General > General Technical Chat
Building thermal insulation.
Gregg:
I installed a product from https://atticfoil.com/ under the rafters with a fairly large plenum at the peak where I put an exhaust fan ducted to a grill in a gable. The ceiling is insulated with fiberglass but before the foil install the top of the fiberglass would get to 165F at times. Now with the fan running it may get to 85F and the bottom of the foil layer may get to 100F.
There are lots of Soffit vents to let in outside air. I ran 2x2 stringers horizontally where each course of the foil ended making a little more space for the outside air to mix and also made it easier to install the long foil sheets by myself. There is also a gap all around the removable central panel that covers the fan to let air from the rest of the attic to be exhausted. The fan is much larger than necessary to keep the temperature reasonable but it made it a lot nicer to work in the attic; now it has a speed control. It is manually switched from below; I wanted to put a nice automatic control panel on the wall in a hallway but my wife thought that would be ugly.
Zero999:
--- Quote from: Gregg on July 19, 2022, 08:43:26 pm ---I installed a product from https://atticfoil.com/ under the rafters with a fairly large plenum at the peak where I put an exhaust fan ducted to a grill in a gable. The ceiling is insulated with fiberglass but before the foil install the top of the fiberglass would get to 165F at times. Now with the fan running it may get to 85F and the bottom of the foil layer may get to 100F.
There are lots of Soffit vents to let in outside air. I ran 2x2 stringers horizontally where each course of the foil ended making a little more space for the outside air to mix and also made it easier to install the long foil sheets by myself. There is also a gap all around the removable central panel that covers the fan to let air from the rest of the attic to be exhausted. The fan is much larger than necessary to keep the temperature reasonable but it made it a lot nicer to work in the attic; now it has a speed control. It is manually switched from below; I wanted to put a nice automatic control panel on the wall in a hallway but my wife thought that would be ugly.
--- End quote ---
My loft has loads of fibreglass insulation. There's no fan but I believe there's some ventilation around the sides. I'm not going to up up there to take a picture, until it's cooled down. I have no idea how hot it was there this afternoon, probably 60oC, 140oF.
I've just got home. It's 21:50 in the evening, the temperature is outside is 29.7oC, but it's 28oC upstairs and 25oC downstairs in my house. There's been light rain for the last half hour. Hopefully it will cool enough for me to open the windows soon.
Gyro:
The temperature outside (22.20) is 20.7'C, down from 33'C at 5pm, that was a really fast drop. Bliss!
P.S. There isn't an opening in the house that isn't open and I'm considering making a few more! 150 200mm (I think) of fibre glass in the loft with soffit and apex vents btw.
tom66:
I notice a lot of people had their windows open around here but when outside air is at like 40C it's probably counter-effective to cooling the building.
A few homes around here have shutters that can cover their windows, I think this is a fantastic idea and will definitely be something to investigate before next summer.
Of course there does come a certain point when air conditioning is necessary, and while the UK does not currently get all that many 40C days even a 30C day can be uncomfortable if a few similar days have preceded it. So I will certainly be installing it in our property.
Zero999:
--- Quote from: Gyro on July 19, 2022, 09:16:50 pm ---The temperature outside (22.20) is 20.7'C, down from 33'C at 5pm, that was a really fast drop. Bliss!
P.S. There isn't an opening in the house that isn't open and I'm considering making a few more! 150 200mm (I think) of fibre glass in the loft with soffit and apex vents btw.
--- End quote ---
Lucky you. It's still above 25oC here and it's nearly midnight. I opened the upstairs windows first and now I've just opened the downstairs windows, because it's the same temperature outside as indoors.
--- Quote from: tom66 on July 19, 2022, 10:08:46 pm ---I notice a lot of people had their windows open around here but when outside air is at like 40C it's probably counter-effective to cooling the building.
A few homes around here have shutters that can cover their windows, I think this is a fantastic idea and will definitely be something to investigate before next summer.
Of course there does come a certain point when air conditioning is necessary, and while the UK does not currently get all that many 40C days even a 30C day can be uncomfortable if a few similar days have preceded it. So I will certainly be installing it in our property.
--- End quote ---
I don't understand why some people open the windows in the middle of the day. It's generally better to keep them closed when the sun is out and open at night. Mine also have a security latch on them, but I don't bother as I live in a fairly safe area and there's nothing worth nicking in my house anyway.
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