40 years for a FLAT roof is hard to beat! Were you in the habit of re-coating it with the aluminized tar stuff every few years? (Flat roof in So-Fla will be shot in 6-8 years w/out frequent re-coating.)

I don't know anything about "IB" roofing systems, but I bet the contractor pushing it will NOT be around as long as the (alleged) warranty on IB roofing... WHO is the mfr. of the key material/membrane??

Anyway, unless hot-mopping is now illegal in Kah-lee-forn-ya (wouldn't doubt it), I'd get a few quotes for that proven, "old-fashioned" method, just so you can be dollar-cost rational in your decisions.

Here is a link that might be useful: My personal fave for flat-roof DIY recoating...

Thanks for the reply Fixizin..

We have recoated every 10 yrs or so, SO actually the roofing hasn't been on as long as the old garage has been standing. The roofing contractor, gave us a $2100 bid for the IB roofing stuff (700 sq ft.) and he also roofed our very high pitched two story home with fire resistant cedar shingles 10 yrs ago. He did a great job then. The manufactor's website for the PVC membranes list they've been in business since 1978 but that's just hearsay ? A hot mop contractor also gave a $2100 bid today but he will pull off the whole plywood underroof and hot mop, while the other will only replace the plywood that looks bad. It might be worth trying this new product tho since the prices are the same. California and it's restrictions can be a PAIN but hot mopping hasn't been outlawed YET ! Just a oversight, I'm sure : )

The cost of materials for flat roofing may vary on what kind of quality do you want to put in your roof. I think the estimated budget given to you is fairly enough. But you can still canvass from another contractor to compare the price range and the quality of materials to be use.

EPDM lasts 30 years and more.

No coating, no maintenance.

For smaller areas you can get a piece with factory made seams to cover the entire roof.

Try 'Flat Roof Solutions'

It is not marketed to single family housing, but is on the roof of many commercial buildings.

What brickeyee said; EPDM, you will get it in any size you need. You may also look into pond liners, they have EPDM in much bigger pieces. It resembles old inner tube tire material, glues down and requires edging

What they are talking about is EPDM (synthetic rubber) single-ply, full adhered membrane roofing. It is usually glued down on top of a wood fiber "recovery board" that is mechanically attached to the old roof sometimes over a layer of rigid insulation.

We provide a wide range of roofing services for residential and commercial. We have responded by providing renovations, replacement windows and doors

I recently reviewed the difrerent flat roof materials. My research is based on a very very flat roof (1/8 inch per foot). The materials available are
built up which I didn't consider
modified bitumen, which could be "torch down" or adhesive applied (usually a peel and stick roll)
EPDM
TPO
PVC
Liquid acrylic roof coating (I couldn't find much information on actual experience)
foam spray: not dependable long term, might only last a few years before trouble starts.
liquid "rubber" coating (not sure if this term is correct): did not go into this in detail, based on some early bad reviews, but not sure how good these reviews were

EPDM is excellent. Not good if people will be walkin on frequently. Not as tear resistant and puncture resistant as TPO and PVC. Black color, which is most popular versio will last a long time. White color will probably not last as long (based on Manufacturers' willingness to warantee for less time than white). As Brick said, you can get a large piece cut to your dimentions and cover your entire garage without field-seaming.

TPO: good, strong material, but a number of articles mention problems with the formulation of the plastic that have caused problems in it breaking down. Manufacturers have changed formulation a number of times, so I believe, there is not any really long-term installations we could point to. Seams are air-heat welded (with air gun, and no flame used)

PVC, in my humble, amatuer, opinion, seems to be strongest and longest lasting, and uses heat-welded seams, so once it is installed, there is no worry about seams comming apart as in some roofing types. This material has been used 30-40 years, and lasts a long time. I do not know why fewer roofers offer this material in my area (Washington DC area). Most offer TPO. This may be a remnant of the days when TPO was much cheaper. The labor is about same. Today, prices are about $0.50-0.70 per square foot difference.

Roofs are never flat because they need to drain instead of collect puddles of water. A slope of 1/8" per foot is adequate but not reliable because structures move. So manufacturers recommend 1/4" per foot of slope and achieving that is the most important design issue in a low-sloped roof.

The advantage of EPDM is the potential size of factory seamed sheets.

"Roofs are never flat because they need to drain instead of collect puddles of water. "

Roofs have been build dead flat with the intention of temporarily retaining some of the water fr a long time.

The biggest problem is often making sure they are flat, with no dips.