The twelfth season of Ask This Old House begins with Kevin teaching the guys how to use Twitter. Tom replaces an old, rusted bulkhead door. Richard discusses several ways to get hot water without waiting. And the guys ask "What Is It?"

Roger builds a garden bed for chile pepper plants in New Mexico. Richard repairs a leaky toilet with a worn out flange. And the guys ask "What Is It?"

Richard replaces a leaking kitchen faucet with a new hands-free model. Kevin explains rechargeable batteries. Roger installs a channel drain in a driveway to divert rainwater. And the guys ask "What Is It?"

Installing a pre-hung exterior door. How to use large containers for shading around the home.

A member of the team learns about styles prevalent in Santa Fe, N.M. Roger teaches the proper way to use a wheelbarrow. How to install a shade sail to a deck. Richard installs a hybrid water heater.

Tommy replaces a leaky skylight. Richard quiets a noisy toilet.

How to make improvements to make your home safer during a tornado, hurricane and power failure. A meteorologist describes how weather is changing and what homeowners should do to prepare.

Tom demonstrates many uses for a router. Richard replaces an air conditioning unit that freezes when it runs. And the guys ask "What Is It?"

Installing an irrigation system designed for a desert climate; new style of heat-pump water heater; reusing an old garden hose reel.

Installing crown molding; replacing a rotted fence post; difference between cement, concrete and mortar.

Installing a Whole-House Humidifier in North Carolina; Installing Hardwired Smoke and Carbon Monoxide Detectors.

"Waffle Gardening" in Santa Fe; Adding Mechanical Dampers to a Forced-Air Heating System

Repairing a Rotted Porch Post; Dealing With High Indoor Humidity

Fitting a Mattress Up a Narrow Staircase; Repairing a Light-Switch in Seattle

Installing a Clawfoot Tub With Shower; Installing a Permanent Fire Escape in a Bedroom

Building a high tunnel greenhouse; converting three recessed kitchen lights into three pendants. Selecting pliers and wrenches.

Quieting a Squealing Shower; A DIY-Friendly Security System and Video Camera

How to start plants from seed. How to prevent an outdoor hose spigot from freezing. How to build a movable kitchen island.

Planting a low-cost privacy screen; and sealing ductwork without removing the walls.

Replacing a shower valve; repairing damage to a baseboard; keeping a lawn mower in excellent shape.

Celebrating 300 episodes of "Ask This Old House" with a review of favorite moments.

Building a simple table from solid fir; removing tree stumps; solar energy.

Modifying a bathroom and stairs to make them wheelchair accessible; rebuilding dangerous staircase.

Replacing fluorescent under-cabinet lights with LED fixtures; working with concrete.

Installing new cabinets; countertop options; the home and restaurant kitchens of chef Michael Symon.