Installing Attic Floor Joists

If you re insulating framed walls make sure the insulation is the correct thickness for your wall studs.

Installing attic floor joists.

If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. If the attic were designed as living space those ceiling joists would become floor joists and be much bigger. Install additional boards on all remaining joists in the entire attic. That s a big size and strength difference between the two types of attic joists even if the joist spacing is the same.

If your attic joists won t bear the weight necessary to finish out a living space but the engineer cleared them to support floor decking for light storage you can install inch plywood or. The difficulty comes from the precise measurement and cutting required and the labor of getting the sheets of underlayment in place. New homes install i beam shaped joists. Strengthening attic joists for live loads by sistering.

Sistering is the process of adding a new joist next to each existing joist. Most floor joists are typically spaced 2 by 8s 2 by 10s and 2 by 12s. 6 carry a piece of plywood to one of the far corners of the attic and lay it on top of the installed boards. The floor framework is mostly made of wood joints running parallel to one another at regular intervals.

Sounds like a lot of work. Lan to use 2x4x36 upright screwed to ceciing joist every 24 to hold 2x6x12 s up above duct work. Measure between joists if insulating a floor or attic or studs if insulating unfinished walls to find the correct width for the insulation. If the air distribution is in the attic space then consider insulating the rafters to move the distribution into the conditioned space.

When joists spacings are wider they should be deeper as well to limit stress and deflection under the load. In unfinished attic spaces insulate between and over the floor joists to seal off living spaces below. Planned on using the 2 6 to support 2x4x12 on 16 centers with one end attached to rafters. Covering part or all of the ceiling joists in the attic is a cheap way to make use of wasted space.

House is a open floor plan so not a lot of support walls below.