View Full Version : Adding a roof over a deck

Bart Kiefer
04-02-2014, 1:46 PM
Hello all,
Quick question for everyone here, just want to make sure that my roof will be "beefy" enough for what I am wanting to do. Currently I have a 16 X 20 deck and I am wanting to put a roof to cover it. Here is what I have in place:

4X4 posts set in concrete every 4' X 4' with 2" X 6" as my trusses on 24" O.C. I am thinking that I can accomplish what I am wanting to do by going 2" X 6" spanning the 16' to a 2" X 8" flitched beam that will span the 20'

As for loads: just the materials as well as Metal Roofing, I would like to implement a swing or 2 under the roof. I will attach a drawing of what I am attempting to explain. Also don't really have to worry about excessive snowfall, normally have around 8" a year. About the drawing, anything that is a solid line is the deck that is already in place, the hashed lines are what I would like to put into place with the roof.

Any and all feedback would be immensly appreciated. Thanks

Andrew Hughes
04-02-2014, 2:44 PM
Bart, I think you have too many posts,there's got to be someone in your area that will help design.That way you stay safe and legal.
Looks like a fun project!

ray hampton
04-02-2014, 3:14 PM
are you thinking about closing the deck walls in for year-round use ?

Pat Barry
04-02-2014, 4:35 PM
It sounds like you want to have 2x6, call them rafters that are 16 feet long. I do not think that is strong enough. I think you would need to cut that length in half. I can't find the information I am looking for right now - google span length for rafters for example. Will this be a flat roof or will there be a pitch to it? Regardless, with the 16 foot span, you wouldn't want to be up on top of it putting up shigles or what have you. It would feel like a trampoline

David Helm
04-02-2014, 7:56 PM
Don't know where you are located, but you should check local codes. Roofs require way bigger footings than decks. 16 feet is way to long of a span for 2X6.

Lee Schierer
04-02-2014, 11:00 PM
Without knowing your location any advice could be bad. As others have mention 2 x 6's should not span 16' You probably need 2 x 10's or possibly 2 x 12's. Check the Uniform Building Code, which most states have adopted for the standards you need for footings , spacings, spans, sheathing etc.

You may need a permit and inspections from your local government to put a roof over a deck.

Jim Matthews
04-03-2014, 8:25 AM
If you get snow, additional roof surfaces will bear considerable load.
If that structure is next to your house, you've shifted the direction of forces
on a load bearing wall - which could be bad.

If the deck is seasonal, consider a retractable awning or Pergola, instead.


Harry Hagan
04-03-2014, 11:18 AM
It's time to consult with your building inspector.

Bart Kiefer
04-03-2014, 11:28 AM
Thank you for the replies, I was mistaken, I originally thought it was a 16' X 20', however it is 12' X 20'. As for some of the questions, yes it will have a pitch to it as to how much pitch don't really know that exactly. I would think it wouldn't be all that extreme as our head room would be impacted if it were. As it stands right now it is just for seasonal use therefore it will not be closed in and my location of it is in the south western portion of Indiana. About 45 North of Evansville, In. to be more precise.

One other question about my flitched 2" X 8", would it be possible for it to span the 20'? I am wanting to maximize the view off the front of the deck. Thanks once again and hope everyone has a good day.

Rich Riddle
04-03-2014, 2:17 PM
I would not use 24" centers with 2x6 lumber. My house has 2x6's in the roof/ceiling but they are doubled up (sistered together) and placed on 16" centers. The span is about 12' and it passed code here (built before we purchased the house).

Lee Schierer
04-03-2014, 6:57 PM
Take a look at this link to determine what size rafters you need for the spans you are looking at. Indiana gets snow so you have to figure in a snow load for your area as live load on the rafters. Understanding Loads and Using Span Tables (http://www.awc.org/technical/spantables/tutorial.php)