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3 Season Sunroom vs a 4 Season Sunroom


3 seaon vs 4 season sunroomWhat is the difference between a 3 season sunroom vs a 4 season sunroom?  The obvious answer - one season!  A 3 season is built to be used in the warmer months of the year, which in Northeast Ohio can vary from a span of 5 to 8 months (if we’re lucky!).  A 4 season sunroom is constructed to allow the sunroom to be used comfortably  year round.  There are three primary differences in the construction of these rooms:  glass, insulation and a HVAC unit.



Since windows/glass panes are the largest component of any type of sunroom the glass type used will effect the overall usability of the room.  In a 3 season room, typically the windows have single pane tempered glass windows which offer minimal energy efficiency.  In a 4 season room, high performing energy efficient windows are used throughout the entire room.  The use of superior insulated glass reduces the loss of radiant heat in the winter and reduces the heat and ultraviolet rays from entering during the summer.



Insulation of the walls, roof and floor are important elements in extending the use of a sunroom for 3 to 4 seasons. Although typically 3 season rooms do have insulation it is the amount or quality of insulation that is the difference between a 3 or 4 season.  The additional insulation found in the walls, roof and floor help to keep the heat in in the winter months extending the usability of the sunroom.



Although a 3 season or a 4 season sunroom can each have an HVAC unit within the room, they are used in a very different manner.  For a 3 season room, the HVAC unit can be used to take the edge off on a chilly evening but not to heat the sunroom during the winter months as there is not sufficient insulation to keep the heat in.  The HVAC unit can be used effectively in a 4 season room for either heating or cooling purposes, creating year round comfort.


How to choose between a 3 season or 4 season sunroom

Choosing between a 3 season or a 4 season sunroom has more to do with how you plan to use your new addition than the construction differences.  If you hibernate like a bear in the winter and are looking for a place to entertain during the warmer months only, then a 3 season sunroom would be a perfect solution.  On the other hand, if you are looking for additional space year round and the thought of being able to be relax with a hot cup of coffee while watching the snowfall right outside your window is enticing, then a 4 season sunroom is your perfect solution. Which type of sunroom is your choice? Let us know ~ comment below!   


photo credit:  Simon Howden/


Want to get great tips and ideas for your sunroom?  Download our free design guide below.

Free Sunroom Design Guide





Very helpful information on 3 season sunroom addition vs a 4 season sunroom. Thanks!
Posted @ Thursday, September 01, 2011 5:35 AM by Sunrooms New Jersey
I currently just bought a house with a 4 season sunroom . Since we have bought it this summer we have noticed that it has been way to hot to be in it ...Now that it is September we are finding it to cold to be in it . We have a small proprane fireplace in there ( which was here when we came ) My question is if it is a 4 season sunroom should I not be able to be in it without having a fireplace on .  
Posted @ Wednesday, September 07, 2011 1:22 PM by Joanne Laflamme
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