Triple Decker Window Replacement: What 40 to 60 Openings Actually Costs

A three-decker in Worcester, Providence, Lowell, or Pawtucket has 40 to 60 window openings across three floors. Most of them are double hung windows with weight-and-pulley sashes that were never meant to come out. That count is what drives the price, far more than the cost of any single window.

Why the count is so high

Triple-deckers were built between roughly 1890 and 1925 as owner-occupied three-family housing. Each floor is a full apartment, with a front room, bedrooms, a kitchen, and a back porch. A typical floor has 13 to 20 openings, counting the bay windows at the front, the paired windows in the bedrooms, and the small windows in the bathrooms and stairwell. Three floors, and the total lands between 40 and 60.

Compare that to a single-family colonial, where the same job is 12 to 20 openings. A project that is routine on a suburban house becomes a major purchase on a triple-decker.

The cost, opening by opening

Costs are estimates for this market, not quotes.

The unit costs used in this site's calculator, installed, for a standard double hung opening:

Vinyl runs 650 to 1,100 dollars per window, with a typical life of 20 to 30 years.

Fiberglass runs 900 to 1,500 dollars per window, with a typical life of 30 to 50 years.

Wood-clad runs 1,100 to 2,200 dollars per window, with a typical life of 30 to 50 years.

Multiply by the opening count and the shape of the project appears. Forty vinyl windows at the low end come to 26,000 dollars. Sixty at the top of the range come to 66,000 dollars. For fiberglass the span is 36,000 to 90,000 dollars. For wood-clad, 44,000 to 132,000 dollars. These are the totals before any adjustment for the house itself.

A triple-decker adds roughly 12 percent on top, since the work involves three floors of staging, access to rear porches, and in many cases working over a close neighbor. That puts the vinyl range at about 29,000 to 74,000 dollars. In Central Massachusetts, where the regional factor is 0.94, those numbers come down a little. In Greater Boston, at 1.22, they go up.

That is a wide range, and it is meant to be. The real number depends on how many windows there actually are, what shape they are in, and what material you pick for the front.

You do not have to do all of them at once

This is the point most owners miss. A triple-decker's windows do not all need replacing at the same time, and the three floors may not need the same thing.

Do the front elevation in a better material, and the sides and rear in vinyl. The front is what people see. A wood-clad or fiberglass window with a decent profile on the street side, and vinyl on the rear and the side walls that face a neighbor, can bring the total down meaningfully.

Do the worst floor first. If the top floor is rented and the tenant is paying for heat, the energy case is strongest there. Heat rises, and the top floor loses the most through a roof and a set of old windows.

Keep the storm windows on the ones you are not replacing. An old double hung window with a good storm window over it performs better than most owners expect. The energy case for replacement is strongest for single pane glass with no storms. The estimated savings from replacing those windows are roughly 12 to 18 percent of heating costs. If the old windows already have storms, or if you are upgrading a window that is already double glazed, the gain is much smaller, roughly 4 to 7 percent. At that point it is a question of condition and comfort, not payback.

The weight-and-pulley problem

Old double hung windows are held in balance by cast iron weights hanging in pockets inside the frame, connected to the sashes by cords over pulleys. When the cord breaks, the sash drops or sticks.

Replacing a sash with a modern balance system is simple on a house where the frame is sound. The decision is between two approaches.

Insert replacement. The new window goes inside the existing frame. The old sashes and the weights come out, the pockets are insulated, and the new unit fits inside. It is quicker, cheaper, and does not disturb the interior trim or the exterior casing. The cost is a slightly smaller glass area, since the new frame sits inside the old one.

Full frame replacement. The old window, including the frame, comes out down to the rough opening. It is the right call where the sill is rotted, the frame is out of square, or the old pockets are leaking air. It costs more, takes longer, and disturbs more trim.

Most of the time on a triple-decker, insert replacement is right for the majority of the openings, with a few full frame replacements where the sills have failed. A contractor who proposes full frame replacement on every opening, or insert on every opening without looking, has not looked at the house.

Lead paint and the 1978 line

Houses built before 1978 may have lead paint on window sashes, frames, and casings. A triple-decker is almost certainly in that group. Federal rules require lead-safe work practices when a contractor disturbs painted surfaces in those houses, and window work is exactly the kind of work that disturbs them. Ask any contractor how they will contain dust, and ask who is responsible for cleanup.

If you are a landlord, or a young child lives in the building, each of the three states has its own lead rules for rental and child-occupied housing. Check the current requirements with the state health department before the work starts.

How long it takes

A triple-decker at 50 openings is typically two to three weeks on site, and the staging on floors two and three is what sets the pace. A 12 to 16 opening Cape or ranch, by comparison, is two to three days for insert work. Add lead time for the order itself, since old openings are rarely a standard size and anything custom takes longer to arrive.

Ask these questions in the quotes

How many openings did you count, and which floors? A bid with a count that does not match yours means somebody has not been through the whole house.

Which openings are insert and which are full frame? Get it in writing.

What is the plan for the pockets and the weights? Insulating the empty weight pockets is a modest job that makes a real difference to drafts.

How is lead handled? The answer should be specific.

What happens to the exterior trim? Many older houses have been wrapped in aluminum coil stock, and the trim underneath may not be in good condition.

Where to go from here

The window replacement guide covers each window type, materials, and what changes between a historic district and a postwar house. For the cost math on your own house, the energy savings estimator shows what window work is likely to return, and the material comparison tool compares window types. If you are in the Worcester area, see the Massachusetts page, and for Providence and the Blackstone Valley, the Rhode Island page.

If you would rather get prices from contractors who work in your town, the free estimate form takes a few minutes. Quotes are free and carry no obligation.