Rule of Thumb: Extended Coverage vs. Standard?

4/24/2024

Is there a general rule of thumb concerning overall installation cost for standard coverage vs. extended coverage sprinklers?

That is, if I can use half as many extended coverage (EC) sprinklers, is the system going to cost significantly less or more?

Two examples come to mind:

Same branch pipe spacing, mostly the same pipe sizes, but - say - 10 EC sprinklers (at 18-ft) vs. 20 standard sprinklers (at 8'-6") on each branch line.
Fewer, but larger branch lines with EC sprinklers vs. standard coverage.

Thanks in advance.

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13 Comments

Pete H

4/24/2024 06:34:19 am

I don't think so. Mostly because labor rates aren't uniform. But that's where most of my savings from using Extended Coverage sprinklers over standard coverage really comes in.

Like pipe sizes aside, if you have enough of a change in head count that you think it will save your men a day of install, that will probably save you more than the difference in material cost.

But I can't tell you what the magic number is for heads per day your crews can install and even if their compensation is enough to make that hold true.

Dan Wilder

4/24/2024 08:05:35 am

Depending on the space overall, yes there is a break even/cost savings for using EC vs SC but that becomes a quantity justification that I can't put a number two. Installing 10 EC instead of 16-18 SC is not enough savings to justify the increased cost of the sprinkler, the calc to prove the design, and the field dealing with two sprinkler types and likely two fitting types (the RC's) for a short drop project, longer drops swing that needle faster.

Warehouse conversions to office space with drop ceilings is a great time to utilize EC's due to the 10' or less BL spacing and lots of outlets 8'-10' on center.

Some MFG and Storage configurations do well with the EC style (14x14) when available.

Most of my AHJ's do not allow EC layouts in shell spaces because of the future build outs that rarely have wide open spaces, but tend to be cut up office areas that swiss cheese the piping with mech tee's in order to get enough locations to supply the new pendent layouts. That also leans toward 2-3 SC sprinklers where one EC was and we have had systems not met hydraulic safety factors because of this.

Anthony

4/24/2024 08:06:32 am

I can think of at least a few times where I was able to 1/2 the number of lines we were installing by using EC heads in an ordinary 1 or 2 application. Happened in a pre-engineered steel buildings where the bay spacing was less than 20'-0.

As far as a rule of thumb, I'd say it's more to do with the type of building than the product. the simpler and more open a building the more useful EC heads will be. Those jobs also happen to be easier too so the margins will be slimmer if the job is an open bid.

Glenn Berger

4/24/2024 08:14:42 am

In addition to the above - Remember that EC sprinklers requires a greater starting pressure and therefore more pressure for system design / operation.

I avoid EC sprinklers as much as possible since the earlier the water flow alarm activates which allows for the occupant notification is initiated and fire department response starts to roll.

Heber Cuellar link

4/24/2024 08:17:12 am

Water supply should also be considered as EC sprinklers require higher pressures and flows to operate.

Jack G

4/24/2024 08:28:04 am

I ve been around and saw the introduction of EC heads.
I d chart the job costs thru the years.
What was a determining factor for choosing EC sprinklers was would they eliminate a significant amount of branch lines.
If the building did not lend itself to this, I ve found the material cost ( equal number of branch lines, and just stretching the heads on the line) would increase about 25-35%.
Warehouses hardly ever reduced the amount of branches when using EC s. Also check the listing as most ec s ( lower priced ones like EC 14 etc) are not listed for storage occupancies just OH-2.
Large drop ceiling areas are ideal.
As indicated above , tenant strip spaces in malls ,should not use them ( just final store configurations. )
If the store is cut up , the EC branches will not be large enough to accommodate standard spaced sprinklers—- using ec s at reduced spacing would overflow the pipe sizes.
Once, I received a contract for tenant fit out work in an outlet mall.
In a lot of cases I had to remove piping and make it larger ( change order) . Passed on to tenant store.
So I never use them in outlet malls either, unless specified- and size the pipe for 2 standard sprinklers for each etc.

4/24/2024 08:28:56 am

I would ask myself some questions along these lines to see if there's a price/schedule benefit to using extended coverage:
1. Uprights or pendents?
2. If pendents, do the arm-overs need hangers?
3. What kind of hangers?
4. How high is the roof?
5. How expensive and how readily available are the extended coverage sprinklers compared to the standard spray sprinklers (this probably doesn't impact a small project that much, but it can impact a large project)?
6. Are we limited on schedule in the field?

Another consideration is whether or not the client will be modifying the system in future or not. Extended coverage doesn't provide a lot of future flexibility for new walls and added rooms. For example, a parking garage isn't modified often, but a speculative office space may change tenants every few years.

Jesse

4/24/2024 08:50:47 am

I think there are too many variable to offer a specific and accurate metric re: cost savings in using EC vs. SC. That being said, over the course of a large project - i.e. a multi-story LH office building, significant cost savings can be had. ECs require a higher operating pressure so I don't even consider it if my water supply is poor.

Kris M

4/24/2024 09:34:08 am

I have had experiences where using EC sprinklers avoided potential damage to sprinklers and lines in certain spots.

I cannot remember the rule off by heart but it does allow for EC to be used in an area with SR around it. I know i may get flak for this comment but there are rules in NFPA 13 that allow this given the architectural layout etc..

But generally, using EC has to give savings and your water supply has to be able to handle it. Saving 1 line or saving 20...

Dave

4/24/2024 10:37:42 am

I agree with the usual suspects above, I lot of schools I have been involved in would have classrooms sized such that four EC's take the place of six or even nine standard coverage, and save a couple branch lines. But it is case-by case and sometimes it's a wash. Though not part of the original excellent question, when reviewing drawings, I always watch for improper use of EC's, in ceilings sloped greater than 2:12 slope, not smooth and flat, obstructions, etc., etc. And checking the particular listing of sprinklers which may have different coverages for SR vs. QR. (And yes, it is okay to have SR and EC in the same compartment.)

Dave

4/24/2024 10:44:35 am

(^Okay to have SC and EC, I meant^)

Danefre

4/25/2024 07:34:39 am

It depends on the building and the structure but typically i shoot for eliminating a 1/3 or 1/2 of the branchlines. Otherwise it's not worth it for us.

In FM projects and pendent layouts, it's worth using EC heads in smaller rooms since you can't use the small room rule.

EC-25's are our bread and butter in rack storage of plastics.

Mark Harris

4/26/2024 02:33:18 pm

Seems like most Target Stores are using EC layouts but as many above noted they are the first and maybe only tenant,

Pete's comment about labor is spot on. And the good old days of sch 40 threaded branch lines verses welded outlets on lightwall pipe have certainly changed heads per day expectations.

Rule of Thumb: Extended Coverage vs. Standard?

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