How to build up a parapet, how to replace a tar and gravel.. Information, help and advice on maintaining, installing and repairing a flat roof. Post your questions and view answers here

[Jason George]

Hi there- I am wondering if anyone out there has extended a parapet (upwards), ripped out an old tar and gravel roof and installed a flat roof with all necessary layers including a 4" or 2" insulation layer, and met all requirements for a flat, green roof.

I am hoping there is some kind of video out there detailing how to do it, but text would suffice.

Much thanks and have a great day.

Jason George.

[stoneyboy]

Jason George,
I assume you are saying that you have a flat roof with a parapet wall abutting it and now that the thickness of the roof has increased you need to raise the parapet wall.
Hopefully you will have formed upstands where the roof meets the wall. You will need to remove any capping, fit a dpc (could be lead) which will lap down and over the upstand, build the parapet wall up to the desired height and refit the cappings. If you have no cappings buy some wedge shaped ones wider than the wall and fit with the drip groove on roof side.
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[Jason George]

Thanks Stoneyboy- you got it right- the thickness of the insulation will necessitate raising the parapet; probably 5" in total.

Do you have any more info on how to affix the insualtion/ is there a membrane that has to go beneath it?

What about on top of it? What layers are required from then on?

Much thanks,

Jason

[stoneyboy]

Jason George,
The insulation boards usually have a dpm bonded to the underside and a ply top. Stick the boards down onto the decking used foam bonding available from roofing suppliers. The joints must be taped to provide a continuous DPM and fitting this tape is not easy but essential.
Bond the layers of felt on top using a perforated base layer, use polyester reinforced felt for the next two layers, the top layer needs to be mineral coated.
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