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Grayson County

Custom home builder in Grayson County

Grayson County has grown more than 13% since 2020, with net in-migration averaging around 3,600 people a year. Texas Instruments started production at its Sherman fab in December 2025 and GlobalWafers opened the same year, which is most of the reason the county is growing at all. Randy O’Brien has been building here since 1998, through the boom and through the 2008 crash before it.

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A custom home built by O'Brien Custom Homes near Grayson County, Texas
County population
~154,000
Growth since 2020
13%+
Net in-migration
~3,600 a year
Building here since
1998

The septic permit

Outside a city, the house waits on the county septic desk.

Anywhere in unincorporated Grayson County the build starts with the OSSF division, and they will not accept an application at all without a current 911 address and the property ID number off your tax statement. Nothing gets built until they issue an Authorization to Construct.

Before that, a licensed site evaluator or a licensed professional engineer has to evaluate the site and decide what the ground will take. If the soil will not support a conventional system, which on this clay is common, a registered engineer or a registered sanitarian has to design a non-standard one instead.

The county quotes five to seven days for the permitting itself once the paperwork is complete. What actually sets your timeline is the site evaluation, and the engineered design if you need one.

An aerobic system also carries a two-year maintenance contract that gets renewed thirty days before it lapses, for the life of the system, plus an Affidavit to the Public filed with the county clerk recording what the property is on.

The ground

What building anywhere in this county has in common

Almost all of Grayson County sits on Blackland Prairie soil. It is a heavy dark clay with a plasticity index in the 40 to 60 range, which swells when it rains and shrinks hard when it does not. That movement is what cracks slabs, and it is why engineered foundations, post-tension slabs and drilled piers are the norm here rather than an upgrade.

Outside the city limits you are on county permitting rather than city, and on septic rather than sewer. Conventional drain fields fail on this clay, so aerobic systems with spray or drip irrigation are effectively standard. Across this part of Texas they commonly run in the region of $10,000 to $20,000 depending on your lot and bedroom count.

  • Land inside twenty minutes of a town is still reachable here, which is the whole reason people move up from further south
  • You are roughly an hour north of DFW without paying metroplex prices for an acre
  • The semiconductor build-out has brought jobs that were not here five years ago
The Wester House, a custom home in Sherman, Texas

Nearest finished house

The Wester House

Sherman, Texas · 3 bed · 2.5 bath · 2,000 sq ft

Dark board-and-batten, cedar posts, 8-foot interior doors and custom casings throughout.

See the full gallery

Grayson County questions

What people building here ask.

What does the county need before it will even take my septic application?
A current 911 address and the property ID number from your tax statement. Without both, the application is not accepted.
How long does the county septic permit take?
Grayson County quotes five to seven days for the permitting once everything is filed. The site evaluation and any engineered design come first and are usually the longer part.
What if my land will not take a conventional system?
That is common on Blackland clay. A registered professional engineer or a registered sanitarian designs a non-standard or proprietary system, which then carries a two-year maintenance contract for the life of the system.
What does the county charge?
As of the county’s January 2024 schedule, $310 for a conventional system and $330 for any system that needs a maintenance contract, with a $50 surcharge if the application is filed on paper. Those are county fees, separate from the build.
Can I start work before the septic permit clears?
No. The county issues an Authorization to Construct and the build waits for it. When the system is in, they need a working day’s notice for the final inspection.

From his clients

We never had to chase him. If we called, he answered — and if he said he’d be there Tuesday, he was there Tuesday.

Hamid & Lisa S.O’Brien homeowner
Watch the interviews

Nearby, and worth reading

Randy O’Brien Ask Randy what your lot will need before you buy itHe has been through this permit desk since 1998 903.821.2482