TrainNut:
Here is a drawing of the beam/rafter construction. The 2x12s were from the foundation forms which the concrete company gave to me in exchange for me wrecking off the forms.
Edit: The board shown at the rafter junction at the very top is blocking which helps support the roof decking at the ridge.
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Ahhh, thanks for that explanation. In that one photo, the center beam looked absolutely huge. Now I see how it was built.
I thought of something wild that it's probably too late to incorporate... a dust lock... like an air lock but to keep out the dust instead to keep the layout nice and clean.
Okay, that ones probably a bit out there and would have taken up too much square footage anyways!
I didn't do much on the building last week due to working late at the real job. Yesterday, I rented a sheetrock lift form HD and got back at it. I'm almost finished hanging the ceiling. Just a few more sheets. The lift sure makes it easy... one person can hang the sheetrock on the ceiling with no struggles.
Along with hanging the rock, I am also insulating it as I go.
One of these days, I'm going to actually be back to working on the layout!
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I have been watching your progress on your building and it is coming along rather nice .The only thing you should be doing before wallboard is vapour barrier.At least a 6 mil poly .If you dont you will end up with wet insulation and a mess that Im sure you dont want .I take it as you intend to keep it warm in some way and warm inside and cold outside creat water vapour and that spells a big mess .It will also creat mold and thats not a nice smell or healthy for that matter.In the warmer months it will keep the vapours on the outside as well .It all has to do with airflow through the eves and out the top .Goodluck .MartyG
Marty, I appreciate the thoughts. Down here in Southeast Texas, the kraft paper on the insualtion is used as the vapor barrier. I haven't ever seen plastic film being used as a vapor barrier in the ceilings or in the walls. Now, I understand that up north, the plastic vapor barrier is a necessity, but down here in the milder climates, apparently it isn't. As an electrician, I've been in more than a few attics in the Houston area, and I've never seen the plastic vapor barrier used... and no one has issues from it.
Here is an excerpt from <!-- w --><a class="postlink" href="http://www.energybook.com">www.energybook.com</a><!-- w -->
"The deciding factor is how cold it gets. Where the
winters are seriously cold, as in Minnesota, the best
compromise is to install the vapor barrier on the inside.
In humid climates where winter temperatures are mild,
as in Houston, the best compromise probably is not to
use a vapor barrier."
Since the subject of vapor barriers has arisen a couple fo times in this thread, I've been doing some thinking.
Let's compare the average temp in Houston against the average temp in say, chicago, by month, from January to December.
Houston: 50, 54, 61, 68, 75, 80, 83, 82, 78, 70, 61, 54
Chicago: 21, 25, 37, 49, 59, 69, 73, 71, 64, 53, 40, 27
Of course, it is warmer in the day, cooler at night. In Houston, the daily high is going to be 10 to 15 degrees hotter than the average temp shown. So, for most of the year, we are running our air conditioners, meaning it is cooler inside than outside for most of the year. I think the opposite can be said for chicago. It is probably cooler outside than inside for most of the year because the heaters are running instead of the air conditioners. So on that note, I can see that Chicago homes need a vapor barrier. But as mentioned in the previous thread, a vapor barrier in Houston is prabably a hindrance, or maybe it would need to be on the outside of the house?
So it appears that the compromise is either Tyvek house wrap or tarpaper on the outside, insualtion with kraft paper attached on the inside. And I've never ever seen any condensation issues here in southeast Texas.
What does this have to do with trains? Well, we gotta keep them babies dry, don't we?
The idea of useing a vapour barrier in the first place is to keep the insulation dry and stop moisture tranfer through the walls to the outside .I know what you have there people wont be having showers or cooking and no moisture vapours to contend with .What your not looking at is the cold concrete floor and the warm air near the roof.Somewhere in between you will get moisture .I guess your in Texas and you still have hot humid days .Its still water vapour and Im sure you havnt seen it in houses there but with your floor you might have a problem.Im up in Ontario and where minimum code is 6 mil poly and that keeps the moisture in .Were as outside its housewrap or what is called Typar .Something that lets the insulation breath and keeps it dry. You can get a nasty zap off a humid rail when you cant see it .I know code is different all over .Just looking out for the other guy I guess .Goodluck and I will watch this thread to the end.Like you said ,Keep them trains dry. MartyG
Thanks for your interest, Marty. Also, The forum says that this is only your second post, so I feel honored that my thread got you to make your first post!
Before the discussion in this thread, I had never even considered a vapor barrier. The reason why is that nobody ever uses one down here. Like I mentioned, I have been in construction since 1980 in Houston. I'm not an engineer or architect, I just copy the designs I have seen before.
From what little research I have doen since the topic came up, it seems that in cold climates like yours, the vapor barrier is needed. But in milder climates, it isn't a vapor
barrier that is needed, but a vapor
retarder. Seems our walls need to "breathe".
Therefore, kraft paper and tarpaper. From the little bit of research, it seems that in hot, humid climates, the vapor barrier causes more issues than it solves.
Hiya Marty, and
to Big Blue. There are at least two or three of us here who are from the Hamilton area.
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Wayne
I understand where your coming from .As I said goodluck .I dont post really on any of the boards but follow many.When I see something I might be able to help out with I jump in .Hello Wayne,You have a very nice layout and I enjoy looking at the pics you post of it .I had a large layout a few years ago .Was even on the H.O.L.M.E.S tour 3 years running .Fun times .Maybe we can get togeather and I can see your layout or just get the Hamilton guys togeather for a coffee.Bye for now.MartyG.
Thanks for the good luck wishes, Marty.
Glad to see you making some posts... you may as well become a regular participant here! We would enjoy your company.
You mention that you "had" a large layout. Do you still have it? I would enjoy seeing pics if you have any
Back to the vapor barrier. I researched the average temperature in Ontario versus Houston (all in Fahrenheit):
Houston: 50, 54, 61, 68, 75, 80, 83, 82, 78, 70, 61, 54
Ontario: 21, 22, 31, 43, 55, 64, 69, 68, 60, 48, 38, 27
Average for the year in Houston is 68 degrees.
Average for the year in Ontario is 46 degrees.
Y'all are typically running your heaters, which are probably gas powered, which creates alot of water vapor inside the house. We are typically running our air conditioners which removes water vapor from the air inside the house. So, Ontario homes have water vapor on the inside trying to go out. We have water vapor on the outside trying to come in. It is not surprising that the drastic difference in climate requires drastically different moisture control systems, and drastically different code requirements.
Thanks for the discussion, it certainly keeps me on my toes so I don't make any mistakes with this project.
I guess that explains the "vapour barrier goes on the warm side" rule of thumb. Either way (moisture inside the building or out) the barrier prevents the moisture condensing inside the insulation as it cools.
Using a closed cell insulation (extruded/expanded styrene, or spray foam) eliminates the need for a vapour barrier, and the associated guessowrk to figure out where best to place it.
By the way, I understand that several good coats of latex paint also count as a vapour barrier in situations where it would be impractical to retrofit one (e.g. old homes with plaster walls and no insulation).
Andrew
Funny you mention the average tempuratures Gary. I think I turned on the A/C once last summer in August. It never did get hot enough to justify using it.
We canucks also go to extreme measures with our vapour barriers to seal the inside of the home to avoid any heat loss through any tiny hole or crack in the structure. I've seen examples of acoustic sealant apllied along the wood structure where the vapour barrier is installed, stapled and then taped over with Tuck Tape (its red in colour). Then we also have to make sure we seal the areas around electrical boxes for switches, plugs and lights as any hole in the vapour barrier can result in heat loss.
All that said, I always find it funny that after going through all the trouble we then proceed to screw drywall into the studs, which of course, punctures the vapour barrier.
