Timber floor joists and flat roof rafter calculations spreadsheet

This is the easy way to calculate the rafters and joists you need for any domestic floor or flat roof. Use this spreadsheet to instantly output professional calculations for your rafters and joists.You can design:

• Garden room roofs and floors

• Home extension flat roofs and floors

• Domestic floors

• Garage re-roofing

Following a simple 5 step sequence is all you need to design your floor or flat roof. Simply enter the joist span dimension, then select from the drop down lists.

Get instant colour coded feedback from the PASS or FAIL results, and read the information box with helpful suggestions on what to change if you get a "FAIL".

Once you have the design you want, print out a set of calculations to PDF or your printer!