# reisdential AC rofo top uinits



## Grumpy (Oct 29, 2008)

This has probably been discussed before, but another go around won't hurt. When you have residential style compressors on a flat roof, the kind that can be lifted by one or two men. Generally how do you factor in working around these units?

It is and has always been my preference to have these disconnected and moved out of our way before we start any work. Sometimes that's just not releasable, especially when you have a price driven customer and alot of units like on a condominium. I tried for awhile to mark the costs into my jobs to have a HVAC contractor come out and drain then recharge the systems, but that does start to add up plus I take on liability if I am subcontracting this work out. Since most of these units are usually old anyways, and ready to go, that's a liability I don't want, "but it worked before you did the roof!"

When we try to lift then to work around them there is about a 25-30% chance we will kink the line. Knowing this number, should I just mark some money into my cost knowing I would have to recharge 25% of the units we work around? Problem is one time this happened and the very litigious owner claimed she needed a whole new AC system, new lines, ne condensor, a $1,200 project.... Ummm no, lying < explicit >!

Therefore I was thinking of adding a line to my proposals in regards to roof top AC units...


AC Units will be lifted so that the roofing assembly may be installed beneath. Although we will take the utmost care in working around the AC units, breaks in the lines and/or wires may form due to age and/or stress of moving the units. If breaks in the line do occur we cannot be responsible. Therefore it is recommended that these units be temporarily disconnected and reconnected by a professional HVAC contractor.


???


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## Grumpy (Oct 29, 2008)

These are the types of units I am talkin' about.


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## Billy Luttrell (May 3, 2010)

I add a charge of 250.00 per A.C. unit. With the non curbed ones as I call them..

We use a floor jack and a small metal cart. Jack them up to get the 4x4s out, set on the cart...move out of the way. Insulate, roof, move back and set new timbers. I have yet to have an issue, but the 250.00 insures me with not only the man hours but in case I have to have my HVAC guy come out and do anything.


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## Billy Luttrell (May 3, 2010)

Also we always set a slip sheet for the timbers.


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## 1985gt (Dec 21, 2010)

It depends on the job for us. New units we will generally just work around and add a bit in knowing we will break a line. If they are older or a bunch of them we will put in there a not responsible clause. 

As far as lifting, depends on the job again. if there are just a few and they look to be easy to move out of the way we generally just have a couple of guys pick them up. If there are a lot of them and are some what organized we will use some cribbing to block up a 24-30' long aluminum scaffolding plank, and 4X6's and strap them up to it.

Thought I had some better pictures of this but all I can find is this one.










Yes the bucket of bonding is for balance.


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## Pie in the Sky (Dec 21, 2011)

I can only say I HATE to see wood 4x4's holding these things up. Even treated wood rots. Was on a job the other day where the 8x8 Timbers rotting under HUGE units. It is going to be a major Operation to fix this. I recommend one of two option although no one here may even care : You can install the wood down to the roof deck cutting out the insulation then flashing over the wood, or you can use a synthetic block curb. Pretty sure when one of these rots and it falls over its going to kink the line. 

From a design aspect, I have always required disconnect/reconnect. Not only is there not damage in the field including leaked refrigerant, but then a proper flashing can be installed, not a Pitch pocket. I also avoid pitch pockets, even with the great pourable sealers out there, they still seem to somehow leak. Vibrations, condensation, I don’t know.... I've typically specified multiple penetration boots like the ones made by Portals Plus or have the contractor separate and field wrap them and then cover the flashing in pipe insulation to the roof surface. 

The only problem with the Multi Penetration boot is its not made by the manufacturer so its excluded from their warranty. So field flashing may be best. But I never cared case we all know how well these manufacturers honer their warranties...


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## Pie in the Sky (Dec 21, 2011)

Also Grump, lets see a closup of that "THING" you are installing that Pitch Pocket around...


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## Pie in the Sky (Dec 21, 2011)

Or you could Just Foam it... :laughing:


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## 1985gt (Dec 21, 2010)

Thats a nice Pitch pocket detail there! "Just add more foam"

4x4's are fine IMO, every roof they *should* be replaced. Larger units like you described we will install the 4x4 or what ever is needed to build a curb and flash and wrap as needed. Always capping them with metal.


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## Pie in the Sky (Dec 21, 2011)

1985gt said:


> Thats a nice Pitch pocket detail there! "Just add more foam"
> 
> 4x4's are fine IMO, every roof they *should* be replaced. Larger units like you described we will install the 4x4 or what ever is needed to build a curb and flash and wrap as needed. Always capping them with metal.


 
Yea I agree, if they are on a TPO they can probably make it through 2 or 3 roofs. :laughing:

The roof I was refering to was a 30 year old BUR that was in fine shape besides the units about to fall over onto it...


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## Grumpy (Oct 29, 2008)

Billy yes slip[ sheets are a must beneath timbers. But the pic is an in action pic. You can tell because the pitch pans aren't filled yet.

Pie, Also yes the pitch pan in the center is a cluster phuck, but pretty common for the area to see hacky stuff like that. We just do the best we can with it. We probably could have field wrapped it but when there is that much tar doped to the pipe, it's better just to use sealant. The previously posted pic was an old pic I posted as for an example. It's not feasible now to go back and get a close up. 


Just so you know we're not total hacks based on the pitch pocket above, here's one we called a choo choo train we did earlier this year. No way I was going to waste time field flashing between these things! I just have the play the cards I am dealt, preferably there'd be 8-12" between.


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## Pie in the Sky (Dec 21, 2011)

Dont think Your a Hack Grump!!!! That pic looks great... 

How Bout this one??? 

:laughing:


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## Grumpy (Oct 29, 2008)

You got me beat, lol.


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## Pie in the Sky (Dec 21, 2011)

I didnt do it... Saw it in FL... Its a good example of doing what you have to do... I can totally understand doing something because doing it the "Right" way is too expensive. Its an important service to provide your client a professional opinion.. Thats where value engineering comes in and can be effective. I would have recommended a hood over that mess...


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## 1985gt (Dec 21, 2010)

Pie in the Sky said:


> Yea I agree, if they are on a TPO they can probably make it through 2 or 3 roofs. :laughing:
> 
> The roof I was refering to was a 30 year old BUR that was in fine shape besides the units about to fall over onto it...



 TPO is a fine product damn it! BUR is better 


Hmm roof under a roof with conduits going though next to the wall, in what basically is a grease pit. Sure we do that.





































As you can see caulking holds up well.

Sorry no after photo's to show you.  I will look look for some photo's of the out side roof, talk about pipeline hell.


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## Pie in the Sky (Dec 21, 2011)

Is that a membrane? Looks like a non reinforced PVC...


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## 1985gt (Dec 21, 2010)

Yeah if you look in the third pic you can make out the reinforcement. I would assume PVC but to be honest I didn't really dig around or get on my knees to find out. You understand right  The membrane was holding up well the flashing and details around the conduits were lacking to say the least.


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## Pie in the Sky (Dec 21, 2011)

Pretty cool.. I bet its 30 years old.. Were those flashings Coated metal? It looks reallly brittle... 

I personally LOVE finding old Gems like this. The history of Roofing is my Favorite Topic. A little Off Topic from this thread...


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## 1985gt (Dec 21, 2010)

Pie in the Sky said:


> Pretty cool.. I bet its 30 years old.. Were those flashings Coated metal? It looks reallly brittle...
> 
> I personally LOVE finding old Gems like this. The history of Roofing is my Favorite Topic. A little Off Topic from this thread...



Yeah the metal "counter flashing" was coated. I would guess the roof is 15 years or so old +/- the part of the building it's in is the smoke house, they changed stuff around every few years so I would guess it was around 15 or so for that one. I wish I had some of the one we did that was almost above this area, another "inside roof" we had to go back and fix what another company did, I have no idea why this place calls anyone else we have done work for them since the 80's not so long ago they started getting other roofers out there, they have more then problems when doing so. You would  at how we repaired the other inside roof but it worked and is holding strong. We will just say it took a lot of Sl-1 and field fabbed metal flashings.

I wish I had some photos of some of the stuff we use to do back in the "olden days" back when people walked from grain silo to grain silo with 2x12 planks, and moping hot in shorts. Better yet probably shouldn't post those. I should have someone scan some of the old Polaroids from that time. It is neat seeing that stuff every once and awhile. Wondering how anyone survived it. Glad I was to young then to be doing it.


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