When to Use Tree, Looped, or Gridded Systems?

10/7/2025

What is your method for determining whether to use a tree, looped, or gridded sprinkler system?

I would think that in most cases, a tree-shaped layout is sufficient, but I'm curious to your take as to why you'd choose otherwise.

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8 Comments

Pete H

10/7/2025 06:20:07 am

Typically when it's the difference between a pump or just being able to use street pressure. Pumps are pretty expensive.

If it is the difference between 2-1/2" Branch lines with uprights directly on the outlet by gridding/looping it or 3" or greater branch lines that would require pendants or candlesticks, the savings in both labor, coordination, and calculation can be worth it (or sometimes you just use 1.25 or 1.5 inch candlesticks or outlets off the branch to the head.)

Basically: When it makes sense to add this to the system installation to save a greater amount of money elsewhere on the system.

Pete H

10/7/2025 06:22:44 am

Additionally, as "Butler Buildings" will often have their mains split and go along opposite walls to feed branch lines that go along the roof pitch but don't grid or connect at the peak.

If something pops up later that requires a change in calculations (increased hazard to a room, a SNAFU means the backflow the bid engineer called out as a DCVA actually has to be an RPZ when the water company is involved), these systems are fairly easy to loop (just connect the two ends of mains where they're capped) or grid (connect the branch lines).

Dan Wilder

10/7/2025 08:07:39 am

Really depends...
·Building Layout
·Building type
·System type
·Riser location
·Water Supply
·Seismic considerations

Wet can utilize any of the above, dry & preaction can only use trees or loops (or a combination) but not grids so that choice gets made for you at times.

A center located riser can allow a tree layout much easier than a corner located one but really depends on the density requirements like Pete said for pipe sizing considerations.

Warehouses - Nearly always a grid, even narrow ones just to get water to the remote area efficiently.

Butler Buildings/Tents/Steeper sloped buildings with a high middle ridge - Grid - solves the drainage issue requirements (unless the lower sides are very accessible).

High rise buildings with center core - Loop system, or a hybrid loop/tree

Long Mercantile spaces (not big box stores) - Tree systems usually work best for these pending structure direction

Residential (single family)- Loops upon loops to make calcs work

Residential (Apartments) - main down corridor with a tree system within each unit (minimizes penetrations that have to be fire caulked). Sometimes grids work, may times the attic space is a tree, looped systems as needed pending calcs.

Parking Garages - Grids (wet) or Loops (dry) just due to the (typically) double tee construction. If it's a flat deck with minimal beams, tree's work at times but owners don't like main running down drive aisles

Goes on and on...

Anthony

10/7/2025 08:22:20 am

Trees are always the most pipe efficient.

Loops for dry systems only when Its absolutely necessary.

Grids for most of my storage or OH2+ hazards.

Also, I've seen grids and loops work well in health care where lots of the HVAC and med gasses is concentrated in halls. This generally leaves for an easier instillation running near the outer walls and branch lining in. Sometimes these can be grids but generally loops.

Glenn Berger

10/7/2025 10:19:00 am

The top 2 reasons are system geometry and hydraulics.

Jose Figueroa

10/7/2025 11:18:18 am

All requirements have been addressed; I emphasize the need for the lowest flow and pressure at the BoR that meet the system's demand, while also considering the cost of installation labor, parts, and maintenance. Does it make sense? I.e. Generally speaking, a hydraulically designed system is more efficient than a pipe schedule.

Franck

10/7/2025 11:22:17 am

Fully agree with statements above, in particular the summary from Glenn.
Dan provided the usual ones to answer these 2 requirements.
Dry and preaction may force you anyway to go to tree system (as gridded is not allowed and tree systems are usually easier to design for full drainage)

Jack G

10/7/2025 04:58:25 pm

Cost is King.
Anything you can eliminate to lower cost puts dollars in your pocket.
By evaluating the building fire sprinkler design to establish which is cost effective.
Pumps, supply and feed mains, pipe sizes with different orifices all will lower the system cost with a proper design.

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When to Use Tree, Looped, or Gridded Systems?

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