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Jeramy McMahon Posted: Apr 13, 2020 06:11 PM	HVAC Units on Roof of ExpandoThane Application So glad I found you Mason and this forum! We have an office building with a flat roof that is perfect for an ExpandoThane application after hail damage so we elected to do the following material application: 1. ExpandoThane polyurea spray applied to a thickness of 250 mils +- 10 mils as the primary waterproof membrane system. 2. Silicone Seal 3000 top coat will consist of 20 mils +- 4 mils spray or roller applied over the ExpandoThane. My question is going to be regarding the HVAC condensing units sitting on the roof. We have 46 units total ranging from 3 to 10 ton condensers in size, and currently they are all sitting on 4X4 wood posts as support pads. I'd like to know the best way to spray and seal around / under these to avoid any issues down the road. Would you keep the wood supports and spray over them? Or by doing that the wood would pretty much become a part of the roof system...is that an issue? Maybe it's better to just replace those with a non-wood type pad on top of the Expando? I just want to make sure we do the right thing while we are up there to hedge potential problems. Again, I appreciate your reply in advance on best practice here! Many Thanks

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Jeramy McMahon

Posted: Apr 13, 2020 06:11 PM

HVAC Units on Roof of ExpandoThane Application

So glad I found you Mason and this forum! We have an office building with a flat roof that is perfect for an ExpandoThane application after hail damage so we elected to do the following material application:

1. ExpandoThane polyurea spray applied to a thickness of 250 mils +- 10 mils as the primary waterproof membrane system.
2. Silicone Seal 3000 top coat will consist of 20 mils +- 4 mils spray or roller applied over the ExpandoThane.

My question is going to be regarding the HVAC condensing units sitting on the roof. We have 46 units total ranging from 3 to 10 ton condensers in size, and currently they are all sitting on 4X4 wood posts as support pads.

I'd like to know the best way to spray and seal around / under these to avoid any issues down the road. Would you keep the wood supports and spray over them? Or by doing that the wood would pretty much become a part of the roof system...is that an issue? Maybe it's better to just replace those with a non-wood type pad on top of the Expando?

I just want to make sure we do the right thing while we are up there to hedge potential problems. Again, I appreciate your reply in advance on best practice here! Many Thanks

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