Questions on adding a gable roof...


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Old 04-11-06, 08:28 PM
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Question Questions on adding a gable roof...

OK after lots of changes we are going to add an 8' x 10' extension perpendicular to the side of our existing gable roofed house. The new extension will also have a simple gable roof. The house is a one story ranch.

#1 The roof will span the 10' distance but does not need to match up to the existing peak, nor is there a need for a usable attic. Is there a recommended pitch for this size?

#2 The existing roof area has 2 layers of asphalt shingles. The original is from 1967 and the 2nd from 1991. We can still get the 2nd shingles. What is the best way to join the new roofing to the old where the gables meet to avoid water penetration? Does a membrane need to go under the original layer and onto the new gable over a tar paper layer? Are there ways of weaving the shingles? I'm at a bit of a loss with this and can't find too much info, so all input is appreciated....

Thanks guys!
 
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Old 04-11-06, 08:55 PM
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syakoban,

Recommended pitch is nothing less than 3/12 for use of shingles. The pitch will be determined by the look you want to achieve. You could match soffit lines and adjust your pitch accordingly or not.

I am assuming you are wanting to do this,

http://dougaphs.smugmug.com/gallery/730808

Depending on your current shingle condition and the fact that you have 2 layers on now, it would be best to tear off and replace all, IMHO.

In replacing all, the use of Ice and Water Shield up 36 inches from exterior walls along with 15# felt thereafter will do the job nicely.

Hope this helps!
 
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Old 04-12-06, 09:18 AM
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Your link does show what we want to do.

The existing visible roof is in good condition w/no issues. It has 50 yr. rated shingles (whatever that really means???). 8-10 more years is good enough for us.

The house is an L shaped ranch with a large cross gabled roof area. If we had to do a complete tear off to add this extension it would end the extension.

Of course we can't create a water penetration situation just to have an addition, but there must be a way to keep the existing roof intact and blend the new roof addition into it without leaks.

Any ideas guys???
 
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Old 04-12-06, 10:44 AM
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syakoban,

Additions are put on everyday so your's is no different.

Process is to cut existing shingles at the valley's in which to allow for I & W Shield and or 30# felt with metal valley tin then shingle as required.

Shingles can be weaved into the old but with 2 layers of shingles, it may not look appealing but this is determined by existing conditions.

Hope this helps!
 
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Old 04-12-06, 11:28 AM
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Thanks for the help Doug! Believe it or not, I have done complete new roofs, but not mods. or repairs, so this part is new to me.

A few more questions though:

Is "I & W Shield" (insect & water?) what I call rubber membrane?

Are you saying to go over the existing double layer side with the I & W Shield and metal valley or work it under the bottom layer and then weave?

The part about not looking appealing - is that because the corner won'ty be sharp but sort of rounded?

Thanks again.
 
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Old 04-12-06, 12:14 PM
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syakoban,

Ice and Water shield is the self adhesive rubber membrame.

The issue of having 2 layers of shingles on and then trying to install ice and water shield under those can be a nightmare. Dealing with one layer is acheivable and easy (usually). With what you mentioned this may be a harder application.

I want to bring up one point. In laying a new tie in onto the existing roof, you can leave shingles in place, including those under the new valley boards and by installing the new roof sheathing, you "could" remove the first layer existing shingles and then go over this with valley tin. You must, however, cut a ventilation hole in the old roof so air passes between existing attic space and the new attic space of addition.

This is not my first choice but is allowable as I would prefer to see this directly over the I & W. As you can see, placing the Ice and Water Shield directly to the existing roof sheathing would be better. Then ensures no problems. The application of weaving the shingles at the valley can then be done.

The key is to avoid any height deviations between new roof and old roof - as you are aware, placing new shingles over an existing will reduce the life span of the new.

Does this help?
 
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Old 04-12-06, 01:08 PM
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Originally Posted by Doug Aleshire
you "could" remove the first layer existing shingles and then go over this with valley tin
I'm not sure I get this part. When you say first layer, do you mean the original shingles under the visible layer? If so, how do you "go over with valley tin" when it's under the top layer?

Thank you again!
 
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Old 04-12-06, 01:18 PM
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syakoban,

It would be the top layer of shingles. The issue is to remove some nails from shingles to insert the metal valley - not fun.

This is why I suggest getting the tin to rest directly on the I & W shield or #30 felt, which should be directly on the roof sheathing, not shingles. You want minimal variations under the tin.

Others may suggest different ways but this is how I would do it.
 
 

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