Freeze damage does not always announce itself. A split casting that is obvious the moment the sun comes up is the easy case. The awkward ones are the failures that stay silent until the system is turned back on in March, by which time nobody connects the two events — so this list is worth walking once temperatures come back above freezing, not in spring.
Look at the domed top first — that is where a pressure vacuum breaker usually fails, because it is the most exposed part and the least tolerant of ice. Run a finger round the seam. Hairline cracks are easier to feel than to see, and a bulge in the casting counts as a crack whether or not it has opened yet.
The vertical below the assembly and any horizontal beyond it. Splits in PVC often look like a fine white line rather than a gap. This is the part most commonly missed, and it is the reason some replacements come back a second time.
Ice deforms small brass parts. A test cock that will not close, or a shutoff handle that has gone stiff or snapped its stem, is common after a hard freeze and is a cheap fix on its own — but a shutoff that will not close is a serious problem the next time something needs isolating.
Lift the lids. A box that stood full through a freeze can crack a valve body or a bonnet, and it is worth knowing about before the zone is next scheduled rather than after.
The fifth is the lawn itself. Ice heave in saturated clay can lift heads out of grade over a hard freeze, particularly where the ground was already wet. It is not damage exactly, but it is a coverage problem waiting for spring, and it is easiest to spot while the grass is dormant and short.
Slowly. A mainline that has been drained refills through empty pipe at high velocity, and snapping the isolation valve fully open sends a pressure slug through the system hard enough to break fittings that the freeze left alone. Crack the valve part way, let the system fill, then open it fully. It costs thirty seconds.
Then stand and watch the assembly for a full minute before going anywhere. Two failures only appear at this point:
A hairline in a casting can be invisible dry and obvious wet. This is why the assembly gets watched rather than glanced at, and why pressurising a system remotely or on a timer after a freeze is a bad idea.
Ice damages the poppet, the check disc or the seat without touching the body. The assembly looks perfect and either discharges continuously or fails to hold at all. That is a rebuild kit rather than a replacement, and it is a much better outcome than it feels like at the time.
Run each zone in turn and walk it. What to look for after a freeze specifically: heads standing proud of the grade that were flush in the autumn, cracked head caps, nozzles that have shifted, and any patch of ground that is wetter than the zone accounts for. A lateral that was cracked by ice heave leaks only while that zone runs, so it will not show up in any other way.
Anything on this list that turns into a repair is better booked in February than in May. The freeze wave has passed by then, the metro-wide queue has cleared, and irrigators have slack before the season starts. It is the cheapest fortnight of the year to have work done.
Once temperatures are reliably above freezing, and before another event is forecast. There is no benefit to rushing it during the freeze itself — with the system shut off, nothing is deteriorating — and there is a real risk in pressurising a system while another cold night is coming.
Entirely, and it is the most common outcome for a system that was drained and wrapped. It is also a reasonable outcome for a brief overnight dip. What is not plausible is an unprotected assembly surviving several multi-day events untouched, so if a system has never been winterized and has never had a problem, the honest reading is that it has been lucky rather than that it is immune.
All of it. Looking at a casting, lifting a valve box lid, opening a valve slowly and watching a zone run needs no tools and no licence. What comes after — the actual repair, or a judgement on whether a hairline is structural — is where a licensed irrigator earns the call.
In most Houston winters, yes, and that is the simplest safe answer. A dormant lawn needs very little, and a system that is shut down cannot be caught out by the next event. Turn it back on with the spring startup in March.
What to shut off, and what the repair options are.
The fuller March pass this checklist feeds into.
Ice heave, clay movement, and resetting heads properly.
The four steps that make this checklist uneventful.
February is the cheapest month of the year to book irrigation work in this metro. Say what the walk turned up and where the property sits.
Call (346) 605-8787 Describe the Problem
Houston