ out.
How to use the attic ladder calculator
- Measure the ceiling: from the finished floor to the finished ceiling, as the makers ask.
- Measure the opening you have, or the one you can cut: its width across the joists and its length.
- Measure the clear floor in front of the opening’s hinge end, the way the ladder unfolds.
- Read the ladders that fit: the sizes, the models and the room each needs.
The rules behind the numbers
The makers’ own tables
Every size here is from an installation table: Louisville Ladder’s (its AA, S, L, C, AL, Elite and aluminum-frame series) and Werner’s (its wood W series, TABLE A). Each gives the rough opening, the ceiling heights the ladder fits, the landing space and the swing clearance.
The opening
Louisville: “You must have a rough opening that matches TABLE 1. If not, proceed to the appendix for framing instructions.” A bigger opening is framed down. A smaller one means cutting a joist and adding headers, and “If the home has roof trusses, do not cut the ceiling joists without consulting an engineer for approval.”
The ceiling
Louisville: “Under no circumstance is any folding attic ladder to be used when the ceiling–to–floor measurement exceeds the maximum ceiling height.” It prints only a maximum for its S, L, C and AL series; the calculator holds them to 7′, the lowest minimum any table here prints (Werner’s W2208).
The room to unfold it
The landing space (where the feet land) and the swing clearance (how far the ladder reaches as it unfolds) are measured on the floor from the opening’s hinge end (Werner’s Figure 1). Louisville: “Allow ample room for the swing clearance and the landing space of the folding attic ladder when it is opened”, and put the opening where “you will have adequate head clearance” in the attic.
Attic ladder sizes, from the makers’ tables
| Model | Rough opening | Ceiling | Landing space | Swing clearance |
|---|---|---|---|---|
| Louisville AA2210 | 22½ × 54″ | 7′8″–10′3″ | 67″ | 74″ |
| Louisville AA2510 | 25½ × 54″ | 7′8″–10′3″ | 67″ | 74″ |
| Louisville AA3010 | 30 × 54″ | 7′8″–10′3″ | 67″ | 74″ |
| Louisville WA2210 | 22½ × 54″ | 7′11″–10′3″ | 64½″ | 74″ |
| Louisville S224P | 22½ × 54″ | up to 8′9″ | 63″ | 66″ |
| Louisville S254P | 25½ × 54″ | up to 8′9″ | 63″ | 66″ |
| Louisville L224P | 22½ × 54″ | up to 10′ | 71″ | 75″ |
| Louisville L254P | 25½ × 54″ | up to 10′ | 71″ | 75″ |
| Louisville S305P | 30 × 60″ | up to 8′9″ | 63″ | 66″ |
| Louisville CS305P | 30 × 54″ | up to 8′9″ | 60″ | 69″ |
| Louisville L305P | 30 × 60″ | up to 10′ | 71″ | 75″ |
| Louisville CL305P | 30 × 54″ | up to 10′1″ | 67″ | 79″ |
| Louisville AL228P | 22½ × 63″ | up to 12′ | 85″ | 87″ |
| Louisville AL258P | 25½ × 63″ | up to 12′ | 85″ | 87″ |
| Louisville AS229GS | 22½ × 54″ | 7′9″–8′9″ | 60⅝″ | 71″ |
| Louisville AS259GS | 25½ × 54″ | 7′9″–8′9″ | 60⅝″ | 71″ |
| Louisville AA229GS | 22½ × 54″ | 7′9″–10′ | 69⁵⁄₁₆″ | 79″ |
| Louisville AA259GS | 25½ × 54″ | 7′9″–10′ | 69⁵⁄₁₆″ | 79″ |
| Louisville AH2240MS | 22½ × 54″ | 7′8″–10′3″ | 67″ | 74″ |
| Louisville AH2540MS | 25½ × 54″ | 7′8″–10′3″ | 67″ | 74″ |
| Werner W2208 | 22½ × 54″ | 7′–8′9″ | 54″ | 64″ |
| Werner W2210 | 22½ × 54″ | 8′9″–10′4″ | 63″ | 74″ |
| Werner W2508 | 25 × 54″ | 7′–8′9″ | 54″ | 64″ |
| Werner W2510 | 25 × 54″ | 8′9″–10′4″ | 63″ | 74″ |
| Werner WU2210 | 22½ × 54″ | 7′11″–10′4″ | 63″ | 74″ |
Louisville’s S, L, C and AL series: the landing space is at the ladder’s maximum ceiling height; at a lower ceiling it lands closer.
Four worked examples
An 8-foot ceiling, a 22½ × 54″ opening. 9 models fit; Werner’s W2208 needs the least room, 64″ to swing.
The same ceiling, a 25½″-wide opening. A 25½ × 54″ ladder fits (6 models), and the narrower ones still fit, framed down.
A 10-foot ceiling. 7 models of 22½ × 54″ reach it; the least room is Werner’s W2210, 74″ to swing.
Only 60″ of floor in front. None fits: the least any of them needs is 64″ to swing. Turn the opening so the ladder unfolds along the longer run.
Common attic ladder mistakes
- Buying by the opening alone. The ceiling height must be inside the ladder’s range, never over its maximum.
- Forgetting the swing. The ladder sweeps 64–87″ out from the hinge end as it unfolds.
- Cutting a truss. Ask an engineer before cutting any ceiling joist in a trussed roof.
- No headroom above. Put the opening where you can stand up in the attic.
- A ladder that’s too long. Trim its feet to your ceiling height, as the manual shows.
Working in the attic? The attic insulation calculator sizes the insulation, the attic ventilation calculator the vents, and the free 2D planner draws the room below to scale.
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Attic ladder size questions
What size is a standard attic ladder?
A 22½ × 54″ rough opening, for ceilings from 7′ to 10′4″: 10 of the 25 models in Louisville’s and Werner’s tables take it. Wider ones take 25–25½ × 54″ or 30 × 54–60″.
What is the rough opening for an attic ladder?
22½ × 54″, 25 × 54″ (Werner), 25½ × 54″, 30 × 54″ or 30 × 60″ (Louisville); 22½ or 25½ × 63″ for a 12-foot ceiling. A bigger opening is framed down to it.
How much room do you need for an attic ladder?
From the opening’s hinge end, 54–85″ of floor for its feet to land and 64–87″ for it to swing as it unfolds, depending on the model and the ceiling height.
What attic ladder fits a 10-foot ceiling?
A 22½ × 54″ ladder rated past 10′: Louisville’s AA2210, WA2210 and AH2240MS (to 10′3″), L224P and AA229GS (to 10′), or Werner’s W2210 and WU2210 (to 10′4″). They need 74–79″ of floor to swing.
What attic ladder fits a 12-foot ceiling?
Louisville’s AL228P and AL258P, rated to 12′, in a 22½ or 25½ × 63″ opening. They land 85″ out and swing 87″.
Is there an attic ladder for a small opening?
Not in these tables: the smallest rough opening is 22½ × 54″. A narrower opening means cutting a joist and framing a header, and in a trussed roof an engineer first.