2 tier pergola, material question

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    2 tier pergola, material question

    hello all, building a 2-tier trellis at my house. i will have a screenwall across the back to conceal woods and also give opportunity to some nice wall features. i have a couple of questions (im in florida)

    – i was thinking of some type of composite wall with little to no gap, similiar to SAMPLE-1/SAMPLE-2, probaby 8″-12″ wide material. anyone have any suggestions where i can find something like this?

    – for the upper feature in the center section, i was thinking something similiar to SAMPLE-3, (changing material and spacing from center high wall). it will have vertical alum posts that extend down into the composite feature. anyone have any suggestions where i can find something like this? i would like this to be aluminium, flat black. maybe this can be constructed at a local alum shop too

    – for the decking, i know trex is the king, but super expensive too. any recommendatoions of an alternative to to trex? im thinkin 6″+ wide boards

    any suggestions on what to use beside a composite wall board (alternate design)? i thought about mcnichols screenwall material on top of some type of larger board/panel material. any suggestions on another direction to go in would be appreciated.

    i attached a cad elevation and also a picture of the current state.

    thanks for the help!


    Nice post!

    Nice project!

    Nice relief from posts about who redeemed what and when!

    The two key components of your question were

    A) asking for suggestions on materials, and
    B) asking for suggestions on going in another direction altogether

    So here are some random thoughts, in no particular order, that should be considered more as questions back to you, rather than answers for you.

    1) Why (oh why) are you trying to “conceal the woods”? Many folks would kill their neighbor’s first born to REVEAL the woods, and you are trying to conceal them?

    Or are you? Is it possible that what you are really trying to conceal is yourself, your family, and your guests on the deck under the pergola, from prying eyes peeking out from the woods?

    If it is yourselves that you wish to conceal, rather than the woods, then consider rethinking those walls that you propose with that in mind.

    For example, that raised berm immediately behind the pergola… is that your land? Can you put a trellis in the berm and grow a living fence?

    How many feet back behind the pergola is your property line? Acres? Do you own the forest? Do you own road behind the berm? If you are trying to conceal YOU, rather then the forest, then we need to know what kind of visual access other people have to your pergola area, and select solutions to obfuscate their visual access, rather than consternate your enjoyment of the great outdoors in you outdoor living area.

    2) Florida = Hurricanes. Hurricanes = Horrific winds. Horrific winds = blown down structures. Unless, the winds can flow through the structure with little resistance. Walls = resistance. A seven foot tall wall (per your drawing) = a lot of resistance.

    While such a wall may appear at first glance to block wind from the outdoor living area, it can counter-intuitively INCREASE the wind in the living area as the wind encounters and climbs over the wall in concentrated form, at higher velocity from the venturi effect, and with increased turbulence from the eddy current effect.

    So before investing in any materials to build a “wall with little to no gap”, consider the effect of wind on the wall.

    How strong will you have to build a solid wall, and how deep will the footings/posts need to be, in order to keep the wall from blowing down on the party?

    At what distance from the wall will wind accelerating over the wall be felt, and how shall the wall’s height be adjusted to minimize those effects?

    Or better yet, how can the wind’s acceleration and turbulence over the wall be better neutralized? By making the wall flow through… just like the pergola is.

    A flow through wall endure less wind load on the underpinnings of the wall, which will require less material/expense/engineering to keep the wall upright.

    A flow through wall will filter the wind, rather than entirely disrupt and redirect a now faster flowing wind over the wall.

    And, a flow through wall may provide more of an outdoorsy ambiance in keeping with the outdoor living space.

    3) Light. Natural light. Already, the towering trees in the background provide shade, and the pergola itself provides shade. Just how shady do you need to be? I’ve worked in Florida, so I know how brutal summer heat and humidity can be in open space… but that doesn’t look like your situation here.

    Solid walls may reduce the ambient light in your space even further, so that is something to consider. And again, all of these comments are really intended to inspire more questions, rather than provide answers. The right answers, and the best answers, will come from you. Sometimes, it helps when others poke their heads in with their virgin first impressions, that helps motivate additional thinking on a project one is already too knee deep in to flutter around the bigger picture once again.

    An operative words that come to mind are translucency, versus complete opacity. Materials and designs for the pergola privacy screen that offer translucency, and flow capacity, are a suggested new direction to consider.


    Check with your local bylaws whether they allow any horizontal fence/wall/deck rail boarding. Where I live it is not allowed with or without any spacing between boards. It’s considered a climbing hazzard for infants.


    CB, thank you for the reply and the kind comments. i live on 25 acres, the trellis is toward the edge of the property, there is another property a couple hundred yards behind us. as for wind, the posts go 48″ into ground, poured solid with concrete. the intention of the wall is more of aesthetics. it is next to our daughters log cabin and i wanted something that broke up the wooded look, also give it some nice LED accent lighting. just not sure which direction to go in. undecided. but thank you for your input!


    It is a lot more fun spending other people’s money when I don’t have to ask for a check.

    What are you going to use the deck for?

    How many people at once do you expect to use it?

    Is the deck / pergola combination more of an architectural feature to look at, rather than actually use?

    Who is going to maintain the structure?

    Who will maintain the wood finish of the wood walls you are considering in Samples 1, 2, & 3?

    With the heavy rain, hot sun, and high humidity in Florida, what species of wood are you considering for the wood slats?

    What is the swell/shrink ratio of the species from season to season?

    Might that swell/shrink modulus effect the optimal SPACING of the horizontal slats, one above the other?

    If you don’t leave enough of a gap between them, when they swell, might they not curl and buckle out of plane with each other, losing the original dead flat appearance when initially installed?

    Limiting selections to only those three samples you provided images of, I’m strongly leaning toward Sample #3 throughout all three bays.

    I’m also leaning toward halving the height of the wall, from 7.0′ to 3.5′ above deck height, in order to give guests something to lean on, and set their drinks on, as party guests splinter off into small groups for quieter and closer conversations. They can lean on the banister wall and take in the view of your 25 acres.

    The shorter wall would be bar counter height (42″), or light switch height, or tool box surface height, or just enough height to keep the crocodiles from snapping the olives off of the martini glasses.

    Ok, now I’m just being silly… but you did ask for suggestions.

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