Garage Door Headers & Lintels: What Holds the Weight Above Your Door and the Signs Yours Is in Trouble

Introduction

Almost every part of a garage door gets talked about. Springs break, cables fray, rollers wear out, openers stop working. The one part nobody mentions is the piece of structure directly above the opening, and it is the piece everything else depends on. Your springs pull against it. Your opener pushes and pulls against it. The top of the door closes against it. The brick above your garage sits on it. It is called the header, and on a masonry wall the steel angle carrying the brick across the opening is called the lintel.

When it is sound you will never think about it once in thirty years. When it is not, the symptoms show up everywhere except where the problem is: a door that will not stay in balance, a gap along the top edge, lag screws that loosen every few months, an opener that shudders as it starts, or a crack stepping its way up the brick beside the opening. Homeowners call us about the door. The door is often fine.

This guide explains what the header and the lintel actually are, what hangs off them, how to tell from the driveway that yours is in trouble, which parts of the job a garage door company can do and which parts belong to a carpenter or an engineer, and what the work realistically costs in London and southwestern Ontario in 2026. Every external link below was checked against a live page before publication.

Header, Lintel and Head Jamb: Three Different Things

These three words get used as though they mean the same thing, and the difference matters as soon as money is involved, because they are repaired by different trades.

The header

The header is the structural beam inside the wall that spans the garage opening and carries the load from above: the wall itself, the floor or roof framing resting on it, and in a two-storey house part of the room over the garage. In most London houses it is built-up dimensional lumber, often two or three two-by-tens or two-by-twelves nailed together with plywood between them. In newer builds it is frequently an engineered beam, a laminated veneer product that looks like very dense plywood stood on edge. You cannot see it. It is buried in the wall above the opening, behind drywall on the inside and brick or siding on the outside.

The lintel

The lintel is the piece that carries the masonry veneer across the opening on the outside. On a brick house it is almost always a galvanized or painted steel angle, an L shaped bar with one leg under the first course of brick and the other leg against the wall behind. Stand in the driveway and look at the top of your garage opening: the thin dark line running the full width just under the brick is the lintel. It carries brick only. It is not the header, and it is not holding up your house.

The head jamb

The head jamb is the finished wood across the top of the opening on the inside, the piece the top of the door closes against and the piece the weather seal is nailed to. It is trim and mounting surface rather than structure, though it is fastened to the structure behind it. Our guide to garage door frame rot covers what happens when that wood decays, which is a far more common problem than a failed header.

Everything That Hangs on the Header

The reason a garage door company cares about the header at all is that three of the highest-load connections in the whole system are fastened into it.

The spring anchor bracket

On a torsion spring door, the bracket in the middle of the wall above the opening is the fixed point your springs pull against. Every bit of torque the springs produce is trying to twist that bracket off the wall, and it is only lag screws into wood that stop it. This is the most demanding connection above your door, which is why the spring anchor bracket is one of the few parts where the wood behind it matters more than the steel itself.

The opener header bracket

The opener rail is anchored to a bracket bolted above the door, and every time the motor strains, the rail is pulling on that bracket. An opener fastened into soft or split wood will shudder, clatter and eventually tear out. Our guide to opener mounting hardware explains how the three mounting points share that load.

Track hardware and the counterbalance

The horizontal track angles, the end bearing plates and, on wider doors, a centre bearing bracket are all fastened into the same band of wood. The forces are lower than at the spring anchor, but they are constant, and they are cycled up and down every single time the door runs.

Add it all up. A typical insulated double door is a few hundred pounds of dead weight, with a counterbalance system storing enough energy to lift it, and our guide to how much a garage door weighs gives the ranges by size and material. All of that lands on roughly four feet of wood above the middle of your opening.

How Big Does a Garage Door Header Have to Be?

This is the question we are asked most often and the one we cannot answer over the phone, because the honest answer is that it depends on the span of the opening, what is bearing on it from above, the roof snow load for your area, and the species and grade of the lumber. A 9-foot single opening in a bungalow and a 16-foot double opening with a bedroom over it are not remotely the same beam.

In Ontario, header sizes for houses come from the span tables in the building code, and anything outside those tables needs a design from a professional engineer. If you are altering an opening rather than simply replacing a door, that is a building permit matter, and the Ontario Building Code is the governing document. Our article on whether you need a permit to replace a garage door in Ontario explains where the line falls between a like-for-like replacement and a structural alteration.

What the industry does publish

The Door and Access Systems Manufacturers Association sets out the mounting surfaces a door needs in its technical data sheet on wood header and jamb detail guidelines. It names the four things the structure has to support: the weight of the door, track and spring assemblies, the torque generated by the counterbalance system, wind load forces, and the vibration caused by the door operating. Where a separate wood jamb or a torsion spring pad is installed for the door to fasten to, the recommended minimum size is a two-by-six, and the spring pad must be free of cracks, splits and knots around the fasteners. It also says plainly that the local building official is the sole and final determiner of whether a particular application is acceptable.

Note what that document is and is not. It describes the wood a door is mounted to. It does not size the structural beam. Those are two separate questions, and they are answered by two different people.

The drywall problem

In a finished garage the header is behind drywall, and that causes real trouble on retrofits. DASMA's sheet on drywall surfaces and the mounting of garage door hardware is blunt about it: if possible, do not mount to drywall at all, cut the drywall away. Where that is not practical, the alternatives are a wood buck anchored over the drywall, or lag screws long enough to bite properly into the wood behind, located with a stud finder rather than guessed at. A lag holding nothing but half an inch of gypsum will pass a quick tug on installation day and let go six months later.

Six Signs Your Header or Lintel Is in Trouble

None of these needs a ladder. All of them can be checked from the floor or the driveway in about ten minutes.

1. A dip in the line above the door. Stand back in the driveway and sight along the bottom edge of the brick or the trim above the opening. It should be dead straight. A visible sag in the middle, particularly on a double opening, is the sign that deserves professional attention soonest.
2. Stair-step cracks in the brick beside the opening. Cracks that climb the mortar joints diagonally away from the corners of the opening are telling you that something above the opening has moved.
3. Rust and a widening joint under the brick. A rusting steel lintel expands as it corrodes and lifts the brick sitting on it. Look for a mortar joint that has opened along the top of the opening, or brick that looks pushed up at one end.
4. Lag screws that will not stay tight. If the spring anchor bracket or the opener bracket needs retightening every few months, the fastener is not the problem. The wood it is biting into is.
5. New daylight along the top of the closed door. If the top seal used to touch and now shows light across the middle, either the door has dropped or the head of the opening has moved. Both are worth a look.
6. An opener that shudders at the start of travel. A bracket moving a few millimetres under load makes a distinctive thump as the door starts. It is usually a mounting problem, occasionally a structural one.

Why Rusting Lintels Are a Southwestern Ontario Problem

Steel lintels fail here for reasons that have little to do with garage doors and everything to do with our weather. Water gets behind the brick veneer, runs down the backing and reaches the lintel. In a climate that crosses the freezing point dozens of times between November and March, that water sits, freezes, thaws and sits again. Add the salt spray thrown off a London driveway all winter, and a lintel that was painted thirty years ago has very little left protecting it.

As the steel corrodes it grows. Rusted steel takes up several times the volume of the sound steel it came from, and since the brick above it is not going anywhere, the expansion lifts the masonry instead. That is why the first visible symptom is usually a mortar joint opening along the top of the opening rather than a stain. It is a slow problem, measured in years, but it does not reverse on its own, and it eventually loosens brick above a door your family walks under every day.

If you are already replacing the door, that is the cheapest moment to deal with it, because the opening is clear and the trim is off. The same logic applies to a rotten head jamb, which is why we look at that wood when we quote rather than discovering it on installation day.

What a Garage Door Company Can and Cannot Do

Being straight about this saves everybody time.

What we handle

We replace rotten head jambs and side jambs, fit new mounting wood or a proper spring pad where the existing wood will not hold a fastener, re-anchor the spring anchor bracket and the opener bracket into sound material, re-seal the top of the opening, and tell you what we are seeing behind the trim once it is off. That covers the large majority of what gets called a header problem.

What belongs to another trade

Replacing a rusted steel lintel means supporting and rebuilding brick, which is a mason's work. Replacing or reinforcing a structural header means temporary support for the wall above while the beam comes out, which is a carpenter's work, and if the opening is being widened or the beam falls outside the span tables it needs an engineer's design and a permit first. We will say so on the quote rather than fastening new hardware into something that should not be carrying it.

One thing we will not do is install a door onto a structure we do not trust. A garage door is the one thing in a house that stores enough energy to hurt somebody, and the point where that energy is anchored is not a place to be optimistic.

Widening an Opening or Fitting a Taller Door

Two renovation plans run straight into the header, and both are worth understanding before you commit.

Going wider, for example turning two single openings into one double, replaces the header outright with a longer and much deeper beam, and usually adds studs at each side to carry the extra load down to the foundation. This is structural work, it needs a permit in London, and the cost of the opening generally dwarfs the cost of the door going into it.

Going taller, from a 7-foot to an 8-foot door, is the one that surprises people. The opening gets taller by moving the head of the opening up, which can mean raising or rebuilding what is above it, and the ceiling then has to have the clearance for the track. Our guide to headroom, backroom and side room explains the clearances involved. On many London garages the honest answer is that the ceiling, not the door, is the limiting factor.

How to Protect the Header You Have

Most header damage is slow, and most of it is avoidable.

• Keep the door balanced. A door the springs no longer hold properly throws its weight onto the opener, and the opener throws it onto the header bracket. Balance takes two minutes to check on a normal service visit.
• Deal with water early. Keep the eavestrough above the garage clear, keep the trim above the opening painted and caulked, and look along the lintel line once a year.
• Do not let hardware stay loose. A bracket that moves under load wallows out its own fastener holes, and a hole that has been wallowed out will not hold the next lag either.
• Treat rot as structural, not cosmetic. Wet, soft wood above an opening is not a painting problem. It is the mounting surface for your springs.
• Have the door looked at once a year. A multi-point tune-up runs $120 to $220 in London in 2026 and includes checking every one of those fasteners.

What It Costs in London in 2026

Our service call is a flat $85, and it is absorbed into the repair if you go ahead with the work on the same visit. That covers coming out, taking the trim off where it is needed, and telling you what you are actually dealing with.

Beyond that we deliberately do not publish a price range for header and lintel work, because it is carpentry and masonry rather than a catalogue part, and the spread between re-anchoring into fresh wood and rebuilding a beam is enormous. What we can promise is a written quote before anything starts, no deposit, and a clear statement of which parts of the job are ours and which need another trade. Where the structure is sound and the problem is the mounting wood, it is normally a single visit.

If the door itself is also near the end of its life, say so when you call. Doing the jamb, the mounting wood and the door together costs far less than doing them separately, because the opening only gets stripped once.

London's Trusted Garage Door Experts Since 2009

AA Advantage Doors has been installing and repairing garage doors in London, St. Thomas, Ilderton, Komoka, Strathroy, Dorchester and the surrounding area since 2009. If the wood above your door is soft, your brackets will not stay tight, or you have noticed the brick above the opening moving, we will come and look at it properly and tell you honestly whether it is ours to fix or whether you need a mason or a carpenter first.

There is no deposit, we quote before we start, and every bit of our workmanship carries a four year warranty.

Frequently Asked Questions

Is the header the same thing as the lintel?

No. The header is the structural beam inside the wall carrying the load from above. The lintel is the steel angle on the outside carrying the brick veneer across the opening. A failing lintel is a masonry problem. A failing header is a structural one.

Can a garage door pull the header down?

In normal use, no. A properly sized header is carrying the wall and the framing above it, and the door is a small fraction of that. What a door can do is destroy the connection: lag screws tearing out of split or rotten wood, or hardware mounted to drywall rather than to structure. That is the realistic failure, and it is a mounting failure rather than a collapse.

The brick above my garage door is cracking. Is that urgent?

Not usually urgent, but it should not be ignored either. Fine stair-step cracks that have not changed in years are common in older London houses. Cracks that are getting wider, brick that has visibly lifted, or any sag in the line above the opening should be looked at by a mason or an engineer before the next winter.

Do I need a permit to change my garage door?

Swapping a door for one the same size in the same opening does not. Changing the size of the opening, altering or replacing the header, or removing structure does. Our guide to garage door permits in Ontario sets out where the line falls and what the City of London expects.

The installer says my header is not strong enough. Is that an upsell?

It can be checked. Ask to be shown the wood rather than told about it. Soft, dark, crumbling material, a fastener hole that has opened out into a slot, or a bracket mounted into nothing but drywall are all visible once the trim is off. A company that will not show you what it is quoting on is a company to be careful with.

Can the spring bracket simply be moved to a better spot?

Not freely. The spring anchor has to sit centred and square to the shaft, so there is very little room to slide it sideways. The usual answer when the wood will not hold is to fit a proper spring pad across the opening, so the bracket is fastened into sound material in the right position.

How long should a header last?

Indefinitely, if it stays dry. Headers are not wear parts, and the ones we find in trouble have almost always been wet for years because of a gutter, a flashing detail or a trim board that was never maintained. Water is what ages them, not the door.

The Bottom Line

The header is the quietest part of your garage door system and the one with the least margin for being wrong. It carries the wall, it anchors the springs, and it is what your opener strains against several thousand times a year, all while being completely invisible from either side of the wall.

You do not need to know what size beam is in there. You need to know the handful of signs that say something above the opening has moved: a dip in the line above the door, brick that has lifted or cracked at the corners, fasteners that will not stay tight, or wood that goes soft under a thumbnail. Any one of those is worth a look, and all of them are far cheaper to deal with before a door goes back onto them than after.