Decks, Patios, Porches and Docks - Some Questions about Patio Cover Construction

I am getting ready to build an attached wood lattice patio cover on an existing concrete slab, have visited my city's planning department for basic specs/requirements(Did not get to speak with an inspector though), and overall have an idea of what I am doing, but have 2 questions that are initially throwing me off.

1) Since I am installing on an existing slab, I will be cutting into the slab to create footings and installing post anchors. My question is that I plan on later facing the concrete slab with Flagstone so I am not sure how I accomodate for the additional thickness(Approx 1 1/2") that the stone will add to patio cover posts after the fact. Can an anchor be raised by 1 1/2" and have the post not sit flush with the slab and still be considered sound(And pass inspection) since there will be a gap between the post end and the concrete slab, or do I have to install flush with the newly poured footing, and then install flagstone up against it(Seems like this will cause rotting issues down the road since moisture will be trapped in this scenario). Or is there a space that is used in this scenario. I am not sure if I am clear on my question. Also for post anchors, rafter joists etc, are the Home Depot type grade just as good as the rest or are there special suppliers that provide better quality hardware used by the trades.

Lastly, I need a long cover but depth is shallow. Looking at 24' x 10' total area(Post would be about 9 feet out from house). I would like to minimize the posts. If my cross beam is spanning 21' between posts(accomodating for beam overhang of 1 1/2'), it looks like my city would require a 4" x 16" x 21' crossbeam minimum which to me seems very wide(16"). Would that asthetically look okay , or should I install a middle post so I can use smaller crossbeams. I plan on using double beams and rafters so not sure how that changes the city requirements(Their specs don't mention it) but it seems to me it would be more stable.

Any insight to these questions would be greatly appreciated.

Sincerely,
Michael

Guitar1969,

Welcome to the forums.

First, the attachment hardware that you'll find at HD or Lowe's is Simpson -- it's exactly the same thing that you would find if you went to a local lumberyard. However, the selection may be more limited at one of the box stores.

I would use 3 posts and a smaller beam. I'm sure that height under the beam will enter into the equation at some point. Also, the cost of the 3rd footing and 3rd post will probably be less than the cost increase from going from an 'in stock' 4X12 to a 'special order' 4X16.

To stand off the posts from the footing, and allow for the future flagstone pavers, I would get creative. Dig the footings. Once the holes are inspected, fill them with concrete, setting a CBS or CBSQ about 1-1/2" above the top of the footing (the top of the footing being flush with the existing slab). While that concrete is still wet, add another layer to the top of the footing using a batch of colored concrete that is 1-1/2" thick, and about 3" wider on each side than the post base or column base. (Have your forms built in advance and the colored concrete ready to mix BEFORE you mix the gray stuff that will be going into the hole. The key is to add the colored to the gray stuff while the gray stuff is still wet, so the pour becomes monolithic. You might even want to leave the gray stuff a few inches low and add the colored on top of that.)

Then lay the flagstone to the edge of the colored concrete.

lefty covered it. I entered San Diego deck code, and this came up:

http://www.sandiego.gov/development-services/industry/pdf/infobulletin/ib211.pdf

Just enter your city and go.

Simpson: Product Category: Post/Column Bases (http://www.strongtie.com/products/categories/post_bases.html)

And main page: Connectors by Category (http://www.strongtie.com/products/Category_list.html?source=topnav)

Be safe, G

Thanks for the replys thus far . I am trying to avoid having a different flooring other than flagstone material around the base of the posts. I was looking at the CBSQs anchors and they provide a 1" stanndard standoff(Plate at bottom of post) but I would need a bit more than that so that I could run flagstone flush up to the bottom of the post. In my Googling I've read that some have custom designed standoffs, but it didn't go into detail on how or what was used of it it was permitable. I guess I should talk to my City Bulding dept again and see what they would allow.

The other problem I am having is I was considering a third post to allow me to use smaller headers as Lefty suggested, but that middle post coincidentially would end up square in the middle of my back glass patio door view, which I would like to avoid. So then I started thinking about how far in from the sides of the patio can the posts be (Header overhang if you will) and in looking at my city specs they discuss overhang in relation to rafter span(1/3 of span max) but they don't discuss the side overhang at all. According to the beam specs I can use a 4x12 beam for a max span of 15' 6" oc. If my Overall Patio width needs to be 24', that would make my header beam overhang on each side about 4.5 feet on each side(giving me a small amount of leeway for end of header design cut). Is that an okay amount of overhang on the sides or is there a somewhat standard guideline patio builders use. I am surprised the City doesn't have a spec for this since it seems to me it could affect the structure rigidity.

Thanks for the help.

Michael

Using the CBSQ's, why can't you set the standoff plate at the top of the footing, which sets your post an inch above the top of the footing, and simply lay the flagstones up against the post? If you are concerned about water getting to the bottom of the posts, simply roll the mortar up the post about 1/2" when you lay the flagstone.

For the beam, look into an engineered beam -- microlam, gluelam, etc. They are stronger than dimensional lumber and one that is about 3-1/2 X 12 will cost less than the 4X16 that you originally mentioned. And you can get it 24' long. If you order ANY dimensional lumber longer than 20' you are going to pay a price for it, if you can even get it.

Using the CBSQ's, why can't you set the standoff plate at the top of the footing, which sets your post an inch above the top of the footing, and simply lay the flagstones up against the post? If you are concerned about water getting to the bottom of the posts, simply roll the mortar up the post about 1/2" when you lay the flagstone.

For the beam, look into an engineered beam -- microlam, gluelam, etc. They are stronger than dimensional lumber and one that is about 3-1/2 X 12 will cost less than the 4X16 that you originally mentioned. And you can get it 24' long. If you order ANY dimensional lumber longer than 20' you are going to pay a price for it, if you can even get it.

Thanks for the info - I was planning on using the CBSQ wit hte 1" Standoff but think I may need more standoff - I see that Strong-Tie makes these 1" composite standoff spacers and was thinking I might be able to use one of those in conjunction with the CBSQ to give me more stand off - Otherwise, like you said I can figure out a way to water seal the gap between the post and the flagstone.

I hadn't priced out lumber in awhile and was quite surprised how expensive DF has gotten. As you mentioned above, I might consider enginered beam, or might even do the whole thing in Alumawood(Or some type like that).

Does anybody have any comments opinions of the Alumawood type of covers.

Thanks,

You may or may not be able to get the material to do it with Alumawood. I've installed hundres of them, but I can't sell the parts to a homeowner who wants to DIY. Part of the authorized dealer agreement.

The up side of them is the lack of maintenance, as well as the material be much lighter, therefore easier to install. And the engineering will tell you everything that you and the building dept. need to know about constructing and inspecting the cover.

I'm surprised that you are thinking that lumber prices are high. You must not have paid too much attention the the prices in the past year or so.

You may or may not be able to get the material to do it with Alumawood. I've installed hundres of them, but I can't sell the parts to a homeowner who wants to DIY. Part of the authorized dealer agreement.

The up side of them is the lack of maintenance, as well as the material be much lighter, therefore easier to install. And the engineering will tell you everything that you and the building dept. need to know about constructing and inspecting the cover.

I'm surprised that you are thinking that lumber prices are high. You must not have paid too much attention the the prices in the past year or so.

I think your right in that I made a mistake on the lumber pricing. I'm in Socal and went to Ganahl lumber last week and was looking at their Douglas Fir and the prices seemed high - for example , a 2"x12" x 16' was $128. a 4"x4" x10' post was $45. Really bummed me out. But today I went to Home Depot and the same dimensions on the 2x12 was priced at $13 but its Green, so its going to twist a bit as it dries out. I started thinking I must have been looking at a special grade (I just need construction grade) at Ganahl and not the right stuff. Not sure if the Home Depot stuff would be fine for a patio cover. If I primer it right away wouldn't that help with the twisting, or should I try to get a better quality . I'll have to go back to Ganahl and look a bit more into it.

I am a newbie when it comes to wood . . .

The only thing that I can think of as far as that 2X12X16 being $128 is that it's Vertical Grain fir, or some other species where clear matters. But that would be used for something interior -- not a patio cover.

What you need for a patio cover is #2 or better, and lumber is graded at the mill. The quality at Ganahl and Home Depot (and any other lumber yard) isn't going to vary, as long as the board is grade stamped #2/btr. Granted, it may be picked over by the time you see it in the stack, but when that unit arrived, the quality was all the same standard.