Three season sunroom to 4 season room


Old 02-10-15, 10:45 AM
Thread Starter
Join Date: Feb 2015
Posts: 3
Received 0 Votes on 0 Posts
Three season sunroom to 4 season room


I'm posting this to get input, opinions, info, etc.. I have a 3 season sunroom with cathedral ceilings (the rest of my home has these as well). The room has windows all around, and has 140sq ft of floor space. I am certain this room is insulated, the interior has drywall throughout as well as the ceiling which also has the textured plaster look to it that matches my home. The underside of the deck this was built on has plastic coming out from the sides of the plywood that was put underneath, which I suspect is also insulated. I'd like to use this room year around, so I plan to replace the floor (it needs it), trim moldings, and paint, and keep the door to it open. I plan to cut a small hole in the wall to confirm insulation, whats he best way to confirm the ceiling has it as well? Given it has a texture to it I don't want to cut any holes.

Before embarking on the small remodel, does anyone have advice? What I should do to ensure energy efficiency, etc.?
Sponsored Links
Old 02-10-15, 11:10 AM
Banned. Rule And/Or Policy Violation
Join Date: Apr 2013
Location: USA
Posts: 4,294
Received 0 Votes on 0 Posts
A cathedral ceiling is by far the least energy efficient type ceilings there is.
All the heat rises and gets trapped at the peak.
It's also one of the hardest to insulate.
In your area there needed to be R50 to R60 which is 12" or over of insulation.
Post some pictures, trying to figure out what your talking about when you say "The underside of the deck this was built on has plastic coming out from the sides of the plywood that was put underneath".
How was it built?
Slab on grade, piers, stem wall?
Old 02-10-15, 11:13 AM
Join Date: Oct 2008
Location: New England
Posts: 10,523
Received 37 Votes on 34 Posts
Hi F1 and welcome to the forum, I see you are buried in snow like many of us.

Unfortunately, few sunrooms up here were built for the conversion you are planning. That doesn't mean it is impossible, jut that there are some issues.

Total insulation is one. Just finding insulation in the walls may not be enough, especially in the ceiling. And all of that glass will be hard to heat.

Do you know if the rafters are vented low (soffits) and high (somewhere)? Is this sunroom attached to the side of the house where those rafters dead end against a wall

If there is no venting you will definitely have a moisture problem once you add heat to this space. Warm air will be loaded with moisture that will find its way into those rafter cavities and condense into moisture.

So, the initial questions are:
1. Is there any venting in place in that vaulted ceiling?
2. How deep are those rafters, 2x6 or other?
3. An elevated floor with a cold space below will need to be well insulated and perfectly air sealed. What's down there?
4. Let us know how much insulation you find and note if there is a vapor barrier anywhere?

Old 02-10-15, 11:23 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 26,229
Received 723 Votes on 669 Posts
3 season rooms are called 3 season rooms because they are built to be 3 season rooms, not 4. What that usually means is that the floor, ceiling and walls are all underinsulated, the window perimeters probably aren't insulated, they may not be double pane or just may not be efficient enough to be warm enough to be usable year round. (for instance, an aluminum single pane slider)

You might be able to use it year round if you throw enough energy at it to try and keep it comfortable, but IMO trying to use those rooms year round in a cold climate is usually not realistic. A room like that is certainly NOT "energy efficient" nor can they usually be made that way. Its basically surrounded by outside air on 5 sides... 3 exterior walls, top and bottom.... and doors usually seal off the shared wall with the house, effectively cutting the room off from it's heat source. Also, if adequate HVAC or heat was not added to the room when it was built, it's hard to add that later.

A photo would help us get an idea of what you have.
Old 02-10-15, 12:17 PM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,588
Received 94 Votes on 83 Posts
Keep in mind that you will need to dump a lot of heat in there to make up for the fact that five of the six surfaces are outside surfaces.
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: