Re-roofing advice...not your average job

[hippikes]

I'm hoping I've come to the right place for some expert advice! We need to put a new roof on our old house, but it is turning out to be quite a education process in trying to figure out what the 'right' thing to do is in our situation. (I'm your average homeowner who is learning about roofing via the internet & by talking to a boat load of contractors!)

Here is the back story:
House is a 2 1/2 story cape. Built 1826. Has ell addition on back that dates to about same time. Current roof is 16 years old. Roof is leaking in valley area & shingles are coming off in wind storms or when roof raking during the winter.

Roof deck is original wide pine with large gaps. Rafters are spaced randomly...well, maybe average 24" apart. Rafters vary in thickness, but about 4" deep. Shingles are in reasonably good shape, but installation was sub par. (Previous owner installation of course!) No ridge vents!

So we have 3 separate roof architectures (from low to high) knee wall, then 5' section of vaulted ceiling in our upstairs bedrooms, then an unheated attic space.

Our biggest problem? ICE DAMS at the eves..all around the house from heat loss.

There is currently some batten insulation in the knee walls, but it has gotten wet & broken down over the years. No insulation in the vaulted section - just the plaster, airspace & roof deck. The attic floor is tongue & groove board that we think has pink insulation underneath.

Here is a photo of the house so you can get an idea of what we are dealing with
http://www.flickr.com/photos/59009466@N00/3864410245/

I've also been told that roofs need to be ventilated. We have no soffits, nor the ability to put them in the knee wall section due to the construction style. Our 3 sections are not joined for proper ventilation. No ridge vents either, only 2 gable windows & an attic fan.

I've been given conflicting advice on how to best handle a situation like this. A 'hot' roof vs. a ventilated roof.

1. Hot: Use closed cell spray foam on the backside of the original roof deck for 2/3 of the roof. (Knee wall & vaulted sections.) So we would have the following layers: 4"-5" closed cell, original roof deck, new plywood, felt & IWC, then new shingles & ridge vents. Attic portion could either have spray foam on roof backside, or 2nd layer of un-backed roll insulation on the attic floor for about the same r-value. (There is a 4K difference between those two choices!)

2. Ventilated: Elevate the roof deck from the outside, so you have now created an airspace from soffits to peak. So we would have the following layers: 4"-5"closed cell foam, original roof deck, 2 1/2" strap spacers, new plywood, hix vent, felt & IWC, then new shingles & ridge vents. Attic portion could either have spray foam on roof deck backside, or 2nd layer of un-backed roll insulation on the attic floor.

Now the price difference between options 1 & 2 is about 12K! (Not including the foam vs batten option for the attic!) That is a lot of $ to us when we also have a 63x36 antique barn to re-roof as well. Going with option #1 would pay for the barn re-roofing.

I've been advised by several people not to do the hot roof scenario on this old house. It is considered new technology, expensive, not easily reversible, water damage is harder to identify, shortens your shingle lifespan. But I've also heard it is great...it is a vapor barrier, about R7 per inch, does NOT shorten shingle life by any significant amount, adds to roof rigidity & would just about eliminate the chance for ice dams because it seals up every nook & cranny.

What do you all think? I'm all for option #2...better safe than sorry, but I'm wondering if it overkill? And it is double the cost. $ is a factor here, but I don't want to make decisions solely on cost. Has anyone had any similar experiences?

Thanks for taking the time to read this!

[cs]

A tough choice, and I don't have an opinion either way... but I do think some of the "cons" you list for Option #1 are straw dogs. Here's why:

"New Technology" The only thing that's "new technology" about option #1 is the use of closed cell spray foam (and even that has been used for a while). Houses have been built with "hot" roofs for a long time. My house, for example, is 1925 vintage and the roof was insulated at the time with rock wool - no ridge vents, no airspace under the deck.

"Will shorten shingle life span" When we bought the house, 14 years ago, we put a new roof on (the old one had last been done about 30 years previously), and it's holding up just fine. I suspect that the commonly heard "shortens your shingle lifespan" is more opinion than fact, or the shortening is slight and insignificant.

"water damage harder to identify" Well.. the underside of the deck is covered, with either option, right? why would this be any harder to identify?

"expensive" It sounds like option #1 is the cheaper of the two, and would allow you to do needed roof repair on your antique barn as well. Making everything weather tight will pay the most dividends in the long run, IMO.

Again, I don't think either option is wrong, but I would not discount option #1. Just some thoughts.

Chris
http://www.saracenihouse.com

[mr Henry]

I live in the "Snow Belt", along the Southern shore of Lake Ontario. We average nearly 10' of snow here each year... I've also been roofing houses for over 30 years, full time, as a sole source of income. Closed cell foam insulation is a relatively new option and I've only seen two so far. Both homeowners swear by it. I'll throw in my two cents here for what it's worth
Until you fully understand the issues of moisture and condensation, where, why and how they occur, the differences between air and vapor barriers and all the implications associated within the installation a high tech. product, that's basically still in it's infancy and for the most part irreversible, within an 1816 structure, you need to really research this one. My biggest concerns would be the collection of condensation or moisture in other un-visable areas as a result of it's installation that could lead to serious problems down the road and any alteration or modification to the exterior of the structure....

[shazapple]

Hi Hippikes, as mentioned over on the Roofing forum (I get around the internet!) #2 is the best option (it would certainly be the 'cadillac' of roofs). Alternatively, you could ignore the spray foam part, and lay down 3-4" rigid insulation, then the furring strips, new plywood, roof. This is probably cheaper due to less labour, but will make your roof look 'thicker' at the gable ends. $12k difference is ridiculous though, I would shop around...

Shingles losing life span due to poor ventilation is not opinion. You can easily see examples of this on many older buildings, and on late 80's building where the designers thought technology has progressed so much we could ignore the fundamentals.

[Don M]

You have a nice steeply pitched roof. When you install the new roof be sure the installer uses the EDPM? rubber underlayment at the roof edge under the shingles which should eliminate the water back-up & leakage from ice dams. I would be inclined to add insulation under your attic floor if possible & not bother with insulating the roof unless you are planning to make the attic area living space. My 1830 vintage stone farm house has a standing seam roof probably installed around 1900 over the original cedar wood shingles. The attic has insulation under the attic floor, nothing on the roof, 4 gable windows with vents for the summer & a whole house fan. I had the metal roof scraped & painted 8-9 years ago & that's all I've had done. Our 56 x 76 bank barn has the same roof as the house & I've also had it scraped & painted. I love your barn, it's a dandy; lots of windows!

[shazapple]

You are thinking of ice and water shield, which is made of 1m wide rolls of 'modified bitumen' (aka an asphalt based product). EPDM is Ethylene Propylene Diene Monomer (aka rubber). It tends to shrink and does not handle punctures well so would not be a good underlayment.

the ice and water shield should start at the edge of the eave and go 1m up the roof beyond the walls of the house. The rest can be covered in standard roofing felt.

[Don M]

That's right thanks for filling in the correct term!

[hippikes]

I’d thought I’d give you all a little update on our re-roofing project that I had asked for advice on earlier this year. Thank you all for the wonderful advice!

We were told this project would take only 2 weeks, but it ended up taking 7! But that is a whole other story. (Darn contractors!)

Anyway, we took the advice of most everyone here, and spent the extra $ to make sure the roof was properly ventilated and better insulated. That entailed using spray foam & putting on a ventilated panel over the existing roof sheathing called cool vent.

http://www.hpanels.com/index.php?option ... &Itemid=56

I know a lot of folks do not approve of the spray foam, and I initially did not either, but in our application it seemed to make the most sense. Since the roof was coming off anyway, we had them remove the original roof sheathing in the areas that had plaster on the other side. They spray foamed from the outside of the house. In those areas, getting insulation in there would have normally required the plaster to be removed from the vaulted bedroom walls. Huge, messy job for sure!

The insulation contractor then went inside the kneeawall, removed the mix of blown & batten insulation and buttered the roof sheathing with foam. This joined the section of foam done from outside & above, making a seal all the way down to the 1st floor plate. This foam provides the vapor barrier and an average of R25. Combine that with the insulated/ventilated board of R6 on the opposite side of the original sheathing, we now have an R30 from the 1st floor joists all the way up to the attic floor. (This is all hidden from view unless you open the access door to the knee wall.)

We did discover the attic floor has previous pink insulation installed between the bedroom ceiling plaster and the tongue & groove attic flooring. We decided to leave that alone and just lay another layer of batten unfaced insulation on top of the attic floor. Ideally we would like to add the spray foam under the attic floor boards instead of the underside of the rafters. It would preserve the most visible & beautiful part of the roof structure while allowing us to use the attic for unheated storage. But that is another project!

The nice part about insulating the knee wall space is now it is conditioned space, so we can use it to run venting for a future heating system upgrade. I really didn’t want to foam the beautiful boards, but our ice dams were so bad, that it was the best solution. In consolation, at least ¾ of the roof sheathing is still unharmed, as they had to remove them before spraying & put them back afterwards.

So far we already notice a difference in how often the furnace runs and the upstairs is much warmer. The roof is a touch louder when it rains because it is metal, but the foam & vented panels help off-set it. The eves were tricky, but the roofer was able to use hix vent and ridge vent, so now for the first time in its life, the roof can breathe from eve to ridge.

Overall we think it came out pretty good. Steel wasn’t my first choice (wood shingles were 1st, but way too expensive!) but it will outlive us with minimal maintenance. And the snow just slides right off!

[hippikes]

And the finished photos!

[shazapple]

That is very nice. I am glad you had it done properly. That roof will outlast you!