wink

we just a quired a 1885 farm house in rhode island, still pretty good structurally, my question to you roofers is can i go over three tab shingles to do cedar shingles? or do i have to tear them off? i am ging to put a material down for the cedar to breath or dry out, forgat what it's called at the moment, you can tell i'm a real roofer, there is only one layer of shingles on the roof at this time, and someone has redecked it with plywood at one point, it is visible in the attack, the problem is that there is no ventilation system at all, in my area wood roofs are common. i know that if i do have to do a tear off that i would cover the entire deck with ice and water shield before i put down the cedar. but if i can leave the 3 tabs on i think i could skip this step and save a little cash both on the ice and water and the dump fee for the old shingles, thanks ahead for your help

RooferJim

you should strip it. a cedar roof will absorb more than double its weight in water. going over is always a half ass job.

Rooferjim
www.jbennetteroofing.com

Ed the Roofer

The most well known complete under the cedar product is called "Cedar Breather" by Benjamin Opdyke company, who also manufactures roll vent for ridge ventialtion.

The quick answer is yes you can, but..............................................

The breathability of the product is the only thing that allows cedar to remain a 50 year product. At least you are thinking in the right direction to consider the underneath air flowage.

I would not advise going over the asphalt shingle due to the heat sump that will be created in the inner space cavity. I have never used the cedar breather product, just bid it on several jobs and to do an entire structure with it, may be very very expensive. It also would allow the height of the product to be visible along the rake/gable edges. So, a j-channel reroof edge metal needs to be bent up for the correct distance to shield the side edges from weather infiltration. Significantly longer nails or staples must be used to fasten down to the decking with the additional height of the cedar breather product, whick may start to loosen up with time as in a toggle effect from expansion and contraction of the product when it swells from moisture absorbtion.

The 100 % Ice and Water shield ideas, although seemingly a good idea, has condensation factors to consider as well. The decking now has no permeability to transfer the moisture and humidity.

Also, cedar is extremely slippery when even the slightest bit wet, so be extremely cautious and use proper safe guards for fall protection including 2" x 6" toe boards on roof hook brackets and a fall prevention safety rope system.

Ask more questions about specific details if you need to.

Ed

red_cedar

I dont understand why one would want to ice and water an entire roof.
But many of those in my industry seem to think that is normal.

I started cedar shingling back in the late 70's doing wood shingles with no felt on spaced sheating. We were taught to gauge the material with our hatchets rather then nailing a board in to keep shingles straight. I havent met that many people that could gauge the shingles though.

In answer to the question, I believe one could fasten 1x4's or 1x3's or 2's in the old roof every 5 (five) inches. Nail the shingle with 3d nails.
If you pay attention to your nailing pattern and alternate the joints every 3 courses you should have a pretty good roof.
As mentioned you will need drip edging to cover up what you are going over.

Grumpy

TEAR OFF THE ROOF. Sorry for the caps but TEAR OFF THE EXISTING ROOF.

I've found that when placing cedar over an asphalt product they last maximum 15 years. I speculate that this is due to the heat which the asphlat retains and thus the wood/cedar loses it's natural tanins/oils much quicker than normal.

You are going to pay a ton of money for cedar, do it right, or pay twice.

__________________
-Grumpy
Chicago Gutters Chicago Roofing

wink

thanks everyone, it seems the old roof will go. it was mentioned not to ice and water the intire roof. would you ice and water up a couple of rows and then use roofing paper?

red_cedar

yes apply the ice and water in areas of potential ice build up, like along the gutter.
Most cedar roofs realy are not applied all that well, that has a direct bearing on how well the roof will last.
I dont realy think cedar shingles last that long anyway. 20 yrs maybe.
They do not make shingles like they use to.

What I would do, is, teat off the old roof. Use a cedar product called tapersawns. They are a sawn type of material, thicker then a shingle but not as smooth. They go on more like a shake then a shingle. Gives a look of a thicker shingle roof. You could even reduce the exposure of the tapersawn to give a more ply roof.

These days when I do a cedar roof which is once every few years. I sell the jobs, saying, thicker will last longer.
I do them now to enjoy the material and roof, not to slap them up there. We make money though, just not selling the jobs just to do them.
We have a 1 1/2 inch handsplit roof we will be doing in June . Should be a nice looking roof.

RooferJim

Ice & water on the whole roof has become quite common here. It is OK if you have good ventilatiom.
We install a lot of cedar roofs both Red and Alaskan Yellow cedar. Tapersawns are also what we recommend but are a lot more money at 7 bundles per square. We would only install them at no greater exposure that 5.5, thus a 3ply roof. treating a roof with a treatment most often does more harm than good.

RooferJim
www.jbennetteroofing.com

wink

thanks everyone, will let you know how it works out as soon as we get done.

PlainPainter

Is there a different grade of cedar roofing shingles than the cedar shakes ( western red cedar R&R's) that I install on siding? It seems they wouldn't be beefy enough for roofing. I have seen some guys double up each row when installing cedar shakes on homes, especially when the distance between rows is much greater than the typical 6". I have seen a new install recently of those 'torn' cedar shakes that are really thick and randomly shaped - didn't know they still existed, would they work for roofing - or are they too randomly shaped for this application?

-plainpainter

p.s. how does one do cedar and slate style roofings anyways? Seems like you can't put up roof brackets like you can on asphalt style roofings. Do you guys just walk these roofs 'freestyle' without any staging?

Mr. D

no freestyle roofing for me on slopes greater than a 7/12. i shaked a 70 square roof 2 winters ago at 4" reveals. lots of fun.

wink

i believe that you leave the shingles out till you remove your brackets then put them in

Same Old

what do you guys use to nail off your cedar shingles? I've always done them by hand, but I've never done all that much. I came across a project yesterday that had them narrow crown stapled. That didn't sound right to me.

red_cedar

We have always done them by hand. With the right tools and training it can be quite productive. But costly never the less.

In regard to the roofing brackets with the cedar shingles. There are several ways to address this. but the one that works best for us, is slating brackets not nailed into the rafters.

Mr. D

i use a hitachi coil nailer that shoots siding nails. i like it.makes for easier shake replacement down the road. if you've ever done tear off or repair with stapled down shakes you will enjoy nails.

3wheeler2004

I just did a 80sq roof for $75000 and some people said it was high some say it was low. this was a total demo and redu what should i charge per square next time? there was a 71/2 reveal.

Mill23

I'm doing a re-roof that has 3 layers of existing asphalt shingles over top of 1 layer of old cedar shake shingles. I tore off all of the asphalt shingles already and I will be doing a full re-deck of OSB. My question is can I put the new OSB sheathing over top of cedar shake shingles or do I have to tear them off and waste the time and money?

thom

You can do what you want but will not get a flat roof. You can overlay then cover the edges with flashing. It's a cheap and crappy way to do it though.

When you do the tear off you may find "skip sheathing" which means you will skin the roof with the osb anyway.

Check with the local building department to insure this does not violate any of their codes. Also do a load calculation to insure you aren't overloading the rafters.

RooferJim

putting OSB over any old roofing cedar or otherwise is a real hack way of doing things and might get you in hot water with the building inspector. Why not do things right ?

J-Peffer

Couldn't the I&W retain almost as much heat as the shingles do?