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[OP]
Deal Addict
Dec 19, 2009
1042 posts
750 upvotes
Ottawa

Flat roof

We have a front awning above the main entrance door to our house. It’s an older home and the maintenance of it had been neglected before we bought the house. It has a flat roof.

Looking for advice on how to clean it up. We’re getting new soffits, fascia and eavestrough on the rest of the house so hoping for some guidance on this part.
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9 replies
Deal Addict
Jan 19, 2011
2990 posts
1251 upvotes
Best advice, pitch it!

meaning build a pitched roof with shingles to replace the flat roof, looks like you could fit a 3-12 or 4-12 pitch gable ended or hipped roof there.
"The truth is incontrovertible, malice may attack it, ignorance may deride it, but in the end; there it is."
Just a guy who dabbles in lots of stuff learning along the way. I do have opinions, and readily share them!
Sr. Member
May 21, 2015
988 posts
542 upvotes
Sarnia, ON
I agree. Flat roofs are future problems waiting to happen. fyi the structure is called a portico
Sr. Member
Oct 22, 2016
748 posts
652 upvotes
Comox Valley
I think that built (portico) looks unique on your house, and I would keep it. This flat roof design should not cause you huge problems with no living space underneath.

Couple options, if you want to get it redone, use torch on instead of the existing tar and gravel flat roof you have now. Or if you feel it is waterproof now, and you do not like the look of the moss on it. Use a moss killer (zinc sulfate?), kill the moss and then lightly sweep it off. I am not a fan of sweeping of green moss off the roof, until it is killed as it may damage the roof membrane. Saying that it may be an idea to lightly step on the roof, to feel how solid the roof deck is underneath and/or has it deteriorated.
Deal Addict
User avatar
Sep 27, 2006
4036 posts
1068 upvotes
Not so easy there Ma…
Does the house have a flat roof or just above the front porch?

In regards to the front porch roof, the tar and gravel roof will typically last on a shorter life span a dozen years. On a well done T&G roof it can last decades. It generally depends on the number of plies, how much tar, and how well covered the tar and plies are with the gravel. The moss is nothing to worry about. As another mentioned, you can replace the roof with built up roofing such as torch-on roll roofing, that has a cleaner look.
[OP]
Deal Addict
Dec 19, 2009
1042 posts
750 upvotes
Ottawa
fieldhousehandyman wrote: Best advice, pitch it!

meaning build a pitched roof with shingles to replace the flat roof, looks like you could fit a 3-12 or 4-12 pitch gable ended or hipped roof there.
Thanks for the advice.
The dimensions of the flat roof is about 122” x 68”.
Any idea on a ballpark price I should expect to pay someone to build a pitched roof and shingle it?

Come to think of it I think the people down the street did this to their portico and their house is the same mode as ours. I guess I could ask them what they paid.
User452441 wrote: I think that built (portico) looks unique on your house, and I would keep it. This flat roof design should not cause you huge problems with no living space underneath.

Couple options, if you want to get it redone, use torch on instead of the existing tar and gravel flat roof you have now. Or if you feel it is waterproof now, and you do not like the look of the moss on it. Use a moss killer (zinc sulfate?), kill the moss and then lightly sweep it off. I am not a fan of sweeping of green moss off the roof, until it is killed as it may damage the roof membrane. Saying that it may be an idea to lightly step on the roof, to feel how solid the roof deck is underneath and/or has it deteriorated.
It was my hope to keep costs down so I tend to like your suggestion to keep the existing structure. And my thought is it’s not over living space so worst case scenario isn’t even that bad. And like you, I don’t mind the look (minus the peeling paint which can obviously be changed).

Good idea...I’ll get up there to test out how solid the roof deck is.

Any ideas for what a torched on roof would cost?

My in-laws had this stuff installed on the flat roof portion of their boathouse at their cottage.
https://duradek.com/vinyl-decking/vinyl ... roof-decks
Any experience with that? Thought it may be a good solution.
[OP]
Deal Addict
Dec 19, 2009
1042 posts
750 upvotes
Ottawa
fergy wrote: Does the house have a flat roof or just above the front porch?

In regards to the front porch roof, the tar and gravel roof will typically last on a shorter life span a dozen years. On a well done T&G roof it can last decades. It generally depends on the number of plies, how much tar, and how well covered the tar and plies are with the gravel. The moss is nothing to worry about. As another mentioned, you can replace the roof with built up roofing such as torch-on roll roofing, that has a cleaner look.
The house roof has a slight front to back pitch...it’s not flat.

And that’s what I heard...tar and gravel (if done well) can last a really long time.

Any ideas for what torch on roll roofing would cost? The space is about 122” x 68”.
Deal Addict
User avatar
Sep 27, 2006
4036 posts
1068 upvotes
Not so easy there Ma…
mikek33 wrote: The house roof has a slight front to back pitch...it’s not flat.

And that’s what I heard...tar and gravel (if done well) can last a really long time.

Any ideas for what torch on roll roofing would cost? The space is about 122” x 68”.
The last time I bought roll roofing was 2015 and paid retail from a roofing supplier. I used TP-250 and the cap sheet was 1 metre by 8 metre (78 square feet a roll), 4 mill thick and that was $56 per roll. As I recollect the base sheet roll was the same dimensions and likely the same price.

It sounds like your "house roof" is either a flat roof or a low pitched shingled roof? A flat roof still has a slight pitch so that water doesn't pool on it, which would otherwise be a disaster waiting to happen if you had a leak. The pitch of a flat roof is very modest and not compatible with shingles. A "low pitched" roof may be shingled or it may have roll roofing on it that is like a long shingle roll (latter tends to be more a shed thing)

Looking at your roof, it has an overhang and if that's a flat roof it really shouldn't have an overhang. If that overhang is the lowest part of the roof, ice would likely form up there in the winter because your insulation is likely modest and the temperature on the deck of the overhang lower. I see a vent under the overhang? That makes me think that the insulation is located on top of the drywall in the ceiling and may be minimal thickness. Venting seems inadequate. Are there more vents? Is there strip vents maybe on the other side? These assumptions are based on a flat roof, not a low pitched roof.

On a new build today they put the insulation directly on top of the flat roof deck, put a protective layer over top that and then the torch on built up roofing. On a new flat roof there would be no vents and no overhangs like that either.
Sr. Member
Oct 22, 2016
748 posts
652 upvotes
Comox Valley
mikek33 wrote:

Any ideas for what torch on roll roofing would cost? The space is about 122” x 68”.
Taking a guess here, $1,000. It is not very big, but by the time you quote it, pick up material and install, I would think that. One trouble area might be, where the new torch on roof meets the house, if it is easy to put the membrane under existing siding. Or as I previously noted, sometimes rot of the roof deck.

I forgo the duradeck on here, as it will not be walked on. A torch on membrane would be more hardy.
[OP]
Deal Addict
Dec 19, 2009
1042 posts
750 upvotes
Ottawa
fergy wrote: The last time I bought roll roofing was 2015 and paid retail from a roofing supplier. I used TP-250 and the cap sheet was 1 metre by 8 metre (78 square feet a roll), 4 mill thick and that was $56 per roll. As I recollect the base sheet roll was the same dimensions and likely the same price.

It sounds like your "house roof" is either a flat roof or a low pitched shingled roof? A flat roof still has a slight pitch so that water doesn't pool on it, which would otherwise be a disaster waiting to happen if you had a leak. The pitch of a flat roof is very modest and not compatible with shingles. A "low pitched" roof may be shingled or it may have roll roofing on it that is like a long shingle roll (latter tends to be more a shed thing)

Looking at your roof, it has an overhang and if that's a flat roof it really shouldn't have an overhang. If that overhang is the lowest part of the roof, ice would likely form up there in the winter because your insulation is likely modest and the temperature on the deck of the overhang lower. I see a vent under the overhang? That makes me think that the insulation is located on top of the drywall in the ceiling and may be minimal thickness. Venting seems inadequate. Are there more vents? Is there strip vents maybe on the other side? These assumptions are based on a flat roof, not a low pitched roof.

On a new build today they put the insulation directly on top of the flat roof deck, put a protective layer over top that and then the torch on built up roofing. On a new flat roof there would be no vents and no overhangs like that either.
See attached pic. It’s a low pitched roof with shingles...with gutters on the front and back. There is a pretty significant overhang of the roof which probably runs over half of the portico.

It’s the original wood soffits with vented spots throughout. The company that will be putting in aluminum soffits and fascia will be cutting more venting holes in the existing wood soffits before covering with aluminum. The roof (shingles) were replaced in 2007 and there were maxi vents installed at that time. The shingles are actually in pretty good shape considering their age (and our climate - I’m in ottawa)...so I’m thinking the roof is breathing okay as-is. We just moved in a month ago though so don’t know the insulation situation in the winters.

I’ll look into the roll roofing...
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