Steel construction company in Manchester, NH, for steel work in buildings that are already standing. We reinforce joists and beams, set frames for rooftop units and coolers, and put in lintels and house beams. All of it goes in to the engineer's specs, because the building is already carrying a load. Call (603) 660-2011 with the scope, or send the drawings that show where the new steel goes.
Steel Construction Company: the work, page by page
A steel frame is drawn for the loads the engineer knows about on the day it's designed. Buildings don't stay that way, though.
A renovation puts new mechanical units on the roof. A floor takes heavier equipment, a store adds a cooler out back, or an owner opens up a wall. So each time, the steel has to change with the building.
That's the work on this page. We add steel to members that already carry a load. Or we set new steel inside a structure that still has to stand. General contractors and steel companies bring us in for it, mostly on commercial jobs, with some residential.
An old building may not match its old drawings, so the engineer checks what's really there before drawing the fix. Then the specs decide. We weld and set what they show, and structural inspectors check the work in phases and again at the end.
None of it gets subbed out. So you call one number for the joists, the roof frames and the cooler steel.
Working in a standing building also means welding next to finished ceilings, stock or roofing. That's hot work, so the hot work permits and the site safety plan come before the first weld. We handle both. The page on commercial welding shows how that works inside a store.
For the building owner, the worry is usually the business, not the steel. That's why we work around the schedule you and the general contractor set.
New buildings are the other half of the trade, since we erect those frames and weld their connections too. That side of the work sits with all our structural steel work on the main page.
A beam that carried the old roof just fine may be too light for the new load. Pulling it out would mean holding up everything it carries on temporary posts while the old steel is cut free. So the engineer usually adds steel to the beam that's there instead, and the frame stays put.
In 2025 a steel company brought us in at the Rockingham mall casino in Salem, NH. The job was beam reinforcement: T-beams stitch-welded onto existing steel.
A T-beam is a steel section shaped like the letter T. Stitch welding fixes it to the old beam with short welds spaced along the joint, rather than one long bead. Once the T is on, the two work as one. That way the beam takes the load the engineer calculated without leaving the building.
We welded what the engineer's details called for, and no more, because the engineer has run the numbers. The welder hasn't.
Bar joists, the open-web steel joists that hold up many flat roofs, work on the same logic. A roof full of them was sized for that roof as it was first drawn, with nothing extra on top. So when new rooftop units go up there, the engineer may call for steel on the joists.
That's the job behind strengthening existing roof joists.
Rooftop units, or RTUs, heat and cool a store from above. They can't rest on the roof membrane, so they sit on steel. Dunnage lifts a unit on posts and beams. Grillage is a grid of beams that spreads its weight over several joists.
We've set grillage and RTU frames on a supermarket renovation in Massachusetts, where the general contractor brought us in. Under them, the joists got steel added too, because each unit's load had to reach steel that could carry it.
Which support a unit gets is the engineer's call. Each type is laid out under dunnage for rooftop units, from posts and grillage to platforms and pipe supports.
Coolers are the other frame on store work. At another supermarket in Massachusetts, the GC brought us in for the columns and beams of an outdoor cooler frame. The steel has to stand before the box goes up, so it comes early in the job. The page on framing for walk-in coolers covers how a frame like that goes up.
A canopy frame is the steel that carries a roof over an entrance, a loading area or a drive lane. It's a small structure, but a real one. Columns stand on footings, beams run across the top, and the drawings may tie it back to the building.
Because a canopy is open on most sides, snow and wind work on it directly. So the base plates and the connections matter as much as the beams.
We set and weld a canopy like any other frame, working connection by connection from the drawings.
A lintel is the steel over a door or window that carries the wall above it. In brick or block it's usually a steel angle, resting on the masonry at each end.
Cut a new opening and the brick above needs one to sit on. Rust is the other reason. A rusted lintel swells and pushes the brick apart, so it has to be replaced.
Who sizes them and which finish lasts is covered under lintels over doors and windows.
Houses are the smaller part of our work, but the steel follows the same rules. A new main beam in the basement gets sized by the engineer first. So does a beam that replaces a bearing wall. We install it to that plan, and steel beams in houses explains what drives the cost.
“I have worked with 603 welding on many different jobs. Highly Recommend any jobs that involves structural steel”
Structural steel is made and graded to carry a known load. It comes as rolled shapes and plate in ASTM grades, like A992 wide-flange beams and A36 angle. Because the grade fixes the strength, the engineer can size each piece. Plain bar or tube may not meet those grades, so it can't be counted on the same way.
Yes, the work follows the engineer's specs, down to where new steel lands and how big each weld is. The structural drawings come with the bid invite. On a renovation, we walk the job with them, so the price matches what's drawn. If nobody has drawn the fix yet, call an engineer first, because we weld to a design.
Start with a call to (603) 660-2011 about what the renovation changes. It might be a unit on the roof, a cooler out back or a wall coming out.
Then send the drawings or the engineer's details, with the job location and your schedule. Pricing it costs you nothing: on paper when the scope is big, over the phone when it's small.
