MECHANICAL ENGINEERS
If Design Professionals are interested in specifying the Mudskipper System on a project, we recommend they email and/or call Tyler McFarlin with McFarlin Construction Services at jacktylermcfarlin@gmail.com (Mobile: 915-276-5416). Tyler will be able to provide guidance on economical specification and design. Tyler can even provide a draft set of shop drawings showing the details of the Mudskipper System. The cost of McFarlin Construction Services providing technical assistance and preparing the Initial Mudskipper Plan will be paid by VoidForm. If the project will utilize the Mudskipper System, this cost will be included inVoidForm's total cost of Mudskipper System components for each project.
Customizing for each project, Tyler will provide suggested specifications and typical details for drawings that fit each project. Because the Mudskipper System isolates the plumbing, the sequence of installation is different than with non-isolated void systems and it is important that the Structural Engineer provides companion specifications and typical details to the Mechanical Engineering specifications. If the structural elements associated with the Mudskipper System are not specified, such as the design of soil retaining walls, VoidForm will not have the direction is needs to bid a project. Refer to the Structural page on this website for additional information.
It is essential that Mechanical Engineers understand that conventional wisdom associated with economical design of under-slab plumbing layout does not always apply with the Mudskipper System because the Mudskipper System isolates the plumbing. And, it is essential that Mechanical Engineers understand that VoidForm will need to issue Minimum Required Order drawings (essentially shop drawings) BEFORE PROVIDING QUOTES TO BIDDERS. A poorly-designed layout, poor coordination between engineering disciplines, and issuing designs or significant modifications by addenda can all cause significant increases in the cost of the Mudskipper System on a project. Therefore, we recommend contacting Tyler in the Design Development phase before a foundation type, an initial under-floor plumbing plan and site utility layout are developed. We also recommend allowing Tyler to perform a review of the drawings when the Architect is perfoming their final Quality Control.
Some general rules of thumb for under-slab plumbing design using the Mudskipper system in many commercial buildings with a design vertical movement of the expansive soil subgrade below being 6 inches or less:
Specify a flexible expansion joint be located inside a vault with a manhole for access at each plumbing egress point. Many Building Officials require that access be provided to inspect, maintain and replace flexible expansion joints over time. Specifying the vault on the original drawings avoids unnecessary costs if this is not in your original bid documents and the Building Official requires it be added after a Contractor is under contract with a defined scope and cost.
Try to limit the length of plumbing to about 175 feet, measured along the plumbing from each plumbing egress point to the furthest point in the distribution of plumbing. The shorter the plumbing length, the more shallow the plumbing trenches can be, but making the distribution systems too short requires more vaults which can increase the cost. There is a balance of these two extremes that provides more economy.
Set the elevation of the egress from each vault no higher than an elevation which the Geotechnical Engineer indicates will reduce the design vertical movement to approximately 3 inches, which typically allows the pvc version of the flexible expansion joint that is much lighter (easier and more economical to install) and corrosion resistant (potentially requiring less mainteance than the epoxy-coated ductile iron version of the flexible expansion joints) and allows a much smaller vault.
Identify on the plumbing plan the highest flow line elevation permitted by code at key locations (e.g. extreme ends of the distrubution system and at stack vents or any other points of interest where the flow line needs to drop below an interpolated line defined by FL's at other points), exclusive of p traps. This allows the initial set of shop drawings to be created more efficiently, allowing more time to coordinate any changes in the plumbing design that may make the system more economical. If this is not done by the Plumbing Designer, each Plumber during bidding may have different opinions on what is the highest elevation permitted by code at each location.
At locations where plumbing interrupts Mudskipper Walls, it is best to keep the interrupting plumbing generally perpendicular and to keep 45 degree segments at transitions as short as possible. These measures will keep the Mudskipper Walls straight, avoiding unnecessary "doglegs", and keep the spans of the Mudskipper Decking and Mudskipper Decking Supports standardized.
Allow the clear dimension between plumbing supports to be 4'-0" maximum rather than requiring the center of the plumbing supports be 4'-0" so as to avoid the need to strip the edges of each sheet of 4'-0" wide Mudskipper Decking. This makes the geometric placement of voidforms and Mudskipper Decking more standardized and economical.
Tyler can provide technical assistance, especially where it is required that the Mudskipper System accomodate a greater design vertical movement.