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Restoration of a 150 year old Barn.
sean_ork:
CM, have another read of Matts post, he is trying to warn you of the same very likely issue.
--- Quote from: MattM on October 22, 2015, 05:47:42 PM ---The advantage to insulation under a radiant barrier is keeping the heat delta off direct contact materials. Your slate gives you a hotside off the insulation, but your airgap isn't stopping radiation with felt underlayment. You also have two airgaps, the second being the rolls of fiberglass. When hot meets cold you get condensation. Your two airgaps will hopefully not have too much difference or the fiberglass is getting soaked over time, and with the moisture barrier paper underneath, there is where it's going to collect.
Look into cathedral ceiling insulation standards before you get too far. I don't want to sound negative, it's just one of those situations you want to avoid with all the readily available data out there now.
--- End quote ---
dnix71:
I noticed that the barn roof doesn't have a tar paper layer. Here in south Florida, the roof will be tongue and groove interlocking slats if you have a ceramic tile roof. The rafters and tongue and groove can support the extra weight over the standard tar paper shingles.
In both cases there is a layer of tar paper on top of the plywood or tongue and groove roof. The overlapping papers laid across the roof are actually what keeps the roof from leaking. When the paper dries out or tears, you have to lift a square of shingles to patch the paper under them before reshingling.
Vapor condensing under the roof wood is still an issue, unless there is some kind of venting. Venting unoccupied attics is common in the south because it makes the roof material last longer and helps stop heat from being transmitted down into living spaces. The building I live in has a slot cut across the length of the crown and covered with a cap. The common name is "Cobra vent."
http://professional-power-tool-guide.com/power-tool-forum/index.php?/topic/5917-cobra-rigid-vent3-ridge-vent/
clockmanFRA:
Insulation is very controversial, just look at the heated discussions on passive house & insulation on the green building forums in particular where and what are the vapour barriers.
I noted MattM's comments.
Remember this is a building within a building, its a barn it and will be a lecture theatre and a garage for my vehicle etc repairs in comfort, it is not a dwelling.
As I said, I await till I am actually up between the 2 roof structures to see if the ventilation can be controlled or not, and if it can be sealed or not, if another vapour barrier is required and what the distances between will be.
Not sure where you are going sean_ork with your over excited gloom and doom comments. You don't offer much practical suggestions or methods, or defined links, just your usual buy this manufacturers products and your armchair waffling.
So for Forum members reading this, please seek independent advice on your insulation techniques.
Happy now?
sean_ork:
The correct method of installing insulation, in a manner that keeps a building healthy, isnt a contentious or controversial subject - if you understand the basic principles its very very simple. There's always a healthy debate over which manufacturers product is best suited, however there's no debate over the science.
You've misread what I've posted, there are no product recommendations mentioned, I'm simply trying to encourage you, as are others, to understand what is going to be happening between your layers.
There's no doom or gloom from me, perhaps Matt will be able to convince you - either way, good luck.
sean_ork:
--- Quote from: dnix71 on October 25, 2015, 07:16:47 PM ---
Vapor condensing under the roof wood is still an issue, unless there is some kind of venting. Venting unoccupied attics is common in the south because it makes the roof material last longer and helps stop heat from being transmitted down into living spaces. The building I live in has a slot cut across the length of the crown and covered with a cap. The common name is "Cobra vent."
--- End quote ---
We tend not to have issues with keeping roofs cool in our part of the world, but correctly venting them is key to keeping them healthy wherever they are. Vented ridges are common, as are all manner of retrofit soffit vents, ventilated tiles and perforated screens - all designed to improve flow and increase the longevity of roof structures built when perhaps the evidence or knowledge wasn't so well spread.
The Government here, from time to time, finances schemes to improve the insulation standard of our, generally, very poor quality housing. This tends to consist of hoards of installers cramming as much FG as they can into cold roofs, usually closing off all openings that were correctly left at the waves - which blocks off the ventilation path, leading to a number of future significant issues.
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