Any insulation experts on here?

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SamWE19

Well-Known Member
I’m converting a loft in a friends house and I’m planning on insulating the roof.

The whole loft will be used as a grow room. No room inside a room.

As far as I understand it, insulation just slows the transfer of heat.

I can put 100mm kingsspan between rafters and 100mm kingspan over rafters And leave a 50mm airgap between tiles and kingspan.

If insulation just slows the transfer of heat and the room is always at a comfortable 27c. Won’t the heat eventually transfer through the insulation and start heating the roof tiles?

It may take a couple of days but because the heat is always there how will it make a difference?
 
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SamWE19

Well-Known Member
xox said:
licensed carpenter here, can you show us some photos i'd be happy to give input.
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Can’t get photos unfortunately. It’s currently got kingspan over the rafters without nothing between rafters.
Kingspan is only 25mm though and put on badly.
My plan was to rip the lot off and do it properly with insulation between and below but I’m wondering if it will even make a difference to stop the choppers seeing?
 
xox

xox

Well-Known Member
im unsure what kingspan is, its likely a brand of insulation i dont see in my country. but as far as insulation and grow rooms go the best insulation you can use in my opinion is closed cell spray foam the best things about closed cell spray foam and grow rooms is this. 1. you get a perfect seal excellent for sealed rooms, 2. excellent R value (unsure if that prevents choppers but i imagine the higher the r value the less heat will be seen from the outside with a flir camera) 3. theres no need to put vapour barrier because the spray foam itself acts as a vapour barrier. im unsure what country your in but where i live you can buy kits it looks like 2 small tanks with hoses from each one going to a gun you open both tanks put a bit of vaseline on the removable tip for the gun and spray away. i cant give much input on the space or the current insulation or tiles if im unable to see whats going on.
 
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SamWE19

Well-Known Member
xox said:
im unsure what kingspan is, its likely a brand of insulation i dont see in my country. but as far as insulation and grow rooms go the best insulation you can use in my opinion is closed cell spray foam the best things about closed cell spray foam and grow rooms is this. 1. you get a perfect seal excellent for sealed rooms, 2. excellent R value (unsure if that prevents choppers but i imagine the higher the r value the less heat will be seen from the outside with a flir camera) 3. theres no need to put vapour barrier because the spray foam itself acts as a vapour barrier. im unsure what country your in but where i live you can buy kits it looks like 2 small tanks with hoses from each one going to a gun you open both tanks put a bit of vaseline on the removable tip for the gun and spray away. i cant give much input on the space or the current insulation or tiles if im unable to see whats going on.
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I’ve considered the spray foam but 700 eur per 600 sq foot at 1 inch depth.

I need 600 sq foot at the very least 4 inch depth.

2800 eur for the spray foam. Kingspan is basically solid slabs of spray foam.

And will cost 800 euro for the same coverage

Photos of the rafters wouldn’t do much. It’s just standard tiles, roof felt, rafters
 
xox

xox

Well-Known Member
if spray foam is out of the question, i would use fibre glass insulation comes in batts. the trick to install batts of fibre glass insulation is to never compress the fibre glass for maximum R value. you will of course need a vapour barrier stapled to your joists/studs 9 millimeter poly should do the trick.
 
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SamWE19

Well-Known Member
From everything I’m reading I don’t think it’s that simple.

I think there needs to be a good airgap with ventilation from the outside between the insulation and tiles to prevent the tiles heating up.

Snow stops air being blown under the tiles by the wind so some sort of ventilation needs to be installed to allow air behind the insulation when it’s snowing. Just not sure how to do that
 
coreywebster

coreywebster

Well-Known Member
Slowing the heat loss down still lowers the heat signature.
If its slowly leaking heat then the outside air flow will dissipate the heat quicker than it can build up.

If it worries you that much then best way is to go room/s within a room.
 
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SamWE19

Well-Known Member
coreywebster said:
Slowing the heat loss down still lowers the heat signature.
If its slowly leaking heat then the outside air flow will dissipate the heat quicker than it can build up.

If it worries you that much then best way is to go room/s within a room.
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What about when snow is on the roof I think that creates no airflow to dissipate the heat.

I’m not too worried just trying to understand fully how it works to make an informed decision
 
coreywebster

coreywebster

Well-Known Member
SamWE19 said:
What about when snow is on the roof I think that creates no airflow to dissipate the heat.

I’m not too worried just trying to understand fully how it works to make an informed decision
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This is true, but plenty of houses have zero insulation in the roof still. I can look down my street and see which ones don't when its snowed. Pretty sure the majority don't have grows going.
The whole loft will look the same temperature through a flir if you insulate and circulate your air properly . Not like when we used to bang a couple of 1000w hps up there and no venting or insulation and it had a huge hot spot at the peak of the roof.
 
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SamWE19

Well-Known Member
coreywebster said:
This is true, but plenty of houses have zero insulation in the roof still. I can look down my street and see which ones don't when its snowed. Pretty sure the majority don't have grows going.
The whole loft will look the same temperature through a flir if you insulate and circulate your air properly . Not like when we used to bang a couple of 1000w hps up there and no venting or insulation and it had a huge hot spot at the peak of the roof.
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Is there any cheap options to increase airflow behind the insulation even when snow sits on the roof?

I’m thinking decent eave vents or something.

I can’t see if there are already eave vents in it doesn’t look like it.
Some sort of vent that is slightly raised or positioned in a way that snow won’t block it
 
Dougnsalem

Dougnsalem

Well-Known Member
I am doing this right now. Drilling out 3" eave vent holes, installing baffles, insulation, drywall, and then a ridge vent. It is not cheap or easy. Without pictures, there's no way to even know if this would work for you.

021221070_xlg.jpg

I have spent 100's of hours on this website. A search on "attic vent" pulled up 600+ articles. Not all are free, but all are excellent, and show how to do it right....

https://www.finehomebuilding.com/2011/07/14/a-crash-course-in-roof-venting
 
xox

xox

Well-Known Member
maby i misunderstood, i thought you were insulating an interior room from the rest of the house to make a climate controlled room. yes you will definitely need venting if the scenario is similar to the photo above. you can buy various products in my country the brand is called moore vents they are essentially pieces of foam you staple to the underside of the roof sheathing and you put your insulation in front of the vents and vapour barrier overtop of the insulation. you do this all the way from the eave to the top of the peak of the roof. venting at the top is not always necessary if you have adequate venting along the eaves of the house. if the venting along the eaves of the house are inadequate and there is no way to add better venting along the eaves there is a vent called a ridge vent that runs along the ridge of the roof it allows air the escape right out the top where the ridge is located. if you cannot purchase a product like moore vents you can do it the old fashioned way and rip a 2x4 in half and screw that to the underside of your roof sheating and scew a 1/2" piece of plywood ontop of your 1x2's to create and airspace between your roof sheathing and your insulation. if you send me some photos from the inside i can give much better insight.
 
Mr_Manny_D

Mr_Manny_D

Active Member
xox said:
if spray foam is out of the question, i would use fibre glass insulation comes in batts. the trick to install batts of fibre glass insulation is to never compress the fibre glass for maximum R value. you will of course need a vapour barrier stapled to your joists/studs 9 millimeter poly should do the trick.
Click to expand...
 
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