Consulting Structural Engineers

27201 Puerta Real #300
Mission Viejo, CA 92691
(949) 248-8588

Specializing in the structural engineering of wood framed structures with the objective of producing clear and concise structural plans and details saving time and money at the jobsite.

Specifically, over the past 15 years, Allen Designs has focused on residential remodeling, a sometimes challenging niche market.

Prior to entering private practice in 1987, Bill had ten years of engineering experience in Southern California with a diverse group of engineering firms. From petrochemical facilities to berthing piers for supertankers to second story additions to medical facilities, his diverse experience provides creativity in problem solving.

Bill prides himself in the fact that he recognizes that there are many ways to build a structure. To achieve a cost effective, structurally sound building, he believes a strong, interactive relationship must exist between all members of the design team.

Biography of T. William (Bill) Allen, P.E, S.E., M.S.C.E.

Position: Principal

Civil Engineer (C.E. 31405), California, 1980
Passed first time!
Structural Engineer (S.E. 2607), California,1984
Passed first time!
Professional Engineer (Structural) (30296), Arizona, 1996


Modifications of existing structures have always interested me. Compared to new buildings, remodels seem more of a challenge. This interest began when the city of Los Angeles instituted Division 88 in which the existing unreinforced masonry buildings were modified to survive an expected earthquake.

Currently, I am interested in Performance Based Design and I am moderately familiar with ASCE 41-17, for the seismic rehabilitation of existing buildings. I am currently seeking out these kinds of projects.


Bill Allen is directly responsible for engineering several hundred projects since going into private practice in June 1987. The scope of these projects includes residential remodels, custom single family residences, multi-family dwellings (apartments and hotels), commercial, institutional, medical and industrial projects. Some of the commercial projects have included retail centers, office buildings and restaurants.

The most notable projects are in four categories:

Residential Remodels
Bill originally “cut his teeth” on residential remodeling. Over the past several years, he has returned to his “roots”. He finds residential remodels challenging, interesting and appreciates that every project is unique. He has prepared engineering for hundreds of residential remodels from simple bearing wall removals to complex additions.
Wood Framed Hotels
Bill has designed several 3 and 4 story wood framed hotel structures in California, Utah, New Mexico and Arizona.
Medical Office Facilities
These projects include medical office buildings, remodels and equipment installations.
Commercial and Industrial Buildings
Bill has designed a large number of these projects consisting of wood framed, concrete masonry and tilt-wall construction and has provided excellent service in preparing structural documentation for smaller projects (5,000 SF to 30,000 SF) when the larger firms are unable to do so.


Materials: (in decreasing order of experience)

I perform structual design on a daily basis on wood framed structures, mostly residential and mostly remodels. These are challenging projects which are sometimes difficult to achieve a cost effective solution. I work closely with contractors and have a good relationship with most of them. It helps to respect their craftsmanship, which I do.
Concrete (foundations)
Most of the concrete I do today consists of modifying existing foundations to accommodate additional loads. This work can be challenging considering access and construction cost considerations.
Gravity framing, Ordinary Moment Frames (OMF) - even in high seismic areas!
Currently, most of the masonry work I do today consists of retaining walls and basement walls. However, in the past, I have designed several buildings consisting of masonry bearing walls (slender walls) and wood roofs.
Structural Concrete Slabs, Beams and Columns
I occasionally run into projects where the soil cannot be counted on to provide structural support. In these cases, I design structural slabs supported by grade beams on micro-piles.
Concrete Precast Tilt-Wall
I no longer design concrete tilt-wall buildings, but have done several in the past.

Skills and tools I use in my practice:

MS Excel
I use MS Excel on an everyday basis to prepare structural calculations. The last time I submitted "hand calcs" to a reviewing agency was 2008. Using Excel reduces errors and improves efficiency. After all, a point load on a beam is merely a reaction from another beam. Why not just link the two beams?
When I first went out on my own in June, 1987, I needed CAD software because I never produced drawings by hand. Sketches, yes. Drawings, no. I found an affordable drawing program called DesignCAD. I think it might still be available in the form of TurboCAD. It was fine for producing structural details. At the time, my clients would produce the structural drawings based on my markups and I would provide sheets of structural details. In 1990, I purchased a basic (i.e., cheap) version of AutoCAD, version 10, in order to read client's drawings. The next year, I purchased the full version and, by the time AutoCAD 12 was released, I was producing structural plans and details in AutoCAD. It's hard to believe that was more than 30 years ago.
Until last year, I was convinced I had the most efficient workflow for the analysis of the types of structures I do, which are mostly residential remodels. However, last year, I purchased a seat for RISA 3D with the goal of generating a structural model for the purpose of modeling the entire structure and merely having to input area loads. I've reached the point where the workflow is efficient enough to be cost effective on some projects. Using RISA 3D certainly aids in exposing secondary stresses and deflections not normally considered with "hand calcs". It's great for applying a concentrated, moving load at the top of a guardrail!
In 2008, I purchased a seat of Revit Structural. My goal was to entirely convert from ACAD to Revit. I used it almost exclusively for 8 years until 2016. However, I found that Revit, while a wonderful building modeling tool, is not (yet) a precise drafting tool suitable for structural detailing, at least in the types of projects that come across my desk (again, residential remodeling). I was not able to remain competitive in my market, and, while attempting to be competitive, the quality of my work (i.e., the amount of detailing I feel is necessary) suffered. With the availability of the subscription option from Autodesk, I can use Revit occasionally when I have a project where the architectural model is in Revit. That way, my client doesn't have to produce backgrounds in ACAD for me and I am able to cut sections so I can clearly understand the structural implications of the architectural design.
I have a moderate comprehension of HTML and CSS coding, enough to put this website together. It's an interesting enrironment and has changed quite a bit over the past 20+ years. I originally launched my website using MS Frontpage where I could get away with building a website with, literally, no knowledge of programming. Frontpage went by the wayside and I toyed with other programs such as Dreamweaver. The cost of the program and the investment of time to learn it adequately led me to using just basic HTML and CSS. My website isn't that fancy and the conveyance of my knowledge and experience in the field of structural engineering is simple to convey with basic HTML and CSS.