Supporting a roof or floor during demolition
It's not impossible – just make sure you do it right.
I wanted to replace the 2×3 bearing wall going down the middle of the house with a 2×4 wall. The weightier wall was necessary for changing door locations and sizes. And it would make it easier to install new prehung doors, since the wall thickness would match new doorjamb widths. Supporting a roof while you tear out a wall or two sounds pretty intimidating, but it’s easier than you think. In this case, the roof was spanning only 12 ft. on either side of the ridge, so it was pretty light.
Here’s what we did. We snapped a line on the underside of the rafters about 1 ft. back from the ridge and nailed up a few vertical 2×4 blocks to the side of the rafters next to the line. To those we nailed a 2×6 temporary beam. That was just to hold it in place while we installed temporary 2×4 posts. These were cut 1/8 in. overlong and placed directly under every other rafter and knocked into place. Then we nailed them to the beam and toenailed them to the floor. Lastly, we cut blocks about 2 ft. long and nailed them to each post tight against the beam for more support. That was it. We demoed the old wall and put in the new one with no sag in the roof whatsoever.
— Travis Larson, Senior Editor
Here’s a detailed story on replacing a bearing wall with a beam: How to Install a Load-Bearing Beam
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