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Wednesday, January 19, 2011

More Questions about California Roofs


Thanks so much for responding. I still have one more roofing
contractor to assess my roof and give me an estimate. He suggested on
the phone that I should put on a roll roof and then shingle over that.
The logic is that the roll roof saves the cost for an underlayment
beneath the shingles and, while the net cost is more, it is a superior
roof providing better leak protection for a longer time.

Jon: Nonsense. I would have thought state licensing would have stopped this roll roofing advice. The lap on the roll roof will cause a bulge and if it occurs where the comp shingles are three thick, it could backfire. Plus felt is for emergency back up only and both would be full of nail holes. The asphalt stays tight against the nail shank since no sun degrades it but eventually, if water is running between the layers, the nails will rust to nothing and a slime mold will digest the roof. You might not contract respiratory illness before that guy goes out of business because I don’t think he understands, but your family will smell wet dog smell from between the layers..

I have never seen that spec.

The question about ventilation prompted me to visit my attic via my
pull down Fakro attic ladder in my hallway. The results:

Jon: Make sure the attic access has weather stripping and insulation.

1. My simple gable roof is about 3000 sf in approximately the shape of
a square which includes the garage. The roof over the garage has 2 X 8
rafters spaced 16" OC. The rest of the house has 2 X 8 rafters spaced
24" OC. I have a large 17 X 11 entrance to my house that the roof
extends over. In that area, I can look up and see the same shiplap
that is on my eaves. Above that is just the roofing planks and roofing
material. In effect, this creates an external, vaulted ceiling.

Jon: Without eaves you can use either GAF’sCobra® FasciaFlow Vent (Intake) or Airvent’s The Edge or Venting Metal Edge.Be careful with using the Edge because you lose slope there.

2. In the back half of the house, there are three rooms with SEALED
vaulted ceilings inter spaced with open attic. The master bedroom
vaulted ceiling is 12 X 15, starts at the eaves and extends 17' to the
master bedroom closet (the 3 feet deep closet extends across the
bedroom and has a standard 8 foot ceiling and the attic above is open
to the roof). The living room vaulted ceiling is 12 X 17, starts after
the bedroom closet, is approximately centered at the ridge of the roof
and extends over the ridge and down to the kitchen drop ceiling (the 9
feet wide drop down ceiling is about 7 feet high and the attic above
it is open to the roof). The family room vaulted ceiling starts at the
drop down kitchen ceiling and extends down to the eaves. The vaulted
ceilings are primed and painted drywall inside the house.

Jon: As long as you make roof for intake, because exhaust without intake is bad too, you can vent between each set of sealed rafters with either vent ridge, low profile vents place between , or even shared if you can meet the 300 Rule minimum attic vent requirements.

3. Again, all of the vaulted ceilings are sealed and the vaulted
ceiling in the living room is isolated from the eaves. I do not have
soffits and the eaves are closed off at the external wall of the
house. I can see external soft insulation filling areas between the
framing of the attic walls surrounding the vaulted ceiling, and wood
barriers extend between the rafters at the beginning and end of the
vaulted ceilings.

Jon: I’d tear off the deck and put furring 1x2 furring strips on the rafters, (cheap cheap cheap) and install radiant barrier decking. With the various intake options and exhaust options you can make the air flow and help your home be happy.

4. The open attic areas above the master bedroom closet and the drop
down kitchen areas flow into the remaining open attic at the front of
the house which includes the bedroom area hallway, two baths and two
additional bedrooms. This square feet of this area is about 25% larger
than the area of vaulted ceilings. I have installed 3/4" plywood in
the open attic over one bedroom at the front of the house, and across
the attic to the garage, for storage.

Jon: Close off all non functioning vents. If you get air moving over the top of the insulation this pit will be fine.

5. Venting: There are three passive dormer vents (two on one side of
the ridge and one on the other in the open attic areas) and one side
vent at the back of the house above the kitchen drop ceiling. There
is also a passive, open T-vent above the furnace (no connection to the
furnace). I can see all of the dormer vents and furnace T-vent
standing on the pull-down ladder and can crawl over the storage floor
to see the side vent at the back side of the house. I also have a T-
vent for one bathroom fan and a T-vent for the microwave hood fan but
these are fan driven exhausts.

Jon: If you have roof fixed exhaust you cannot have dormer or gable end vents. More holes can mean less venting. Read my blog on “Should a Roof Have Vents or Ventilation.” Also I have a very dry step by step E-How title “ How to Calculate your Attic Ventilation.”
6. With the exception of leaks caused by the solar panel screws I have
had no problem with the roof. In the summer, the attic does not get
extremely hot, even in hot weather. I have, on occasion, opened the
pull down ladder a foot or so on very hot days, thinking that it would
help keep the attic cool. But, in any case it has never been
inhospitable and we seldom get freezing or below temperatures. My 16
year-old cat likes to spend times in the attic most of the year
because it is warm.

What is your thoughts about the last roofing proposal using a combined
roll and shingle roof. It seems like two roofs to me but maybe it is a
superior roof?

Jon: Terrible

Do you think I should go to the trouble to ventilate the attic at the
vaulted ceilings? The middle, isolated vaulted ceiling does not extend
to the eaves creating an odd problem if I added ventilation. I also
came across this blog which suggests that sealed vaulted ceilings may
have been designed that way and do not need to be vented:

Jon: You must be losing a lot of cool air from the home to keep the attic comfortable. Your home was built in an era when men were men and they didn’t care as much about air conditioning or utility costs.

An improperly vented attic will shorten the roofs life, affect your health, and even leak sooner. The plank deck may have been helping to save you but with all these nails being pulled out and new ones being put in, you can expect surprises. Sometimes the boards break months after the roof was put on. Look for knot holes and severe grain swerving near the edge of a plank. These are fracture points.

Anyway, you are spending some money so make sure you do it wisely and spend enough to get it done right.

One last item. I like 4" exposure three tabs. Instead of a 2" headlap you get four as only 1/3 of the shingle is exposed. With two ply felt, a good professional starter shingle, and not a three tab turned around upside down and backwards, you have a lot of coverage. The manufacturers don't like because of wind but they allow stapling and power nailing. I do not. I like a roofing hachet because it will drive a roof nail flush only and not overdrive it. It is hard on plank decks sometimes though.

Hope you are feeling better - keep up the education columns, I find
this type of information very useful

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