Warm Roof Insulation - I'm SO SO confused

[Adrianlondon]

Hi all

I'm so so confused as to which insulation I should be buying. I'm not concerned about the make. It will most likely be either Celotex or Recticel. My problem is what type do I need???

The plans state the following.........

To achieve a U value 0.18 W/m2K

Flat roof to be single ply membrane roofing providing aa fire rating for surface spread of flame with a current BBA or WIMLAS certificate and laid to specialist specification. Single ply membrane to be fixed to 22mm exterior quality plywood over 12mm Celotex TA4000
Insulation bonded to 22mm external quality plywood decking or similar approved on sw firings to minimum 1 in 80 fall on sw treated 75mmx220mm C16 flaat roof joists at 400mm ctrs.


So, with all stated above, I believe that I need Celotex XR4000 between two pieces of plywood. I think the architect has got it wrong and that using Celotex TA4000 is wrong.

I think it should be as follows.........

· Roof Finish

· Plywood

· Insulation

· Plywood

· Furring’s

· Joists

· Plasterboard and Skim.

What I'm not sure about is whether I can use a different type of insulation (the stuff with the plywood built into it) Celotex TD4000

Also, can someone give me an idea as to what to 'bond' the exterior plywood onto the insulation with.

Please check out the link below. It is for a youtube clip of the screenshots of my plans for the roof. I tried to put pictures here but I didn't know how to!!

https://www.youtube.com/watch?v=hnh74oKKRto

I'm not even sure if the pictures and the text on the plans tell the same story!!!! The reason I think this is that the picture states using plywood with a foil underside and the text doesn't.

PLEASE HELP ME




Adrian

 

[tony1851]

There should be some plywood between the finish and insulation, but not 22 thick- something like 6 mm would do.
Presumably the insulation is 120 thick, not 12?
The plywood deck on the joists need not be 22 thick - 18 would do.
OSB would be cheaper.

 

[ban-all-sheds]

I tried to put pictures here but I didn't know how to!!

Step 1
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Step 5
Step 6
Step 7
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Step 9
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Step 11

Although that is a desperately cumbersome way to do it - a much easier and quicker alternative is to use an image hosting site, e.g. http://postimage.org/ (other sites are available) to upload your images.

Some hosting sites don't allow direct links to the images, and make you use thumbnails, but if so the good ones will provide the code all packaged and ready to paste in.

 

[theoldun]

PLEASE HELP ME

You are about right with your build up, except that yop have left our the VCL

Go to the Roofing and guttering forum, and read Bonding a warm deck flat roof. All the information you require is in there.
Regards oldun

 

[Adrianlondon]

There should be some plywood between the finish and insulation, but not 22 thick- something like 6 mm would do.
Presumably the insulation is 120 thick, not 12?
The plywood deck on the joists need not be 22 thick - 18 would do.
OSB would be cheaper.

Yes, I did indeed mean 120 and not 12 LOL. Typo. My bad.

Thank you for your advice. I believe the correct insulation to get would be the Celotex TD4126

This has the foil on one side (which I believe is the vapour control) and ply on the other side which the EDPM rubber roof will sit on the other side.

Your opinion would be welcomed.



Adrian

 

[theoldun]

This has the foil on one side (which I believe is the vapour control) and ply on the other side which the EDPM rubber roof will sit on the other side.

In both instances, you are wrong.
Read the post that we suggested.

 

[Adrianlondon]

This has the foil on one side (which I believe is the vapour control) and ply on the other side which the EDPM rubber roof will sit on the other side.

In both instances, you are wrong.
Read the post that we suggested.

Will do. Thank you