How to keep cabin warmer

[DonTee]

I’ve had this cabin I’ve been working on for about ten years. With how Covid is changing things I’ve had a lot more time to work on it recently. My question is about how to keep the place warmer during the winter.

A few details about the cabin. It’s 24x30, and two story. It sits on posts, and has a wood skirt wrapped around it. The skirt has felt paper underneath and is pretty tight. I have R30 insulation in the attic, and R19 in the walls. The floor is about half done with R19 and that will be finished soon.

At some point I’ll need to bump the attic up to R49 minimum, and the floors up to R25 minimum.

So basically when it’s less than about 25 degrees the warmest I can get the place is about 60-65 degrees inside. This is using a VC Encore woodstove burning hardwood. Stove top temps 500-600 degrees. I’m worried what it’s going to be like when it’s -20 outside. This is in upstate NY.

Right now the insulation in the walls is exposed. It’s faced on the inside, but there is no drywall. Will drywalling the place help retain heat? Will it make that much of a difference bumping the attic and floor insulation up to code minimums or higher?

The cabin has newer doors and window (installed within the past ten years). Not super duper expensive units, but not 50 years old either.
All Windows and doors have been spray foamed around the edges.

The house doesn’t have siding on all sides yet, but has 1” sheathing on the exterior walls covered by house wrap.

I feel like for a newer, tightly built house I should be able to keep it warmer than this. The VC encore says it’s good for around 2,000 sq ft I believe. I’m a little less than 1400.
It’s a pretty open floor plan, with downstairs being all one big room (except for the bathroom) and upstairs being divided into 3 bedrooms. The house stays very close to the same temp in all the rooms.

Any advice on how to keep it warmer? I figure if I can’t get it to the mid 70’s inside when it’s around freezing outside, I’ll never be able to keep it in the 60’s inside when it’s negative temps outside.
I feel like the woodstove is big enough, but maybe it’s not.

Sorry for the long winded post

 

[NickW]

As @begreen reminded me in another thread, it takes a lot more BTU'S to raise temperature than to maintain temperature. Have you ever spent some time really letting the stove rip and reloading more often until you get it up to 68 or 70 inside and then see how hard it is to maintain that temperature?

 

[DonTee]

I agree that’s the case for sure. When I let the place get down to outside temp it takes all day to get it warm again.

I’ve spent about 3 days in a row working on the place where I have the woodstove going 24/7. The warmest it’s been inside is 66, and that was on a day it was around 32 out.

 

[bigealta]

Maybe the local fire department will let you borrow their IR heat gun (thermal imaging camera). Shows the hot and cold surfaces, where you are loosing the most heat from.

i found this on youtube.

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[DonTee]

That’s a good idea. The fire department is right down the road. And my neighbor used to be a volunteer fire fighter there. I’ll have to ask him.
I do have a cheap IR thermometer. It doesn’t have the cool display like the nice ones.

Basically I figure I could get a bigger stove and crank out more heat. Wood is basically free and not an issue. But I’d like to make the cabin as efficient as possible. So if I can get the desired temps with the size stove I have right now, that would be great.

Basically I’d like to have it around 60 degrees on the coldest nights.

 

[peakbagger]

Standard energy auditing technique is go after infiltration first then move onto insulation. Ideally have blower door test done and chase down the air leaks and cracks. Once the place if tight, then move onto insulation or lack thereof with a thermal camera check. Finally chase radiant heat issues. Windows are frequently set up for the view during the day but at night they become major radiant heat losses. This makes the space feel cold and usually the fix is to crank up the heat. Blocking the windows outright in cold weather using fail faced iso board foam can really help but obviously not something you want to remove often. Cellular blinds with side tracks (or proper window quilts are the next best and can be opened. Curtains can work but unless they are tight to the windows they can end up causing a lot of convective losses.

As mentioned, thermal mass takes a long time to warm, bringing it up to temp takes time and BTUS. Once the place is up to temp the stove needs capability to turn way down.

My guess is if you have a blower door test done you will be quite surprised at the infiltration into the cabin. Its can be DIY https://www.builditsolar.com/Projects/Conservation/BlowerDoor/BlowerDoor.htm Check with your utility they may do low/no cost energy audits.

 

[DonTee]

The DIY blower test is definitely something I want to get setup. I’ve heard about the blower test before, but have not let looked into the details.

One question I didn’t see answered by that link, is how do you track down the individual leaks? I had envisioned something using smoke or similar, where you pressurize them house and then fill it with smoke. Then look for smoke shooting out outside. I think that’s what they do for RVs.

I work on commercial aircraft for a living, and one test we do when I plane comes in is pressurize it, and then do a leak down test. Then after all the work is done to the plane we do the same test. If it fails they will hold the plane at pressure while people go around with little sticks with streamers attached. They check around the doors etc for leaks.

Also my dad has a little place that has a sliding glass door in the back. He got some insulated curtains for that door and it really helped keep the heat in.
My cabin has a lot of windows. I think it’s 17 total. And they’re big. Either 32x60 or 36x60.

 

[peakbagger]

You can buy smoke sticks for the use but a sponge and wet hand on cold day works well. Excuse me for possibly being politically incorrect that many women seem to be far better at detecting drafts

 

[NorMi]

Using the IR camera or that link mentioned those glycerin fog machines with the blower door test, actually pretty cheap on amazon these days, plus it might be good 2nd use for Halloween or something too! With your window area you might also consider the clear shrink film to bump up the R value for winter if you don't want to shut the light off with thermal blinds, it is very very cheap to do, either way it could be good to address as that is a lot of window area... 1. Infiltration test and fix 2. finish your insulation 3. address the windows/other low R value regions. Finishing the drywall might actually cut your infiltration by a decent, measurable amount, especially if you don't have the house wrap really really taped up at all the seams and edges.. Did you house wrap under the floor, or just rely on the skirting to prevent infiltration underneath? If not, adding a air barrier on the underside of the joists could make a big impact, too - catching what the skirting and felt paper doesn't. Do you have a lofted ceiling anywhere? If so, you could put a ceiling fan there as well.

 

[DonTee]

I agree that the ladies have better senses. If it’s too hot/cold, loud, stinky, or whatever they will notice it first. Haha.

The house wrap is not super tight or taped. It’s stapled on. Not loose and flapping in the breeze, but on there.
I was hoping when I put the siding on it will hold it down tighter. The front has hemlock clap board siding, and the other sides will have the same.

Under the floor does have felt paper. And I’m using faced insulation with the Kraft paper facing up towards the floor. I was actually reading about the crawl space under the house and I might have made a mistake by making it so tight. I think it’s supposed to be like an attic where it’s either vented or non vented. By me insulating the floor I probably should have put vents down there.

I was thinking the same thing about the drywall. That it will tighten the place up even more.

I know of a few small places where I’m leaking air. I need to spend some time and fix those. I don’t think it’s enough to bring the temp down that much, but maybe I’m underestimating it.

I do think the priority list in the above post is probably the best way for me to handle things. Thanks.

 

[NickW]

I'll tell you that the insulator I hired for our cabin build was at least as concerned if not more concerned about air infiltration as insulation. He told me absolutely to tape the housewrap. Interior vapor barrier is caulked at all joints.

 

[zrock]

What type of wood are u burning makes a huge difference between hard and soft wood as well if its dry or wet. You should be getting much warmer than that. I had a old shop minimal insulation, gaps in the doors and even at -30 it was so warm in their i would have to take my coat off and just work in my t shirt. All i had was a cheap camp stove basically a barrel with a pipe and door and it was the smallest one i could find. All my wood was dry unless i ran out at the end of the year and used some wood that was just cut that year my heat output was noticeably lower

 

[DonTee]

I could probably do a better job of taping up the inside vapor barrier. Since I don’t have drywall up yet I still have time. Maybe that’s what I’ll focus on first while im getting the supplies to make a blower.

I was thinking it should be warmer also. Last place I heated was a 1850’s house with poor insulation. It was a pretty split up floor plan with the woodstove in the living room. It wasn’t uncommon for that room to be in the lower to mid 80’s, and the rooms off of that to be in the 70’s. Obviously as you got farther away from the stove it got colder, but no place in the house ever got below 60 when I had the stove going. That was in weather down to around -15 outside.

Right now I’m burning mostly ash and beech. All below 20% MC. Most around 16-18%. It’s been a hard year to dry wood here. I have some maple and red oak that are still drying out, and might be ready towards the end of winter. But I have a lot of ash that’s ready now.

I’ve never had a wood stove thermometer on any stove I’ve ever operated until this current stove. Plus I have an IR thermometer now. I can say that this stove at 600 degrees feels hotter than my previous stoves have.
The stove at the previous house I described was a Federal Airtight, and while not verified with a thermometer I don’t remember it ever getting this hot.

I do have a blower on the stove, and like I said, the house is equally warm everywhere. Just not warm enough.

The house has 9’ ceilings downstairs and 8’ ceilings upstairs.

 

[gthomas785]

The facing on fiberglass insulation is not that good as a vapor barrier. It's kind of a joke honestly.
I would sheet over every interior surface with plastic and tape all the seams before putting up drywall.
When I did my back room I foamed around the windows with expanding foam and bedded the plastic into the foam as it came out of the can. Same with outlet boxes, etc.

 

[blades]

got to watch out with thermal drapes and the like, those windows still need to breath or moisture will condense causing problems of mold an worst case rotting of the wood sills and sashes. For all the hype of fiberglass insulation the one dirty little secret never mentioned is that as the temps drop so does the R rating of fiberglass. I forget the numbers right now. It also allows air travel through it, in the case of non faced batts, or any exposed ends. in the case of more or less standard construction your wall studs transmit cold or heat through them. So every 16" you have this cold/hot spot in your wall/ceiling. Vinyl windows shrink as they age + they do not expand contract at the same rate of your wood framed home, Alum. is worse in that department as well conducting cold/hot straight through the frames and sashes. Fiberglass window assemblies are almost the same as wood ones in all departments. 50+ years of dealing with ways to save heating / cooling costs you learn a thing or 2. You can jump on me, but the specs are out if you dig.

 

[Max W]

Gotta be pretty frustrating to be cranking out the heat and not being warm. I echo the blower door test and sealing leaks as the place to start. Also fiberglass insulation allows air movement within it and cold can transfer through spaces that sometimes can be left at the edges when studs or joists can be slightly off of their 16 or 24“ oc. framing. I found faced insulation can make it easier to unintentionally leave a bit of space than when using friction fit. Also there is significant heat loss through all of the wall framing and and roof rafters. Before you sheetrock you could consider covering walls and rafters with a minimum of 1 inch of foam insulation, xps or iso and sealing the seams. It does mean some extra work trimming windows and horizontally strapping walls to take the drywall and of course dollars. All that said and without anything to go on I can’t help wondering if heat loss through the floor is a big culprit.

 

[hansenjw]

We recently finished a 15x40 cabin in Wisconsin and we’re really happy with how well it retains heat, and it’s full of windows.

We were very careful to make sure there were no gaps around the edges of any insulation, and we double taped all the seams in the moisture barrier per the instructions. Where the moisture barrier meets the floor, we overlapped a couple inches onto the subfloor and caulked and stapled it down.

We also used a product called boxshell, which is a simple cardboard “box” that goes around each exterior electrical box, making a square shaped cavity all the wall from the sheathing to the interior. The insulation can be more easily fitted around that (vs trying to stuff some behind the box), and then spray foam is used to fill up the entire inside of the box, which perfectly seals up around the outlet. It seems to have sealed up all air movement around those boxes.

Also, I would say that drywalling definitely helps. Any wind against the side of the cabin will be sneaking pressurized air between your house wrap, around tiny gaps between the insulation and studs, and make it into your house. I saw this first hand because after we installed the interior moisture barrier, it would puff up during the wind.

 

[bigealta]

Yes i agree about the drywall and same thing for siding stopping the wind. You should be getting way more heat into your house than what you have described. When the wind blows here at my house (Poorly insulated) it gets significantly cooler inside.

 

[bigealta]

How is the VC installed? in a fireplace? is there a block off plate if so? take a few pics and post here. thats the fastest way for a good answer to the problems.

 

[begreen]

Get the vapor barrier up, taped and sealed well, including all penetrations for outlets, switches, etc. That should make a notable difference. Tape the exterior barrier too and maybe consider adding a layer of insulation on the exterior if there's no siding. Consider covering the floor insulation with a skin of 1/4" plywood or other covering. This will help stop infiltration and rodents which love to burrow in insulation and steal it for nesting material.

 

[bigealta]

Consider covering the floor insulation with a skin of 1/4" plywood or other covering. This will help stop infiltration and rodents which love to burrow in insulation and steal it for nesting material.

Yes for sure. They make a big mess and then you have to crawl under there and fix it. A Huge PITA.

 

[DonTee]

Sorry I’ve been gone from the forum for a few days. I did finish the floor insulation. That’s a good idea about putting some kind of barrier between the insulation and the area under the crawl space. I know there are mice and probably red squirrels that want to get in there to nest. Definitely mice.

I’ve also heard of people putting something under the floor insulation to keep it from sagging and dropping out of place. It’s friction fit right now.
So maybe whatever holds the insulation up can also double as something to keep the critters out.

I had the house warmer than it has been, but still not as warm as I’d like. Yesterday it was 24 outside and I had it up to 66 inside. Making progress but still some left to go. I kept the stove over 500 degrees, and reloaded while the coals were still very hot. I could see once I get it up to temp it will take less heat to maintain that.

When I left the cabin last night around 11 the stove had just coals in it, and was around 425 degrees. When I went inside the cabin at 8 this morning it was down to 52 degrees. So not terrible but it could be better. It got down to 14 last night.

The woodstove is installed with a Duravent triple wall chimney. 6” flue. It’s a new install with no existing fireplace. I used the correct through the wall kit to go from stove pipe to outside chimney section. The only thing I feel I could do better with that is caulk around the spot where the chimney goes through the wall. On the inside it’s pretty tight, but on the outside there is a 1/8” or so gap.

I’ll really tighten up the vapor barrier before doing drywall. I have to get rough plumbing signed off before I drywall anyways.
The plan is to drywall and then side the rest of the house. I’ve been using Amish hemlock siding. I did the front this summer, and have enough for one more side. Just gotta go get some from the sawmill down the road.

 

[semipro]

Excuse me for possibly being politically incorrect that many women seem to be far better at detecting drafts

And "hot air".

 

[peakbagger]

I’ve also heard of people putting something under the floor insulation to keep it from sagging and dropping out of place. It’s friction fit right now.
So maybe whatever holds the insulation up can also double as something to keep the critters out.

Keeping the insulation up tight to the floor is important and most folks miss out on it. Any air gap can really screw up thermal performance. Get some bulk uncoated welding rod at a welding supply store, cut it a bit longer than the inside distance between the floor joists and push it up between the joists, the wire will make a curve and will apply force to each end. Make sure the curve is facing upwards into the insulation. It takes some fiddling to get the correct length. The ends stick in better if you cut the rods at a angle so they form points. Some folks tug down on the bow and that locks the wire into the joists. Do this every 2 feet and it will do a good job holding up the insulation but is real easy to remove in the future.

 

[stoveliker]

Correct length is not that important; can angle the rods. (That's what I did.)

I believe you can buy rods for this too at the orange store. Already pre-curved a bit.