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Steel vs. Fibreglass Entry Doors in Ontario: Dents, Rust, Sun, Insulation, Price, and the One Wall Where Steel Is the Wrong Answer
Windows & Doors
Steel or Fibreglass: Both Are Foam Inside. The Skin Is the Decision, and the Sun Decides It.
A steel door and a fibreglass door are the same door with a different skin: a wood or composite frame around a slab of foam, faced with a thin sheet of steel or a moulded sheet of fibreglass. The foam does the insulating, so they are about equal there. The skin decides whether the door dents, rusts, warps in the sun, or takes a stain. Here is where each one belongs.
The numbers
$2,200steel, basic, installed
$3,500fibreglass with glass, installed
R-5 to R-6both, foam core, without glass
20 vs 30+years, steel vs. fibreglass, in weather
Steel
A 24-gauge (or thinner on cheap doors) galvanized steel skin bonded to a polyurethane foam core, with wood stiles and rails, and on better doors a composite bottom rail so the wood does not sit in water. Factory primed, painted on site or factory painted. It is strong, it is cheap, it is the right door on a side entrance, a garage man-door, a rental, a cottage, or anywhere under a deep porch.
What goes wrong: dents, from a bike, a boot, a hockey puck, and they do not come out. Rust, along the bottom edge where the paint chips and the salt sits; the composite bottom rail delays it. Heat: a dark steel door in afternoon sun gets hot enough to warp the skin away from the core on cheap doors and to cook the weatherstrip on all of them, and the warp lets air in at the top corner forever. Condensation on the inside face in a cold entry, where the steel is the coldest thing in the room.
Fibreglass
A moulded fibreglass skin, smooth or with a wood grain pressed in, over the same foam and frame. It does not dent, does not rust, does not conduct cold the way steel does, and barely moves in the sun. The woodgrain ones take a gel stain that fools people at three feet. It costs about $1,300 more installed in its ordinary form and more again with decorative glass, which is where most of a $5,500 door’s price is. It is the right door on a front entrance, a south or west wall, anywhere the door takes weather, and anywhere you want a colour other than white.
What goes wrong: not much. Cheap fibreglass skins can crack if struck hard in deep cold; the stain fades on a sunny wall in ten years and wants a recoat; the glass insert frames (the plastic surround around the lite) are the weak point on both materials and yellow or crack before the door does.
Side by side
| Measure | Steel | Fibreglass |
|---|---|---|
| Installed, 36 in., with half-lite glass | $2,900 | $3,500 |
| Insulation, no glass | R-5 to R-6 | R-5 to R-6 |
| Dents | Yes, permanently | No |
| Rust | Bottom edge, eventually | No |
| Full sun, dark colour | Warps, cooks weatherstrip | Fine |
| Cold inside face | Yes; condensation in a cold entry | Less |
| Finish | Paint | Paint or stain |
| Life in weather | 15 to 25 years | 30 years and more |
| Security | Equal; the frame and the lock decide it | Equal |
The frame matters more than the skin!
Both doors hang in a frame, and the frame is what a boot or a crowbar actually tests. A finger-jointed pine frame with a 1 in. strike plate screw is the same weak point on a $5,500 fibreglass door as on a $2,200 steel one. Ask for a composite or at least a solid-wood frame, a reinforced strike with 3 in. screws into the stud, and a sill that is composite or aluminum, not wood. The locks and security page is about this. A good steel door in a good frame beats a premium fibreglass door in a bad one on every measure but looks.
Solid wood, in one paragraph
Beautiful, heavy, and the only door that can be refinished for a century. Also the only door that swells in August, shrinks in February, and needs a coat of finish every few years or it checks and the glue lines open. Under a real porch, on the house it suits, with an owner who will maintain it: wonderful. On a bare south wall: no. $4,000 to $12,000 installed, and the install has to be perfect because the warranty assumes it was.
Where homeowners go wrong
- Dark steel, south wall. The one combination that fails on schedule.
- Premium fibreglass on a side door nobody sees. Steel, and spend the difference on the front.
- Judging by the slab. The frame, the sill, the strike and the weatherstrip are the door. Ask about them.
- Cheap glass insert frames. The plastic surround yellows and cracks in five years on a sunny wall. Ask what it is made of.
Questions people ask
Which is better, steel or fibreglass front door?
Fibreglass for a front entrance in weather or sun, or anywhere you want a colour or a stain. Steel for a protected door, a side door, or a budget. Both insulate the same.
Are fibreglass doors worth the money?
On the front of the house, yes: no dents, no rust, no warp, 30-plus years. On a door under a porch that nobody sees, the extra $1,300 is better spent on a multipoint lock.
Do steel doors rust in Ontario?
Along the bottom edge, where salt and chips meet, in 10 to 15 years on a cheap door and later on one with a composite bottom rail. Keep the paint on the edge.
Price both
The door calculator has steel and fibreglass as the first menu, with the glass, the lock and the wall underneath. Run it twice.
Sources and further reading
- JELD-WEN Canada: windows and exterior doors; the rough opening sheets and warranty documents are on the site.
- Keeping the Heat In: Natural Resources Canada. The free guide to windows, doors, air sealing and insulation written for Canadian houses.
