How to find the right Window Sills AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Window Sills
- Interior stool vs exterior sill
- An interior stool is trim. An exterior sill must slope outward and have a drip edge. An exterior sill without slope directs water into the wall.
- Moisture-resistant material
- Use cellular PVC, composite, stone or cultured marble in bathrooms, kitchens and humid rooms. Avoid MDF there. Condensation running down the glass swells and rots MDF and finger-jointed pine.
- Depth and length
- Measure wall depth to the window frame plus the overhang you want, and the length between casings plus horns (the ends that extend past the trim). Stock sills are cut to fit, so you need enough material for the horns and the return.
- Rot repair vs replacement
- Replace the sill if soft wood goes deeper than a surface consolidant-and-filler repair can reach. Patching deep rot leaves the hidden source of moisture in place.
Brands that matter
- AZEK: Cellular PVC trim boards, suited to wet locations.
What to avoid
- MDF sills in bathrooms or above kitchen sinks
- Flat or back-sloped exterior sills