Fit check
Key measurements
Rough openings the holes in the framing for the doors
Plans dimensions govern — do not scale
Cut list every framing and trim piece with its code, grouped by stage
Parts checklist every part to proportional length, with its code — tick each off as you cut and label it
Glazing layout & cutting diagram where every twinwall panel goes, and what to cut from each 4 ft panel
Lumber list & cutting diagrams what to buy, and what gets cut from each board
Sheet layouts the plywood floor, knee-wall panels and door kick panels
Shopping list & estimated cost typical Home Depot prices — click a price to match your store
Fastening schedule how each joint is fastened — IRC Table R602.3(1), the sections noted, and the glazing makers' guidance
Hardware & fasteners
Build steps
Build it step by step each page adds the next stage — new parts are outlined in orange
Important: read before building
Plan a DIY twinwall greenhouse
Greenhouse Planner frames a wood gable greenhouse glazed with twinwall polycarbonate to your size. Enter the footprint and wall height, pick the panel thickness and your snow load, and add a door and roof vents. The planner puts a stud or rafter under every panel edge, spaces the purlins and girts for the panels, lays out and packs every glazing piece, and lists every piece of lumber to cut. Everything is a preliminary DIY estimate: your building department sets the final requirements.
1. Size it
Width across the gable, depth along the ridge, and the wall height.
2. Pick the glazing
6, 8 or 10 mm twinwall — thicker panels span further and insulate better.
3. Vents & doors
Automatic roof vents and a glazed door. The fit check keeps the vent area at 15–20% of the floor.
4. Check, buy and build
Fix anything the fit check flags, then work from the plans, glazing layout, cut list, shopping list and build steps.