Loft Floor Joist Calculator

This is the distance between joist centres.

Loft floor joist calculator. True floor joist span calculations can only be made by a structural engineer or contractor. Span calculator for wood joists and rafters also available for the android os. Domestic floor joist calculator. The highest is a fully loaded floor 70 pounds per square foot.

This demo version is fixed at 1m clear span. There are six choices. Usually 400 450 or 600mm but any value can be used up to 610mm max. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.

The full version allows any size. In the example the joists have a spacing of 16 inches and a span of 11 feet 2 inches. Most lay outs are on 16 so the field is pre selected. Floor joist span calculator.

These small areas are usually door opening on the interior and people are trained that these areas are the strongest. This is how far apart they will be. To use the joist span calculator below first select the species of lumber you will use for your construction project from the drop down list. No matter what the specs say.

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. The loft room will also have to be separated by a fire door either at the top or bottom of the new stairs. Next use the buttons in the table to select the maximum length in feet or metres in brackets that your floor joists must span. The lowest is a plain ceiling joist with no storage 10 pounds per square foot.

Select the on center spacing for the joists. 1 enter joist details 1 1 span and joist spacing. It has been my experience to never use a beam smaller than a two ply 2 x 8. When you re carrying out your planned loft conversion it s highly likely you ll find that the existing ceiling joists or gang nailed roof truss chords in your property are not designed to carry a full domestic floor load.

Timber loft floor joist calculations trimming joists. In this case your joists are adequate to support a 30 psf live load and 10 psf dead load. The span table for a 30 psf live load 10psf dead load floor indicates a required fb value of 1 315 and a minimum e value of 1 800 000.