# Master Bedroom built on Deck



## Windows on Wash (Aug 30, 2011)

They are treating the crawl as conditioned in this application by insulating the exterior wall. 

In doing such, you don't need insulation on the underfloor if the insulation on the walls is correct.

Here is what I would do:


Remove existing fiberglass insulation on the wall. It is not anywhere near an R-20
Put down complete vapor barrier on the floor of the crawl (if dirt) and run it up the side walls and seal with foam or suitable mastic
Spray foam band joists with closed cell foam and put about 4-5 inches on them
Install rigid foam (poly iso) to the side walls to a thickness of about 4-5 inches. Use suitable adhesive and attach through furring strips
Open up some supply side air to warm the area up
Vermiculite is fine if you don't disturb it too much. If it is blown over with cellulose, it should be fine.

If you don't have 14-16" of insulation, you don't have enough. 

Use cellulose instead of fiberglass.


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## BeMurda (Nov 28, 2011)

Windows on Wash said:


> They are treating the crawl as conditioned in this application by insulating the exterior wall.
> 
> In doing such, you don't need insulation on the underfloor if the insulation on the walls is correct.
> 
> ...


Thanks for the advice. What makes you certain that the insulation isn't R20? It certainly feels like a lot of heat loss could be coming from the windows. 

I am hesitant about going in the attic but it might be necessary. The inspector's report says there is only about 4-6" of insulation in the house's attic generally.

Also, for clarification, were you talking about the crawl space throughout the list or was some of it in reference to the room?


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## Windows on Wash (Aug 30, 2011)

BeMurda said:


> Thanks for the advice. What makes you certain that the insulation isn't R20? It certainly feels like a lot of heat loss could be coming from the windows.
> 
> I am hesitant about going in the attic but it might be necessary. The inspector's report says there is only about 4-6" of insulation in the house's attic generally.
> 
> Also, for clarification, were you talking about the crawl space throughout the list or was some of it in reference to the room?


My point about that not nearly R-20 was referencing the fact that fiberglass does not perform anywhere near its intended R-Value at temperature extremes and not whether or not it was 6" thick.

The reality is that if it is an R-20, it is working closer to an R-10 at those temperatures.

4-6" is less than half of what you need up there. Think of the improvements in terms of total square footage. What is the square footage of your attic vs. how many square feet of window (a sealed double pane window at that) you have. Attic and crawl space repairs are going to much, much cheaper per improvement dollar as well.

The punch listing of what I would do was for the crawlspace.


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## BeMurda (Nov 28, 2011)

Windows on Wash said:


> My point about that not nearly R-20 was referencing the fact that fiberglass does not perform anywhere near its intended R-Value at temperature extremes and not whether or not it was 6" thick.
> 
> The reality is that if it is an R-20, it is working closer to an R-10 at those temperatures.
> 
> ...


An update: 

I have the energy efficiency guy coming to look at the whole house on the 10th. However I did figure out what is completely strange and illogical about the crawl space being insulated and 'conditioned'. It's vented to the outdoors. According to the federal government, conditioned spaces should not be vented. It makes perfect sense, and the way it is now makes no sense; why bother insulating if you're going to open up a big hole to the outdoors? I think the solution is removing the external venting and adding heat supply, the latter as per your suggestion (other details as well).


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## ccarlisle (Jul 2, 2008)

In some places, 'venting' crawl space is season-dependent i.e. that the venting is closed off in winter and opened in summer, much like our cold-rooms up here are. So, sure it makes no sense that the crawl space is vented to the outside, when there is insulation on the inside and no heat source. So right now, your building "envelope" (that is, the part that you heat) runs along your master bedroom floor. Everything beyond that is "outside". And unless your mb floor is well insulated from underneath, it sure will be cold in that room. 

So you have two options: insulate the underside of the mb floor really well - say like spray-foam it - and insulate the heating ducts too and consider the crawl space 'outside' OR insulate the walls of the crawl space, seal up the vent and consider the crawl space as part of your inside, conditioned living space.

It seems like the process of sealing up what was once a three-season deck and converted into a conditioned living space wasn't taken the whole way.


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## joecaption (Nov 30, 2011)

I also would never just rely on foam on the crawl space walls. Add what ever thickness insulation will fit in your bays under that room with the paper toward the conditioned surface (bedroom floor)
Let me make a guess on those sliders. There's a deck area right at the threshold not a small step down at least 4", or there's little over hang on the additions roof. What happens in water can splash back up, and will at some point get in under the threshold. I'd bet if you remove the flooring that's there and expose the sub floor there will at least be a stain if not rot by now.
It's almost never a good idea to do what they did by inslosing that room and inclosing that space. Reason being a deck is almost never built strong enough to support the walls and new roof unless it was designed for those loads in the first place.
I've seen people build the room right on the deck and never even took off the decking boards and the building was built slightly small then the deck it was covering so there was a ledge of old decking sticking out all around two sides. Since the walls and door were even with 1/2 the old deck the sheathing was rotted out 2' up the wall and the floor was also shot.
http://www.pima.org/contentpage/ContentPage.aspx?ModuleID=8&SubModuleID=90
What's the thickness of the wall studs? If there 6" then R20 is all they could fit in there. To change that you would have to remove all the sheetrock and hire someone to spray foam it or have to build the walls out, add extention jams to the windows and door jams so thicker insulation would fit uncompressed. (Not likly to happen)
Sliders all leak air, poor windows or even a poor insulation of any window will result in air leaking.
No insulation or foam around the door opens in the area between the rough framing and jams will leak air.
I've been under at least a 1000 homes in my life time and without question the one's that tryed to close up the crawl space instead of venting it were in the worst condition. Fungus on the floor joist and under side of the subfloor is very common. All from rizing moisture in the soil below.
It may work where it's dry and but not where it snow, rains a lot, or gets cold in the winter.
I'm mostly a remodler of 100 plus year old houses not a builder, so I get to see what happens long after the builder has left and I'm stuck trying to fix it.


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## ccarlisle (Jul 2, 2008)

I doubt the OP could even find paper-faced insulation; we don't use it up here.


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## joecaption (Nov 30, 2011)

And why is that?


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## ccarlisle (Jul 2, 2008)

Because of the greater differential in temperatures between the outdoors and the inside of the house, there is a greater 'push' from the vapour on the inside to get through the inside walls to the outside; thus, you need either a good vapour barrier with a perm rating of something around 1, or have almost none at all. Used to be a time when codes suggested - and they still do - to put 6mil plastic vapour barrier on top of the fibreglass batts. That's your set-up right there; and for years this was followed to the letter. No vapour sandwiches, please...on top of that you had to air seal as well, making the whole insulation proposal a chore in itself. Especially a retrofit. 

So *no* facing on the batts; not the old tar-paper facing that some batts used to have and neither the newer plastics. But what with the new thinking on insulation in general in cold climates, and spray-foam insulation popularity, this method (fibreglass+6mil sheet vapour barrier+air sealing) has fallen into some disuse nowadays and newer construction goes right for the foam.

So, I honestly don't remember the last time I saw paper-faced fibreglass batts on sale anywhere in Canada, it's all the unfaced.


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