Can You Fit Steel Doors to Standard Doors Frames?

Short answer, sometimes, most times it will involve some adjustments. Steel doors are much heavier, and are rigid, and are made to different tolerances than timber or uPVC doors. Residential, and lightly commercial, frames are built to be more relaxed. Steel door requirements firm up those tolerances, and this is where complications arise.

What most standard frames are actually built for.

Most door frames in UK properties, especially in residential ones, are built to house doors that weigh anywhere between 20 to 40 kilograms. Internal doors made of hollow core materials, weigh towards the lighter end. Solid timber external doors, sit at the heavier end. Steel doors are a completely different case. A basic steel security door for a residential property will often weigh 60 to 80 kilograms. More commercial grade and fire rated versions can be over 100 kilograms. That weight needs to be supported somewhere, and a standard frame built to house doors of much lighter weight will sag, warp, and fixings will loosen over time.

Older homes often have timber frames that can be vulnerable. While frames may look sturdy enough, they may not have the depth or additional supports to withstand the long-term stress from the weight of steel doors.

Different frames work best with different doors 

Most steel doors are fitted into steel frames. This makes sense, as all the materials are consistent, all the components work compatibly, and the thermal expansion and contraction will be the same throughout all the materials. If a steel door is properly fitted to a steel frame, that is a great door/frame combination.

It is also common to frame doors that are fitted into the masonry. This is classic in construction. The door frame (which is typically a pressed steel frame) is constructed into or fastened directly to the masonry, usually of bricks. This all works really well in solid masonry (bricks or blocks) construction, provided the correct fasteners are used, and the depth of the frame is adequate.

Timber frames are more complicated. While it can be done, the timber frame needs to be substantial and constructed of solid (hardwood) and deep enough to accommodate the load and the fasteners. The fact is that most residential timber frames do not meet that requirement without additional reinforcing.

uPVC frames won’t work. They can’t cope with the weight, or the fixing loads, that a steel door puts through the frame. Trying to do so creates problems that aren’t always obvious, but tend to appear within a couple of years.

Typical alterations

Even if an existing frame is, broadly, acceptable, some alteration is almost always necessary. The reveal depth – the distance between the wall face, and the frame edge – needs to allow for the greater thickness of steel doors over timber doors. If the reveal is shallow, the door won’t sit flush, or the frame will need to be reset further back in to the opening.

The same goes for the structural fixing points. Steel doors transfer loads differently to timber doors, especially in the hinge areas. Most steel doors have three hinges, some of the heavier ones have four. Each hinge has to be fixed into something substantial, and not just a facing board or a thin section of frame.

The other thing that often needs attention is the sealing and weatherproofing around the frame. Steel construction is affected by temperature and over time, open gaps may occur because the frame was not bedded and sealed correctly during installation. This is crucial for externally mounted doors that need to be draught-proofed and fire rated.  

When a full frame replacement makes more sense  

For most commercial installations, the frame retention discussion does not occur, as a part of the package, a steel subframe is installed into the opening. In residential properties, this is less clear cut. If the existing frame is timber, ageing, or showing any signs of movement, then replacing it as part of the installation is usually more sensible. It adds cost on the day, but it avoids having to revisit the job later when the frame starts to cause problems.  A good installer will assess the existing frame before committing either way. If they don’t, that’s worth asking about directly.

Obtaining a Survey First

As a rule of thumb, surveys should be obtained prior to ordering anything more complex than a simple commercial installation into a masonry opening. The sizes of doors differ, and older buildings tend to have openings that don’t match standard sizes. Furthermore, the need for significant prep work on openings that can accommodate a steel door is not always obvious from a quick picture or measurement.

Although it is an extra step, it is certainly more favourable than discovering how much work the frame requires on installation day, work that the supplier did not anticipate.