I live in a house my parents bought in the
late 1940's. In the back is a low-slope
roof. The low-slope portion has been untouched
since at least the 1960's if not the 1950's.
This summer I had a new roof installed on the
rest of the house. The roofer told me he would
not do the low-slope part. I told him that suited
me just fine because it never gave me any trouble
and had been zero maintenance.
It turned out that he sub-contracted out the
entire job. He didn't watch "his guys" and
they roofed the entire roof including the low-
The manufacturer said they
would not warrant the low-slope portion because
of insufficient slope. Another roofer told me
the roof will not last.
Problem: No one knows how to put the roof
back the way it was. Everyone I have consulted
about the roof says that the technology is lost
and that any roof that is put there will have
to be coated every three years.
Have we regressed that much?
Is it impossible to construct a low-slope roof
(1.75 in 12) so that it does not need to be
Our back roof was only 1.8 inches per foot like yours, and was shingled with
comp. roofing, which failed within two years. Shingles are not applicable,
as most manufacturers will void their guarantee for shingles if pitch is
less than 4 inches - read the left over package covers on the product.....
So we had roof stripped to wood decking, then had a five layer non-shingle
commercial roof put on. You need to get better info, and keep away from the
idiots that do jobs poorly and give erroneous advice (eg the technology is
lost!) . Get local references from neighbors you know, and use local roofers
that have high volume business and good reputation, with warrantees. Our
roofer had a 3 year unconditional warrantee, but de facto much longer, as he
is known to correct mistakes way behond this period. On the steeper 4 inches
per foot front roof, we got 30 year shingles.
Anyway, the low pitched roof we had put on was first underlain by
fiberglas/rubberized padding or blanket, then three layers of lapped hot tar
mineral felt, followed by a walkable mineral grain surface, hot tarred to
the tarred 3-ply felt underneath. It should be good for 20-30 years, and has
9 years on it so far, with little signs of aging. I hate tar and gravel, as
it is hard to diagnose leaks, and is more prone to damage by walking.
I did read it - several times. The shingles were made by Tamko.
Somewhere in there the warranty said it was good down to 2" per foot.
But, it doesn't really matter since the slope was about 1 5/8" per foot.
Thanks for the information. Now, I know something can be done. I have
had two doses of misinformation. The second "lost technology" guy does
have an excellent reputation. However, it seems like he recently took
over the business from is father and is a bit young.
We are just getting out from under
a foot of snow right now. I don't know what actually was done to
the roof. I am hoping at least part of the original roof is still
there so I can see how it was done. If not, I can use your
information as an IQ test.
Low cost solution is half lap roll roofing with full cement undercoat.
Modern far superior product is full glue down EPDM. Think big rubber sheet
and you understand what this is. Not sure what the actual rating is but I
would guess 25-30 years.
I also have a roof problem. My sun porch drops one foot in a distance of
sixteen feet. The inside ceiling is interior drop ceiling asbestos roof
panels and they leak continually. The
exterior is the wavy metal and I am looking for something to put on top
of it. The frame is metal underneath the metal roof, so I would rather
not try to deck it. any suggestions. Will rolled roof go over the
corrugated roof, or will I have to deck it? Thanks Al
Any port in a storm, friend, but you'll want your roofing membrane to be
supported at all points.
Think about roofs in commercial buildings. They are rather flat. Plywood
sheeting is attached to rafter stock. Then roofing material is laid upon
Curious / What kind of roofing material is on it now & what was there?
I'm in a mid 50's Florida home with about 2:12 pitch roof which originally
was tar and gravel, which is still available no problem.
I see low slope roofs around your pitch all over the place and its not
unusual to use asphalt shingles which this homes roof is now but you only
expect about 15 yrs service - Torch-Down modified bitootem(sic) is popular
on roofs too,, kind of like an asphalt roll roofing except thicker with the
overlaps melted together. Put it on about a 24'x 32' oversized two car
garage a couple yrs ago $2000 total for strip/install and that was a high
priced job as everybody were too busy after some severe gusty weather.
I don't know what it was other than not shingles. If I knew,
I wouldn't be as concerned. If I knew I could get more of
it, I wouldn't worry at all.
I don't know if it is still there or not. I'll find out
Wasn't asphalt shingles.
- Torch-Down modified bitootem(sic) is popular
You've got a problem. Instead of shingles, at a miniumum your low slope
roof should have been recovered with BUR (built up roofing), a
multi-layer covering that is designed just for this application.
Your shingled low-slope roof won't last long, and worse yet, could begin
leaking immediately due to the lack of a sealed membrane between the
shingle and the deck. This isn't too much of a problem on sloped decks
because the water runs down the underlayment surfaces. But on a flat
(or near flat) room the water can back up under the underlayment laps,
and presto, you've got leaks.
Another problem you should be aware of: when you replace the flat roof,
you need to make sure it is "tied in" to the shingled roof above / below
it. This is not a trivial job and requires someone who is really good
at reroofing. Obviously, not your previous contractor.
Depending on how long you want the new flat roof to last, you should ask
for a multi-ply (3 or more) BUR. There are other technologies available
for this application, but IMHO hot (asphalt) applied BUR has been around
for a long, long time and has a good reputation.
Hope this helps.
Travis is giving excellent advice. That roofhelp website is really good, and
reminds me that I used all the wrong terminology in my earlier comment.
Ok, to repeat,
On my 1.8 inch pitch, I had a built-up roof applied.
Fiberglass basesheet, then three ply hot tarred roll roofing (each
successive layer covers 2/3 of underlying layer, so that you get 3 plies,
net), followed by a tarred-on mineral surfaced capsheet. Worked like a
dream, and is very sturdy and walkable.
Now how do you suppose they do all those office buildings and warehouses
that have virtually FLAT roof?
Some are tar and gravel, but these days most are rubber membrane roofs that
will last virtually forever.
That's how I had my home's nearly flat roof done and it works perfectly and
guaranteed for as long as I own the home.
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