Thread: TPO roofing

I inspected a roof with GAF Everguard TPO 60 MIL.
There are areas of the roof with variatons in roof heights of up to 5" with the membrane roofing installed over them, how much variation is allowed for this type roofing?

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As I recall, no ponding water, 1/4" per foot slope minimum.

That looks like (looking on my phone) to be a PPRJ ... (Piss Poor Roofing Job) ... with a vertical elevation change and likely no cant strip at the bottom of the vertical change. I recall that TPO is permitted to be run up the side of parapet walls (which looks like was done) - I don't recall what the maximum height up the parapet wall is ... but that would also be the limit of a vertical elevation change.

Just write it up as a PPRJ ...

Those humps are roof deck expansion joints. Usually the joints are made of flexible rubber bellows to wood can't strips. Nothing between the decks but space to allow expansion and contraction.

- - - Updated - - -

Originally Posted by Charlie Crouthamel

I inspected a roof with GAF Everguard TPO 60 MIL.
There are areas of the roof with variatons in roof heights of up to 5" with the membrane roofing installed over them, how much variation is allowed for this type roofing?

Try this link. http://www.thermoply.com/pdfs/TPO%20...n%20Manual.pdf
Best.

Originally Posted by Jerry Peck

As I recall, no ponding water, 1/4" per foot slope minimum.

That looks like (looking on my phone) to be a PPRJ ... (Piss Poor Roofing Job) ... with a vertical elevation change and likely no cant strip at the bottom of the vertical change. I recall that TPO is permitted to be run up the side of parapet walls (which looks like was done) - I don't recall what the maximum height up the parapet wall is ... but that would also be the limit of a vertical elevation change.

Just write it up as a PPRJ ...

Ponding is relative to time Jerry.
Ponding water is defined as the water which remains on a roof (48) hours "or longer."

I report, " Observed standing water. If water stands on a roof surface for more than 24-48 hours it becomes ponding water. Ponding water can have adverse effects on roof coverings."

Recommended slope, 1/4" per foot.

Originally Posted by Charlie Crouthamel

I inspected a roof with GAF Everguard TPO 60 MIL.
There are areas of the roof with variatons in roof heights of up to 5" with the membrane roofing installed over them, how much variation is allowed for this type roofing?

That was not the worst thing, the metal roof decking was rusted out and collapsing, roofer repaired with welded in fence post and installed new roof.

Originally Posted by ROBERT YOUNG

Ponding is relative to time Jerry.
Ponding water is defined as the water which remains on a roof (48) hours "or longer."

I report, " Observed standing water. If water stands on a roof surface for more than 24-48 hours it becomes ponding water. Ponding water can have adverse effects on roof coverings."

Recommended slope, 1/4" per foot.

Some roofing materials and codes do not allow for any ponding, by any definition, Robert, as they require a slope which "has positive drainage" and does not hold any water for any length of time.

The typical minimum required slope is 1/4" per foot, this is to provide for that "positive drainage" and no standing/ponding water. Ponding water is a structural issue as much or more than a roof covering material issue as ponding water loads the structure beyond its intended design ... unless it is designed to have ponding water. That is why many of the older "flat" (they were "flat") roofs now sag - because there was no positive drainage and water was allowed to stand, which gradually caused the roof structure to sag, and each additional sagging of the roof structure allowed for more standing/ponding water, which caused the cycle to repeat itself until the roof structure finally caves in and falls in on to the occupants during a heavy rain.

From your link:
- Expansion Joints
- - The function of a structural expansion joint is to minimize the effect of stresses and movements on building components and to prevent these stresses from adversely affecting the building. The design, location and use of building structural expansion joints must be considered at the time of original building design and are the responsibility of the architect, engineer and building owner.
- - Expansion joints:
- - - Must be continuous along the break in the structure and not terminated short of the end of the roof deck.
- - - Should never be bridged with insulation or roofing membrane.
- - - Construction ties must be removed in order for expansion joints to function properly.
- - - Extend expansion joints at least 8” above the roof surface on curbs and use either Metalastic® flexible expansion joint covers or metal caps or covers.
- - - Design drainage flow patterns so they are not blocked by any structural expansion joints.
- - - Where possible, position walkways on roof access points to limit roof traffic over expansion joints; provide protective coverings for expansion joints at locations of repeated roof traffic.
- - Area Dividers
- - - Area dividers are not considered structural expansion joints They can be installed to separate different roofing systems and can be either a curb or low profile type. Contact our Technical Helpline for recommendations regarding area dividers.


H. Parapet and Building Walls
- 1. Flash walls with membrane flashing adhered to the wall substrate with bonding adhesive, or with coated metal flashing fastened 4" on center to pressure-treated wood nailers.
= 2. Secure membrane flashing at the top edge with a termination bar. Water Block shall be applied between the wall surface and membrane flashing underneath all termination bars. Exposed termination bars shall be mechanically fastened 6" on center; termination bars that are counterflashed shall be fastened 12" on center.
- 3. Roof membrane must be mechanically attached along the base of walls that are flashed with membrane flashing with screws and plates/termination bar at a fastener spacing in accordance with in-lap attachment requirements, with a 12" on center maximum spacing.
- 4. All coated metal wall flashings and loose membrane flashings must be provided with separate metal counterflashings or metal copings.
- 5. Metal counterflashings may be optional with fully adhered membrane wall flashings depending on guarantee duration. All termination bars must be sealed with caulking.
- 6. Flash wall scuppers with a scupper insert of coated metal that is mechanically attached to the wall and integrated as part of the wall flashing. Refer to scupper section.
- 7. Maximum flashing height without intermediate fastening:
- - 18" - Loose-Applied Flashing
- - 54" - Adhered Flashing

That indicates that, for that brand of TPO, the maximum vertical height is shown at H.7.

And if those 'ripples' are "expansion joints", then they are not done properly, see:
- - - Extend expansion joints at least 8” above the roof surface on curbs and use either Metalastic® flexible expansion joint covers or metal caps or covers.

As I said, a PPRJ.

- - - Updated - - -

Originally Posted by Charlie Crouthamel

That was not the worst thing, the metal roof decking was rusted out and collapsing, roofer repaired with welded in fence post and installed new roof.

Yeppers, that needs more than just a roof replacement.

[QUOTE=Jerry Peck;271271]Some roofing materials and codes do not allow for any ponding, by any definition, Robert, as they require a slope which "has positive drainage" and does not hold any water for any length of time.

The typical minimum required slope is 1/4" per foot, this is to provide for that "positive drainage" and no standing/ponding water. Ponding water is a structural issue as much or more than a roof covering material issue as ponding water loads the structure beyond its intended design ... unless it is designed to have ponding water. That is why many of the older "flat" (they were "flat") roofs now sag

The roof is new, roofers just finished $150.000 roofing job!!!!!!

Originally Posted by Charlie Crouthamel

The roof is new, roofers just finished $150.000 roofing job!!!!!!

If inspecting a new roof as for a roof inspection for your client, I would have the manufacturer's installation instructions in hand and photo/document from the installation instructions what does not meet the installation instructions, and if inspecting a new roof as part of a building inspection ... I would do the same thing because of the liability involved.

Then, when through with my list of things which do not meet the manufacturer's installation instructions, I would also recommend that the manufacturer's representative 'accept the roof and issue a manufacturer's warranty certificate for that specific roof.

Let the manufacturer be the one to tell the roofing contractor that it needs to be replaced ... or no warranty ... that works ... and means more to the owner and to your client than just you saying what is wrong.

From the manufacturer's link Robert provided:

Roof Decks
- Most common structural roof deck types are suitable substratesfor the installation of an EverGuard® roofing system.
- It is the responsibility of the engineer, architect, buildingowner or roofing contractor to determine the fitness of a deckfor a specific roofing system installation.

Roof Drainage
- Providing positive roof drainage is important. Standing watercan result in deck deflection and possible structural damage.In addition, in the event of an opening through the roofing membrane, standing water can significantly worsen damageto the roof system, the building itself, and interior contentsby providing a reservoir of water ready to gravitate throughthe membrane opening. Providing structural slope in the deckassembly, installing a tapered lightweight cellular concreteoverlay, installing a tapered insulation system, or addingadditional drains are the most common methods of achievingpositive drainage.

Kind of late to this post but wait - that's a brand new roof? Wow, then I have to agree with Jerry PPRJ. Looking at it I thought it was maybe 2-4 years old.
As a general comment, not specifically at you Charlie, whenever an inspector is going to look at the new installation of any specialty product, that inspector should download, print, read and bring with the manufacturer's info for that product. If you aren't you aren't serving your client properly.
I do a fair amount of the oddball 'can you come inspect X new installation for us before we sign off on paying the contractor'. Partly because most inspectors around here don't want to do it, partly because my name gets passed around because I show up prepared.
Often times, the contractor is onsite and trying to counterclaim everything an inspector says. If you aren't prepared the client or their Rep ends up standing there watching a he says / he says between a contractor and inspector. When you show up prepared you reduce or eliminate that problem.
The inspector says X portion is wrong; contractor says no its not you are just a stupid picky inspector trying to justify your fee, inspector shows client on Page 4 of manufacturer's install document where its not compliant and discussion over.
If an inspector is doing this type of work, the report should include a description of the defect, a picture of the defect and the page number, etc. where the manufacturer states that manner of installation is either not compliant, not allowed, etc.
If, at the very least, you aren't providing those 3 points for each defect (or what you as the inspector are claiming to be defects) you really aren't doing a good job, serving the client properly or serving our profession.

I pointed out how the raised section are possibly/likely expansion joints.

When you see blistering on TPO, or any other member roof system. it is likely saturated underlay. Water turning to vapour then expanding below the surface pf the membrane like blowing up a balloon.
The OP question was the raised sections, henceforth my answer.

Roof inspections are performed using Tramex MRH III moisture meter and Ti300 80 hz infrared camera.

Originally Posted by ROBERT YOUNG

I pointed out how the raised section are possibly/likely expansion joints.

However, if those are expansion joints, or intended to be expansion joints, they are completely wrong, as I pointed out, and pointed out the section of the installation instructions which you linked to.

Just 'looping the roof covering up and back down' to provide flexibility is not a proper expansion joint.

Just like laying that roofing material up that vertical step with wrinkles in it is not correct.

For a new roofing job, it is a PPRJ, for an older roofing job, it was a PPRJ (because it would not look like that had it been properly laid - not unless there was some serious shifting of the structure underneath to roof covering).