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dead level flat roof

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Joined: Feb 2 2004

Just got a bid for a new roof (T&G; $12K). An addendum to the bid refers to the possibility that if the house was designed with a "dead level flat" roof, positive drainage measures must be included (plus $8K!) per building code chapter 32, section 3207.

Anyone had any experience with this? My Eichler is flat but was designed that way?


Joined: Oct 10 2003

Not directly related, but if its going to cost an extra 8K, you might as well take that extra money and consider getting yourself a foam roof. They'll shape the foam to provide drainage (or something like that, I'm admittedly not an expert) plus you get the insulating properties.

In any case, taking the cost from $12K to $20K should allow you many more options than Tar & Gravel. Maybe just that knowledge will help you negotiate the price.

Joined: Mar 22 2003

I cannot comment about whether "flat" and "dead level flat" are one and the same thing, except to say that one of the T&G roofers I interviewed for a past article on roofing did talk about this code requirement.

From what he said, it sounded like flat-roofed Eichelrs or those with sections of flat-appearing rooflines would all fit the criteria of "dead level flat." He just basically indicated that "if your roof is flat, code now requires us to put a small pitch on it, thus increasing the price of the job."

I agree with fxlarry, for that kind of $$ I would do foam in a heartbeat. You get the added benefit of:

-lightness. Foam is much much ligher than T&G, thus less stress on your structure

-water proof. Truely waterproof and no seams to leak. With our old T&G roof, it began to leak horribly at the 3 year mark and though under warranty, the roofer never was able to locate the source of the leak. We replaced with T&G 6.5 years ago and are glad we did.

-insulating properties. Foam is a great insulator and is often used under other types of roofing systems just for this purpose. Why pay extra for that?

The main justificaiton that I have heard for choosing T&G is price. This goes away, if in fact your house is subject to this new code requirement.

And don't forget, re-roofing is the opportune time to take advantage of other upgrade potential, such as electrical, or even AC (certain types can only be done in combination with foam roofs)...I wish we had known about this when we re-roofed, but then we might not have been able to afford it anyway.


Joined: Jan 4 2004

Try getting another estimate; the cellulose fiber taper strips (which is one way of making a roof have pitch) really shouldn't cost $8k; If they are designing tapered foam pieces to cover the whole roof and slope towards the outside; then 8K is about right; it will give your roof a longer life (I've heard from roofing consultants 10+ years; provide more insulation; and unlike foam can be re-roofed over one more time (two times in some municipalities). Tar roofs generally last about five years longer than foam or modified bitumen; it is true that they do weigh more; but the structure is engineered (and it still calcs out by todays' live load standards) to support more weight than is on the roof.
If you are retrofitting any plumbing or electrical to the roof to avoid future repairs to the failing below grade work; foam does make sense (with respect to not adding more work for the roofer) because it is easier to apply than nailing down slivers of insulation board between conduits and water lines (to create a flat surface that additional insulation or the roofing membrane can be laid over), and is self-insulating, so you get an r-13 if they apply it a little over 2" thick. Check this website for referrals for roofers, or you can email me directly.


Joined: Sep 12 2003

There are tapered systems that use foam as the insulator as well as providing the slope necessary to allow water to run off. This system will prevent any 'ponding' on the roof (which is typicall of any flat roof). After installing the tapered foam, you can choose whatever type of roof you want (i.e. tar and gravel, foam coat, etc.)

Two things to be aware of with this design:

1) It will cost you. The upside is you can make a standard 12 year roof (flat with ponding) into 20+ year roof.

2) The design needs to be thought out so that you can avoid installing gutters along the face of the roof edges.

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