Seal the Joints Before December, Not After April

Driveway maintenance advice is mostly written for cold climates, where it is about protecting concrete from freeze-thaw damage and deicing salt. Neither of those is the main event in Conroe.

Here, the maintenance that matters is much duller and much more effective: keeping water from getting underneath the slab.

Why water under the slab is the whole game

The soils around Montgomery County are sandy at the surface over sandy clay below. Sand is easy to move. Water running into a joint, down through a crack, or under a slab edge carries fine material with it, and over a few seasons it opens a void.

Once there is a void, the slab is bridging rather than bearing, and bridging is what cracks concrete. Every settled panel is a void that was allowed to develop.

Add the seasonal element and the timing becomes clear. USDA records a perched water table on the Splendora soil series, mapped across this county, sitting fifteen to twenty-eight inches deep from December through April. Water going into a joint in January has somewhere wet to go and stays there. Water going into the same joint in August largely does not.

Which is why this is a job for autumn.

What to seal

Control joints. The lines cut or tooled into the slab, deliberately, to control cracking. They are the intended route for water to get in, which makes them the intended route to seal.

Tight cracks with no step. A crack that is narrow, has no vertical difference across it, and has not changed over months is a maintenance item. Sealing it keeps water out.

Isolation joints. The full-depth separation where the slab meets the garage, the house, or a step. These take movement, so they need a flexible sealant and they need checking, because they are the most likely to have opened.

The slab edges. Not sealed as such, but this is where to look at where water runs. A downspout emptying beside a driveway edge is a machine for keeping that strip of soil wet, and no amount of joint sealant compensates for it.

What not to seal, and what sealing will not do

A crack with a step across it. If one side has dropped, the ground has already gone and sealant does nothing about it. That is a lifting or replacement conversation, covered in the repair, lift, or replace guide.

A crack that is actively widening. Measure it, date it, and watch it before filling it, because filling it hides the evidence.

The whole surface, necessarily. Whole-slab sealers are a separate question from joint sealing. Decorative concrete is normally sealed as part of the system and needs a resealing cycle. A plain broom-finish driveway can go a long life without one, and selling a surface sealer as though it will fix a slab that has moved is not honest.

Getting the joint prepared properly

The single most common reason joint sealant fails is that the joint was not clean and dry when it went in. Surface-cleaning a joint that is packed with dirt three-quarters of the way down leaves the sealant bonded to dirt.

Backer rod is the other thing people skip. Pressing foam rod into a deep joint before sealing means the sealant forms a shallow band bonded to the two sides of the joint, which lets it stretch and compress as the slab moves. Sealant poured to fill a deep cavity is bonded on three sides, cannot stretch, and tears.

Timing it around the weather

A dry stretch with a day or two of no rain forecast is what you want. Morning is better than afternoon, because a slab that has been baking in full Texas sun is hot enough to affect how some sealants set, and because joints hold overnight moisture that needs to be gone.

How often

Less often than you would think for a sound slab, and it is easy to check rather than guess. Walk the drive once a year, look at whether the sealant is still bonded on both sides and still below the surface, and redo the sections that have failed rather than all of it.

The honest value proposition

This is not a glamorous job and it does not make a driveway look new. What it does is stop the specific mechanism that turns a fine driveway into a settled one on this particular ground, and it costs a fraction of anything else on the list.

More on why the ground here behaves this way in the soil and subgrade guide, and on the crack pattern it prevents in why Conroe driveways crack along the edge.