You have your renovation drawings, your contractor, and a clear picture of how your Gresham home will look, but no one has really discussed what happens to your heating and cooling once the walls go up. Maybe you are adding a primary suite, opening up the main floor, or finally finishing that basement. The new space will look great, but you are not sure if your current furnace or heat pump can keep up.
This uncertainty is common. Many homeowners assume the general contractor will handle the HVAC, or that adding a vent or two is all it takes. Then, the first winter or summer after the project, they discover a beautiful new space that is always a little too cold or too hot, or energy bills that climb higher than expected. Planning the HVAC side of a renovation early helps prevent those surprises and protects the money you are putting into your home.
At Gresham Heating and Air Conditioning, we have been working on homes in Gresham and nearby communities since 1992. Our licensed, NATE-certified technicians are often called in after renovations to solve comfort problems that could have been avoided with better planning. In this guide, we share what we have learned from decades of Gresham HVAC renovation projects so you can integrate heating and cooling into your plans from the start and get a home that feels as good as it looks.
Why Gresham Renovations Put Extra Demands on Your HVAC System
Any renovation that changes the size or shape of your living space affects how your HVAC system has to work. Adding square footage, raising ceilings, or removing walls means your furnace, heat pump, or air conditioner now has more air to condition and a different path to move that air through. Even if the equipment was a great fit when the home was built or last upgraded, the original design was based on the old layout, not the new one you are creating.
In Gresham, the climate puts both heating and cooling demands on your system. We see cool, damp winters where a system needs enough capacity to keep indoor spaces warm and dry, and warm summer days where air conditioning or heat pumps work hard to remove heat from the home. When you add a large south-facing window wall, finish a basement, or enclose a porch, you change how much heat your home gains or loses during these seasons. Without adjusting the HVAC design, you often end up with rooms that lag behind the rest of the house on the hottest and coldest days.
We routinely hear from homeowners who finished a bonus room over the garage or converted an attic, only to find that the space is uncomfortable most of the year. The equipment might be in good shape, but the system was never designed for that extra load. After more than 30 years working on Gresham homes, we see predictable patterns in how different renovation styles strain older systems. By understanding where those stress points occur, you can plan HVAC changes that align with your new layout and reduce the risk of paying twice to fix problems later.
How Renovation Changes Affect System Sizing and Comfort
Your HVAC equipment is sized to handle a certain heating and cooling load. In simple terms, load is how much heating or cooling your home needs to stay comfortable. It depends on square footage, ceiling height, insulation levels, window area, and how air moves between rooms. When you add a 400- or 600-square-foot addition, remove walls, or upgrade windows and insulation, that load changes. The system that was the right size for the original house may now be too small or too large for the renovated home.
An undersized system will run longer and harder, struggling to keep up on the coldest winter mornings or warmest summer afternoons. You might notice that the original part of the house is just barely comfortable, while the new rooms never quite reach the set temperature. An oversized system will tend to cycle on and off frequently, a pattern called short cycling. The equipment runs in short bursts, which can lead to uneven temperatures, increased component wear, and, in cooling mode, poor humidity control.
We see this often when a homeowner adds a large primary suite over the garage or finishes a basement. The new space may sit over unconditioned areas or partly below grade, which affects how it gains and loses heat. Even if you installed your furnace or heat pump only a few years ago, it might have been sized for the old footprint. Once you change the building envelope and floor plan, the math changes. Our NATE-certified technicians perform load calculations for renovation projects to determine whether your current system can handle the new layout or if adjustments are needed to keep every room comfortable.
Without that calculation, most decisions are guesses. Rules of thumb like sizing by a set number of square feet per ton of cooling capacity almost always break down in renovated homes because they ignore details like window orientation, ceiling height, and insulation upgrades. A proper evaluation looks at all of these factors so you get equipment that runs in steady, efficient cycles and keeps both old and new spaces at the temperatures you expect.
Ductwork, Airflow, and Why You Cannot Just Add Another Vent
Many renovation plans treat ductwork as an afterthought. The assumption is that the contractor can simply tap into an existing duct and add a new vent to feed the addition or reconfigured room. In reality, your ducts were originally sized to carry a certain amount of air. Every time you add a new branch without checking capacity, you ask that system to do more than it was designed to do. The result is often reduced airflow, extra noise, and rooms that never feel quite right.
Airflow in a duct system depends on both duct size and a parameter called static pressure, which you can think of as the resistance to airflow through the ducts. When you add long, narrow runs to reach a new room, you increase that resistance. The blower in your furnace or air handler can only push so much air against that resistance before performance drops. Just like trying to run more water through a garden hose already near its limit, the pressure builds, the noise increases, and less air reaches the spaces that need it.
Another overlooked piece is return air. Supply vents deliver conditioned air into rooms, and return grilles pull air back into the system for reheating or cooling. During renovation, walls move, doors shift, and sometimes returns get blocked or removed. If you add supplies to a new space but fail to provide adequate return paths, pressure imbalances and comfort issues follow. Finished basements and bonus rooms in Gresham sometimes rely on a single undersized return grille to serve too many rooms, which leads to stuffy, uneven conditions.
As Ruud Pro Partners, we have been installing and adjusting duct systems in local homes for decades, and we design duct changes with both comfort and efficiency in mind. That might mean resizing existing trunks, adding dedicated supplies and returns for an addition, or recommending a separate solution when the main duct system is already at its limit. Planning ductwork alongside framing, rather than squeezing it in after the fact, is one of the biggest differences between a renovation that feels great to live in and one that causes frustration down the road.
Choosing Between Extending Your System and Adding a Separate Unit
Once you understand that renovations change load and airflow, the next question is how to serve the new space. Sometimes, extending the existing system makes sense. If you are doing a modest layout change, such as moving a couple of walls or adding a small office, and your current equipment and ducts have spare capacity, adding or relocating a few ducts may be the most straightforward solution. The key is to confirm that spare capacity rather than assume it.
In other cases, especially for additions, attic conversions, or rooms over the garage, a separate unit or zone is usually a better fit. Ductless mini split systems are a common choice here. They deliver heating and cooling directly to the space through a small wall cassette or ceiling unit, without relying on long duct runs from the main system. This can offer better temperature control in hard-to-condition areas and avoid overloading the existing ducts and blower.
Each approach has tradeoffs. Extending the existing system can mean fewer pieces of equipment to maintain and a lower upfront cost if the modifications are simple. However, if the main system is already near its limits, this route can leave you with marginal comfort and higher energy use. A separate ductless system or new zone often costs more up front, but it can provide precise control for the new areas and sometimes reduce the load on the main system. Operating costs will depend on the equipment's efficiency, how you use the space, and Gresham’s seasonal temperatures.
Because every home and renovation is different, we take a no-pressure approach when helping Gresham homeowners choose between these options. Our team reviews your current equipment, duct layout, and renovation plans, then walks through the pros and cons with clear pricing. As a Ruud Pro Partner with access to reliable Ruud and Maytag systems, we can offer both high-efficiency central systems and quality ductless options, and then recommend the path that fits your home and budget rather than automatically steering you to the most expensive upgrade.
When to Involve an HVAC Contractor in Your Renovation
One of the biggest misunderstandings we see is around timing. Many homeowners wait to involve an HVAC contractor until framing is done or even right before drywall, assuming the system design will be simple. By that point, key decisions about equipment location, duct chases, and mechanical room size have already been made. If the existing plan will not support proper ductwork or required clearances, your choices become limited and more expensive.
The ideal time to bring HVAC into the conversation is during the design phase or early in the permitting process. When we can review your drawings early, we can flag issues like long duct runs to remote rooms, equipment squeezed into overly tight spaces, or a lack of return air paths. Adjusting layouts on paper is much easier than reworking framed walls. We can also advise where to place mechanicals and duct chases so they remain accessible for service and do not force awkward bulkheads or dropped ceilings later.
As the project moves into rough-in, HVAC work typically proceeds alongside plumbing and electrical work. This is when ducts are run, refrigerant lines are routed, and equipment placement is finalized. If we have already been involved, this stage proceeds more smoothly because the plan matches the space. If we are called in late, we may have to thread ducts through whatever openings are left, which can compromise airflow and create future service headaches.
Because we work with contractors and inspectors throughout Gresham and the surrounding areas, we understand how local projects typically flow. Early coordination between your builder and our team helps keep HVAC work aligned with other trades and in compliance with mechanical installation codes. That coordination supports your project schedule and reduces the risk of last-minute surprises that could delay inspections or require opening up finished work.
Energy Efficiency, Rebates, and Long-Term Operating Costs
Renovation is often the smartest time to think about energy efficiency. You already have trades on site, walls open, and a budget allocated for improvements. Upgrading to higher efficiency equipment or improving ductwork while everything is accessible can be more cost-effective than doing it later as a separate project. It also helps align your monthly utility bills with the investment you are making in your home.
Three main ratings help you compare HVAC efficiency. SEER describes cooling efficiency for air conditioners and heat pumps. A higher SEER rating generally means the unit uses less electricity to provide the same amount of cooling. HSPF is similar but applies to heat pumps' heating output. AFUE measures how efficiently a gas furnace converts fuel into heat for your home. For example, a furnace with 95 percent AFUE turns 95 percent of the gas it burns into usable heat, with the rest lost through exhaust.
In Gresham, where winters require reliable heating and summers can call for steady cooling, choosing equipment with higher SEER, HSPF, and AFUE ratings can trim energy use over the life of the system. The actual savings depend on your home, habits, and local utility rates, but in general, the more efficient the equipment, the less energy it needs to keep you comfortable. When you combine efficient equipment with renovation upgrades like better insulation and new windows, those gains often multiply.
As a Trade Ally of Energy Trust of Oregon, Gresham Heating and Air Conditioning can help you identify energy-efficient options that may qualify for incentives. While specific rebate amounts and programs change over time, the basic idea is that choosing certain high-efficiency systems can make you eligible for financial incentives that offset some of the upfront cost. We can walk you through current program requirements, help you weigh long-term operating costs against initial investment, and design an HVAC renovation plan that supports both your comfort and your energy budget.
Planning for Ventilation and Indoor Air Quality in a Tighter Home
Many renovations focus on tightening the home. New windows, doors, and insulation reduce drafts and make spaces feel less leaky, which is good for comfort and efficiency. At the same time, a tighter home does not breathe as well as an older, draftier structure. Without proper ventilation, you can end up trapping humidity, cooking odors, and everyday indoor pollutants inside, which can affect how your home feels and put more strain on the HVAC system.
Ventilation means bringing in fresh air and exhausting stale air in a controlled way. In a renovated home, this often starts with properly sized and ducted bath and kitchen exhaust fans that vent outdoors, not into an attic or crawl space. During HVAC upgrades, it also makes sense to review filtration and fresh-air strategies. Options range from improving the filter in your existing system to adding dedicated fresh air intakes, depending on your home’s design and needs.
Return air plays a role here, too. When renovations change room layouts or close off certain areas, returns can become isolated or undersized. This can make some rooms feel stuffy while others are comfortable. As part of renovation-related HVAC work, we look at how air circulates through your home, not just how much heating or cooling the equipment produces. Balancing supply and return air and ensuring key areas have a clear path for airflow helps keep your indoor environment fresher and more even.
We focus on practical ventilation improvements that pair well with your renovation scope. That might mean relocating returns, upgrading exhaust fans, or improving filtration while we are already working on your ducts and equipment. Addressing these details while the project is underway is much easier than retrofitting solutions after the house is sealed up and finished.
Protecting Your Investment With Proper Startup and Maintenance
Once the dust settles and the last coat of paint dries, it is easy to assume your HVAC system will simply run as intended in the new layout. However, construction creates dust and debris, and new duct runs or equipment need to be checked under real operating conditions. A thorough startup and system check after renovation is essential to protect both your new space and your HVAC investment.
A post-renovation check typically includes verifying airflow to each supply register, confirming that returns are working as planned, checking thermostat location and programming, and making sure filters and coils are clean after construction. In some cases, small adjustments to dampers or duct balancing can make a noticeable difference in how evenly your home heats and cools. Skipping this step can shorten equipment life and leave small issues to grow into larger repair problems.
Ongoing maintenance matters as well. New or upgraded equipment still needs regular filter changes, inspections, and cleaning to maintain its efficiency and reliability over time. This is especially true in the first year after a renovation, when residual construction dust can clog filters and settle on components. At Gresham Heating and Air Conditioning, we offer comprehensive annual maintenance plans designed to keep systems running efficiently and support long service life, which helps you get the full value from both your renovation and your HVAC upgrades.
By scheduling maintenance alongside your renovation timeline, you ensure the system is set up correctly from day one and stays tuned as the seasons change. That way, the comfort and efficiency you planned for on paper have a better chance of showing up in your everyday life.
Plan Your Gresham HVAC Renovation With a Local Team You Can Trust
A successful renovation is not only about open sight lines, new finishes, or added square footage. It is about creating a home that feels comfortable in every room, in every season, without surprise energy bills or constant thermostat battles. When HVAC planning is part of the design conversation rather than an afterthought, you give your new layout the heating and cooling support it needs to perform as you expect.
If you are planning a renovation or already working with a contractor in Gresham or the surrounding area, we can review your plans, evaluate your current system, and lay out clear options for duct changes, equipment upgrades, or additional units. As a local, family-owned company in business since 1992, a Ruud Pro Partner, and a Trade Ally of Energy Trust of Oregon, Gresham Heating and Air Conditioning focuses on no-pressure recommendations that fit your home and budget.
Share your drawings with us early, and we can help you avoid common HVAC renovation pitfalls and aim for a finished space that is comfortable and efficient for years to come.