Home Roofing

[lawman]

My home is foam encapsulated and has open cell foam spray foam on the bottom side of the roof decking..When I re roof if there is decking that needs replacement can I just lay down new OSB decking over the bad decking or does the bad decking have to be removed and replaced?

 

[calmloki]

Good question. Did it leak? If it did and the OSB is bad then I'm thinking you replace the bad 1 or 2 sheets. Going over the top means re-sheathing the whole roof or side/section, as well as being poor practice to bury bad wood(flakes). Of course that leaves you with an un-foamed panel or two. Maybe cover them with fiberglass batts?

 

[lawman]

Good question. Did it leak? If it did and the OSB is bad then I'm thinking you replace the bad 1 or 2 sheets. Going over the top means re-sheathing the whole roof or side/section, as well as being poor practice to bury bad wood(flakes). Of course that leaves you with an un-foamed panel or two. Maybe cover them with fiberglass batts?

No leaks...Just curious.....Thanks

 

[calmloki]

Just had our flat Santa-Fe style roof re-done. It did leak, which cost for drywall/paint repair. Thought about foaming over the top as a fix as well as gaining some insulation. Didn't. They swapped one sheet of OSB. It was due - starting to swell apart and get soft. Have seen a roof that had foam over the top get removed. Looked like a PITA to work with after.

 

[pb4uski]

My home is foam encapsulated and has open cell foam spray foam on the bottom side of the roof decking..When I re roof if there is decking that needs replacement can I just lay down new OSB decking over the bad decking or does the bad decking have to be removed and replaced?

We have a hot roof at one of our homes. While we haven't had to reroof yet, when we do if there is decking that needs replacement, I would remove the suspect decking, inspect the underlying foam and roof joists and then replace as needed.

I think most likely it would just to remove and replace any rotted decking. I think one can remove decking without disturbing the foam too much.

If you put OSB over the decking then it would be flush and you'll have to OSB over the whole deck, which IMO would be a waste of money and add additional weight to the roof unnecessarily.

 

[old medic]

I'm assuming you currently have a shingle roof, and no leaks. I would seriously consider just putting a metal roof over the existing roof.

 

[street]

I'm assuming you currently have a shingle roof, and no leaks. I would seriously consider just putting a metal roof over the existing roof.

I would second that. I do know when you talk to people in the construction business, they recommend taking shingles off before installing metal roofing.

Is there any moisture issues going right over the top of shingles with metal?

 

[calmloki]

I went over wood shingles with 3-tab - cut the replacement time about in half due to shingle curl, so i got to do our roof twice. Friend went over 3-tab with metal at his coast house and the wind took off a bunch of it. He's pretty meticulous, so I think he did a good job. Could be that the extra space between the metal and the wood deck allows the screws extra lateral motion; the screws don't really clamp in the shingle material?

 

[pb4uski]

I'm assuming you currently have a shingle roof, and no leaks. I would seriously consider just putting a metal roof over the existing roof.

IME, the cost of a metal roof is much higher than replacing an asphalt-shingle roof and n most cases we are at an age where it will be our last roof replacement, so I wouldn't go there.

 

[euro]

I'm assuming you currently have a shingle roof, and no leaks. I would seriously consider just putting a metal roof over the existing roof.

+1. I did that 10 years ago and the metal roof is still doing great.

 

[pb4uski]

^^^ Do you remember how the cost of a metal roof on top of the old asphalt shingles compared to jut replacing the asphalt shingles?

 

[street]

Of course, the metal roofing costs more and if you go over the top of asphalt you save money on tear off and hauling expense. If you go back to asphalt, you have those expenses.
The other savings is you pay less for Home Insurance with the metal roof any way in my area you when you get quotes.

 

[euro]

^^^ Do you remember how the cost of a metal roof on top of the old asphalt shingles compared to jut replacing the asphalt shingles?

I don't recall the exact numbers, but the labor involved in peeling a layer of asphalt shingles and the cost of disposing them are significant. If I had to throw out a number I'd think $1000-2000. Obviously, it also depends on the size and probably slope of the roof. Plus, every roofer I ever met despises peeling the shingles - it is actually very hard work, often under sketchy conditions. I recently re-roofed just a tiny 10x16 shed and I can confirm that I did not enjoy the process....

 

[MC Rider]

We had a 12' x 40' patio roof redone. Tear off old roll on roof, replace about 1/2 sheet of OSB, torch down new roll on roof, plus flashings. Added 2 metal panels over old plastic panels to a leaky shed roof. About $2700 all in, done in 1 day.

 

[old medic]

We spent $2300 for the metal, screws and trim, then around $250 for underlayment and foam pieces... no labor... (well beer and food for a bunch of friends). We got a quote from a company to do the roof in shingles for $12K. Our county adds tax value for a metal roof.
I'm 60 and love the idea I'll never have to deal with it again.

 

[MC Rider]

We spent $2300 for the metal, screws and trim, then around $250 for underlayment and foam pieces... no labor... (well beer and food for a bunch of friends). We got a quote from a company to do the roof in shingles for $12K. Our county adds tax value for a metal roof.
I'm 60 and love the idea I'll never have to deal with it again.

I'm 65 and figured asphalt roof is good enough.


If not I'll pay some one else when I am 80 something, or just let it rot.

 

[calmloki]

Figure we were about 2200 sqft of flat roof, including some garage space. Tear off, 1 sheet OSB, new stick down roll roof $11,000 here in SoCal. Better material than HD, but it would have been about $3000 in materials from them. That was about three weeks ago.

 

[pb4uski]

We spent $2300 for the metal, screws and trim, then around $250 for underlayment and foam pieces... no labor... (well beer and food for a bunch of friends). We got a quote from a company to do the roof in shingles for $12K. Our county adds tax value for a metal roof.
I'm 60 and love the idea I'll never have to deal with it again.

DIY vs purchased is apples and oranges and irrelevant so not helpful at all.

 

[pb4uski]

I'm 65 and figured asphalt roof is good enough.


If not I'll pay some one else when I am 80 something, or just let it rot.

+1

 

[Sunset]

OP - If you have rotten decking in a place or two, best to remove and replace a sheet for each spot.

A neighbor across the street, had his roof done, and somehow they talked him into removing ALL the decking and replacing it, when it was re-shingled. I looked via binoculars and there was simply no way that was needed.

I've done a few roofs myself, and will replace a sheet if it's "bouncy or soft" long before it shows deconstruction of the wood.

 

[ncbill]

We spent $2300 for the metal, screws and trim, then around $250 for underlayment and foam pieces... no labor... (well beer and food for a bunch of friends). We got a quote from a company to do the roof in shingles for $12K. Our county adds tax value for a metal roof.
I'm 60 and love the idea I'll never have to deal with it again.

exposed fasteners?

 

[old medic]

exposed fasteners?

Yes, the screws with the gaskets, color matched to the roof. Also got the side trim to keep the wind from getting under the edges.

 

[ncbill]

Yes, the screws with the gaskets, color matched to the roof. Also got the side trim to keep the wind from getting under the edges.

warranty on the gaskets?

 

[MC Rider]

Our last house was built in the 1950's and had NO decking plywood under 2 layers of comp shingles and the original wood shingles. Seems this was typical in the area and time. So the whole thing needed radiant barrier OSB on it. $$,$$$.

 

[lawman]

Our last house was built in the 1950's and had NO decking plywood under 2 layers of comp shingles and the original wood shingles. Seems this was typical in the area and time. So the whole thing needed radiant barrier OSB on it. $$,$$$.

Wow! That's nuts!