Structural Engineering and Construction Estimating

[MJB315]

I am trying to not to reach too far past this forum's purpose, but I often find while writing structural condition assessments that I am asked to provide a preliminary estimate on probably construction costs. How do other engineers prepare these estimates?

I am familiar with RSMeans, but I am always a little leery depending upon that alone. Is there a manual/textbook that engineers use to serve as a good primer on estimating?

"We shape our buildings, thereafter they shape us." -WSC

 

[kylesito]

Honestly, we have gotten to the point where we make sure it is understood up front that we won't be doing a cost estimate. The construction industry is way to volatile and there are too many "insider secrets" for lack of a better term. What ends up happening is that we do an "engineers estimate" which then becomes the basis for decisions it was never meant to provide confidence for...like financing decisions. To us, it's a lose-lose scenario. If we are conservative and high, the owner feels that the contractor is low bidding it or is stuck with allocated money that "must be spent". Conversely, if we are low then the bid is usually dismissed and the owner blames the design team for an expensive design!

On moderate to large projects, we have encouraged the owner to engage the services of an independent construction estimator. They are usually retired contractors that understand where to get good information. We also sell this as a benefit to the owner in that the estimator can, in some ways, bring successful elements of a design-build job to a design-bid-build team because the impact of the price of design decisions can be measured while the design is ongoing. Those that have had good design-build jobs in the past often see the benefit in this and bring the estimator on board.

For small projects, where there isn't a lot of "stuff" included, I use some basic cost figures:

4 laborer crew with foreman = appx $3,000 / day
Concrete = $300/cu. yd. - $500/cu. yd. installed
Steel = $1/lb fabricated plain steel
Wood = lowes website with the labor rate above
masonry = no real good value for this...usually means

These are very rough figures but usually get me close when it's a simple design.





PE, SE
Eastern United States

"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi

 

[bridgebuster]

What type of projects are you working on? What type of work are you involved with? DOT's have unit prices available; some also have manuals with production rates. There are bridge items that are common to building repair. Of course, discernment is necessary when using DOT average bid prices, or any average for that matter.

RS Means is OK; although I take their production rates with a grain of salt. There is no silver bullet to estimating. Textbooks generally present different methods of preparing preliminary estimates. The key in coming up with a good estimate, if you're going bottom up, is production rate; that establishes the labor and equipment costs.

If these are small jobs you're working on, try calling some contractors. Often they're happy to get the inside track on a job.

 

[charliealphabravo]

I ran into the same question recently for some very large Facility Condition Assessments. We had hundreds of task items that had to be estimated in order to calculate a Building or Facility Condition Index (BCI/FCI). My discovery was that RSMeans and Yardstick costing is better for new construction than for repairs/retrofits/remediation. We ended up projecting estimates, based mostly on our experience, that were within a fraction of an order of magnitude. You would then need qualifiers in the report explaining that detailed estimates will need to be prepared for each project on a case-by-case basis and that more invasive examination of the deficiencies are needed to narrow down the estimate.

 

[Ron]

RS Means has a variety of estimate packages available, but they all have to be used with judgment. I use the renovation/remediation package for my work (forensics), but I often supplement their data with historical bid data from the area. In my opinion, local and project specific data are more relevant and accurate.