Home Addition Guide: How to Heat a Room Addition

A home addition is an exciting way to expand your living space, whether it’s a new room or an expansive new wing. However, it comes with a unique set of challenges, particularly when it comes to heating. Unlike the original structure, a room addition may not be integrated into the home’s existing heating system, requiring alternative solutions to ensure efficiency, comfort, and affordability.

Whether you are adding a sunroom, a guest bedroom, a home office, or an expanded living area, maintaining a comfortable temperature is essential to enjoy your new space. In this guide, we discuss what to consider when heating a room addition. and review the different room heating options available.

What to Consider When Heating a Home Addition

Before choosing a heating solution, you need to take several factors in mind that will influence the efficiency, comfort and heating performance of the new space.

1. Type of the Room Addition

The type of the room will greatly affect what type of heating options are available. We have written specific guides for popular room types, including:

• Living room fireplaces
• Large / open rooms
• Attics
• Basements
• Garages
• Sunrooms
• Crawl spaces 

2. Room Size

The square footage of the new space will impact heating requirements. Larger rooms require more powerful heating systems, while smaller rooms can make do with compact or supplemental heating options

Check out our handy Heating Calculator to determine the BTU needed for your room addition.

3. Existing HVAC Compatibility

Determine if your current HVAC system can handle the extra load. 

If you use central heating, extending ductwork may be an option, but it could strain an already taxed system and could interfere with the static pressure in the ducts.

If you have a multi zone mini split, check if the system can handle an additional indoor unit, as well as the wire routing to the outdoor compressor.

4. Vented vs Ventless

Vent-free heaters may not be recommended for some enclosed living areas. Depending on your location, local codes may also not allow the use of ventless heaters.

For vented heaters, they require an exhaust to an exterior wall where gases can be expelled outside.

5. Climate and Seasonal Use

Consider how often and during which seasons the room will be used. A sunroom used in the summer may not need the same heating system or BTUs as a bedroom that is occupied year-round.

6. Fuel Source

If you will be getting a new room or unit heater for the space instead of ducted heating, you have a choice of electric, natural gas or propane heater. Consider whether the space has a gas or propane line, or limited to an electrical outlet. Each type of heater has its own pros and cons, depending on your room addition.

7. Insulation

Some home additions are less insulated, whether by design or due to semi-occasional use. These include garage, attics, and basements.

The type and thickness of insulation should be taken into account when choosing the heating system. A less insulated space may require more BTU capacity.

8. Budget and Installation Costs

Some heating options require a significant upfront investment but offer long-term savings, while others are more affordable upfront but may have higher operational costs.

For example, if you have central heating, you may want to compare the cost of extending the ductwork to the new space, versus getting a new room heater.

Types of Room Addition Heaters

1. Extended Central HVAC

If your home has a forced-air HVAC system, extending ductwork to the new addition may be an option.

Pros:

• Provides uniform heating throughout the home
• No need for additional standalone units
• Uses the existing thermostat for easy temperature control

Cons:

• May require upgrading the HVAC system if it’s not powerful enough
• Installation costs can be high depending on the ductwork length
• Extensive heat loss depending on the distance from the central heating

2. Ductless Mini-Split Heat Pumps

Mini-split heat pumps provide both heating and cooling without requiring ductwork. If you have an existing multi-zone mini split, it may be able to support an additional indoor unit.

Pros:

• Highly energy-efficient and cost-effective
• Offers zoned heating control
• Can be installed quickly without major renovations
• Offers a variety of indoor unit types to adapt to the requirements of the space

Cons:

• Higher initial cost than some other options

Featured mini split heat pump for home additions:

Daikin FTXM18WVJU9 / RXM18WVJU9

This unit offers 18,000 BTUs AC capacity and 21,600 BTUs heating. Not only does this system run on the efficient R32 refrigerant, it meets the more stringent DOE regulations. The 18,000 BTU Atmosphera system features 12.5 EER2, 22.7 SEER2 and 10.0 HSPF2 ratings with a 3.6 COP rating.

In addition to efficient ratings, it offers enhanced capacity comfort with 100% heating capacity at 5°F. By installing an optional drain pan, the unit will continue to offer heating as low as -13° (with optional drain pan heater). Additionally, it also offers 100% cooling in temperatures as high as 115°! These ambient temperature ranges for heating and cooling, make the Atmosphera capable of year-round comfort in many US climates.

3. Electric Baseboard Heaters

Electric baseboard heaters are a simple and cost-effective heating solution for room additions.

Pros:

• Easy to install with no ductwork required
• Quiet operation
• Low upfront cost

Cons:

• Can have high utility costs in colder climates
• Limited heat distribution compared to forced-air systems

Featured electric baseboard heater for home additions:

King 6K2415BW 6 Foot 1125/1500 Watt Electric Baseboard Heater

The King K-Series baseboard heaters are easy to install and attractive to look at, with a smooth, baked enamel, bright white finish and rounded edges for safety. The series uses exclusive crush-proof ribbon aluminum finning that is compression welded to the heating element, to provide a chimney-type flue for maximum heat transfer.

This baseboard heater is 72″ long and uses 208/240V electricity and delivers 1125/1500 watts of electric heat. It can be wired on either the right or left side. The SureStop high temperature-limit feature shuts power off to the heater in an abnormal event.

4. Gas or Propane Heaters

Standalone gas or propane heaters provide powerful heating for room additions, and can be more efficient than electric heat.

Pros:

• Cost-effective fuel option
• Provides fast and powerful heating
• Ideal for off-grid or rural locations

Cons:

• Requires ventilation and may produce emissions
• Installation can be more complex

Featured gas heater for home additions:

Williams Furnace Company 3003 30,000 BTU Gravity Direct Vent Wall Furnace

This highly efficient indoor heating unit provides up to 30,000 BTUs of heat in a slim compact design that’s only 10 1/4 inches deep.

Its sealed combustion chamber completely seals the gas flame inside the unit and away from all contact with the air in the room for added safety, operating completely electricity-free for use even during a power outage. Electricity is only required with installation of an optional blower (sold separately).

It is available in both Natural Gas – 3003822 and Liquid Propane Gas – 3003821.

5. Wall- or Ceiling-Mounted Electric Heaters

These types of heaters are compact, inexpensive and provide direct warmth. However they have limited coverage and are less efficient.

Pros:

• Simple plug-and-play installation
• Affordable and space-saving
• Works well for small additions like offices or sunrooms

Cons:

• Less efficient for large spaces
• Can create uneven heating

Featured wall heater:

King W2415-W 1500/750 Watt Dual Wattage Fan-Driven Wall Heater

This electric, fan driven heater is a great option for adding supplemental heating. It boasts a fan blade and an open coil heating element behind a slatted front. The upper fan blade draws the air in and the heated air goes through the NiChrome coil element and is discharged through the bottom towards the floor. 

The W series features the option of two wattages to meet your heating needs. You can use this heater at full 1500 watts or drop it to 750. It is a quick installation as well, with a 3.5″ deep frame that easily fits in a 4″ wall.

6. Electric or Gas Fireplace

For living spaces that could use a cozy and aesthetic source of warmth such as living rooms and dens.

Electric fireplace

Pros:

• No gas lines or ventilation needed
• No real flames, so the unit stays cool to the touch
• LED flames can change colors and brightness

Cons:

• Less heat output
• Lacks the realistic flames of a true fire
• Won’t work during power outages

Gas fireplace

Pros:

• Higher BTU capacity for larger spaces
• Offers a more authentic fire experience
• Lower operating cost in places where gas cheaper than electricity
• Works even during blackouts

Cons:

• Requires a gas line, ventilation (for vented models), and professional installation
• Cost more than an electric fireplace, especially if retrofitting is required
• Carbon monoxide and gas leaks are potential risks

To know more, check out our complete guide to Electric vs Gas Fireplace.

Featured electric fireplace for home additions:

Simplifire SF-ALLP60-BK 60″ Allusion Platinum Built-In Linear Electric Firebox

This attractive minimalist firebox measures 60″ linear and can be wall-mounted or fully recessed for a sleek, built-in look. It has the heat equivalent of a freestanding space heater with 750W or 1500W modes for energy-saving versatility and can service spaces up to 400 square feet.

It features four flame colors and thirteen ember bed color options, beautifully illuminated by long-lasting LED lights. It comes with multiple media options to match your desired aesthetic: clear crystals for an ember bed with thirteen color options, or ceramic white stones for a natural look. The fireplace also comes with both small and large clear acrylic crystals and ceramic white stones. For a different interior style, an optional 12-piece driftwood kit (SF-MEDIA-LOGS) is available, as well as additional white ceramic stones (SF-STONES-WHITE), sold separately.

Featured gas fireplace for home additions:

Superior DRL3545TEN 45″ Contemporary Linear Direct Vent Fireplace

This contemporary-style linear fireplace features a clean face design with a low profile, showcasing a beautiful tempered glass and a protective barrier screen that meets all ANSI Z21.88 barrier requirements. It is a fully equipped fireplace, packaged standard with a variable speed blower and multi-function remote control.

The electronic ignition has a battery back-up for continued operation even in a black-out / power outage. It boasts mood-enhancing floor lighting with six distinctive settings to help customize your fireplace to your mood. The reflective, crushed platinum glass media on the floor of the firebox offers a fabulous bed for the dancing flames to rise through.

Also included is a variable speed blower with six speed settings, and a multi-function remote that controls the thermostat, flame height, blower and lighting control.

7. Radiant Floor Heating

Radiant floor heating or underfloor heating provides warmth through heating elements installed under the flooring. They provide a cozy and discreet way of heating a room.

Pros:

• Delivers even, consistent heat
• Energy-efficient compared to forced-air systems
• No visible heating equipment

Cons:

• Expensive and complex to install
• Requires significant renovation if not planned in advance

Featured radiant floor heating for home additions:

Nuheat Electric Floor Heating Mats

Nuheat Floor Heating Mats are easy to install and are available in just about any size you may need. They come in various widths to meet the needs of your smaller areas: 27″ (F1006), 32″ (F1008), 40″ (F1010), and 48″ (F1012). Nuheat floor mats are pre-wired and cannot be cut, but they can be laid in either direction so if the width and length don’t match your needs, you can turn it.

The mats are highly energy efficient, with up to 12 watts/sq. ft.; 41 BTUs/ sq. ft. They are almost all DIY – an electrician is only needed to install a dedicated line. If your room already has one, simply lay your thinset, roll out the Nuheat mat right onto the thinset, apply another layer of thinset and install your flooring.

7. Wood or Pellet Stoves

A wood or pellet stove can add rustic charm while providing heat.

Pros:

• High heating efficiency
• Provides ambiance along with warmth
• Does not require electricity or gas lines

Cons:

• Requires ventilation and chimney installation
• Needs regular maintenance and fuel replenishment
• May not be ideal for urban areas or places where wood is hard to source

Warm Up your Room Addition

The best heating solution depends on your specific needs, budget, and climate. If your home’s HVAC system can support an addition, extending it may be the most seamless option. For energy efficiency and versatility, ductless mini-splits are a top choice. If affordability and simplicity are the main concerns, electric baseboard or wall-mounted heaters may be ideal, while gas heaters provide more heat for the buck.
No matter what heater you need, Total Home Supply carries a wide range of home addition heaters covering different models, fuel sources, and budgets. If you don’t know where to start or feel a little overwhelmed, give us a call and we’ll be glad to help you heat up your home expansion.