Diy Loft Conversion Floor Joists

Trimmer joists form the periphery of the new floor.

Diy loft conversion floor joists.

The rim joist sits vertically on top of the sill plate along the outside of the frame to create a lip for the main floor joists. Once the joists are in all that remains is the noggins cut. The new floor joists of your loft conversion will need to offer at least 30 minutes worth of fire protection which could mean replastering the ceilings in those first floor rooms below. If you intend to board directly on to the joists instead of having a raise floor then start by placing the first board across the joists.

The loft room will also have to be separated by a fire door either at the top or bottom of the new stairs. If the attic joists are not adequate one way to strengthen the floor for live loads is to sister the old joists. For most jobs 2 in 5 1 cm x 10 in 25 cm boards are an ideal size. If the board overhangs mark it at the centre of the last joist it crosses and make a straight cut at this point with a jigsaw.

Remember to double up the joists where the stairs are going to be installed and to treble up the joists under the dormer walls of our loft conversion. You ll use the same size lumber to assemble the rim joists as you will for the main floor joists. This means that new floor joists are fitted alongside them slightly raised above the ceiling plasterboard to avoid contact with it. There are many ways of altering roof structures for loft conversions but they all have one common element the ceiling joists will almost certainly be inadequate as floor joists.

Clearing the loft area of all debris insulation struts and temporary boards to expose the ceiling boards. The strong timbers approx 225mm x 75mm timber are secured to the wall plates brickwork and bolted to the walls. We can now start installing the joists if you haven t already done so mark out the position of the joists at 400mm centres. A basic floor system is installed in about 10 stages from preparation to boarding the floor.

Sistering is the process of adding a new joist next to each existing joist. A new floor system is installed using a frame trimmer joists to support the floor joists that span the width of the loft.