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Lightweight bldg matls?

Discussion in 'Scenery, Props, and Rigging' started by roundhouse, Aug 4, 2003.

  1. roundhouse

    roundhouse Member

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    Our church has, on the stage a "choir rail" its a wall 36 in tall, that is removable, in 5 foot sections. Has a 2 in galv pipe that drops into a corresponding hole in the stage to keep it from tipping over.
    Some are curved slightly.
    Each section weighs at least 200 lbs. They are a solid 5 inches thick, on the bottom you can see at least 7 different layers of wood. Center frame, plywood front and back, MDF panels on front, and baseboard front and back.

    They wall is getting moved in and out alot, and this is a workers comp claim looking for a time to happen.

    I am in charge of building a replacement that will be much lighter, finished on the front only and am looking for options on using lightweight bldg matls for this,

    Planing (at the moment) on using like 2x2 framework, with X in the middle, and like a 1/4 luan sheet on the front.

    Will be painted with a baseboard and trim on the bottom , and a stained mahagony handrail on the top,

    the exixting panels have MDF panels, like a 6 panel door. I plan to simulate this on the new wall using trim applied to the Luan, from the second row, no one will notice the difference, and the surface mounted trim is currently used on the walls under the windows, so it will match ok.

    I have looked at Outwater plastics and other places, but cant find anything that seems suitable for this project.

    The one option that is seeming the best is using a 30x60 plastic table, as the base for the Luan and trim. The table is very light, and strong, I can stand on it.




    Question : what is the lightest wood to use for the braces and framework? fir, spruce, cedar?
    redwood?
    Am also considering using steel sheetmetal studs
    instead of wood.

    Is there some foam, or plastic that I can use?

    My house has western red cedar 4x8 sheet siding, and what appears to be 1x4 redwood trim on the corners, the trim is VERY light, feels about half the weight of the pine that I had to replace some with.

    I have some 8x8 redwood timbers salvaged from a playground, removed because the timbers were getting eaten by something that made tunnels in the wood. like termite tunnels, but larger with no dirt,
    I was thinking about ripping them down to 2x2, 2x3 and using them for this.

    Like to hear anyones advice, tips.

    Thanks
     
  2. ship

    ship Senior Team Emeritus Premium Member

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    I believe it’s a daisies not a stage.
    What ever the case, I’m still a big fan of MDO plywood. Granted it does not have to be 7 layers thick of 3/4", but ½" to 1/4" even single sided MDO plywood is going to be much more paintable and dimensionally stable than especially luan mahogany plywood and much less susceptible to warp, punch thru or cracking when it drys out for something that’s a permanent feature even if portable. It is afterall available in single sided sheets in ½" or thicker - no reason to pay for the extra paper face on the glue sides.
    The paper face helps the sheet tremendously in it’s strength. One sheet of ½" MDO is about as strong if not stronger than fir 5/8" ACX. On the other hand, if you went luan, you would be much more able to match a gentile curve than with MDO due to its smaller thickness. Can be done but a little more difficult with the MDO. If the curves are too sharp, no matter what the material you will have to use either bending luan or cut slits int the back of the plywood and wet the face. 1/4" MDO would probably be bendable enough however for your application given it’s screwed into place. Given the budget, that’s what I would go with for inner panels.

    Given the panel nature of the rail, even if heavy, 3/4" MDO would be much more damage resistant to build up the panels. This thing is going to be moved. Not only plan on the weight, but plan on the damage it’s going to get. Luan and pine won’t live up to much abuse. For other molding, avoid pine. Go at least with fir, if not poplar or oak. They will stand up to dings and abuse much better. Granted if oak and painted, you would have to sand it’s grain flat.

    I’m not a real fan of 2x2 stock lumber. I’ll use it for certain applications but it’s strength is only slightly more than a 1x2 in strength. Even a 1x3 is going to have more resistance to bending perpendicular to it’s 2.1/2" axis than a 2x2. That said, if you are set on a 2x2 frame, avoid buying store bought 2x2 pine lumber. Instead rip some out of Douglass Fir say 2x12 sections. Doug fir is much stronger and resistant to splitting than southern yellow pine. Buying a good expensive rip saw blade will be required to cut it. Get one good one for plywood and one good one for ripping and even an underpowered table saw or circular saw will have less stress on it. Just ensure you put the blades away after use or they will quickly get trashed. Also, put their price on your quote or it’s going to throw the budget out of wack.

    Here is what I would do. By the way, that galvanized pipe is measured by it’s nominal inside dia. not seemingly outside dia unless structural aluminum pipe. Thus it would probably be the case that your 2" Galv. Pipe is actually 1.1/2" Sch. 40 pipe. That said, you will run into problems with thickness with a 2x2 lumber frame in thickness. If at all possible, install and plan for some Kee Klamp floor flanges to be installed and countersunk into your frame. It would take some work and engineering, but when needed, as opposed to just bolting the pipe to the frame you could remove the pipe when needed given some holes to access the pipe set screws and countersinking your frame around the flange. At least bolting and shimming will be needed otherwise to secure the 1.7/8" OD pipe to the frame so it doesn’t wiggle.

    The hollow core panel idea works, but can be improved. Instead think hollow core door but use 2" blue Dow Board insulation between layers instead of the honeycomb cardboard.

    More specifically, I would start at the galv. Pipe and lay out a frame of Doug Fir 1.1/2 x 2" ripped lumber around the frame and pipe areas. Cut Blue Dow board to fit into the holes of the frame. Trace your frame on the 1/4" MDO plywood and apply foam grade contact adhesive to both the back of the plywood, and the frame/foam section. Once dry, adhere both together and screw the plywood to the frame with 1.5/8" drywall screws about 8" on center. No need for a X frame, the plywood and foam will prevent sway, and the extra thickness of the lumber and it’s better lumber grade will prevent it from warping or drying out and cracking.

    Once the MDO is installed (cut slightly larger than the frame) you can router it flush to the frame. Now, cut up a 3/4" single face MDO plywood sheet to make the rails in the paneled wainscoting. Apply beaded or other molding as needed for trim or router the edges of the MDO as needed. Wood glue and pneumatically staple the sections with a narrow crown gun and 1.1/4" to 1.1/2" staples to the frame of the panel. Same with any inside panel trim if you don’t just use pneumatic finish nails. In areas of the trim that would need to be attached to the 1/4" backer with foam under it, toe nail your staples into place instead of sending them directly into the frame, or use drywall screws as needed. After the trim is applied, cover the holes with your choice of Bondo or spackle. Bondo will adhere better. Apply the hand rail in a similar way. Go to a home center and get a pamphlet on installing stairway spindles and hand rails as a refresher course in the best way to install it.

    Such a wall would be light but very strong. If needed, you could substitute the 1/4" MDO for Luan but it’s going to be much more grainy and less resistant to damage. At least you might consider going with 1/4" BCX or ACX. You can go with pine 1x lumber in place of the 3/4" MDO and it would make it lighter, but if at all possible, MDO plywood is still the best materials to use even if slightly heavier. At very least for the 1x lumber, use poplar if you want damage resistance and something that’s not going to split as it ages. If you go with any 3/4" or 1/2 " plywood, the more layers of thickness the better. 7-ply 3/4" plywood is going to be much better than 5-ply, 5-ply 1/2" plywood is going to be much better than 3-ply in both damage resistance and strength. Poplar plywood is going to be better yet. All above would be more expensive but cost effective in the long run.

    My thoughts at least.
     
  3. ship

    ship Senior Team Emeritus Premium Member

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    Missed the lower section in your questions:

    My answers at least:
    Avoid cutting the timbers up into 2x2 or other sizes. They have not the same moisture content all the way thru the timber and by the time you are done you will probably end up with some interesting pieces of lumber if not seriously bog down and trash your saw.

    Besides, such timbers are very expensive and it would be a serious waste of materials to use them. Western Red Cedar if memory serves is a very good dense lumber much similar to at least hemlock fir if not douglass fir in strength. Were you to use it in spite of the waste of materials, difficulty, and warpage/splitting, it would be fine for strength. Should be much heavier like the above fir lumbers than pine or normal white cedar. I don’t know much about redwood or spruce - they are not common framing materials. White cedar is tremendously light but also by nature of lightness is also much more effected by seasons and water than normal more closed grain wood. In other words, it might swell up a lot during the spring and crack when dry. It’s also not going to take a coat of paint as well, and like balsa wood when dry, is going to get dinged very easily. Cedar in general smells nice and prevents bugs, but for inside structural use, they are not really economical.

    Avoid steel or aluminum studs for something like this especially that’s going to be portable. They lack torsion strength and unless welded are very prone to falling apart. It’s also far more likely that if a panel is dropped, that the plywood attached to the stud and giving it strength is going to rip right out of the stud unless glued, and even than it might. In other words a portable wall using standard steel studs is going to fall apart rapidly.

    The sheet siding you talk about is called T-111 for a trade name if I remember right. It’s nice stuff but rough to the finish. In other words if you wipe your hand across it, you can probably knock a few flakes of saw dust off it. When it gets dry, you might even be able to pull a sliver of wood off it. At very least, it’s going to be tough to paint and keep painted well if it’s flaking. Lightness of it is partly because of the lumber used, but also because of how much of it is cut away. I have used it for stuff before, but for your application, I probably would not.

    Besides, with such siding are you not introducing a kind of design style that’s not really similar to what is already in the church? Also, T-111 siding is very hard to mask it for what it is. In other words, anyone that has used it before will easily know what it is and thus how you constructed your barrier. It would look a bit hack in my opinion for a design choice here.

    If you did decide to use it, still glue it to the frame with wood glue, but on the face, you will probably need a Liquid Nails spread with a trowel to adhere trim to it and have it stay on.
     

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