NO sheathing under wood shingles?


#1

hello everyone,
new here to the forum. after purchasing my first home 4 years ago, i’ve now come to grips with the idea that i do need a new roof. specs;

current roof - wood shingles (age - unknown). the shingles look pretty old and are slowly falling off my roof one by one.

size - i did some rough calculations and looks like its about 1700 sq ft (17 squares)

i recently bought some owens corning 30 yr oakridge shingles (got pretty good price $11/bundle).

now my question - when i go up to the attic, what i see are 4 inch wide by 1 inch thick slats. nailed on top of the slats are what looks to be the wood shingles. i.e, there doesn’t seem to be any wood sheathing between the attic and the wood shingles. is this normal? if i rip out the wood shingles and replace them with the OC shingles, i will have to buy new sheathing correct? haven’t checked on prices of sheating lately but from what i remember, they’re still ~$30 a sheet (4’x8’). thats gonna run me another $1500 for the sheathing.


#2

That is called “Skip Sheathing” or “Spaced Plank Board Decking”, which is the proper way to have installed Cedar Shingles.

Yes, you will have to overlay the roof with new plywood, or a cheaper, but less quality method would be to buy enought 1" x 2" firring strips and install them betweent the gaps in the Skip Sheathing, if they are equally sized gaps.

The 1" x 2"'s are more prone to cracking and splitting when they get nailed through them in the openings between the rafters though.

If you use new plywood as an overlay, you will also have to account for the perimeter edge Gutter Apron Drip Edge metal and the rake edge Overhanging Drip Edge Metal to cover the new exposed edge of the plywood or OSB sheathing.

Ed


#3

thanks ed. much appreciated. if i go with the plywood, the idea is i have to rip all the plank boards off correct? then nail the plywood directly onto the 4" x 1" slats?

thanks again!


#4

You can deck right over the existing skip sheathing.
Plywood is better if a good grade is chosen but osb will serve the purpose very well also.
IMO osb is better than** low grade** plywood.
3/8" sheeting is minimum but it is best to use 1/2" or better/thicker.

Your old roof breaths through the roof itself so to get the most out of your new roof you will need to make sure there is good ventilation.
This involves an intake at the soffits or lower edge of the roof and a ridge vent for exhaust.
There will need to be clear airflow from the lower roof to the ridge for this to work.
Ed is the ventilation man, and he explains it best.


#5

I would agree with Ed except that if you raise the rake trim you do not need to run that ugly metal up the rakes. With 3/8" CDX plymood overlay its not that much of a gap but its nice to account for the hight of the cedar breather on the rakes as well.


#6

[quote=“mjuevos”]thanks ed. much appreciated. if i go with the plywood, the idea is i have to rip all the plank boards off correct? then nail the plywood directly onto the 4" x 1" slats?

thanks again![/quote]

Incorrect. You are adding on unnecessary work for yourself for no advantage and actually decreasing the structural stability of the decking structure.

Follow as Axiom stated, and I too prefer 1/2" 4-ply CDX plywood sheathing versus 15/32 or 7/16 OSB board.

You will not be dealing with any “Cedar Breather” as suggested by RooferJ, but you WILL be raising the decking height by that new 1/2" CDX overlay, therefor a properly installed and aesthetically pleasing and functional Overhanging Drip Edge Metal will be required to conceal the exposed edge grain of either the plywood or the OSB decking.

Balanced Fresh Air Intake is VITAl to provide the proper flowage of Attic Exhaust.

If you need more information on the venting, please ask further. I am too tired to be long winded tonight. Long Day.

Ed


#7

ditto everyone.

just wanted to add.
if the roofs is steep.
for a few years in GA i removed theese old 3 layer
roofs by busting them out from inside the attic.
hitting inbetween the gaps with tear off spade, busting out the wood shake shingles,and everything on top of them.

then we just nailed on plywood over the
spaced 1x whatever. make shure nail goes through
1x and into rafter.

earned it at wilde roofin.
earned it indeed.

gweedo.


#8

thanks guys for all your help. obviously since im a newbie, all these terms are going right over my head. guess i have more readin’ to do. between the self help books and great info on the web (a la this site), hopefully i can get a good idea of what to do.

p.s. my roof is quite steep so thats kinda scary =)


#9

Their is a good pictorial step by step tutorial on a site, which I think is called, www.HammerZone.com for youir exact application.

Yes, here is the Step 1 tear-off article:
hammerzone.com/archives/roof … r_off2.htm

And here is the Step 2 Roofing article:
hammerzone.com/archives/roof … ingl2x.htm

Ed


#10

good grief batman. looks like a carpenter installed roof. Whats up with the step ladders and silly boards nailed all over the felt?


#11

The Hammer Zone, eh? lolz

Sounds like a gay bar…


#12

It had good pictures for the guy to see what he was getting himself into.

BTW, How did you know about the Gay Bar connection? Just Curious.

Ed


#13

very good info ed. you’re right the pics do help as do the rest of you guys on this forum. im sure i will be back many times to ask many questions.

thanks again guys!