In this post, you will learn:
- The key differences between a three season sunroom and a four season room addition
- The pros and cons of each option
- How to determine which sunroom design is best for you

Renovating your home with a personalized sunroom can be a liberating decision.
From expanding your living space to increasing your property value – the addition of bright, natural lighting can offer huge improvements to your lifestyle, your bank account and even your mental health!
As Canadians, we are constantly finding new ways to embrace the outdoor experience despite the harsh and changing seasons.
Unfortunately, there is no one-size-fits-all when it comes to selecting the best sunroom design.
To make the best choice for your family, it is important to have a clear understanding of the differences, advantages and disadvantages between your options.
The following guide will give you a detailed comparison of sunrooms and room additions to help you make the best decision:
What is the Difference Between A Sunroom And A Room Addition?
The term “sunroom” is often used to define a glass enclosure that bridges the indoor and outdoor living areas.
However, the different styles of sunroom designs are subcategorized by the number of seasons they can be comfortably enjoyed!
While a traditional sunroom (or porch enclosure) would be suitable for warmer seasons, a “room addition” (or four season sunroom) is constructed in a way that ensures comfort all year round.
While they may look aesthetically similar in design, there are a few major differences to be aware of:
Insulation
The main and major difference between a three-season sunroom and a room addition is their thermal resistance and insulation capacity.
As a three season sunroom would only need to be insulated for the warmer months of the year, they would not require as much insulation.
A traditional room addition, however, would make use of stronger, higher-quality insulation to provide comfort and enjoyment despite the drastic weather changes.
Materials
Three Season Sunrooms are typically built with a light aluminum frame using strong, low maintenance, cost effective materials with up to 80% of the wall space constructed in glass.
As this space would not need to be heat-regulated during the winter, many homeowners opt for the affordable single-pane glass option for this particular sunroom design.
While a traditional room addition would be built much like a house, this option woulduse more stable building materials such as wood, drywall, shingles, concrete, and glass.
An important difference to note is that there are International Energy Conservation Codes in place that will only allow for up to 40% glass windows throughout the room addition build.
In this case, double pane windows would often be selected to minimize solar heat changes and help regulate internal temperature during the colder months.
Climate Control
While three season sunrooms are not required to have electricity or central heating/cooling (HVAC), custom-built sunrooms can often include some form of fan-driven heater or electric baseboards.
Essentially, this design is intended to let in as much sunshine as possible, while keeping out the wind and rain.
Unfortunately, seasonal sunrooms would only be suitable during the spring to fall months as the space would be too cold to enjoy during our long Ontario winters.
Room additions, however, would be equipped with the same type of HVAC as a typical home allowing for room enjoyment throughout the entire year.
Space & Versatility
Both sunrooms and room additions can do a great job for adding space and versatility into your home.
From an additional dining and entertainment space to an extra playroom or guest room – the positioning and size of your space can inspire a variety of fun, functional uses.
Three season sunrooms are typically built onto an existing deck or patio with few structural changes.
As they are built on concrete slabs (much like a garage or basement), these sunrooms are typically limited to the front porch, side deck or back patio.
Pursuing a room addition, however, can build an extension onto any area of your home, and if you have a smaller sized lot – you can even build up!
A room addition would also add square footage to the overall size of your home, which can do a great deal for boosting your property value!
Since the building styles are so different, it is important to select the option that would most benefit you in the long run, as upgrading or downgrading would be a very lengthy (and expensive) process.
Average Cost
Building a customized sunroom is a personalized process that can cost anywhere between $10,000 and upwards of $70,000.
Influenced by the size, materials, design layout and labour – the overall cost will often fluctuate from project to project.
Since seasonal sunrooms will require much less insulation and building materials, it is no surprise that this option will be considerably cheaper by comparison.
As a result, this has become a very popular option for those looking to enjoy the beautiful sun on a bit of a tighter budget!
For a four season room addition, the construction process would be much more extensive, requiring heating, plumbing, building a foundation and even removing existing walls.
Time Frame
The process of building a seasonal sunroom is much faster than building out a room addition.
Sunrooms are typically built without any heavy construction or need for knocking down walls – so the installation process would be much less disruptive.
For a room addition, the time frame would depend on the full scope of the project.
What Are the Pros and Cons of Sunrooms and Room Additions?
The main concern that many homeowners come across is determining which sunroom design will be in their best interest.
As the building process, cost, materials and functionality differ so much between the two, it can be overwhelming to make the “right choice”.
To help you narrow down the best option for you, here is our list of pros and cons for each design:

Three Season Sunroom:
PROS | • Enjoyed during the warmer months • Therapeutic Natural Lighting • Additional space for lounging and dining • Efficient construction time • Cost Effective |
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CONS | • Limited to the side, front or back of house • Separate from the rest of the house • Not insulated enough for the winter • May not include electrical wiring or HVAC • Limited Privacy |
Four Season Sunroom:
PROS | • Can be added to any area of the house • Energy efficient • Increases square footage & property value • Therapeutic Natural Lighting • Quality Insulation & HVAC to support year-round enjoyment |
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CONS | • Expensive • Less window space • Disruptive construction process • Possible increase in property taxes & insurance • Limited Privacy |
How to Determine Which Sunroom is Best for You:
Although the differences between a traditional sunroom and a four season room addition vary greatly, it is important to consider your personal needs.
To help you determine the best option, consider the following questions:
- Where would I like to build my sunroom?
- What will I be using the extra space for?
- Which months of the year would I like to utilize my sunroom?
- What is my budget?
As each sunroom design is unique to the qualities of each home and family, it is important to consider how this renovation could benefit your family not only today, but for the years to come.
If you are interested in expanding your home with a beautiful sunroom addition, allow our experts at Stouffville Glass to help build out your dreams!
Click here or call (905) 640-4016 for a complimentary consultation.