# Air Duct Installation and Repair Service > Leaky, undersized or damaged ducts waste energy and cause uneven temperatures. Lancaster inspects, seals, repairs, replaces and installs residential and commercial ductwork across Hamilton and Niagara. Source: https://lancasterheatingandcooling.ca/ductwork/ Last updated: 2026-11-01 Leaky, damaged or undersized ducts waste energy and leave some rooms too hot and others too cold. Lancaster Heating and Cooling inspects, seals, repairs, replaces and installs ductwork for homes and commercial buildings across Hamilton and Niagara. [Book a Ductwork Consultation](https://lancasterheatingandcooling.ca/quote/) ## Do you have leaky ducts? Many heating and cooling problems that seem to be equipment issues are really duct problems. ENERGY STAR reports that leaky ducts can reduce your system's efficiency by up to 30%. Leaks also let in dust, moisture, bacteria and pests, which can trigger allergies and asthma. **Signs your ducts need attention:** - Rooms that are always warmer or cooler than the rest of the house - Unusually high energy bills - Dusty rooms or visible dust around registers - Damaged, crushed or tangled ducts - Weak airflow from some vents ## Duct repair and sealing We take a pressure reading to measure how much air your ducts are losing, then explain your options in plain language: sealing, repairing damaged sections, or replacing ductwork that's beyond repair, with a fair estimate before any work starts. ## Duct installation and replacement Installing a new heating and cooling system, finishing a basement or building an addition? We design and install well-insulated ductwork that fits your space and delivers even, efficient airflow for years. **How it works:** 1. **Assessment:** we evaluate your layout and the size and condition of your existing ductwork. 2. **Design:** we plan duct sizes and runs for balanced airflow in every room. 3. **Installation or repair:** using quality materials and proven techniques. 4. **Maintenance:** regular care, including [duct cleaning](https://lancasterheatingandcooling.ca/air-quality/duct-cleaning/), keeps your system performing. ## Why choose Lancaster for ductwork? Through Lancaster Group's own sheet metal fabrication shop, we design and fabricate [custom ductwork](https://lancasterheatingandcooling.ca/ductwork/fabrication/) in-house, giving homes and businesses precise, efficient solutions from design to installation. Pair it with an [HVAC service plan](https://lancasterheatingandcooling.ca/service-plans/) for ongoing care. ## Questions about ductwork ### What is ductwork and how should it work with my HVAC system? Ductwork is the network of pipes that carries air between your furnace or air conditioner and the rooms of your home. Supply ducts deliver heated or cooled air to the registers, and return ducts bring air back to the system to be filtered and conditioned again. Well-designed, sealed ducts give every room even airflow and help keep indoor air clean. ### What are the signs of a problem with my ducts? Common signs include rooms that are always warmer or cooler than the rest of the house, weak airflow from some vents, rising energy bills, extra dust around registers, and whistling or rattling when the system runs. You may also see crushed, disconnected or damaged ducts in the basement or attic. If you notice any of these, [book a ductwork consultation](https://lancasterheatingandcooling.ca/quote/). ### Why are some rooms in my house hotter or colder than others? Uneven temperatures are often caused by the ductwork rather than the furnace or air conditioner. Leaky or disconnected ducts, undersized runs, long runs to rooms far from the equipment, closed dampers and missing return air can all starve a room of airflow. We measure airflow and inspect your ducts to find the cause before recommending a fix. ### How do you find and fix leaky ducts? We take a pressure reading to measure how much air your duct system is losing, then inspect the ducts we can reach for gaps and loose joints. Depending on what we find, we seal the joints, repair damaged sections or replace ductwork that's beyond repair. You get a plain explanation of your options and an estimate before any work starts. ### Can ductwork be the wrong size? Yes. Undersized ducts restrict airflow, which can cause noisy registers, weak heating and cooling in some rooms and extra strain on your blower motor. Oversized ducts can leave air moving too slowly to reach the far end of the run. Properly sized ducts are planned around each room's heating and cooling needs and the equipment's airflow. ### Why does my ductwork whistle or rattle? Whistling usually means air is being forced through a restriction, such as an undersized duct, a closed or blocked register, a dirty filter or a gap in a joint. Rattling often comes from loose duct sections, hangers or registers. Check your filter and make sure registers are open first. If the noise continues, we can find the cause and fix it. ### Do I need new ductwork when I replace my furnace or air conditioner? Not always. Many homes can keep their existing ducts, but a new system may need modified or larger ducts if the old ones are undersized, leaky or damaged, or if the new equipment moves more air. We check your ductwork during the [replacement quote](https://lancasterheatingandcooling.ca/heating/furnace-replacement/) and tell you honestly whether changes are needed. ### I'm finishing my basement. What should I plan for the ductwork? Plan the ductwork before the walls and ceiling go up. A finished basement usually needs its own supply and return air so it stays comfortable, and existing ducts may need to be rerouted to fit the new layout. Keep access to dampers and joints where you can. In Hamilton, new or replacement ductwork needs a building permit, and we'll confirm what your project requires. ### Is duct sealing the same as duct cleaning? No. Duct sealing and repair fix leaks and damage so air reaches the rooms it's meant for. [Duct cleaning](https://lancasterheatingandcooling.ca/air-quality/duct-cleaning/) removes dust and debris from inside the ducts to improve indoor air quality. They solve different problems, and some homes benefit from both: sealing for comfort and efficiency, cleaning for air quality. --- **Lancaster Heating and Cooling** — HVAC contractor serving Hamilton, Niagara and surrounding areas since 1955. Phone (24/7 emergency): 905-388-3333 · Email: info@lancasterhvac.ca Address: 1250 Stone Church Rd. E, Hamilton, ON L8W 2C8, Canada · Hours: Monday – Friday: 8:00AM – 4:30PM Request a quote: https://lancasterheatingandcooling.ca/quote/