Insulation contractor in Gilroy - attics, walls and crawl spaces done in the right order
Thermal Gilroy Spray Foam Insulation is an insulation contractor in Gilroy, CA. We insulate and air seal attics, walls and crawl spaces in Gilroy homes and commercial buildings, fixing what needs fixing first so nothing gets buried.
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Gilroy houses and the ground under them
Gilroy is where we started in 2021, and our jobs here range from older houses near downtown with a few inches of tired insulation to newer subdivisions where the room over the garage never quite cools off. I hear from people who just bought an older place and want to know what's in the attic, and from property managers looking after commercial buildings around the city. The work carries on up the valley into Morgan Hill and south to Hollister, and the houses there raise a lot of the same questions.
The ground matters here too. Gilroy sits on expansive soil, the kind that swells when it's wet and shrinks as it dries, and over the years that movement can open gaps along the foundation and crawl space that let air and moisture in, so I check for those openings before anyone talks about insulation.
What we know from working in Gilroy
Permits here go through the City of Gilroy's Building Division, which issues them for renovation work, and whether your insulation job needs one is the division's call, so I ask before we put anything on the calendar. If it does, we pull the permit and set up the inspections, and that review decides when we can start. You can follow the review and the inspection dates yourself on the city's GO Permit portal. The city also requires every business working in Gilroy to hold a city business license, even one based somewhere else, so it's fair to ask any contractor for theirs. We're licensed and insured, and our work is backed by our satisfaction guarantee.
Price on a Gilroy job mostly follows how big the attic or crawl space is, how many inches are already up there and whether old insulation has to come out before anything new goes in. The schedule turns on any permit review and on doing things in order, with repairs and sealing first and insulation last, and your estimate gives you that plan and your own number. We drive the same roads out to San Martin and north into Santa Clara County, so if family a few miles up the road has the same drafty house, we can look at theirs too.
What do Gilroy houses need most from insulation?
Gilroy is rated Very High for termite damage risk, and that changes how I start a job here. Before we cover crawl space framing or attic wood, I look for damage and droppings and tell you what I find, because insulation packed over a termite problem just hides it until it's worse.
The other calls are the ones you'd expect. Upstairs rooms stay hot well into the evening, the room over the garage never matches the rest of the house, and floors over the crawl space feel cold all winter. On older houses I usually find settled insulation, open gaps around can lights and the attic hatch, and coverage piled deep in the middle and thin at the edges, which is backward. So we seal those gaps first, keep the eave vents clear so the attic can breathe, then bring the depth up evenly from wall to wall.
- Call (669) 205-6284
- Mon–Fri: 6 AM–11 PM, Sat–Sun: 7 AM–11 PM
- Gilroy, CA 95020
Insulation work we do in Gilroy
Spray foam insulation
When ductwork runs through a hot attic or the room over the garage won't hold its temperature, spray foam insulation seals air and insulates in one pass. It costs more than loose fill, so I'll tell you straight when your house needs it and when it doesn't.
Attic insulation
Most older attics we open in Gilroy have a few inches of settled material and thin spots along the edges. We measure what's there, fix the gaps and bring the whole attic up to an even depth with blown-in insulation, which is loose fill blown through a hose.
Insulation removal
If the old insulation is soaked, full of droppings or hiding damage, putting more on top just keeps the problem. We bag it out, clean up and let you see the bare attic before anything new goes in.
Crawl space insulation
Cold floors in a Gilroy house usually trace back to an open, uninsulated crawl space. We check the framing for damage first, then insulate under the floor so the rooms above stop losing heat through it.
Attic air sealing
Air sealing, closing the gaps before we insulate, is what stops the drafts around can lights, pipes and the hatch. We do it first on nearly every attic here, because insulation can't do much against air moving straight through it.
Retrofit insulation
Plenty of Gilroy calls come from people who just bought an older house and have no idea what's in the walls. We add insulation to finished houses through the attic and small openings, then patch up so you're not living in a remodel.
What happens when you call us in Gilroy
Call or send a message
You call and I usually answer myself, or I call you back and we pick a time for me to come out. I'll ask a few questions first, like how old the house is and which rooms bother you.
I look and write a plan
I go up in the attic and under the house, check the walls and note anything that needs fixing first. Then I walk you through a written plan, so you see the price and the order of work before you decide anything.
Our installers work in order
If the city requires a permit, the work starts once it's issued, and then our installers clear or repair what I flagged, seal the gaps and insulate last. If we're spraying foam, I'll tell you ahead of time when everyone needs to be out and when you can come back.
Walk the finished job together
I go over the finished work with you before we pack up, so you see what went in and where. If there's an inspection, I set it up and let you know the date.
Get a written insulation plan for your Gilroy home
Send the form and we'll reply within 1 business day to set up a free on-site estimate at your Gilroy house. I come out myself, look at the attic, walls or crawl space, and walk you through a written plan, with no pressure to book.
- Licensed and insured.
- Phone
- (669) 205-6284
- Location
- Gilroy, CA 95020
- Hours
- Mon–Fri: 6 AM–11 PM, Sat–Sun: 7 AM–11 PM
Questions about insulation in Gilroy
What happens in Gilroy if insulation work starts without a permit it needed?
The city can hold the project until it can move forward under current planning and building rules, which means a delay. If the job gets a red tag, the city's stop-work placard, the owner contacts the Building Division at 408-846-0451 to learn the next steps. We check whether a permit is needed before we schedule, so it doesn't come to that.
Which building codes apply to insulation work in Gilroy in 2026?
Starting January 1, 2026, the city enforces the current California building codes, called Title 24, which include the state energy code that insulation work follows. The city places Gilroy in Climate Zone 4 of that energy code, and the zone is part of what sets the requirements for a house here. When a job needs a permit, the inspection checks the work against those codes.
How much does it cost to insulate an attic in Gilroy?
Your price comes down to the size of the attic or crawl space, how many inches are already up there and whether the old material has to come out first. Spray foam costs more than blown-in loose fill, air sealing adds a little up front but makes the insulation do its job, and a tight crawl space or a hard-to-reach room over the garage takes more labor. I'll give you your own number in a written plan at the estimate.
How long does insulation take, and when can my family and pets go back inside?
With blown-in insulation you can usually stay home while we work, but with spray foam everyone, pets included, stays out until the re-entry time has passed, which is the wait the foam's maker sets before it's safe to come back in. How long we're in your attic depends on its size and on what has to come out first. I'll tell you the work days and the hours away before we book anything.
How do I know if my Gilroy attic needs more insulation?
Look at how many inches are up there and whether the depth is even, because thin edges, a matted look or bare spots usually mean it's time. Upstairs rooms that stay hot, a draft under the attic hatch or a climbing power bill point the same way. If you'd rather not climb up there, I'll measure it when I come out and show you what I found.
Is spray foam or blown-in insulation better for a Gilroy attic?
For most Gilroy attics, sealing the gaps and topping up with blown-in loose fill is the better buy. Spray foam costs more and seals air while it insulates, so it usually wins when your ductwork runs through the attic. Closed-cell foam, a dense foam that blocks moisture, earns its place in damp spots like some crawl spaces.
Call about your Gilroy house today
One look at your attic or crawl space tells you whether it needs a simple top-up or a cleanout first, before you buy any new insulation.
Request an estimateCall (669) 205-6284