The first decision in a window replacement project is not the style or the glass package. It is which installation method your openings actually support. Retrofit installation, also called insert or pocket replacement, fits a new assembled unit inside the existing frame, replacing the sash, glass and hardware while leaving the frame, jambs, and trim in place. Full frame replacement, commonly called brick-to-brick, removes everything down to the rough opening.
One factor decides it, and it is not budget. If the existing frames are structurally sound, plumb and dry, retrofit is a practical route to new glass, better seals and working hardware at a lower cost and with far less disruption. If the frames are rotted, racked out of square, or concealing moisture damage behind the casing, opening the wall is the honest recommendation even though it costs more. A new window fitted into a failing frame installs a new problem on top of an old one.
This article explains how each method works, what each one can and cannot fix, the trade-off in clear opening size that matters more than most homeowners are told, how Alberta conditions change the assessment, and how to check your own frames before anyone quotes anything.
Key Takeaways
- Retrofit replaces the sash and glass only. The frame, jambs and trim stay in place, which is why it is faster and cheaper. It works only when the existing frame is sound, square, and dry.
- Full frame exposes the rough opening. That access is the whole point: it lets you inspect and re-insulate the wall cavity, install new flashing, and repair a compromised sill or header instead of covering it up.
- Retrofit shrinks the clear opening, commonly by 25 to 50 mm on each side. On most windows, that is a cosmetic trade. On a bedroom window, it can push the escape opening below what the building code requires, which makes it a compliance question rather than a preference.
- The assessment comes before the method, and the method before the product. Choosing a method before anyone has looked at the frames is the most common sequencing error in residential replacement, and it usually gets discovered on installation day.
- Alberta conditions make frame condition harder to read. Chinook swings move frames, sustained cold loads every seal and joint, and dry indoor air moves moisture through wall assemblies in ways that do not show in August. A frame that looks acceptable in summer can be concealing damage.
- Neither method fixes a drafty wall. Retrofit renews the perimeter seal around the insert and leaves the cavity untouched. Full frame reaches the cavity but stops at the edge of the opening. If the draft is coming from the wall rather than the window, that is a third scope.
- Get the method, the scope and the reasoning in writing. A quote that specifies an insert without explaining why the frames support it is a quote that hasn’t been thought through.
How Retrofit Installation Works
Retrofit is a frame inside a frame. The existing outer frame stays fastened to the wall. The old sashes, hardware, and interior stop mouldings come out, and a new factory-assembled unit sized to the remaining opening is set inside, then shimmed, fastened, insulated, and sealed.
The sequence is consistent across careful installers and documented in the Building America Solution Center, a resource maintained by the Pacific Northwest National Laboratory for the US Department of Energy. Interior stops come off first; use a broad chisel so you don’t damage the casing. Old sashes, parting stops and hardware follow. Clean the jambs and sill, fill holes and gaps, and run a continuous bead of sealant along the inside face of the exterior blind stop to establish a water barrier before setting anything. Rest the new unit on the sill, tilt it up into the opening, press it against the exterior casing, then loosely fasten it, check it diagonally for square, shim at each fastening point, and fully tighten. Stops go back on, the gap under the sill is insulated, and the perimeter is sealed inside and out.
The shimming is where careful and rushed installations separate. Shims do two jobs at once: they hold the unit square inside a frame that may not be, and they distribute load across the fastening points. A skipped shim or an overdriven one puts the sash out of true, and the symptom appears as binding, usually in the first winter rather than the first week. Asking an installer to describe their shimming practice before the work starts is a reasonable, revealing question.
Because the rough opening is never exposed, the wall’s existing water management is modified locally around the perimeter rather than rebuilt. That is both the method’s advantage and its boundary. It is faster and less invasive because it doesn’t touch the wall, and anything already wrong inside stays exactly where it is.
How Full Frame Installation Works
Full frame reverses the logic. Instead of working within what is there, the crew removes it. Interior casing comes off, exterior trim and any capping are taken back, and the entire window assembly, including the frame, the sill and the fasteners holding it to the structure, is removed until the rough opening framing is visible.
What happens next is the reason the method exists. With the opening exposed, the sill plate, jack studs, and header can be inspected directly rather than inferred. Rot is cut out and replaced. Remove and replace wet or compressed insulation in the cavity around the opening. Install a sill pan or flashing membrane to carry any future water outward rather than into the wall, which many houses built before the mid-1990s never had in the first place.
Only then is the new unit set. It goes directly into the rough opening rather than inside an older frame, is shimmed and fastened to the structure, and the perimeter is sealed with backer rod and sealant on the interior and an appropriate exterior detail tied into the flashing. Interior casing and exterior trim are then rebuilt or replaced, which adds time and is the part homeowners underestimate.
Two consequences follow. First, the new unit can use the full rough opening, so the glass area isn’t reduced and the opening size can be changed if that is the objective. Second, the work is genuinely invasive: the opening stays open longer, the exterior cladding is disturbed, and finishing trades may be needed afterward. That is the cost of the access, and the access is what you are buying.
The Clear Opening Problem Nobody Mentions
Every article on this subject notes that retrofit reduces the visible glass area, usually describing it as a minor aesthetic trade. In most rooms it is. In a bedroom it can be a code compliance failure, and it is worth understanding before you sign anything.
Article 9.9.10.1 of the National Building Code, Alberta Edition, requires each bedroom to have at least one outside window or exterior door that opens from the inside without keys, tools or special knowledge and without removing sashes or hardware, providing an unobstructed opening of at least 0.35 square metres with no dimension smaller than 380 millimetres. That measurement is the clear opening when the window is fully open. It is not the glass area, and it is not the frame size.
Now apply the retrofit trade-off. Consider a bedroom window with a clear opening of 600 by 600 millimetres. That is 0.36 square metres, just over the minimum, which is a very ordinary situation in a house built in the 1980s. Fit an insert that takes 38 millimetres off each side, and the clear opening becomes roughly 524 by 524 millimetres, which is about 0.27 square metres. Both dimensions still comfortably exceed 380 millimetres, so nothing about the window looks wrong from across the room. The escape opening has nonetheless dropped below the code minimum.
This is not an argument against retrofit. It is an argument for measuring the clear opening on every bedroom window before choosing the method, and for accepting full frame on those specific openings if the arithmetic does not work. It is also why egress windows in Calgary are worth treating as a separate conversation from the rest of the house rather than as part of a single house-wide decision.
Two related points. A casement or an awning gives a larger clear opening than a slider of the same frame size, because the sash swings clear rather than stacking beside the fixed panel, so the window style can rescue an opening the method would otherwise fail. And if any of those bedroom windows are basement windows, the rules extend further into window well dimensions and sill height, which is a permit conversation rather than a product one.
What Retrofit Does Well
Speed, and the Exposure That Comes With It
An insert replacement often takes about an hour per opening on install day, so a crew can work through several windows and leave the house weather-tight the same evening. No siding removal, no interior casing repair, and no wall-finish patching after they go.
In Calgary, that speed is worth more than it is elsewhere. An open rough opening in January, or during a Chinook wind event, exposes the interior and the crew. The shorter the window is open to the weather, the smaller that risk, which is a practical argument for retrofit on a winter project where the frames support it.
Lower Cost Per Opening
Full frame adds removal of the whole assembly, inspection and potential repair of the cavity, new flashing, and finishing on both the interior and the exterior. Every one of those is labour and material. Retrofit skips all of it when the frame is sound, and across eight or ten openings the difference compounds into a different project. Reference figures on window replacement cost in Calgary will give you a range to judge quotes against, though the method chosen moves the number more than most product decisions do.
Trim and Finishes Stay Where They Are
Retrofit leaves the casing alone, which matters in two situations. The first is an older house where the interior trim has been painted through several decades, and any patch will show. The second is a house with custom or discontinued profiles, where matching after a full frame replacement means a separate carpentry scope or an accepted visible difference. In mid-century neighbourhoods across Calgary where original profiles are still intact, that is often the deciding factor.
A Real Glass and Hardware Upgrade
The sash and glass are replaced entirely, so a retrofit can take you from a failed double-glazed unit to a current triple-glazed one with a low-emissivity coating, an argon fill, and a warm-edge spacer, along with new operating hardware and locks. The glazing performance improvement is genuine and not reduced by the method. The method can’t reach insulation or flashing deficiencies behind the frame.
“The question I ask on every site visit is whether the frame is plumb, dry and square. If all three are yes, retrofit is usually the right call, and I say so directly. If any one of the three is off, I explain why opening the wall is worth the extra cost, because the alternative is installing a new window into a problem that comes back in two or three years.” – Chris Perry, Project Manager, Weather Pro Windows and Doors
Where Each Method Fits
Sound Frames With a Glass or Hardware Problem
The standard retrofit case. The unit has fogged from a failed seal, the operator no longer works, or the original double glazing simply isn’t adequate for an Alberta winter, but the frame is square, solid, and dry. The frame is still doing its job, and replacing what sits inside it is the proportionate response.
Frames That Cannot Be Trusted
Soft spots at the bottom corners, a sill that gives under pressure, staining on the interior casing, paint bubbling below the window, or a sash that has needed more force each year all point the other way. These are signs that water has been getting past something for a while. Fitting an insert over them hides the evidence without removing the cause, and the next person to open that wall finds a larger repair than the one available today.
Occupied Houses and Multi-Window Projects
When a household is living in the house during the work, retrofit is the far less disruptive option: no siding off, no interior patching, and no opening left overnight. Across five to ten openings, a crew can often finish in one or two days. Full frame on the same count extends the schedule and adds coordination with finishing trades. Reviewing a company’s completed projects is a fair way to judge how they handle this, and seeing what window installers have actually delivered on comparable houses tells you more than a description of the process.
Brick, Stucco and Stone Exteriors
The phrase brick to brick comes from masonry, and on a masonry or stucco house the method carries a cost the term does not convey. On vinyl or fibre cement siding, removing exterior trim to reach the rough opening is straightforward, and the cladding goes back. On brick, stone, or stucco, you can’t simply lift and replace the exterior detail around the opening. Stucco has to be cut back and patched, and a patch on an aged stucco finish is visible unless you refinish the whole elevation. Brick and stone require care at the opening perimeter and a mason rather than a window crew.
This is why retrofit is disproportionately common on older Calgary houses with stucco or brick fronts, and why the cost gap between the two methods is much wider on those houses than on a sided bungalow. It does not change the rule that failing frames need a full frame. It does mean the decision has bigger consequences, and it is worth raising with the estimator rather than discovering it in the quote.
Projects That Change the Opening
Any project that enlarges an opening, adds a new one, or converts a pair of small windows into a single larger unit is full frame by definition, because the rough opening itself is being altered. That also brings structural and permit considerations that a like-for-like replacement does not.
Timing the Work in an Alberta Climate
Season affects both methods, but differently, so factor it into the decision rather than treating it as a scheduling detail.
Window replacement does go ahead through an Alberta winter. Openings are taken one at a time and closed the same day, so the house is never broadly open to the cold. What changes in winter is the margin for error. Sealants have minimum application temperatures, and a product applied below its rated range does not cure to specification, so the crew must use materials rated for the conditions rather than whatever is on the truck. Foam behaves differently in the cold. And an opening left exposed during a wind event loses far more heat than the same opening in October.
The method changes the exposure. A retrofit opening is open for perhaps an hour and the exterior envelope is never broken, because the original frame and trim stay in place throughout. A full frame opening is open longer; the cladding is disturbed, and finishing work may not be completable until conditions allow. On a winter project with sound frames, that difference is a genuine argument for retrofit. On a winter project with a rotted sill, it argues for scheduling rather than the wrong method.
Demand is the other variable. Spring and the first hard frost both produce a surge in orders across the whole market, which lengthens manufacturing lead times for everyone. A project planned in the off-season generally gets both better availability and more of the contractor’s attention, and since units are built to your measurements, the lead time sits ahead of installation day regardless of which method you choose.
Retrofit and Full Frame Compared
Use the table to identify which rows apply to your house, then read the notes underneath.
| Dimension | Retrofit, also called insert | Full frame, also called brick to brick |
|---|---|---|
| What is replaced | Sash, glass and hardware. The existing frame and jambs stay | The complete assembly down to the rough opening, including frame, sill and trim |
| Rough opening | Never exposed. Work stays inside the existing frame | Exposed, so the wall cavity and framing can be inspected and repaired |
| Interior and exterior trim | Preserved. No patching or matching required | Usually removed, then repaired or replaced |
| Clear opening | Reduced, commonly 25 to 50 mm per side, which matters on a bedroom escape window | Full opening recovered, and the opening size can be changed |
| Cost per opening | Lower. Narrower scope and minimal finishing | Higher. Additional removal, inspection, repair and finishing |
| Time on install day | Often about an hour per opening, so several can be done in a day | Longer per opening because of the removal, inspection and finishing scope |
| Water management | The perimeter seal is renewed. The original flashing behind the casing stays as it is | New flashing and a rebuilt water management detail at the opening |
| Insulation | Seal the gap around the insert. The wall cavity is not reached | The cavity around the opening can be re-insulated |
| When it is right | The frame is sound, plumb and dry, and the problem is the glass, the seals or the hardware | The frame is rotted, racked or wet, drafts come from the wall, or the opening needs to change size |
The trade is clean once it is stated plainly. Retrofit exchanges structural access and clear opening size for speed, cost and preserved finishes. Full frame exchanges time, money and disruption for the ability to see and fix what is behind the casing. Neither is the better method. One is correct for a given opening, and you determine that by inspection, not preference.
How to Assess Your Own Frames
Step 1: Sound, Plumb and Dry
Three tests, in this order, on every opening.
- Sound. Run a hand along the sill and press firmly at both bottom corners, which is where water collects and rot starts. A sound frame feels solid throughout. A compromised one gives slightly or feels spongy under thumb pressure.
- Plumb and square. A racked frame will show it in operation before it shows it to the eye. A sash that catches on one side, a lock that needs the sash pulled toward it, or a visible gap that varies along the closing edge all indicate movement.
- Dry. Look for staining on the interior sill, paint bubbling on the casing or the wall below, and any discolouration in the corners. Press the drywall immediately under the window. Softness means moisture has been present long enough to do damage you cannot see.
If all three pass on an opening, retrofit is viable there. If any one fails, that opening is a full frame candidate regardless of what the rest of the house needs. The assessment is per opening, not per house, and a mixed scope across one project is a normal and honest outcome.
Step 2: Measure the Clear Opening on Bedroom Windows
Before settling on a method, measure the unobstructed opening on every bedroom window with the sash fully open: width and height at the narrowest point, then multiply. If the result sits near 0.35 square metres, a retrofit insert may take it below the requirement, and that opening needs either full frame or a window style that opens more fully. This five-minute check can prevent an expensive discovery later.
Step 3: Identify What Is Actually Bothering You
Be specific about the complaint, because different complaints have different answers. Fog between the panes is a sealed unit problem. A draft you can feel at the sash with the window locked is a seal and hardware problem that retrofit addresses well. A draft at the junction between the frame and the wall, or from the casing itself, is coming from the rough opening or the cavity, and retrofit will leave it exactly as it is.
Run a hand slowly around the perimeter on a cold or windy day and note where the movement is. That single observation separates a problem retrofit solves from one it does not, and it is worth doing before you ask anyone what a window installation service should include in the quote.
Step 4: Get the Method and the Reasoning in Writing
A quote should state which method applies to each opening and why. If you assessed the frames, record the result. A document that specifies an insert across the whole house without a word about frame condition assumes the answer rather than establishing it, and the assumption gets tested on installation day with the crew standing in your living room.
Ask the same question about the product while you are there. Whether the openings take an insert or a full-frame unit, choose the home windows for the elevation and the room rather than applying a uniform approach, because the method decides the scope and the specification decides the performance.
Six Questions Before the Method Is Settled
- Which method applies to each opening, and which of the three frame conditions did you check to decide?
- What is the clear opening on each bedroom window now, and what will it be after installation?
- If this is a retrofit, what happens to the original flashing behind the casing?
- If this is full frame, is a sill pan or flashing membrane included, and is interior and exterior finishing in the price?
- What is the change order process if something turns up once the wall is open, and who authorizes it?
- Who obtains any permit that applies, and is the fee inside or outside the total?
Each of those has a short answer. A contractor who can give six short answers standing in your hallway has done the assessment. One who deflects on the second and third has quoted a method rather than a house, and that distinction shows up later, not sooner.
What Neither Method Reaches
Three things sit outside both scopes, and all three account for projects that disappoint after completion.
The wall beyond the opening. Full frame gives access to the rough opening and the cavity immediately around it. It does not re-insulate the wall, seal the top plate, or fix an attic bypass. Where a whole room is cold rather than the area near the glass, the windows are being asked to solve something they did not cause.
Hidden damage may appear only once the wall is open. An in-person assessment reduces uncertainty substantially and cannot eliminate it. Rot in a sill, a compromised header or wet sheathing can surface after removal begins. Ask how change orders are handled and who authorizes them before work starts, because agreeing that process in advance is a very different experience from negotiating it with the wall open.
Permit position. Requirements depend on the municipality and on whether the opening changes size or the work touches structure. A like-for-like replacement is treated differently from an enlarged or new opening, and bedroom and basement windows bring egress requirements into the picture. Contractors are generally right about this, but responsibility often rests with the homeowner, so confirm the current position with your municipality and have the quote state who is obtaining any permit and whether the fee is in the price.
The Frames Choose the Method
Retrofit and full frame are not competing products, and neither is a budget tier. They are two scopes of work, each correct under a specific set of conditions. Sound, plumb and dry frames make retrofit the proportionate choice: new glass, new hardware, renewed seals, minimal disruption and a lower cost per opening. Rot, racking, or moisture behind the casing make full frame the only method that actually resolves the problem, and calling it an upsell in that situation misreads what is being bought.
Alberta makes the assessment matter more than it would in a mild climate, because Chinook cycling moves frames and sustained cold finds every weakness a summer inspection misses. Check each opening for the three conditions, measure the clear opening on the bedrooms, identify where the draft is actually coming from, then let a quote tell you which method applies and why. Done in that order, the decision is straightforward. Done in reverse, it gets made on installation day by whoever is holding the chisel.
Frequently Asked Questions
Can I replace just the window and keep the existing frame?
In many cases yes, and that is exactly what retrofit or insert installation does. It replaces the sash, glass and hardware while the frame, jambs and trim stay in place. It is viable only where the frame is structurally sound, plumb and dry. Where the frame is rotted, racked out of square or showing moisture damage, keeping it means installing a new unit into a failing component, and a full frame is the appropriate scope.
How much smaller will my window be after a retrofit?
The clear opening is typically reduced by 25 to 50 millimetres on each side, because the new unit nests inside the existing frame. In most rooms, that is a minor visual change. For a bedroom window, it is worth measuring first: building code requires an unobstructed escape opening of at least 0.35 square metres with no dimension under 380 millimetres, and a window close to that minimum can drop below it after an insert. Full frame recovers the full opening because the new unit goes directly into the rough opening.
Is a retrofit as energy efficient as full frame replacement?
On the glazing, yes. The sash and glass are replaced entirely, so you can use the same triple glazing, low-emissivity coatings, argon fills, and warm-edge spacers either way. The difference is everything behind the frame. Retrofit renews the perimeter seal around the insert but leaves the wall cavity insulation and original flashing as-is. If your frames are sound and the cavity is intact, retrofit delivers comparable performance at lower cost. If the losses are coming from the cavity, only full frame can reach them.
How long does retrofit installation take?
On install day, an insert replacement is often about an hour per opening, so a crew can work through several windows and leave the house weather-tight the same evening. Full frame takes longer per opening because of the additional removal, inspection and finishing. Install day is only one part of the timeline, though. Units are built to your measurements, so manufacturing lead time and scheduling come first and should be stated in the quote.
When should I choose full frame instead of retrofit?
When the frame is rotted, soft or structurally compromised. When it has racked out of square, and a new unit would bind or seal unevenly inside it. When there is evidence of moisture damage or reason to suspect it behind the casing. When you want to change the opening size or configuration. When a bedroom window is close enough to the minimum escape opening that an insert would take it below the requirement. And when the draft you are trying to solve is coming from the wall rather than from the window.
Do I need a building permit to replace windows in Calgary?
It depends on the work, not the method name. Replacing a window in an existing opening at the same size is treated differently from enlarging an opening, cutting a new one, or altering anything structural above it, and bedroom or basement windows bring egress requirements into the review. Requirements and fees are set by the municipality and can change, so confirm the current position with the City of Calgary rather than relying on a general answer, and have the quote state explicitly who obtains any permit and whether the fee is included in the price.
Can I use retrofit on some windows and full frame on others?
Yes, and on many houses that is the correct answer. Frame condition varies by elevation because sun exposure and water shedding vary by elevation, so the south and west openings are often in different shape from the north ones. A mixed scope suggests the frames were assessed individually rather than treated as one decision. Ask for the method to be stated per opening in the quote so you can see the reasoning.
