What Size Floor Joists Do I Need For A Loft Conversion

This means that new floor joists are fitted alongside them slightly raised above the ceiling plasterboard to avoid contact with it.

What size floor joists do i need for a loft conversion. Ceiling joists are tied to the floor joists with steel straps to stabilise the ceiling. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry without the help of any walls underneath. Joist span and spacing is set by your local building code. While not the ultimate voice in spans these calculators do provide a reality check.

First floor live loads have higher requirements than second floor live loads 40 pounds per square foot vs. For example with such a calculator you will find that for a 15 foot span you need 2x10 douglas fir heart joists spaced every 16 inches. The pack will contain a new floor design which we create using our innovative beam calculations for loft extensions. Joists you may have thought adequate for your attic floor may not come close to being strong enough.

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. An inaccessible attic space on the other hand might have a live load of only 20 psf. This design provides you with the vital plan you need to create a structure capable of carrying the new increased domestic floor loads and existing ceilings. Spacer noggins solid struts are installed between joists to reduce joist deflection vibration improve floor rigidity and performance.

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. New floor joists are measured and trimmed to size then dropped into the joist hangers and secured in position. In addition to the new floor joists trimmer joists will be required. A room used solely for sleeping might need to carry only 30 psf whereas a garage floor over a basement would need 50 psf or higher.

The loft room will also have to be separated by a fire door either at the top or bottom of the new stairs.