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Adding roof to existing deck

stewartahunt's picture


Looking for plans or guidance in building a roof on an existing deck.  The house is a 1960 ranch single-story with gabled roof.  The deck is a good 1.5-2.5 feet high if not more.  So if I attach a ledger to the existing fascia, the headroom would be too low.

So I envision a pergola-style (but solid) cover, constructed by removing existing decking, standing 12' posts on concrete pads, and lagbolting to deck framing. 

Partly because I have no roofing skills, I would like to NOT attach to house or house roof.  Don't want to go there if it can be avoided.  So you might say, a free-standing, flat (slightly sloped) deck cover whose underside is higher than bottom of house roof and maybe partly overhangs it.  If that makes sense.

It occurs to me there would be a runoff issue when it rains.  The deck cover would shield from direct rain, but runoff from roof would obviously hit the deck.   Might rain gutters be effective, on house and perhaps on deck cover ?

Summarizing above, I have three questions:

1. Is this approach feasible, and is it a good idea ?

2. Best way to attach/support the posts in the context of an existing deck ?

2. How, if any, might I minimize rainflow ?

Any suggestions, articles, links to plans greatly appreciated.

How big is the deck?  How (post #190346, reply #1 of 4)

How big is the deck?  How many posts will you have.

I'm suspecting that there won't be enough rigidity in the roof against lateral and torsional motion.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Good morning, Thank you for (post #190346, reply #2 of 4)

Good morning,

Thank you for your reply.  The deck is 35' long (runs the entire back length of house) by 13' deep.  I intend to cover only part of it - say half.  I am researching post placement in several books.  I am removing decking and plan to place posts at each deck pier position perhaps, or maybe every other.  Sorry I am not sure yet but will try to follow whatever standard placement is, every 6' perhaps. 

I take your comment about roof rigidity to be consistent with my plan to NOT attach to house roof, yes ?

As of this morning, I am thinking of a standard open pergola design since those plans are easy to find, and easy to build.  1x2 or 1x3 strips on top for shade.  For rain cover, add hinged raisable rigid clear plastic sold in Home Depot (the corrogated sheets, mounted in hinged frames on top of structure, which could be lifted to open position from beneath, using poles).

In other words, divide project into two parts 1) basic pergola, which I think I can accomplish with my existing skills, then 2) tackle the rain protection separately, using a paneled approach, instead of a single roof.  This would give sunlight benefit of pergola, with occasional rain protection.

So next step is to research what the standard practices are for pole and beam spacing, then layer that on my existing deck measurements, taking into account that only part of the deck will be covered.  I expect to use 12' 4x4s (6x6s seem pretty huge) which will rest on concrete pads and be lagbolted to existing deck framing.  I may reduce post height depending on how it looks relative to roof height.  The deck overhead will definitely be higher than the roof edge.  I may add a minimal pitch for drainage.  Was thinking pitch UP from the house to the yard might be cool.  But pitch is a complexity that might be wise to omit, seeing as how this is my first project.

Thanks again.  If you have any thoughts, I'd sure appreciate hearing them.

Well, be sure to allow enough (post #190346, reply #3 of 4)

Well, be sure to allow enough space between this new roof and the house so that it doesn't bang against the house when it moves about in the wind.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

You are trying to design this (post #190346, reply #4 of 4)

You are trying to design this wrong to accomadate your lack of roofing skills which will lead to problems you have not yet begun to imagine.


Get some help and do it right.



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