Natwerk Designs

What size board would I need to span 20ft and support a roof.?

Building a covered outdoor kitchen/dining area 20x20. I only want posts at the corners (if possible). What size board would I need to accomplish this? The roof wont have any extra load on it, as I live in southern GA and we dont get any snow.

Public Comments

1. just like a regular house on any thing else..2x4.at least. what kind of pitch is on the roof? are u northern or southern hemisphere..what are the weather conditions...the worse conditions,,the more sturdier wood u will need...i hear most people are using metal now to build houses..cheaper and faster,stronger,cheaper insurance. i help build metal buildings. so cant give you a specific size board because dont know all details. but if just like regular house...just use 2x4...build it right and should last.
2. Depending on the load, you would probably need Douglas Fir 2x12's @ 12" on center, with doubled or tripled 2x12 beams supporting the joists. Check with your local building inspector to see what your codes require. 2x4's are FAR from adequate. Hope this helps. EDIT: What do you plan to put on top? Is it going to be open, or do you plan to put roofing on it? With no snow load to take into account, you just have the dead load of the roof itself. You can probably use Southern Yellow Pine 2x10's @ 16" o.c., and doubled 2x12's for the beams on each end. To be sure, though, check with the inspector. Depending on how tall the posts are, you may want to use 6x6's, and install some diagonal sway braces in the corners. Good luck. Sounds like a fun project.
3. What kind of roof? That makes a big difference. You need to find someone with span-tables. Each kind of support - type of wood, laminated or not, or metal RSJ etc has a load carrying capacity. The span tables will tell you how far you can span to support a given load. That's a long span. See the tables in the links it will give you an idea at least.