I am having a metal roof put on a summer place in Maine. No winter usage. They will be removing the old roof, and then adding rigid foam insulation, 1x sleepers, plywood sheeting, paper, and then the raised seam metal roof.
This stack leaves a 3/4″ high slot over the insulation and below the plywood which runs from the eaves up to the peak.
A ridge vent (along with openings at the eaves) would allow this slot to breathe and I expect keep the roof a bit cooler in the summer. At $900 for the ridge vent, this is expensive.
Two questions:
1- Will venting just the slot give me significant cooling improvement to justify the cost? We are talking about summers in Maine, and not winter heating concerns.
2- Would you recommend cutting the ridge vent into the building? The underside of the roof is unfinished and open to the building (no ceilings). It has not had a ridge vent. A ridge vent would probably be great in the summer, but not so great in the late spring and early fall when it is heated with a wood stove. With the stack up of materials that I described above, are there any special details or issues that need to be taken care of?
Thanks for your thoughts.
Allen
Replies
So you have vaulted ceilings? You can see the metal from the inside when installed?
That wouldn't work here in the south I don't think, not sure about Maine. Driving rain would put the water in the living area, although they are not supposed to do this...... There is no way to properly heat and cool as you would have an opening at the ceiling for utilities to escape. IMO...........
What about flying insects?
I am not a roofer but this doesn't sound right to me.
“Some people wonder all their lives if they've made a difference. The Marines don't have that problem.”
Reagan....
Failure is the condiment that gives success its flavor.
-Truman Capote
From inside the building you see the rafters, and the underside of the roof deck boards. All of the insulation, strapping, plywood, and paper are between the roof deck boards and the metal roofing, so you do not see any of them.
Allen
PS All vents need to be screened for bugs.
Edited 4/15/2008 8:30 am ET by townsend
What exactly does the $900 get you? Your roof already needs a ridge cap. There may be a small difference between the type used for vented vs. unvented, but I'm that's not a $900 difference unless you have quite a bit of it.
The quote that I have for the metal roof is $7300 for the metal roof without a ridge vent. If I want a ridge vent it is $900 more (30 ft at $30/ft). I understand that forming and installing the ridge vent is much more labor intensive than the normal cap. I do not have much more to go on than this.
Allen
Seems a bit much to me.
Can you get another bid?
So this is metal that the roofers will bend for you in their shop, rather than premade stuff from a manufacturer? What are they using for a ridge cap if you don't go vented?
The major difference is installing some sort of screen between the seams vs. solid pieces and the potential for windblown rain/snow to enter with the screen. Ridge cap probably has to be a wider girth if venting is used. Sounds a little high, but it might be a high waste operation - lots of metal left on the table from each sheet to get the right width. Just guessing.http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
David,
I have had one roof put on by this roofer. On that one I did not go with a ridge vent. The man brought a machine in a trailer to the site and formed the metal there. I watched as the main panels went up, but not the cap. I expect you are right about waste and time.
I think venting into the building does not make much sense because of wanting to heat in the spring and fall. However, Does the cooling that comes from venting just the 3/4" space under the roof make a lot of difference in the summer?
Thanks,
Allen
I put a ridge vent on the copper roof I did, based on the CDA design. It never leaked, even with the rain coming nearly sideways in the wind.
-- J.S.
my ridge vent was $56
was that on a raised seam metal roof?
It never leaked, even with the rain coming nearly sideways in the wind.
Well, there's one that didn't. How tall are your seams? 1"? Most roll formed standing seam pans are 1 1/2" or taller. Makes a big difference.http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
Yup, 1" seams, with the top ends breadpanned to vertical. The vent cover is overall about 16 3/8" wide. The top edge of the breadpan is 3" horizontally and 2 1/4" vertically from the bottom hem of the cover. The roof is 7 in 12.
If all goes well, I'll be signing the paperwork to sell that place on Friday.
-- J.S.
If all goes well, I'll be signing the paperwork to sell that place on Friday.
Good Luck. You gonna start all over again?http://grantlogan.net/
But you all knew that. I detailed it extensively in my blog.
Not really. I've been working on an oak floor in my stepdaughter's room, and finally figuring out that maybe I'm too old to take on big projects any more.
-- J.S.
Your description sounds like what we call a 'cold roof'. There is no need for venting this type of structure at the ridge.
A few comments though:
- Why only 1x sleepers? Sounds a bit wimpy to me. I used 2x10, 24" OC, with Simpson clips.
- You should probably put down some Grace or other peel & stick over T&G decking. It serves as a vapour barrier and extra protection from water infiltration.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
Scott,
1x was recommended. 2x10 on 24" centers would be much more substantial. How did you arrive at that size?
We are using the peel and stick stuff selectively; ie in the valleys, along the drip edge, and under the chimney flashing to the eaves.
Thanks for your suggestions.
Allen
my ridge vent is just the standard cap over a two inch hole. no fancy wind flap. with just window screen under the cap. It took hurricane force rain with no leaks.
>>>1x was recommended. 2x10 on 24" centers would be much more substantial. How did you arrive at that size?It's what the engineer and I came up with. We never really considered 1X because of the "tippiness" and inability to hold fasteners.>>>We are using the peel and stick stuff selectively; ie in the valleys, along the drip edge, and under the chimney flashing to the eaves.So where is your vapor barrier? Seems to me that you'll inevitably have a condensation problem as moisture migrates to cold surfaces inside the roof.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
What is the size and pitch of your roof? Mine is roughly a 20'x30' building with 11/12 pitch roof.
The entire roof is covered with a the modern version of tar paper. But this is just a summer place, with occasional heating in the spring and fall.
I expect if we (or someone) want to winterize the place, we would add insulation under the roof and the vapor barrier would go between that insulation and the living space.
Allen
>>>What is the size and pitch of your roof? Mine is roughly a 20'x30' building with 11/12 pitch roof.Our house is a mixture of conventional rafter construction (mostly 10/12) with vaulted ceilings and the living room which has exposed 2" x 14" rough sawn fir rafters with pine T & G decking above, similar to your 'cold roof' construction.>>>The entire roof is covered with a the modern version of tar paper. But this is just a summer place, with occasional heating in the spring and fall.Right, sorry, I forgot that a vapor barrier may not be such a concern if you don't plan to heat in the Winter. However, for the miniscule cost, compared with retrofitting later, I'd give some serious consideration to putting it in now. Think about resale value. I'd guess you're looking at no more than a few hundred dollars of Grace.Scott.Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
If you are in a high wind area it might not be a good idea. Snow blows into just about every design. There are those with flaps that close tight to the windward side, but that seems like another point of failure not too many years down the road. In the winter it's especially suspect due to ice messing with the flaps.
I'd be very careful.
Beer was created so carpenters wouldn't rule the world.
Thanks,
It seems like the problems with this could be more than the benefits.
Allen