How to board up a window — weather-tight or break-in-proof

The method, step by step

1. Protect yourself before touching anything. Heavy gloves, closed shoes, and eye protection. Broken residential glass keeps breaking as you handle it — most board-up injuries are hand lacerations in the first ten minutes.
2. Clear the opening. Remove loose shards from the frame (wiggle straight out, never sideways), sweep the sill and floor, and box the glass in cardboard before it goes in a trash bag. Leave firmly seated glass in place unless it blocks the board.
3. Measure the opening, then decide inside-fit or overlap. Inside-fit (board sits inside the window reveal, flush) looks cleaner and anchors into the frame sides. Overlap (board covers the trim by 3–4 inches on all sides) is stronger and faster — the default for security jobs. Measure to the method.
4. Cut 1/2" or 5/8" plywood (or 7/16" OSB) to size. A 4×8 sheet ($15–$25) covers most single windows. For wet climates or waits beyond a couple of weeks, plywood outlasts OSB, which swells at cut edges with moisture.
5. Anchor for weather: screws into framing. Drive 2.5–3" exterior screws every 8–12 inches around the perimeter, into the window frame or wall framing — not just siding or trim skin. Snug, not crushing: over-torqued screws spin out of old wood.
6. Anchor for security: through-bolt with interior bracing. For break-in protection, screws that face the street can be unscrewed by the next visitor. Instead, drill through the board and wall opening, and bolt through to horizontal 2x4s spanning the opening inside (carriage bolts, washers inward). Nothing outside can be removed without destroying the board.
7. Weather-seal the top edge only. A bead of caulk or flashing tape along the top edge stops water tracking behind the board. Leave sides and bottom unsealed so any moisture that gets in can drain and dry.
8. Photograph the finished work. Date-stamped photos of each boarded opening complete your insurance mitigation record — and you want them before repairs eventually remove the evidence.

When DIY stops making sense

The honest breakpoints: height (second-story windows move this from carpentry to ladder work with a sail-sized board — the injury profile changes completely), count (five hail-broken windows is an afternoon of cuts and climbs; a crew does it in ninety minutes with volume pricing), and doors and storefronts (secure temporary door systems are genuinely specialized). And if the break was a burglary, the professional anti-entry spec plus a police report number is the combination your insurer wants to see.

The one mistake that ruins half of DIY board-ups

Screwing into siding or trim skin instead of framing. Vinyl siding, aluminum trim wrap, and rotten sills hold screws for exactly one wind gust. Find the solid framing — it’s at the window’s perimeter, behind the trim — and put your screws there. If the driver suddenly stops resisting as a screw seats, it isn’t gripping wood; move it.