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2009 Construction

Written by Sean Avent, 11/20/2008. Original "Wall Construction.doc" at http://groups.google.com/group/sfuwh/files.

Wall Construction - San Francisco Style

Materials

All the parts listed here come from McMaster Carr (http://www.mcmaster.com/).  We did not order anything for them since we could get it cheaper in hardware stores or at industrial supply stores.  For fasteners, do not go to West Marine as they are about 8 times more expensive than an industrial supply place.  Home Depot or the like is probably fine for 10’ metal studs and the composite 2x4 deck material. But you’ll probably not find the 20 gauge or 20’ sections there.

Metal Framing Studs

(77095T42) – 25 ga.; 3 5/8“ by 1½” x 10’

            These studs are the base of your walls.  You can by them at some hardware and building/drywall supply stores. We found only one supplier in the city, SFG. 20' lengths are nice because they take less time to install but are harder to find, transport and store and take more weight to stop them moving on the pool bottom. Lower gauge is thicker and heavier. 20 gauge is the minimum you want, especially for 20' lengths. 16 gauge is probably best. You can cut these with a hacksaw or with a chopsaw with metal cutting blade.  Make sure to deburr your cuts and edges, because they are sharp. Do this with a file or deburring tool (4289A14 or 4286A14).

Composite Studs

Trex, Timbertech, Evergrain, or other brands will do.  Size: 2”x4” (true size is 1½” x 3½”).  You can get this stuff at Home Depot or other building material places. It’s more expensive than the wood 2x4’s but it does not expand or rot when it gets wet.  If the wood expands inside the metal stud when under water, you may never get them apart.  Cut these into 1 foot lengths and then cut off about ½” of each corner so that they slide into the metal studs above. You’ll want to create a template piece so that you can drill all exactly the same.  We centered two 3/8” holes at distance of 8 inches on center (OC).

PVC Sheet

This is the wall material.  It’s the same stuff they use at Club Puck (San Jose State University).  It is attached to the metal stud with fasteners (see below) every 2 or 3 feet.  McMaster Carr only has 1/4” thickness sheets, but we used 3/8” sheet.  It comes in white and grey.  We think grey is  good color.  I would highly recommend the 3/8”.  We got our PVC sheet form an industrial supplier in San Jose; they sold us full sheets and cut it to 6” widths for us.  Sometimes these sheets come in 8’ foot sheets, and sometimes 10’ sheets. The longer the sheets, the less you have to do with it.

(87265K52) – 8’ x 54” x ¼”

Plastic Milk Crates

You know what these are. You can find them for sale online or ask the grocery store and they may let you take them.  You’ll need one for every place two metal studs join together.  If you use 20’ metal studs, you’ll need half the amount of milk crates as if you used 10’ metal studs. We used about 15 per court with 20’ studs.  If you build a double wall in between two playing areas, then you’ll probably need 25 to 30 using 20’ studs.

Non-Slip Rug Liners

This is a mat that is placed on surfaces so they don’t slip.  You can find it at Home Depot or maybe even Wallgreen’s definitely cheaper than McMaster Carr. It usually comes in rolls. We haven't found these very useful; they are fiddly to install.

69275T55 – nonskid matting underlay

Lead

For one court, we used about 700 pounds of lead.  That was about right.  With this amount, we could slide the walls a bit one way or another, but not more than 3 inches at a time.  Overall it was good.  I’m not sure that it would take someone big kicking off the walls, but it might have.  The lead was poured into 5 or 10 pound pieces so that it could be distributed evenly between the multiple milk crates around the court.

DO NOT USE CONCRETE as it does not have the density.  To get the same stability as lead you’d probably need to double the number of milk crates and fill them all with concrete.   The same goes for other materials that do not have a high density.  Remember you could use water jugs that weigh a lot on the deck, but when you put them in water, they weigh nothing!  Concrete weighs barely more than water. 

Lead is expensive, but sometimes you can find it for cheap.  Consider hitting up all the tire places for buckets of the wheel weights.

Machine Screws for Crates

These are the fasteners that will bolt the ends of the metal stud/PVC wall assembly to the milk crates.  We found that 3” stainless steel ¼-20 bolts with a fender washer worked best.  You need two sets for each crate plus an extra two sets for each corner. If you plan on bolting the goals to the walls, you may need longer bolts.

Bolt – 91771A554 – ¼-20 3” Stainless Steel with flat 82 degree Philips head

Wing Nut - 92001A321 – ¼-20 stainless steel

Fender Washer - 90313A107 – ¼” ID, 1” OD flat Stainless washer

Machine Screws for PVC

We initially used self tapping sheet metal screws (Zinc-plated; pan-washer head; Philips drive; 1”, #8 thread)  to attach the PVC walls to the metal studs.  But we found that if the PVC heats up, it expands significantly and will just snap the head off the screw.  We also had a few sheet metal screw not holding in the metal stud.

In 2012 we used stainless steel self-tapping screws to hold 12" high PVC to a metal stud. Stainless steel is less likely to corrode but is brittle. The screws were snapped (sometimes at the head, sometimes sheered at the PVC/stud surface) during regular play without players kicking the walls. It takes a little more time to drill a hole but we recommend using a machine screw that is slightly countersunk into the PVC and nut on the back side – especially if a thinner stud material (lighter than 20 ga.) or 12" high PVC is used.

Screw - 90273A537 – ¼-20 1/2” Stainless Steel with flat 82 degree Philips head

Nut - 90675A005 – 1/4-20 Stainless Steel hex nut with tooth washer

Alternatives

If you have a tile bottom, we have seen, as in Sheffield (World Champs 2006) that suction cups can work very well. Make sure you get large ones (greater than 3” in diameter- 53535A45) and ones that can be pumped to create a better suction would be better

Tools

I’m a firm believer in the right tools.  Make the job go much faster and safer than rigging something. Having multiple tools allows multiple people to work on a wall assembly.

Drill and drill bits – You’ll need a good one for drilling holes in the metal and PVC and composite wood and milk crates.  I prefer a corded drill for more power and no down time for battery charging.

Wood Saw – For cutting the PVC sheeting and the composite wood pieces. You can use a hand saw or a chop saw or a circular saw.  The latter two make the job go much quicker and nicer.

Metal Saw – For cutting the metal studs to length.  You can use a hack saw or a chop saw or jigsaw with metal blade.  The chop saw is the quickest, but almost not worth the cost.

Countersink Bit – For countersinking the machine screw heads into the wall material. 2846A125 – like this one.  This way you won’t have the head of the screw sticking out above the wall surface so that someone can cut themselves.

 

 

Notes:

PVC sheeting will expand lengthwise with change in temperatures.  Plywood could substitute just fine if you can paint it to make sure splinters don’t develop, but you’ll have to do a lot of upkeep. Other materials such as aluminum could also be used.  Metal edges can be freaking sharp. 

 

1) Cut raw materials

Cut the metal studs and PVC lengths as needed.  We used as many 20' sections as possible and finished off with smaller sections on the ends. Route or file off any sharp corners of the PVC sheeting and use the deburring tool for the edges of the metal studs.

 

2) Make the wall sections

Screw the PVC sheeting with sheet metal screws to the metal studs so that the metal studs are just flush with the bottom edge of the PVC. You may need pilot holes.  The studs can be shorter than the PVC sso that the PVC butts up together with minimal gapping. We found that 1 screw every 2 feet was sufficient, but if temperature is not variable, then one every 3 feet is good.

 

3) Connect wall sections

Make small 18” connectors out of the composite 2x4’s to connect the metal studs of different sections together.  We used the composite instead of wood so that it would not swell while in the water. You may need to trim or plane the connectors to fit into the metal studs.  We had no trouble if they were looser than tighter as they bolts hold them pretty well. Drill 3/8” holes through the wall section (PVC and metal) and through the connector so that the 3” bolt can fit through. Make sure to countersink the hole on the wall playing side so that the bolt head does not protrude and is able to cut someone during play. Leave a little ¼” gap between the wall sections for expansion/contraction. Ideally these wall sections sand connectors would be identical (especially the bolt hole patterns) so that any wall section could be placed in any spot along the wall, but we found that was hard to do and ended up just numbering the sections to keep them organized and make sure they fit.

 

4) Lay out the walls

Lay the walls out to make sure they all match and fit well along each side – we do corners on the next step.  Take into account any slope the pool bottom may have (we used long copper ½ tubing to form to the bottom of the pool to get angles close where we needed them. Adjust and cut and repair as necessary to get the walls straight.

 

5) Attach milk crates

We attached milk crates on the outside of the walls to provide stability and hold the lead. A crate every 20 feet is fine. Just drill two additional holes in the crates so that the 3” bolts will pass through them as well. The gap in the wall sections should be in the middle of the crate.   Use large washers to help distribute the force of the bolt on the crate. For the corners attach the side walls (as opposed to end walls) so that the end of the crate is flush with the end of the wall section. The end wall will connect to the crate on that flush side.  You can overlap the end wall section with the side wall section to make sure no gap exists in the corner. 

 

6) Attach the goals

It’s best to bolt the goals to the walls to make sure they stay put.  You may want to put a backing behind the goal to prevent puck being thrown over the goal, but this is optional.

 

7) Lead

We used a lot of lead and it still moved a bit.  Try to put foam antislip sheet material like that you use for drawer lining or the like on the bottom of the crates.  I think we used 30-40 pounds of lead per crate and at every 16 feet and corners, it amounted to about 500 pounds (but that's opnly a dozen weight belts.  Don't use concrete or brick - they are not dense enough and don;t eigh much in the water.

 

If you have questions, please pose them to me at sean@seanavent.com or 415-377-2380.  I'll try to update this document with a FAQ.

 

Sean

 



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