Add Joist To Exisiting Floor

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

Add joist to exisiting floor.

As a footstep falls on one joist some of the force is transferred to neighboring joists. The retroheat floor heating system was designed specifically for providing electric radiant heat to existing floors by accessing the floor joists below. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. Most new construction uses 2 by 8 lumber for joists although 2 by 6.

This add on has joist running perpendicular to the rest of the house. Use a tape measure to measure the length width and height of your existing floor joist. Even if your joists already have a row of bridging at the center of the span adding a row on each side of the existing bridging will stiffen the floor. Building codes specify the minimum joist depth and spacing typically 12 or 16 inches on center for spans up to 20 feet but those requirements are intended to prevent plaster ceilings from cracking not to.

Nail the new joist to the existing joist with two rows of 10d to 16d nails spaced 6 in. In the case of 2x6 joists you can pair them up with additional 2x6 joists by nailing them together side by side. Driving 16d common nails in old hard wood is difficult. If your floor joist is an i joist for example buy an i joist.

However doing this does not fix the slant that the floor has taken since the old joists got damaged. Purchase the type of lumber that matches the width of the existing joist. I have added pictures of the crawl space to illustrate the current conditions. Measure the width and length of the existing joist.

The retroheat system can be installed to heat tile hardwood laminates. So if you have open access to your floor joists now you can add the comfort and efficiency of radiant floor heat to your home. But it s usually best to run the sister joist over the entire span. Bridging or x bracing allows joists to share weight.

Sistering is the process of adding a new joist next to each existing joist. Find a new floor joist with these exact same dimensions. Of the existing joist. Use a sledgehammer or a pry bar to force the bottom of the new joist along the mudsill and center support beam of the floor system or the opposite mudsill on short spans until it s flat against the existing joist.

Find a replacement joist that is the same size as your floor joist. Then attach the sister joist using three 16d common nails driven every 16 in. Make sure you also buy the same type of joist. General area of concern.

Take some extra time and jack the damaged area up so that the new lumber doesn t need to be. The best way to limit annoying flex in a floor is to make sure that joists are sized correctly before a house or addition is built.