Using Felt with Cedar Shakes

Dale Chomechko · 04-29-2009, 11:08 AM

Quote:

Originally Posted by freddmc

On another thread in the contractors forum there was a discussion about using felt with cedar shakes. Some felt it may not been necessary.

In my case I am re-roofing my roof with a 4/12 pitch. It has 20 year old 24 inch cedar shakes(split on one side and sawn on the other) The underlay is not solid sheeting but rather is spaced sheeting. On top of the sheeting is felt paper (with about 6 inch overlap).

I will be tearing off the old shakes and will be applying 18 inch hand split shakes(split on both sides). I realize I will have to put in some extra sheeting where the nailing for the shakes does not line up.

My question is about the use of felt. So the question is "is felt necessary at all?". Some say that the felt is REALLY for water protection, others say it is for wood movement and some even say don't use any felt at all so the shakes can breath and dry out properly.

And the last question is do the same rules apply to shakes that are split on one side and tapersawn on the other?

Thanks

Fred McNeill

Hi Fred
Felt was originally used for blowing snow(would fill up attics)
All shakes used to be triple layered & cedar shingles still are.
In this case felt is not required.
Most shakes are now double layered & any double cracks would become a potential leak without felt.
If you are willing to spend the extra money to install 3 layers it makes for a real good installation, but the cost for felt would be fraction of the cost for the extra shakes.
I have not seen any substantial difference in shakes felted or not, layed on strapping or plywood.
The biggest difference is in the quality of the product -for cracking & splitting-blowing holes through spaces at thin points-curling. The mills that are certified actually do make the best material.
CCA pressure treatment is the best thing you can do for the least amount of money. I walk on 500 roofs a year & have yet to see one rot.
Dale Chomechko
DC Roofing Inc

webbyonweb · 04-29-2009, 11:40 AM

Thanks Dale, why the interlayment. Can you not just cover the deck with it and layer the shakes without cutting into strips ? Some people still just using strapping alone with no paper, that's why I ask.

thanks again for the reply.

Eric

Dale Chomechko · 04-29-2009, 11:48 AM

Quote:

Originally Posted by johnk

Felt,felt,felt as Ed says.Shakes arent the same as they were 50 yrs ago for one and why not have the extra protection and its code where I come from

A 400 year old tree 50 years ago is now a 450 year old tree.
Problem is that 50 years ago they wasted half the tree because they thought there was an endless supply
Now they have more grades & more products & bad manufacturers will get the lower grades into the higher end bundles.(worth almost twice as much money)
Don't blame the tree!!!!!!
Dale Chomechko
DC Roofing Inc

**Ed the Roofer** · 04-29-2009, 02:15 PM

A solid layer of felt paper under the cedar prevents the interior attic air from breathing through the cedar, which keeps allowing them to dry, which prevents them from rotting, curling or cracking so quickly.

Ed

Dale Chomechko · 04-29-2009, 11:17 PM

Quote:

Originally Posted by Ed the Roofer

I would be extremely cautious, and make sure I use the felt shake liner, especially in view of the low pitch.

Shakes on a 4/12 pitch st as long as on a steeper pitch, especially if you are in a snow region, where it will soak up moisture and start to bow, and split. Cedar shingles, since they are applied in a 3-ply coursing, which is standard, will probably last longer, but thet too wil start to bow from retaining moisture prematurely.

Ed

I agree with Ed on the 4/12 issue, especially if your using something thicker than a cedar shingle. The roof pitch starts to get more shallow with a heavier shake.
Curling however is only a problem with sawn shakes & shingles, it is never a problem with split shakes. I have seen split shakes many times on plywood & solid shiplap last 20-25 years unteated with no curling.
The reason- because sawn material cuts through the grain, if that grain is curved from coming up to a knot in the tree, the shake curls.
In a split shake this does not happen because the grain is continuous from top to bottom. If a split shake is curved on a roof it is more likely thats the way it was when installed. Keep in mind that this may not hold true in Saskatchewan or the US midwest where shakes have been on the roof for 50+ years

Dale Chomechko · 04-29-2009, 11:29 PM

Quote:

Originally Posted by webbyonweb

Thanks Dale, why the interlayment. Can you not just cover the deck with it and layer the shakes without cutting into strips ? Some people still just using strapping alone with no paper, that's why I ask.

thanks again for the reply.

Eric

Hi Eric
The problem is that if a shake developes a crack & it is above or below a space between two shakes water can get underneath. once it gets underneath every nail hole becomes a potential leak.
This scenario does not happen with asphalt shingles because they do not crack(or are not supposed to0
Here is an example of a roof where the installer "cheated"
30 lb fet on the first 3 ft
roofer didn't start interlaying his felt until the top of the 30lb felt (34" up)
all the leaks were at the walls on the eaves
This is a real case example of a complex(39 units) 12 years old that cost $20,000 to shim the first 3 ft only
This did stop the leaks

**Ed the Roofer** · 04-30-2009, 12:26 AM

Quote:

Originally Posted by Dale Chomechko

I agree with Ed on the 4/12 issue, especially if your using something thicker than a cedar shingle. The roof pitch starts to get more shallow with a heavier shake.
Curling however is only a problem with sawn shakes & shingles, it is never a problem with split shakes. I have seen split shakes many times on plywood & solid shiplap last 20-25 years unteated with no curling.
The reason- because sawn material cuts through the grain, if that grain is curved from coming up to a knot in the tree, the shake curls.
In a split shake this does not happen because the grain is continuous from top to bottom. If a split shake is curved on a roof it is more likely thats the way it was when installed. Keep in mind that this may not hold true in Saskatchewan or the US midwest where shakes have been on the roof for 50+ years

It is so common here in the Chicago area to see Hand Split Cedar Shakes, typically mediums, but also some Heavies, to bow like a bannana.

These are commonly installed on steeper pitched McMansions in many presigious communities.

They do bow, significantly, which is primarily due to not having a breater area on the underside of the shakes.

Ed

judith rausch · 06-09-2009, 08:03 AM

How should my roofer have installed the cedar shingles? We had a garden house and covered swing house built and both roofs have rotted decking now from massive leaks through the cedar shingles. 5 Years old. We have to replace the roofs now and do not want to give up the cedar shingles. All roofing bidders we have gotten say cedar shingles always leak and we should not replace the cedar but use regular roofing materials.

Please advise what you think. Walking on 500 roofs and none leaking is impressive. What is the method roofers need to use to acoomplish this?

Dale Chomechko · 06-09-2009, 11:44 AM

Hi Judith
There are different grades of cedar shingles #2s, #3s & #4s all are allowed to have knot holes in them to varying degrees. If your roofer has installed one of these products without felt (which is ok with #1 & #2 shingles) or at the wrong exposure(5 1/2" for a #1 & 4 1/2" for a #2) then your going to have leaks.
#3 & #4 shingles are not even allowed on a residence in my area.
Shingles are a good product but have to be properly installed & you want to buy good product.
You could put a cheap product on a garden house but would need to rely on an underlayment layered between the shingles to make it watertight
Dale Chomechko
DC Roofing Inc

judith rausch · 06-10-2009, 12:39 PM

Thanks Dale. Most helpful. Also I read online that stainless steel nails should be used or coated galvanized but not the electroplated. What would be your advice about that?

BTW felt was not used and the weight of shingles is thin from our view, we have no info from the installer from 5 years ago. He hung up on us.

**Ed the Roofer** · 06-10-2009, 09:37 PM

I guess those wannabe roofers do not know how to install Cedar correctly.

Do you have any photos to see if they did anything wrong, from the areas that it is leaking the most?

Ed

judith rausch · 06-12-2009, 08:19 AM

Thanks Ed. Thank you for your reply. I found one cedar shingle literate roofer in my area and he will (at great expense) replace the roof. Correctly. Buyer beware. We have to find out and know the correct way to do things these days just to look after our contractors!!

RidgeWalker · 06-16-2009, 12:37 PM

No one bothered to give the details in the IRC.

The code book says underlayment is required. And there is specific instructiones based on slope and the average daily temprature in January.

Additionally if where you live the average daily temperature in January is 25 degrees or less, solid sheathing is required on that portion of the roof requiring ice barrier.

Every one has an opinion, some good some not so good. The code books opinion is what really matters, wether the roof gets inspected by a city official or not.

Good luck!

Dale Chomechko · 06-18-2009, 09:55 AM

Quote:

Originally Posted by judith rausch

Thanks Dale. Most helpful. Also I read online that stainless steel nails should be used or coated galvanized but not the electroplated. What would be your advice about that?

BTW felt was not used and the weight of shingles is thin from our view, we have no info from the installer from 5 years ago. He hung up on us.

You can use stainles nails but they are expensive, hot dipped galvanized nails are prefered.
The electro galvanized nails (staples are EG on ridgecaps) rust apart in the cedar within about 10 years, they are only used as a temporary measure to hold ridgecaps together until the can be properly nailed to the roof. The new pressure treated lumber needs stainles but cedar roofing products do not as they are still using the old CCA pressure treatment
Dale Chomechko
DC Roofing Inc

PDB · 10-20-2009, 01:15 AM

Hi Dale,

I am doing a cedar shake roof on 6 inch center strapping with 18 inch shakes -hand split resawn. Where does the felt come down to if looking from the top of the shake?

What would be your felt of choice?

My roof is 4/12 and I am located on the wet coast.

Cheers

Picolo

04-29-2009, 11:40 AM	#17
webbyonweb Newbie Join Date: Apr 2009 Posts: 2	Using Felt with Cedar Shakes Thanks Dale, why the interlayment. Can you not just cover the deck with it and layer the shakes without cutting into strips ? Some people still just using strapping alone with no paper, that's why I ask. thanks again for the reply. Eric

04-29-2009, 02:15 PM	#19
Ed the Roofer Super Moderator Join Date: Jan 2007 Posts: 2,384	Using Felt with Cedar Shakes A solid layer of felt paper under the cedar prevents the interior attic air from breathing through the cedar, which keeps allowing them to dry, which prevents them from rotting, curling or cracking so quickly. Ed __________________ Stay Tuned For Our New Informative And Helpful Web Site, Coming Soon To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

06-09-2009, 08:03 AM	#23
judith rausch Newbie Join Date: Jun 2009 Posts: 3	Using Felt with Cedar Shakes How should my roofer have installed the cedar shingles? We had a garden house and covered swing house built and both roofs have rotted decking now from massive leaks through the cedar shingles. 5 Years old. We have to replace the roofs now and do not want to give up the cedar shingles. All roofing bidders we have gotten say cedar shingles always leak and we should not replace the cedar but use regular roofing materials. Please advise what you think. Walking on 500 roofs and none leaking is impressive. What is the method roofers need to use to acoomplish this?

06-09-2009, 11:44 AM	#24
Dale Chomechko Member Join Date: Mar 2008 Posts: 94	Using Felt with Cedar Shakes Hi Judith There are different grades of cedar shingles #2s, #3s & #4s all are allowed to have knot holes in them to varying degrees. If your roofer has installed one of these products without felt (which is ok with #1 & #2 shingles) or at the wrong exposure(5 1/2" for a #1 & 4 1/2" for a #2) then your going to have leaks. #3 & #4 shingles are not even allowed on a residence in my area. Shingles are a good product but have to be properly installed & you want to buy good product. You could put a cheap product on a garden house but would need to rely on an underlayment layered between the shingles to make it watertight Dale Chomechko DC Roofing Inc

06-10-2009, 12:39 PM	#25
judith rausch Newbie Join Date: Jun 2009 Posts: 3	Using Felt with Cedar Shakes Thanks Dale. Most helpful. Also I read online that stainless steel nails should be used or coated galvanized but not the electroplated. What would be your advice about that? BTW felt was not used and the weight of shingles is thin from our view, we have no info from the installer from 5 years ago. He hung up on us.

Using Felt with Cedar Shakes