New patio roof

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24
Location
San Diego, CA
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.
 
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.
 
Hi Robert, welcome to the Family! :wave:

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! :thumb:
 
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...
 
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:rolleyes:...
tod
 
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..... :eek:

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! :doh:

Hope my experience helps you. :thumb:
 
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.
 
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
 

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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:eek:....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
 
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:eek:....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.
 
Decided what to do with patio roof

Thank you all for your input. It all helped me decide what to do.

Todd is right, if I build such a heavy roof, I need to tie it into the rafters, meaning roofing, framing, stucco, etc. I don't really want to do that much for a simple patio. Bill hit the nail on the head by saying "what you have here is a decorative feature rather than an actual structure". So I've decided to improve on what I have and eliminate the part I don't like which is the lattice. I will leave the structure alone and remove the lattice. What I'll add to finish off the top is six 2x6's laid face down perpendicular with the 2x6 stringers. That will give me 2x6 stringers with 2x6's at right angles. All wood would then be the same dimension. Also I am going to wrap the 4x4 vertical post with 2x6 wood to give the vertical support post a sturdy look. I'll check all stringer to eave connections and give the whole thing a fresh paint job.

Should look good. Will share a picture of the completed project.
 
Tod and Bill expertly confirmed what my gut was telling me. That is a scary weak structure. Methinks if you want a real roof and enclosure, you have a complete rebuild job ahead of you.
 
A potential alternate solution that would be convertible would be one of those "Sundowner" type of rolling awning. Since your area is fairly small one of these would be very cost competitive and could be retracted if you wanted some sun or had bad weather.
 
Now, wait a minute! I'm no engineer, but I *am* from southern california. Todd's right, that lath house roof is what it is, and won't be more. But it's a perfectly nice lath lattice shade structure, ideal for growing fuchias, tuberous begonias, or just hanging out underneath and sipping margaritas. I'd give my (no longer extant) eye teeth to live in a climate again that would allow that kind of structure. My grandmother had one, spanning between the house and garage, that was an absolute haven most of the year. Are you *sure* you want to rip the lath down, instead of fixing or replacing it? That's kind of like cutting down palm trees to make room to plant maples... :huh:

Alas! How I miss my native shore! Can you tell? ;)

Thanks,

Bill
 
changed my mind--another approach

After considerable thought and examination of the structure as built, I discovered something I didn't bargin for....TERMITES. I should have known that all So. Cal homes will have a termite problem sooner or later. I have found them in my fascia adjacent to the patio. They have eaten a good portiion of the fascia. What I don't know yet is how far they have gone into the rafters or the roof (although I refoofed, including substrate, about 9-10 years ago). So I have to address that problem by first removing and replacing the affected fascia.
So back to the patio roof. I'm thinking of tying the patio roof to the family room wall using a 2x10x16' ledger board anchored to the wall studs or the double header using lag bolts. From the ledger, using 2x6 joist hangers, run the 2x6x12' stringers to a horizonal 2x6. The vertical posts will be 4x6 for extra strength. Run my T&G across the stringers and apply felt and rolled roofing. Finish off with fascia boards.

Questions:
1) Any comments on this type of construction? Note--I don't really want to open up the roof and tie in to rafters because the adjacent family room is an open beam type construction, nor do I want to go to that expense.
2) Would it be appropriate to use "pressure treated" ledger boards and 2x6 stringers to avoid termites? Not real warm and fuzzy about using that type of treated wood in a living area even though it will be primed and painted.
3) Would it be appropriate to apply 30# felt and rolled roofing directly on the T&G or should I install plywood on top of the T&G then roof?
4) If plywood is necessary (see q.3) what thickness? I can get 3/8, 1/2, 5/8 or 3/4" at the local home depot.
 
bummer on the termites robert!
i`ll start with your construction questions in order;
1) the 2x10 ledger board, i saw stucco on the exterior of your home, what type of stucco is it? metal lath and portland/lime plaster or styrofoam and dryvit, or maybe wood lath and lime stucco(doubtfull).....lags will be fine to secure a ledger to the framing but if you use pressure treated you`ll need hot dipped or stainless.....either way the stucco is an issue....it`ll crumble and permit the ledger to move, the more it crumbles the more movement you`ll have.........moving above the ledger....you`ll need to provide some type of flashing to direct water away from the ledger/house joint and onto your new roof.......aluminum cannot come in contact with the acq treatment used for todays pressure treated lumber, it will eat through the flashing in short order.....


2) rafters spanning 12`......you ask about using 2x6`s.....even in california with no/minimal snow load, going with such a flat pitch i`d advise against it.
2x8 would be as small as i would suggest using...(i ain`t no engineer;))


3)verticle 4x6 support posts....how far appart? anchored to the porch how? tied to the outer ledger how? diagonal braced how?what type of outer ledger do your rafters rest on?

let`s get the framing sound before we look at roofing......
tod
 
...From the ledger, using 2x6 joist hangers, run the 2x6x12' stringers to a horizonal 2x6. The vertical posts will be 4x6 for extra strength. Run my T&G across the stringers and apply felt and rolled roofing. Finish off with fascia boards...

In SoCal, (where I used to live) the 2X6's will most likely be hem/fir. My joist span tables say that the most you should span with a 2X6 on 16" centers is 10.5 feet, assuming a 40 lb ft² load. For a 12 foot span, you'd need to go to 12" centers.

Half inch ply, two layers of 30# felt, and then the roll roofing should do the job. You might want to look into torch-applied bitumin roofing. I had it done on my flat patio roof in Tustin, and it was holding up much better than the rool roofing it replaced.

Addendum: If you can get the wood treated with borates before you paint, it'll help in the long run with the dry wood termite problem. Most exterminators can apply the solution for you, at a minimal cost, when compared to the termite damage repair cost potential.
 
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answer questions & ask new ones

To answer Tod's questions.
1) pretty sure the stucco is metal lath and portland. Common in Calif. Flashing-will do. The idea of the stucco crumbling will be considered but if I'm careful tightening the lags if should be ok as there is no other stress or movement on the structure.
2) I checked with the City of San Diego building code and I can go 2x6 on 24"oc spanning 12' as long as I sheath with 1/2" plywood. I'm going 24"oc because I'm installing 2'x4' skylights.
3) the vertical posts (I went back to4x4;and will face them with 2x material to make larger looking square posts. The post will be tied to the ledgers with 2x6 horizontal beams. Also to code.

New questions:
a) the ledger against the open beam family room, which is an add on, is built higher than the adjacent wall, which means that the ledger attached to the FR will have to be installed lower on the wall. That means, I can't attach the ledger with lag bolts to the double header. How do I find the vertical studs in which to sink my lag bolts? There should be a 4x12 solid header above the sliding glass FR entrance; so I should have solid wood for the lags. The vertical wall studs should be 16" oc. But how do you find them without using small nail holes? Will a stud finder work thru stucco?
Cement anchors would not be stable or strong enough in the stucco alone..would you agree?
b) are 3/8x51/2 lags sunk in the walls vertical studs be adequate? I figured 1 1/2" ledger, a flat washer and 3/4" to 1"stucco leaves about 3" to 31/2" into the studs.
c) I want a light at the far end of the cover away from the house. Any tips on concealing romex wire, other than conduit, to the far end taking into account and open beam ceiling? I'm trying to avoid using a surface mount solution.

Thanks for your input.
 
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