Mechanical Pit


#1

What is the best method to re-roof in a mechanical pit that is 25’x30’ with a cooling tower in the middle of the roof (footprint of 20’x20’ with only 12" clearance)? We cannot feasibly demo old roof and space is tight. Old roof is modified bitumen type system over a concrete deck. Old roof has been compromised and excessive moisture conent in insulation below. Roof will see some chemicals from tower water and foot traffic.


#2

Hi,

First are you a building owner or a contractor?


#3

Mike represents the building owner and I also work with him. We are in Colorado, north of Boulder.

The pit area offers a very challenging situation. The area sees lots of foot traffic around the cooling towers and some chemicals. The roof is currently a mix of Mod-Bit and EPDM (installed at two diffent times with a weird seam). The oldest section was installed in 1992. Mike…correct me if I’m wrong on these types.

Moisture scans have shown that most of the underlayment is very saturated around the cooling towers.

Our initial thought was to do some sort of PVC (FiberTite) around the cooling towers and then do a fluid-applied (SPF or other) under the towers extending slightly over the PVC or with some other transition.

Thoughts?

Thanks, in advance for any advice you can give us.

Mike…see if you can post some pictures of the area, because it really is a challenge.


#4

IB Roof makes a PVC membrane that is resistant to chemicals / oil / grease - IB ChemGuard.

The also have a special walk-thread membrane that is used for heavy foot traffic.

All seams are hot-air welded so you won’t have leak problems even with ponding water.


#5

Hi,

**Our initial thought was to do some sort of PVC (FiberTite) around the cooling towers and then do a fluid-applied (SPF or other) under the towers extending slightly over the PVC or with some other transition. **

This does not make sense to me.

**Moisture scans have shown that most of the underlayment is very saturated around the cooling towers. **

Find out how the moisture got in the insulation. This will help with the desicion what product to use. If you do not know why the moisture is there you may not fix the problem with the new roof.


#6

Mike. Send me an E-mail. I know just the person to help. Bet Lefty knows who I’m thinking of. :smiley:


#7

[quote=“Lefty”]Hi,

Find out how the moisture got in the insulation. This will help with the desicion what product to use. If you do not know why the moisture is there you may not fix the problem with the new roof.[/quote]

To start, the original roof is in very poor condition. In addition…for years, the basin on the older of the two cooling towers leaked onto the roof. Our environmental group, instead of insisting the cooling tower basin be repaired, mandated the roof drains be plugged and the water tested prior to allowing to drain!!! Smart, huh?!! So, you can imagine what consistent ponding water on the roof has done to it.


#8

Well just contact Mike if you don’t want to e-mail.
http://scieroofing.com/index.htm


#9

Sounds like the existing is going to HAVE to be removed.

Polyurea will take care of most of the problems, but you CANNOT go over that saturation. Polyurea is a true vapor barrier and will not allow any moisture to dry out and you dont know what condition the roof deck is in.

What types of chemicals come in contact with the roof?

If it is logistically possible, a 4 lb foam roof with a 80 or 100 mil polyurea coat over the top could be pitched to the drains and hold up well to the foot traffic.

This would give you SEMALESS encapsulation of a foam roofing system with the redundancy of a heavy ultra-durable SEAMLESS polyurea topcoat/waterproofing system.

This is only possible if the saturated roofing is completely removed. Besides the polyurea/vapor barrier factor, with that kind of long-term consistent leakage, you will want to inspect the roof deck for structural integrity. With that type of leakage, you will likely have roof deck issues that will need to be remedied before installing ANY type of system.

If the roof holds water, be sure to have a drainage system installed. SPF pitched to drains or tapered boardstock insulation will usually do it.

I say from the sound of the project and the conditions I am picturing, Tapered insulation with PVC roofing or SPF and polyurea are the contenders.

The need for durability for HEAVY foot traffic, foam and polyurea is the winner in my professional opinion.