Heating a room suspended in the air

[HoughMade]

I have a sun room off of my master bedroom that is about 14x14. It is built on the same plane as the deck off of the family room which is a story in the air because the house has a walkout basement. This means the floor of the sunroom is open underneath, kind of. Part of it is over a shed, part of it over open ground, all the below is unheated. The floor is insulated- the joists are 2x10 and there is bat insulation in them, but I do not believe it is full thickness. I believe it is the insulation that was used in the rest of the 2x6 walls.

The sun room itself has standard insulated 2x6 walls, but 6 large double hung windows and a door to the deck. The ceiling is insulated as well. Here's the kicker- there are no heating ducts running to the sun room (see the "open to below" issues mentioned above). When we leave the door to the master bedroom open and run a quartz electric heater in there, it can get comfortable on cold days, but it's never quite as warm as other parts of the house.

Eventually, I want to put a mini-split in there, but right now I suspect that the cold air underneath is sapping a fair amount of heat. If you were dealing with this space, what would you try....I am thoroughly able to do most any home improvement project myself.

 

[drop45]

Is electric floor radiant heat an option? I think it comes in rolls that get stapled down and then your flooring of choice gets laid down on top. I think it's also plug and play, all grids get joined together.

 

[HoughMade]

I've been thinking about that. I know hot water heat can be installed below the sub floor and then you insulate the heck out of it. I don't know about electric under the subfloor. The reason I bring "under the sub floor" up is that the room has nice carpeting in it, but O guess it could be pulled up and reinstalled.

 

[Leadeye]

Had a similar problem at my old house, even with the space optimized with insulation it was still chilly.

 

[WilsonMD]

Electric baseboard. 220 if possible. Radiant heat should work well since you probably don't have any cold air returns either. They are thermostatically operated as well.

 

[IndyGunworks]

Spray foam, and a mini split.

 

[ErickW]

Yes, mini split. I sell them and when the load is calculated properly they are amazingly effecient and cheap to operate. Not to mention quiet. I took a whole house off baseboard last winter to mini split and the owners were amazed by the results.

 

[HoughMade]

Yes, mini split. I sell them and when the load is calculated properly they are amazingly effecient and cheap to operate. Not to mention quiet. I took a whole house off baseboard last winter to mini split and the owners were amazed by the results.

Like I said, that's the ultimate plan, but is spray foam the only way to go? If so, with 2x10 deep bays, should I just fill them up and pay the piper, or is there a less expensive way to get adequate insulation?

 

[CountryBoy19]

More details on the windows. Size? Energy Efficiency? Those are critical factors here, your windows may already be the largest point of heat loss and adding more insulation will be well into the realm of diminishing returns.

None-the-less, any room that has 5 exterior sides is going to be a really big energy loser...

 

[Cameramonkey]

+1 on spray foam. They can lay out something crazy like R60 values if done right. and if you use some of this before nailing down the underside covering, you can virually eliminate the heat transfer between the exposed surfaces and joists.

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[Tobryan]

Put kraft faced R-38 in the joist space and cover it with soffit material. Cheap. Closed cell spray foam is the ultimate. If they spray 2-3" that will more than suffice. Get a couple quotes. Still need to put some sort of sheathing on the joists either way.

 

[smokingman]

We have a back utility room with a similar issue.
I can not offer the best advise on how to heat it,but think I can give you the best solution possible to cut heat loss.
Spray foam.We did our entire crawl space and the utility room.The difference in floor temperature is amazing.We used Foam It Green while leaving our existing fiberglass in place.
Yes it is rather expensive($337 for 202 sq feet),but I can not begin to tell you how much warmer our entire house feels.We are in Northern Minnesota,and when it is -30F you learn what works and what does not.Sealing over our existing fiberglass made sense.You keep the R value of the fiber with some additional R value from the foam and have ZERO cold air intrusion.It works.

I would not call it an easy do it yourself project.I would also recommend better PPE than the manufacturer.It did not take long to do or to get the hang of,but it was messy spraying it up vs vertically.Here I am after 4 hours or so of spraying,which was how long the entire process took.Just over 1000 sq feet.My arms where tired for sure.You can not stop once you have started or you will lose to many nozzles to clogging(it takes less than 1 minute to clog a nozzle).I was in a crawl without the best ventilation so went with appropriate PPE.

If I had to do it again I would probably just hire a pro.

 

[churchmouse]

Like I said, that's the ultimate plan, but is spray foam the only way to go? If so, with 2x10 deep bays, should I just fill them up and pay the piper, or is there a less expensive way to get adequate insulation?

Spray foam has advantages beyond just an "R" factor. Properly applied it seals up all the nooks/cranny's that allow intrusion. Keep the outside out is the key to conditioning the space.

 

[churchmouse]

We have a back utility room with a similar issue.
I can not offer the best advise on how to heat it,but think I can give you the best solution possible to cut heat loss.
Spray foam.We did our entire crawl space and the utility room.The difference in floor temperature is amazing.We used Foam It Green while leaving our existing fiberglass in place.
Yes it is rather expensive($337 for 202 sq feet),but I can not begin to tell you how much warmer our entire house feels.We are in Northern Minnesota,and when it is -30F you learn what works and what does not.Sealing over our existing fiberglass made sense.You keep the R value of the fiber with some additional R value from the foam and have ZERO cold air intrusion.It works.

Hah....you beat me.

 

[HoughMade]

Thanks for the links and all the tips. Seems like a viable option would be to remove the sheathing (the part not over the shed is sheathed with plywood), remove the fiberglass batts, then spray in 2" of foam, thenn replace the present batts and re-sheathe with a thermal barrier between the sheathing and the joists. I wanted to replace the plain plywood that is visible with beadboard anyway (had it on the porch ceiling at my old house), then reuse some of the plywood to sheathe in the shed. Headroom is not a problem (nearly 10 feet from ground to joists), so I have even kicked around rigid foam as a third layer of insulation before the sheathing

As for the windows, I'm sure they could use work, but they are in good condition, Pella insulated double hung- top quality for 1997 when the house was built. The door is insulated and tight. I was wondering whether exterior storm windows would make much of a difference. While the windows seem sealed well, that's a lot of glass.

 

[gungirl65]

I have a sunroom off my master bedroom too. I think it is approximately a 12' X 14' or 12' x 16 ' . It and the laundry and mud rooms below were add ons built in probably the 50's. So it is not set up to receive central air or heat. We put in one of those wall unit ac & heater combos about 10 years ago. I don't use it all the time but when I do it heats or cools the room fairly well. It just looks like a monster AC unit in the wall.

 

[hoosierdoc]

I've seen this heat something suspended in air very well. It's a bit loud though.

 

[Brian Ski]

None-the-less, any room that has 5 exterior sides is going to be a really big energy loser...

Well that is a start. That many sides are going to lose heat.

Is the room something you are in all the time (going to heat 24-7) or is it a once in a while thing???

Do you have Natural gas available??? We have one of these heaters in the basement (playroom) It works excellent.
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You can pick find them all over and do not need to be vented. The one we have is a little different it has a log in it to make it look like a fireplace. They also have them in radiant. Eh I like the regular ones better. The down side is when they run a lot they put moisture in the air. I guess that is also an upside in the winter. The moisture if ran a lot on high may condense on the windows. It is nothing as bad as the moisture from a shower. Got a friend using one to heat his entire house and works great but he was having moisture problems. (we were guessing that was where it was coming from) Something easy and kind of cheap. They have them from 10-30,000 BTUs. I would get the larger... It has a generic style thermostat.

I got mine cheap off of craigslist with a wooden surround.

 

[BigBoxaJunk]

I've got a 16' X 20' breezeway in between the garage and the house, fully enclosed with a brick floor, but not insulated.

I've never heated the space except for when we have a family gathering I'll put a kerosene heater out there to make it more comfortable.

 

[Brian Ski]

I've got a 16' X 20' breezeway in between the garage and the house, fully enclosed with a brick floor, but not insulated.

I've never heated the space except for when we have a family gathering I'll put a kerosene heater out there to make it more comfortable.

I have a beer barn (thats what it is nick named) about the same size. We use it for the family gathering too... Normally it was going to be a 3 season room... But if we can get a path through the snow we use it all year. I use a propane heater. It looks like a metal 5 gallon bucket. can go up to 80,000 btus. Works great. No smell and heats up the place fast. Just would not recommend it for the house. Maybe in an emergency.