ᐅ 1970s attic ladder, but ceiling joist spacing is only 69 cm

Good evening.

I have the opportunity to get a new attic ladder measuring 70x120cm (28x47 inches) at a good price. However, the ceiling joists at the intended installation location are only 69cm (27 inches) wide.

Would it be possible to taper both ceiling joists by about 7-8mm (0.3 inches) over a length of 120cm (47 inches), or would it be better to buy a different attic ladder, for example 60x112cm (24x44 inches)? Unfortunately, that one costs three times as much.

Are you referring to a retractable attic ladder? These are usually slightly narrower than the specified dimension, and the gap is typically filled with insulation material. Just refer to the installation manual for the exact measurements. It might fit anyway. Otherwise, you can’t make a general statement about tapering the joists. It depends on how strong they are in their original condition and what percentage you want to reduce.

How wide are the beams?