How To Make Floor Joists Stronger

If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists.

How to make floor joists stronger.

How to make floor joists stronger. After several centuries of service floor joists in older homes may sag or crack. If you build a wall to support joists be sure to place a stud directly and tightly under each joist. Common sense tells you that large floor joists can carry more load and spacing joists closer together also increases the load bearing capacity of a floor.

Laminated and single piece beams are often reinforced with plywood. In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together side by side. Fasten new lumber to old using pairs of 12d nails every 16 inches. Homes because the floor joists often are smaller or are spaced farther apart than the joists in modern homes.

But larger is not always better when builders are constructing a home or adding a room addition. The floor above will be stiffest if you place the wall in the middle of the joists. The longer the distance a joist spans without support the more it will flex. To prevent sag in 2x6 s and strengthen at same time you could secure lengths of stainless steel or galvanized cable attach at each end of individual ceiling joists have cable go over a one or two spreaders or strut projecting down from the underside of the ceiling joist maybe 12 14 or so as not to lose too much headroom these could.

This is also routine procedure for some ceiling or floor joists that are manufactured in. Follow the rules to keep your floor solid. Long span joists may meet design criteria and the build ing code yet still feel uncomfortable. The extra two inches of vertical distance when a floor is framed with 2 x 10 joists rather than 2 x 12s can be quite important for example.

Of course new homes also can have bouncy floors if the joists are approaching the maximum spanning distance for the weight they are supporting. The notching and boring rules of thumb for solid lumber are shown in fig. How to strengthen beams using plywood. Long spans of joists in newer homes may wobble or bounce from foot traffic.

You can notch and bore joists without sacrificing critical strength but you must follow the rules. Still stronger is a flitch beam which uses a steel plate bolted between the old joist and its new sister for sistering i joists see page 4 of this article.