P-300 uPVC-steel window
System cross-section
Photos are illustrative and not necessarily this exact system.
uPVC-steel · No. 01
The most window for the money.
NFRC certified · U-factor from 0.15 · Triple glazing
P-300 is the window we suggest when the brief is "good windows, whole house, sensible budget." It's a six-chamber, steel-reinforced uPVC frame, about 3-3/16 inches deep, with two continuous gaskets and room for glass up to 54.8 mm thick. That's enough for a properly spaced triple-pane unit or a laminated acoustic one. It's NFRC certified, so the U-factor on your quote is a tested number you can hand to your energy-code reviewer.
Who is P-300 for?
- Homeowners replacing every window in a 1950s–1990s house on a fixed budget.
- Landlords and ADU builders who want low upkeep and a real seal.
- Builders who need a certified U-factor for permit paperwork without paying for aluminum.
If you want slimmer sashes and a sharper modern profile, look at P-500. If you're chasing Passive House numbers or want aluminum cladding outside, look at P-700.
Why a deeper frame helps in a Seattle winter
At 81 mm, P-300 is one of our deeper uPVC frames. Depth gives room for six chambers and a thick insulated glass unit, and it puts more material between the cold outside face and your trim. In a long, damp winter that means a warmer frame and inside pane, so less condensation collects at the bottom of the glass in bedrooms and bathrooms.
Two good gaskets, done right and adjusted right, beat three gaskets on a window nobody adjusts.
Two seals, not three. Does it matter?
P-300 uses two sealing lines: one on the frame, one on the sash. Systems with a third, middle seal, like P-500 and P-700, add extra airtightness and sound control. For most replacement windows, two well-compressed gaskets and correctly adjusted locking cams keep wind and water out. If you're next to a busy arterial or under a flight path, we'll talk about acoustic glass first, and a three-gasket system second.
Installation options
For new construction and full-tear-out replacement, we integrate the window with the WRB. For retrofit into existing frames, we detail the opening with flashing tape, sill pan and low-expansion foam. See Window replacement in Seattle.
P-300 specifications
U-factor is the best value from product data; your quote lists the rated value per window.
Why choose it: lowest cost per window in our range · NFRC certified · deep, six-chamber frame · takes thick triple or acoustic glass.
Trade-offs: frames look heavier than P-500 · two gaskets, not three · not the choice for very large sashes or slim modern sightlines.
Specifications
Performance
- U-factor
- from 0.15 Btu/h·ft²·°F
- SHGC
- 0.14–0.38 (depends on glass)
- Visible transmittance
- 0.27–0.58 (depends on glass)
- STC
- 37–47 (triple glass)
- OITC
- 28–38 (triple glass)
- NFRC rating
- Certified
Construction
- Frame depth
- 3-3/16″ (81 mm)
- Chambers
- 6
- Gaskets
- 2 sealing lines
- Reinforcement
- Steel
- Glass thickness
- 23–54.8 mm; double or triple
Options
- Opening types
- Tilt-and-turn, turn-only, tilt-only, fixed, combinations
- Colors
- White, colors and woodgrain foils; ask for the current palette
- Glass
- Low-e, argon, warm-edge spacer, laminated safety/acoustic, obscure
Ordering
- Lead time
- 3–4 months; made to order and shipped by sea freight
- Warranty
- 20-year limited manufacturer warranty; 3-year installation warranty. See warranty terms
More P-300 views
Product photos and renders; colors and details vary by order.
P-300 vs P-500 vs P-700 table · Also consider: MB-79N Pro if you want aluminum at a value price.
Is P-300 triple-pane?
Is P-300 NFRC certified?
Can P-300 be a door?
Does P-300 come in black?
Pricing a whole house in P-300?
Send us a list of openings or a few photos. We'll measure and send a clear, itemized quote.