Garage floor concrete in Portsmouth NH - a slab that stands up to road salt
Is your garage floor pitted, flaking or cracked from years of salt and slush? We pour a new slab mixed and cured for winter.
- Fully licensed and insured.
- Free estimates at your property.
- We respond within 1 business day.
What does a new garage floor in Portsmouth involve?
The short answer: Garage floor concrete is the slab your car parks on, poured and then cured inside the garage. In Portsmouth, NH, it has to stand up to the road salt your car drags in all winter. How well the slab is installed and cured decides how well the surface resists scaling, which is the top flaking off in thin chips, so the work under the slab and after the pour matters as much as the pour itself.
Most calls start with a floor that's flaking, cracked or sunk near the door, or with a new garage that needs its first slab. The price mostly comes down to the size of the garage, whether the old floor has to be broken out and hauled away, and what we find underneath it. The schedule turns on the weather, because a cold-season pour needs protection planned in, and on whatever the city wants before we start. After I've looked at your garage, you get a written estimate with your own figure.
How can you tell your garage floor needs replacing?
Flaking and pitted surface
If the top of the floor is coming off in flakes or is pocked with little craters, that's usually salt and freezing water working on a weak surface. It tends to spread every winter, and a rough floor holds even more salty slush against the concrete.
Cracks and a sunken edge
Cracks that keep widening, or a slab that's dropped near the door or along a wall, usually mean the ground under it settled or washed out. The longer you wait, the more water gets under the slab, and the more we end up breaking out.
Water pooling on the floor
If meltwater off your car sits in puddles or runs toward the back wall instead of out the door, the floor was set with the wrong slope or has sunk. That standing salty water is hard on the concrete and on anything you store along the wall.
How we do garage floor concrete, start to finish
I start by looking at what the old floor sits on and where the water goes, because that's where I see most slab trouble begin. Our crew breaks out the old concrete, digs out soft fill from the subgrade, which is the ground the slab rests on, and packs a new base so the slab holds instead of settling with the dirt. We set the slope so meltwater runs toward the door, lay rebar where the slab needs it so the steel holds any cracks tight, and pour at a cooler part of the day so the top doesn't dry out weak and dusty. Then we finish the surface, cut control joints, shallow grooves that give the slab a place to crack where we chose, and let it cure, the wait while it gains strength before you use it. Cars bring road salt in all winter, so we plan the mix and the curing around that, and before we leave we'll show you an easy way to rinse the floor down. If the budget gets tight, the base is the last place I'd cut, because it's hidden on day one and a nice finish on a bad base usually cracks anyway.
Some jobs reach past the garage door. If you'd like color or a pattern on the floor or the walk up to it, our decorative concrete work covers that. When the garage is cut into a slope and the ground beside it keeps washing onto the slab, we build concrete retaining walls to hold that soil back.
Replacing a worn-out floor
This suits an older garage with a slab that's flaking, cracked or sunk. Tearing it out lets us fix the base and the slope that caused the trouble, instead of putting a new skin over the same problem.
First floor in a new garage
This suits a garage that's being built, where we can set the base and slope from scratch. Pouring before the building is closed in usually gives the truck and the crew more room to work.
What happens after you call about a garage floor?
Here's how a garage floor job goes with us, from the first call to the day you park on the new slab. Most of it is planning, so pour day goes the way it should.
- Step 01
Call or send us a message
Call (603) 956-1034 or use the form on this page. We'll get back to you and set up a time to come out.
- Step 02
I walk the garage with you
I come out myself, look at the old floor and where the water runs, and ask how you use the space, from a workbench to a plow truck. Then I send you a written estimate, so you see the number before anything is booked.
- Step 03
Sort permits and set a date
We sort out anything the city needs first, then pick a pour date with the season in mind. A late fall or winter pour can work, but the cold-weather protection gets planned before the truck is called.
- Step 04
Prep, pour, finish, clean up
Our crew preps the base, pours, finishes the floor and cleans up. Before we leave, we tell you when it's ready for foot traffic and for the car, based on the weather during the cure.
Garage floor concrete and Portsmouth's permit rules
The city's Inspection Office issues building permits for new construction and general renovation, including new garages, while floor repairs costing up to $3000 need no application. A full garage floor replacement can fall somewhere between those two, so we don't treat it as settled until we've asked. Before we set a pour date, we check what the building office needs and help pull together any sketches or site plans they ask for, and if your property sits in a historic or flood area, we plan around that review from the start. If the concrete truck or a pump has to sit on a Portsmouth sidewalk or other public way, the city's Inspection Department first needs to issue a Street Encumbrance Permit, applied for online through ViewPoint Cloud, so that goes into the date too.
We're based in Portsmouth and work in the cities around it on both sides of the Piscataqua River, in New Hampshire and Maine. A lot of the garages we see are older, with floors laid right over dirt and pitted from years of winter salt, and we find the same thing on jobs in Kittery and Dover. That's why I look hard at what's under the old slab, because the surface is rarely the only problem.
Get a written estimate for your garage floor
We respond within 1 business day to set up a visit, and I come out to look at the garage myself. The estimate is free, done at your property, and there's no pressure to book.
Why Portsmouth homeowners call Portsmouth Concrete Works
The owner writes your estimate
I come out to look at the job and write the estimate myself, and our own crew does the work with me on site for the pours. The person who walked your garage with you is the one there when the concrete goes in.
In business since 2017
I started this business in 2017 after years on other crews learning flatwork, the slabs, walks and drives that sit on the ground, along with foundations. We're known for the awkward jobs, like tight side lots and old slabs that need opening up, in older garages on both sides of the river.
Fully licensed and insured
Portsmouth Concrete Works is fully licensed and insured. With a crew breaking out concrete inside your garage, you shouldn't be the one carrying that risk.
Backed by our satisfaction guarantee
Our work is backed by our satisfaction guarantee. We go over the slope, the finish and the cure with you before pour day, so you know what you're getting before the truck shows up.
On a garage floor, the parts that count most are the base and the cure you won't see once it's done. Send us a message or call (603) 956-1034 to set up a visit.
Garage floor concrete questions from Portsmouth homeowners
How much does it cost to replace a garage floor in Portsmouth NH?
There's no honest number until I've seen the garage, so your price comes in a written estimate after a visit. Rebuilding a soft base, changing the slope so water runs out the door and protecting a cold-weather pour all add to it. A plain broom finish, a lightly brushed texture that gives tires and boots some grip, costs less than a decorative one.
What is the best way to pour a garage floor in cold weather?
Plan the protection in before the pour. Fresh concrete freezes if its own temperature drops below about 25°F, and frozen concrete loses strength and won't be durable, so it should be kept from freezing until about two days after it's placed. Snow and ice come out first, and anything the concrete touches should be above freezing, which can mean heating the ground under the slab. Fuel-burning heaters in a closed garage should be vented, for safety and because the fumes can leave the new surface dusty.
What causes a concrete garage floor to flake and pit?
Usually it's scaling, where salt and freezing water break up a surface that wasn't dense enough or wasn't cured well. Good quality, dense concrete with entrained air, tiny air bubbles mixed in that give freezing water room, lowers the chance of it. When you compare quotes, ask whether the mix has entrained air and how the crew will cure the slab.
Which deicers damage a concrete garage floor?
Ammonium sulfate, ammonium nitrate and magnesium-based salts destroy concrete surfaces, and cars can track magnesium-based road salt onto your slab. On a new floor, clean sand for traction is the better choice where you can use it. If you do use a deicer, pick one outside that list and go easy, because heavy use raises the chance of scaling.
Can I get a smooth trowel finish on an air-entrained garage floor?
It can be done, but ask how the floor will be finished first. One supplier's cold-weather guide links hard troweling air-entrained concrete with more than 3% air to blistering and other surface defects. We go over the finish with you at the estimate, along with how slick a smooth floor gets when it's wet.
Who do I call with permit questions in Portsmouth NH?
Call the city's Inspections Office at 603-610-7243, since they answer permitting questions. The Building Inspection Department reviews and approves building plans, so have the address ready and say whether it's a repair or a new garage.
Related concrete work around the garage
Decorative concrete
If the garage doubles as a workshop or gym, a colored or patterned surface can make the floor feel like part of the house, not a parking spot.
Concrete retaining walls
A garage set into a slope often has soil and runoff crowding the door, and a wall holds that ground back so the new slab stays clear.
Call or message us about your garage floor
Have the garage address ready and tell us whether it's a new floor or a replacement, so I come out knowing what to look for.