Edited..Putting a Pergola (Trellis) over my back deck. Looking for some input please...

[Kevin Palmer]

Pretty much like it says. I have a rather large deck that covers substantial area. This issue is, the deck gets VERY hot at the day goes on. I am looking to build some sort of a over / roof / terrace over the deck.



My thoughts are to follow the existing outline which is a unique shape with the top outer edge being about three foot further out that the deck is now.



Off hand, I am thinking of putting pole in the ground at each of the points where the deck takes a different angle. This is for two reasons. One, it will allow for a separate free standing structure in the event I need to fix, repair and or replace my deck in the future. Also, it will give me a good source to mount the upper wood word without have the weight rest on the deck itself.



I am thinking some sort of angled wood on top as it would block most sunlight until the sun starts to set. This would allow light to pass through and not act as a roof that catches the weather as well.



Any pictures of your deck top and or advice is welcomed.



My one BIG question is, how to attached the main board to my roof? I want no leaks as I have no leaks in my house at this time. If I mount it below my gutter line it will be too low and not look good. So the answer is to go about 5 feet up from my gutter, lay a board down and mount my vertical boards from there out to the posts I put into the ground at the outer edge of my deck.



Thanks in advance...

 

[Rodger Tellefson]

Kevin,



I did a search on Pergola, so check this out. It might be what you are looking for.

 

[Thomas Rogers]

CoastieJoe, unless a regional dialect is kicking in I suspect the word you are thinking of is "trellis", not "terrace", but as Rodger points out the "pergola" variant is what you seem to be describing.



I don't have one, but the ones I like are simply boards stood on their sides like in the Wikipedia picture below:



TJR

 

[Kevin Palmer]

Trellis terrace,,, whatever it takes... LOL



Auto spell checker kicked in and I missed it...



Thanks for the info guys, it is appreciated...

 

[Bill V]

A lot of questions come up, primarily about your current layout. How big is the current deck? How far off the ground is it? Where are the deck's main support posts--on the corners supporting the rim joist, or set further in supporting a beam? What are your current house and roof line like? What kind of railing does the deck currently have, and is there any desire to replace it (take off the railing, put in the pergola mounted directly to the sides of the deck, and then build the railing into the pergola supports)?



Some pictures of the current structure (both deck and house) may be helpful.



Take a look at the Home Depot do-it-yourself book about deck building. (Lowe's may have their own version as well--I'm not sure--and there are others as well that are sold at both store.) It's about $15, and most larger libraries have it and the others available as well. (690.184 and 690.893 in the Dewey Decimal System.) If I remember correctly, there's a whole section in the Home Depot one on pergolas (and likely in the others as well), that has a lot of excellent tips and ideas.



Regarding attaching to the house--if you're attaching to the side of the house, what you're describing is called a ledger board. And you can do that using the exact same instructions that are in one of those books regarding attaching a ledger board for a deck. But if you're going above the gutters, are you talking about building it into your roof?

 

[Bill V]

How set are you on the idea of a pergola? There are other options out there you may wish to consider, like a shade sail. (See link.) You might also be able to do an awning (permanent or retractible).

 

[Kevin Palmer]

Bill, here are some answers to your questions.



Without measuring, the deck is probably 60 to 65 feet wide and extends out about 30 feet from the house. The deck is level with my back sliding door and is about 2 1/2 feet off the ground and has three areas you can walk down stair to get to the grass. There are 30 in ground supports on the existing deck and an additional 20 in ground supports where my hot tub is. The hot tub deck is a miniature copy of the original deck.



The roof line where I would be mounting the wood is a face of the roof which is of course shingled. It is my intention to mount to the roof as doing the ledger board under the shingle would not allow for the height that I want/need for the Trellis.



I could remove the railing and mount posts that would support the Trellis, my concern is how strong of a mount would it be to simply be sitting on the deck. I have thought about this and I could box them in with wood that would give good lateral support but not the best support as far as top end over-all side to side motion in heavy winds and what not.



Am I sold on a Trellis? No, but it is the direction I think my wife wants to go. The sun shade above is an option which I will show her as it is unique and would be an easy solution as well. I would be concerned about how it holds up to the environment as it would be up all the time with the possible exception of winter.



As far as mounting to the roof, I do not want to open the roof to mount to it as the project simply does not justify the structural type work in my opinion. I would think the some sort of sealant and or rubber mounting pad as well as flashing would do what I am after. If I need to remove shingle to do so, I am OK with that as I still have shingles left from when I re-did my roof with dimensional shingles last year.



I am not home right now, I will do my best to get pictures up of the deck.



Thanks...

 

[Thomas Rogers]

Coastie, it's very low tech, but if you have Windows XP, take some digital photos, store them on your computer, then open them up in MSPaint. You can then draw "wire frame" (lines) of where your trellis might go, and do it over and over again until you get what you like (just keep your original photo files).



TJR

 

[Richard Kolb]

Why not have the trellis free standing from the roof? Like basically it would be attached to the ground and nothing else. You may have to go through the deck to do that but then it doesn't attach to the roof and shouldn't cause you roof issues.

 

[Bill V]

OK, first of all--



You have 1800+ square feet of deck???!!!???!!! OMG!!!! Most people I know think our deck is monstrous, and it's only about 600sf! (Then again, it is all elevated about 11' off the ground.)



OK, now to the actual trellis...



Regardless of what direction the boards on this trellis run (parallel or perpendicular to the deck), I'm suspecting that you're going to have trouble finding materials that will span 30', let alone 60', without some sort of splice, and likely also some sort of center support. Which would mean putting posts in the middle of your deck. (I haven't done any engineering weight analysis on it or anything, but just from the description, that's my gut feel.) Even if you're going to build it yourself, you may want to subcontract a professional engineer/architect to go over your plans and make sure it is structurally feasible. I realize that it doesn't need to be sound enough to support the weight of people or snow or anything, but it won't exactly be lightweight itself, and all those vertical boards could be subject to significant wind forces that may need to be accounted for.



And the post previous to this one may be worth considering as well--leaving your roof/wall alone, and making it free-standing, may save you some headaches with mounting it to your roof. (Then again, you'd have to sink the support posts right next to your house--so there are some disadvantages to such a design as well.)

 

[Kevin Palmer]

Bill and others....



I told you it was a big deck... LOL





It is these types of thoughts, questions, and concerns that I am posting here. They will help me make a good sound decision. As far as construction it goes, other than some of the LONG pieces of wood I will be good to go as I am pretty good at wood type construction. I built my extra garage behind my home with no one but my wife (which was interesting at time.. LOL) and the tools I own. The inspector asked who built the garage as he wanted to recommend him to others. When I told him it was just my wife and myself he was pretty much in shock. The garage is pretty good size considering it is a spare where I keep my toys (jet skis, lawn tractor etc etc). It is 40 feet by 60 feet with the traditional peeked roof. Matched the shingle to my home and wrapped all exposed wood with aluminum for additional protection.



At any rate, yes, I can make it free standing by removing some planks and putting poles in the ground but prefer not to as I think the appear acne would be better to come from the roof.

I will put poles out on the outer edge as it will add strength and act as support for future expansion as well.



Any more thoughts.

 

[Bill V]

No further pergola thoughts at this time--but regarding the sun shade or shade sail option, I haven't seen many on private homes, but I know I've seen them in public places (parks, amusement parks, etc.) where they're up year round, and seem to hold up quite well. So I wouldn't let that concern prevent you from at least investigating it.

 

[Thomas Rogers]

CoastieJoe



Here is what I suspect you might want to try given the size of your deck:



1) Figure out how much of it you want to shade with a trellis, if all of it, or part of it, probably doesn't matter, but if you can stay with a rectangular or square footprint to the trellis it would be better/easier.



2) As others have said, you are going to have a "span" issue, so figure on a column or pillar (an upright) every "few feet"...what is every few feet, oh, I dunno, probably no more than 8', 10' or 12'. I suspect you should be able to cut holes in the floor of your deck next to floor joists for the uprights and bolt them against the existing floor joists.



3) Between the uprights hang joists in one direction, then the upright "ceiling" boards for the trellis in the other direction.



If you use "light" wood you should be okay with just fastening the uprights to the floor joists...but if you are concerned with the weight and can get under your deck then at the very least rest the uprights on a sunk cinder block then fasten to the joists.



Now, this setup might be more permanent than you want, and I am sure that some will say it probably isn't architecturally "sound" as I have described it, but those are my thoughts.



Oh, here is a picture, looking down (gray is the perimeter of your deck, brown the uprights, joists and trellis roof) covering only about 1/3 of the deck...and with only a few of the ceiling boards on:



[Broken External Image]:



TJR

 

[Kevin Palmer]

TJR, you are basically correct with what I think that I am after. Bolting the uprights to the joists is not a bad idea and is something I can do with little hassle as every single deck board is screwed down, not nailed so it will be easy to pull a few boards to give me working area.



You general idea is close. Pretty sure I want to follow the outline of my deck plus out a few extra feet. Also want to lean the overhead boards at an angle that will block most of the sun most of the day.



Just looking for pictures to see what others have out there as it may help with the design...



Thanks all...

 

[Thomas Rogers]

Coastie,



Glad I was on the right track. Yeah, I suspected you probably wanted to "overhang" the deck...I think you can probably get away with fewer uprights and wider spans if you use really light roofing material.



Good luck.

 

[Bill V]

I don't have a pergola myself, but all the ones I have seen have the shade boards standing vertically. I would think that angling them (assuming that by that, you mean setting them up non-vertically) might increase the shade as you intend, but wouldn't be the greatest appearance visually, and might baffle the wind on your deck in unintended ways, for better or for worse. I would think you'd be better off keeping them vertical, and instead working with the position and size of your boards. Taller boards will block out more sun, as well more boards closer together, and the direction of the boards will obviously have a big impact.



When you exit your house and step out onto your deck, what direction are you facing, and how tall is the house behind you (and thus, how much shade does the house itself provide)?

 

[Kevin Palmer]

Good points Bill. I had mentioned the closer together option to my wife as well. This would aid in mounting them as well. The deck itself has angled decking. The boards run from somewhat from a center line of the deck and then away from center on an angle. Like this

\\\\|////

.\\\|///

. \\|//

I will have the slats run straight out from the door as this will look good as well as do what I need to block the sun for most of the day and into the night as it comes from the strong left side for the most part.

 

[Bill V]

I'm anxious to see the pictures of this deck--although at 1800sf, I have my doubts that you'll be able to get it all in one picture! :lol:



FYI, here are a few pictures of ours--from the website of the deck builder. (My wife and I designed it--but with two kids under four and a third on the way, we weren't about to try to build it ourselves!!! )



[Broken External Image]:

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[buzz worth]

Having just helped a friend renovate his pergola, be aware that the sun is a cruel villain to fresh, treated wood and will cause it to "pretzel" very quickly.

I'm sure you're familiar with what happens if you leave a stack of treated wood in a pile. The top one ends up bending one way or another.

He had used 2 x 8 joists and they held up well, but the 2 x 6's that were laid across (vertically) to form the "shade" twisted ALOT, even though they were well secured.

Buzz

 

[Kevin Palmer]

Good point Buzz.



Maybe I will mount the boards into slots as this will help with both the mounting as well as the twisting issue..