What a good installation needs, and what we send with the windows.

Vistaza supplies High Performance uPVC windows and doors. It does not install them. Your installer fits them, and that split works well as long as everyone knows where the line runs.

The ratings on our test reports belong to the window. What the building gets also depends on the joint between the window and the wall, and that joint is made on site. A laboratory mounts its sample plumb, level and square in an opening built for the test. The site has to repeat that in the wall as it was actually built, opening after opening, in the weather. Then a field water test checks the result.

So the useful question is not who installs. It is what the installer has in hand on the day.

The laboratory did the easy part.

In the lab the opening is perfect, the sample is new, and one unit is tested. On site the opening is whatever the frame, the slab edge and the masonry left behind, the unit has been on three trucks and a hoist, and there are hundreds of them. That is why a window that passed its test can still leak in a building. When it does, the path is usually the perimeter, not the product. Our strength guide makes the same point from the testing side.

Five things a good installation gets right.

Where this differs from the installation manual issued for your job, the job's manual wins. It is written for the types on that job, and it is the document the ratings assume.

1. A true opening, before the window arrives. Plumb, level, square and true. A frame forced into a crooked opening binds, and the resident feels that for the life of the building as a handle that is hard to turn.
2. A sill supported straight and level. A sagging sill strains the welded corners and tips the drainage the wrong way. The symptom arrives long after the crew has left.
3. Anchors that hold, and still let the frame move. uPVC expands about five times as much as steel and about two and a half times as much as aluminum. A meter of profile changes length by about 1/16 in [1.2 mm (1/16″)] over a 20 °C (36 °F) swing, and a dark frame in sun runs hotter than the air. A frame packed solid has nowhere to go.
4. A way out for water. No outer seal stops every drop in a storm. The frame is built to drain, so the weeps stay open. We do not use a sill pan. The window is sealed to an opening that has already been waterproofed. Sealant over a weep traps the water the frame was designed to let go.
5. A perimeter seal tied to the wall. The joint connects to the wall's air barrier and its water barrier, inside and out, with the cavity filled and no voids behind the trim.

At close-out, the hardware is checked and adjusted, and every sash is opened, closed and locked.

The installation standards were written for houses.

North America's two common installation documents do not cover a mid-rise job. The residential practice most often named covers new work in detached one- and two-family dwellings and townhouses not more than three stories above grade, and only windows with a mounting flange in a stud wall. The broader ASTM practice is aimed primarily at residential and light commercial buildings.

Both say the same thing about conflicts: where the practice and the window maker's instructions disagree, the maker's instructions prevail. On a mid-rise building, with clip-fixed frames, coupled units and a wall that is not a stud wall, that sentence is the whole answer. The manual issued for the job is the standard, which is why it is worth reading before the first truck.

What arrives on the truck.

Deliveries are packed by floor and elevation, the way the building goes up. Every unit carries a sticker with its opening number, its floor and elevation, and its type, matching the tag on the shop drawings. Every container has a packing list to tick against. A site-readiness checklist goes out ahead: an unloading window, a forklift, and dry, flat storage.

What happens between the truck and turnover causes most window damage on a job. That is its own article: windows on site.

What Vistaza sends with them.

Shop drawings you can build from. Your plans and elevations with the windows dropped into them, a tag on every opening, and sections at head, sill, jamb and mullion for each condition in the building. A unit that does not fit shows up on paper instead of on site. See what is in a set.

One number per opening. The tag on the drawing, the sticker on the unit and the entry in the app are the same number. Nobody carries a window up six floors to find it is the wrong one, and a damaged unit is reordered by number without re-measuring.

Instructions, twice. A standard set covers clips, mullions, transoms, doors and the accessible sill, the nailing fin on Vi5, handles, storing and protecting, and operation and care in English and Spanish. On top of that, every job gets a manual built from its own window types. Both open inside the app.

The parts the installer needs. Install clips, mounting brackets, spacing shims, mullion posts, steel, covers, adjustment tools, hex keys and a touch-up marker are in the parts catalog. Ask by name, with the series and the frame color.

The Install app. Each opening carries its stages, and each check-off carries a name and a time. Only a manager can undo one. On any night the job moved, a report goes out by email with the day's check-offs, how far along the job is, anything undone, and photos. A crew member can file a service request from the opening it is about, with the opening, type, floor and series already filled in.

Water-test support. Our technician trains the crew at delivery, sends a test prep kit, and attends the water test. No charge. If something leaks, the person who knows the product is standing there.

What Vistaza does not do.

• It does not install. The installer is contracted by you, and the workmanship is theirs.
• It does not run the field test. An independent testing agency does that. Our technician attends.
• It is not the envelope consultant. The wall section, the air barrier and the flashing sequence belong to the design team. Our sections show how the window meets that detail; they do not design it.
• It does not supply the perimeter materials. Tapes, membranes, foam and sealant are by others.

The field test is run softer than the laboratory test.

Settle this in the specification, not on the day. Under the common North American field-testing practice, the water test runs at two-thirds of the tested and rated laboratory pressure by default, and field air leakage is allowed to be up to 1.5 times the laboratory figure. If the specification names the ASTM field method on its own, that reduction does not automatically apply. One line moves the pass mark.

Test early. The field practice is written for newly installed windows. Once a building is occupied and some months have passed, the exercise becomes a forensic investigation, which is slower for everyone.

A checklist for the general contractor.

1. Read the job manual before the first delivery, not on delivery day.
2. Agree the field-test method, the pressure and the number of openings in the specification.
3. Check rough openings for plumb, level, square and true, and fix them before the windows arrive.
4. Decide who owns the waterproofing of the opening, the perimeter seal and the air-barrier tie-in, and write it into a scope.
5. Install the first opening of each condition with the technician present, then look at it together. See who decides the windows.
6. Confirm the weeps are open before any trim or sill goes over them.
7. Book the field test early, on a low floor, while there is still time to change the method.

To get drawings and a manual for your job, send your plans. What the crews need on the day is on the professionals page.