ᐅ Leveling the floor of an attic using OSB panels

Hello everyone,

I want to install a new subfloor made of OSB panels in an attic. However, the collar beams are uneven. Along the length of the beams, there is an average height difference of 12.5mm (0.5 inches) more on one side. Diagonally across the entire room, which measures 5.6 by 6.4 meters (18.4 by 21 feet), the difference is 22.5mm (0.9 inches). The flatness of the surface on the beams is about 3-5mm (0.1-0.2 inches).

How would you level this out?

I have tongue-and-groove boards that could be used to enclose the collar beams as a pair on the left and right side of the beam to help level the floor.

However, the dryliner said for the later interior finishing that this could also be leveled with a leveling compound, which he thinks would be easier. Leveling compounds for wooden subfloors are generally only suitable for thicknesses up to 20mm (0.8 inches). The screeds I found elsewhere usually require a minimum thickness of 30mm (1.2 inches).

It also remains questionable how a leveling compound behaves on a flexible wooden floor structure.

Thank you very much for your opinions and best regards

billiebillson

Hello Billie, basically you’ve summarized it perfectly yourself. Adjustment "mass," whatever that means, is the worst solution. So adding layers of wood (whatever type) and boards on top. This lasts forever and easily handles the huge temperature variations.

Hello "Billie".
The only reasonable solution for the local situation has already been correctly identified by "Vicky Pedia".
Using a leveling compound is not advisable for several reasons.
Firstly,
there is the new ceiling load of 500 kg to 600 kg over approximately 35 m² (375 sq ft) caused by the leveling compound. Additionally, there would be the new subfloor, such as chipboard or OSB panels. Altogether, an estimated load of over 1,000 kg (2,200 lbs) would likely be applied to the supporting joists.
Moisture, as a second point,
should be kept out of timber constructions as much as possible. Using a filler compound would introduce significant amounts of water into the structure.
The load-bearing capacity
of the supporting joists should not be overestimated, especially in existing buildings (see point 1).
Furthermore, with the construction method recognized as correct by "Vicky Pedia," it is possible to integrate a satisfactory impact sound insulation into the setup. With the "Spama solution," the feasibility of this is not apparent at first.
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Best regards and good luck with the renovation: KlaRa

Hello everyone,

Thank you very much for your answers!!! I will then level the floor using tongue and groove boards plus impact sound insulation.

Best regards

billiebillson