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Thread: New patio roof

  1. #1
    Join Date
    Aug 2007
    Location
    San Diego, CA
    Posts
    24

    New patio roof

    I live in Southern California and have a 17' x 12' patio adjacent to my family room. The floor is a concrete slap covered with half brick. The roof structure is made of 12 horizontal redwood 2x6's set 16" o.c. and attached to the eave with face mounted hangers. On top of the 2x6 stringers are 4'x8' lattice panels to provide minimum shade.

    I want to remove the lattice panels and install a solid weatherproof roof with two 2'x4' sky lights, a ceiling fan and some kind of light. I want to have the ceiling look like the ceiling in the family room which consists of tongue and groove and exposed 4"x6" beams. The exposed beams in the patio could be smaller beams or false beams.

    Question: What's the best roof construction method taking into account that it will be a flat roof with roofing paper and rolled roofing? Should I try to use the existing stringers and install plywood and roofing on top of them or should I start new with 2x4 framing to frame in the skylights, and install T&G underneath with exposed false beams installed somehow?

    Question: How much slope or fall is needed to drain away rain? The house and family room will direct water to the patio roof. Should the slope run the same direction as the stringers? How do you waterproof the seam between the eave and the patio roof?

    Question: Will 4"x4" vertical posts be beefy enough to carry the roof load? These posts are bolted to metal u-brakets set in the concrete floor.

    Suggestions are greatly appreciated.

  2. #2
    Join Date
    Dec 2006
    Location
    Floydada, Tx
    Posts
    1,941
    I can tell that my flat roof drops 2" over a 12' lenght. For the skylight I would probaly just move one of the joist over enough to place it.

  3. #3
    Join Date
    Oct 2006
    Location
    Tokyo Japan
    Posts
    15,582
    Hi Robert, welcome to the Family!

    Sorry, I'm not a roofer, or do I know much about your structural questions, but I know a picture would help a lot, if you can.

    Again, welcome!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  4. #4
    Lets see if I can help answer a few of these questions, but please keep in mind I am in a different location then you (Maine) and our weather is quite different. Still I think the same principals apply mostly.

    First with run-off plumbing. The standard drop per foot is a quarter of an inch. That is for every foot of horizontal run, you drop your pipe down by a quarter of an inch vertically. Incidentally, this is the ideal slope. Dropping your pipe more per inch does NOT make for a better drain, it actually makes it worse. The reason is, with a 1/4 inch slope per foot, the water is moving enough to help carry any solids along with it. With a steeper pitch, the water runs out leaving the solids behind. You should not have many solids in your case, but leaves, grit off the existing roof, etc may get into the pipe so staying with the 1/4 pitch drain makes sense. By the way, an easy way to get the proper pitch is to take a block of wood that is 1' thick and tape it to the end of your four foot level...whallla...when the level reads level, you have achieved the 1/4 inch pitch.

    I am not sure rolled roofing is the way to roof a flat roof. Now I am from Maine so flat roofs are unheard of here. Still I can picture what you are doing and I think if you can not be persuaded to use rubber roofing then you may be in luck. Here in Maine we use Grace Ice and Watershield a lot. I have used it on my eves and on my valleys for added protection against leaks to my over-laid asphalt shingles. I even use it around my windows and doors as a sort of flashing. In fact, on anything less than a 5/12 pitch, we use Ice and Water Shield up here on the whole roof.

    Its neat stuff. It has a very sticky backside that is covered with plastic. You peel this off and stick it to the roof. Then on the next coarse you overlay it by 6 inches and go again. DO NOT let the stuff touch itself. It is so sticky that it will not come off. Just cut it and start over.

    The stuff is truly incredible. What happens is, as the sun warms it, it turns it into this thick layer of roofing tar that seeps into nail holes and makes the roof water tight. We use it on the eves because in the winter the freezing and thawing of snow will back the water up under the shingles. This Grace Ice and Water Shield is so waterproof, it stops that. Its expensive though. 150 bucks a roll. Still I think if you laid this under your rolled roofing, you would be alright. I would still rather see you go with a rubber roof, but this is an option.

    As for the 4 x 4's, I really cannot say. I am neither an architect or a structural engineer. Considering you have no snow load out in California, nor any live loads above it, it sounds like it would hold, but that is a very bad assumption to make. Better find out from a more qualified individual than me.

    Hope all my typing helped you...
    I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"

  5. #5
    Join Date
    Oct 2006
    Location
    ozarks
    Posts
    4,992
    hi robert!
    me thinks you might need to reevaluate a bit.......the 2x6 redwood rafters are actually spanning how far? 12 or 17 foot....neither is going to hold a roof well being as redwood is soft and not generally used for structural framing.
    how far apart are your 4x4 posts spaced? how tall are they and what`s keeping them plumb? how is the ledger board affixed to the 4x4`s? what size and type of wood is it?
    i understand that barn tin can be nailed to a 2x4 deck with rafters spaced 24"o/c but from your post i think you`re trying to build a safe long lasting structure and from the sound of things you`re hoping to apply a deck and skylites to a structure designed as a shade arbor?
    take some pictures, ask more questions.....we`ll chip in with advice and help you spend your money...
    tod
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

  6. #6
    Join Date
    Mar 2007
    Location
    Escondido, CA
    Posts
    4,741
    Used to live in Southern California so I know what you are trying to do. Did the same thing myself.

    The 4x4 posts will handle the load, but... spacing is everything.

    As with the 2x6's. There the span and the spacing is important. Your roof load is increasing dramatically from lattice to full roof with ceiling and fan. This will also affect the attachment to the house. If you are attached to the fascia board now and the not the house itself, you will have to address this issue.

    There is yet another issue - wind shear. Are you affected by the Santa Ana winds? They can get pretty strong, as I remember. Had some clocked at over 75 MPH at my place in San Diego county. That patio roof becomes a big sail with sufficient wind.....

    So, what to do? Check loads and spans of roofs. Your building department will have information, or you can find it on the Internet. Check with roof contractors about how they would do it to be up to code. Insurance companies look for any way they can find to NOT pay your claim. If your 'improvement' is not to code, you are SOL. Also affects resale value when it is time to sell. Do it right now or do it over when you are trying to move or take the financial hit then at the prevailing rates. Now is less expensive. Talk to a real estate agent about 'DYI home improvements' and what they do to the value of the house.

    I encourage you to get all the information you can from all knowledgeable sources to your area. Not that we can't offer an opinion, but do consider the sources and make your decision accordingly.

    Lots at stake here.

    By the way, I wound up cutting the eave off and tying back into the roof trusses, putting the patio roof load directly on the wall. I also put aluminum flashing under the roof shingles where it tied into the patio roof and gooped it generously. My patio rafters wound up sized up and I had no finished ceiling weight to deal with. I don't remember the slope any longer but it carried the water sufficiently.

    My brother helped me with the work, but everything was done to code, and yeah, your property taxes will go up. It is an 'improvement.' Every year or two, the entire county was photographed from the air. New structures and 'improvements were noted and followed up on. Hope you knew that!

    Hope my experience helps you.

  7. #7
    Join Date
    Oct 2006
    Location
    The Heart of Dixie
    Posts
    4,265
    First, WELCOME! Noticed this was your first post.

    Second, I second Carols comments. Photos would help a lot too. But as a Home Inspector and General Handyman/Jack of all Trades I think you may be facing starting over. Just adding weight to that may cause it eventually pull the fascia away from the house and then fall.
    God grant me the senility to forget the people I never liked anyway,
    the good fortune to run into the ones I do,
    and the eyesight to tell the difference.


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  8. #8
    Join Date
    Aug 2007
    Location
    San Diego, CA
    Posts
    24

    Pictures of my patio

    Thanks for the replies to my project. I thought pixs would help when I started this thread. So here are some pix of my existing patio structure.
    Hopefully, this answers some questions.

    Note, the rafters are running the 12' side

  9. #9
    Join Date
    Oct 2006
    Location
    ozarks
    Posts
    4,992
    robert, what i see in the pictures is not suitable for any more than it is....i wouldn`t try to put a roof over that structure as it`s built. in pics 74 &75 it looks as though the joist hangers are installed up-side-down....and then only to the fascia board......in pic 73 it appears as though lag bolts where relyed on to connect your ledger board to the columns.... back to pic 75.....there is one joist that`s installed level, the one that appears to connect to the stucco via a joist hanger installed right-side-up...i`m betting that single board is what`s keeping the whole structure from swaying in the wind....
    if you`re not well versed in framing, roofing and stucco repair you might be biting off a bigger chunk than you really want?
    if you want to tackle it yourself there`s a wealth of knowledge here and i`m sure folks would be glad to offer advice......
    what you have now does appear to be seperating from the fascia allready, see the gaps between the rafters and fascia..if those get any bigger you`ll need to take corrective measures quickly...
    keep us posted on what you decide?
    tod
    [SIZE="1"] associated with several importers and manufacturers.[/SIZE]

  10. #10
    Quote Originally Posted by tod evans View Post
    robert, what i see in the pictures is not suitable for any more than it is....i wouldn`t try to put a roof over that structure as it`s built. in pics 74 &75 it looks as though the joist hangers are installed up-side-down....and then only to the fascia board......in pic 73 it appears as though lag bolts where relyed on to connect your ledger board to the columns.... back to pic 75.....there is one joist that`s installed level, the one that appears to connect to the stucco via a joist hanger installed right-side-up...i`m betting that single board is what`s keeping the whole structure from swaying in the wind....
    if you`re not well versed in framing, roofing and stucco repair you might be biting off a bigger chunk than you really want?
    if you want to tackle it yourself there`s a wealth of knowledge here and i`m sure folks would be glad to offer advice......
    what you have now does appear to be seperating from the fascia allready, see the gaps between the rafters and fascia..if those get any bigger you`ll need to take corrective measures quickly...
    keep us posted on what you decide?
    tod

    Tod is correct, you have more of a decorative feature than an actual structure. To do such a change should involve adding roof rafters extending above the Facia and into the roof structure of the house, This should be sheeted over and roofed. Also you can add some extra column supports.

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