Help with unusual liftable deck
Great forum! First post for me... :)
I have an unusual deck in that, I need it to raise.
It's actually a "lid" for a underground filter pit for a Koi pond...
The pit is about 3 1/2 ft. underground, so I'll need the deck to raise up to
about a 45* angle... I'll use electric actuators to accomplish this.
The actuators though need to be on one side of the deck... so here's my
dilema: with about a 8' x 5' "lid", how can I keep it from twisting when
raising from one side?
I was going to use diagonal decking to provide more support, but wondered
if there are other ways I could do this. I need to keep the deck as light as
possible (since the actuator's are rated at about 400 pounds). Also, this
deck will recieve very light traffic (i.e. it'll be closed off, but just in case a
child or very stupid adult ventures out on it, I don't want anyone to fall
through it! :))
Here's a pic of what I have in mind:
The actuators have to be 50% or less away from the hinged side... consequently
the opposite corner will try and "droop"... How can I avoid this?
Thanks for any and all help on my project! If I've left out important details
(this post is already longer than I had intended! :() don't hesitate to ask!
Use two actuators, one on each side.
Or install an angle bracket with notches cut in it, sort of like a clock escapement. As the actuator raise up the notches drop into a pin on the side carring the weight. This will only take the weight off between drop points, the deck will still rack unless you can build it, "unitized".
Or put the actuator in the middle of the opening.
The manufacturer cautions to only use one per side because they admit that
they won't rise in sync and they'll end up "fighting each other"...
They can be as much as 1 1/2" off... Here's a link
to the ones I was going to use if you want to take a peek:
I'll be honest, I don't have a clue what a "clock escapement" is. :( Sorry!
But I might be able to put at least one towards the middle, the right hand
side one... the left would be right in the middle of one of the filters (wooden
tower structure in the pic).
I think I need ideas for the "unitized" approach... you don't think the
diagonal decking would do it? I'd envisioned building two rectangles out of
2x6's (5' wide, 8' long) and have the stringers run parallel with the 8' span...
then 5/4 decking diagonally on top...
I'm not sure if I can link to a video, but I'll try... this shows one someone did
similarly, except his opens from the center and I'd like mine to open from the
Thanks again for taking the time to help!
If the Decking doesn't make it stiff enough,....
Cables,+ turnbuckles can be strung to Stiffen it.....
Why are you using a 12V actuator,... No Power on site, What runs the fish pumps,..??
decking and then if it's still trying to sag, I can add the cables.
Lots of power to the site :yes:, 2 20 amp circuits for water pumps, air pumps,
lighting, etc..., but I need to be able to open it even if the power goes out. :thumbup: (quite often here)...
it'll be hooked up to car batteries with a constant trickle charger attached.
is it possible to,,,
incl an elec winch underneath to pull down on 1 end instead ?,,, we used 12v actuators on equip over the yrs but never in tandem.
idea correctly) is I'd have to hinge them towards the middle and the bottom
would swing down... but the filters would get in the way in my scenario.
They'll be just a few inches below the top of the deck.
Are there steel "straps" or some such thing that pro's use on deck tops for
diagonal support? I'd think something like that might offer more stability
than the 5/4 decking and/or cables... ??
Thanks again for the great ideas! :thumbsup:
There is a kewlness factor with the electric actuators but you could go a bit lower tech and use pressurized pneumatic assists on both sides of each hatch.
Another option to minimize the twisting is to build the framing for the deck out out of rectangular aluminum tubing. I don't know how you could spec the size of tubing, however.
Anyway, just brainstorming, good luck.
Originally, I was going to build the entire lid/deck as one piece out of
2" square stock... but I don't know how to weld. :wink: And use hydralic's
to lift the whole thing. But I was warned about using hydralic fluid and
ponds in the space... if something broke, I'd have lots of expensive, dead,
So if I can make this work with wood, I'll be much more at ease. :)
But I can always keep the pneumatic option open.
Here's another interesting video of how another was done... this was how I
was going to try and do it... but I think he's using hydralics in tandem. I can't
understand what he's saying, but the "good" part starts about 2 minutes into
the video... where he shows you his "herd"... then the deck lift starts at about 4 minutes. :)
how about makeing two lids say 4x2.5 then put an actuator on each one you could then open the whole thing or just half but your twisting and weight problem would be solved
I'd have to crawl around the rest of the area. :no:
But thanks for the idea! I have thought about trying to reduce the area that
I actually need access to... but with the lack of underlying supports, I think
it's probably best to build each half as a whole unit, and not try to lift it in
Okay, just thinking a little outside the box here...
Does it have to be traditional decking?
i don't have the figures i'd need to calculate the weight of the lumber, but consider this- Build your 5' x 8' sections as a hollow box, with latitudinal stringers. Probably 2x4 PTL. On the bottom, 1/4" plywood. On the top, treated flooring-grade plywood, 3/4" or whatever it needs to be.
Then fill the space in between with something like the 2lb/ft^3 marine flotation foam here:
Make sure it completely fills the voids- i'd mix it about 5% over volume just to be sure. Just cover the exposed wood (and the ground if necessary) with plastic dropcloths for cleanup, and wear gloves and old clothes/tyvek- that stuff STICKS.
Angle the whole unit slightly towards the hinge end for drainage, cover with outdoor carpet, use some healthy screws for all fasteners.
Assuming a 5' x 8' x 4" profile, the foam will only add 13lb or so to the weight of the structure, but a heck of a lot of rigidity. Neat stuff.
This has me thinking hard... :thumbup:
The only part that I wish I could have is the traditional decking on top, as
I'll have another deck right next to it, and I'd like them to kind of "blend"
So let me ask, having never worked with this stuff before, is there any
way to pour it, and top with plywood... let it set up, pull the top plywood off, then use traditional
decking after it's set? Or does it stick so well I'd never get the top piece
of plywood back off? And it adds that much strength even though it's not
"one" pour, but filling in the "cells" created by the stringers?
I love the fact that it's pretty much water resistant, as I was going to have
to find a drainage system to go under the decking to keep the filter pit dry
anyway... so it sounds like this stuff might do everything!
Thanks so much for the idea! Any extra help is very much appreciated!! :thumbsup:
cant you make the lid or cover "less" than the thickness of the decking you want to use? Use the foam and plywood method and then just deck it to match the other side; heck I would ICWS the plywood for good luck then deck it
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