Code for gap between siding and roof.

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Old 09-17-18, 08:58 AM
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Code for gap between siding and roof.

Can someone tell if there is a building code that discusses the height of the gap between wall siding above an adjacent roof and the shingles and where to find it if it exists?

I'm in a townhouse. My roof ends at the neighboring wall. There is wood siding (4ft x 8ft sheets) on the neighboring wall that ends about 1.5 inches above my roof. Over the wood siding is vertical vinyl siding that touches my shingles. There is also some metal flashing that was caulked to my roof. I now need to put new shingles on my roof, I think this siding sitting on my roof will complicate the job. I'm wondering what the code is for this type of situation so I will know how to come into compliance.

Thanks.
 
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Old 09-17-18, 11:21 AM
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There is no such "code" but certain siding manufacturers will recommend a certain amount of clearance for their siding products.
 
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Old 09-17-18, 11:50 AM
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Like XSleeper said, I have never seen a code so the manufacturer's guidelines for each product are about all you have. The problem comes with your situation with multiple products coming together in one spot.

I personally do not like to see siding come down and touch the shingles. I prefer to have the siding and any trim up an inch or two off the singles so the shingles can be worked on without having to remove the siding. If the job is done properly with flashing there should be no caulking.
 
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Old 09-17-18, 02:27 PM
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Thank you both for your answers.

I was hoping there would be a code that gives a minimum height, I couldn't find it but I'm not known for my ability to find things. If two knowledgeable people have not seen a code for this then it probably doesn’t exist.

I've read in multiple places 1.5 or 2 inches is a good height but haven't found that in any authoritative document. Inspectapedia has a vinyl siding guide that said the siding should stop 1/2 inch minimum distance above the shingles to prevent damage to the siding.

My main concern is that the roofers will not be able to do a good job installing the roof with the siding so low. They would like to install a waterproof membrane along all edges of the roof but they won’t be able to put that membrane up the wall behind the siding since there is no space to work. It may also increase the difficulty in placing the step flashing.

A lesser concern is that since the siding was installed touching the shingles moss has been growing on the shingles along the base of the siding. That can’t be good for the shingles.

Any advice on what I should do, if anything, before and/or after the shingles get replaced?
 
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Old 09-17-18, 02:33 PM
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The best thing to do is do not rely on the roofers. Remove the vinyl siding for them so that they can flash against the wall. After they are done, tape their flashing to the wall with window flashing tape and then put the siding back up. I will gap vinyl siding 3/4" by laying a 1x4 flat on the roof, then lay your j-channel on that... once the j-channel is nailed you can remove the 1x4.
 
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Old 09-17-18, 04:57 PM
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If I remove the vinyl siding I will expose the 4ft by 8ft sheets of wood siding. The wood siding has vertical groves in it.

I trust that water will not get behind the wood siding. The vinyl is Certainteed Ironmax 5” vertical Glacier Arctic. On page 70 of the installation guide Certainteed says it is not a water tight material so water can get through it to the surface of the wood siding, then it could follow the grooves down behind any tape and step flashing that might be in front of the wood siding. The current step flashing goes behind the wood siding. I think the new step flashing would have to go behind the wood siding as well so taping it will not be possible without pulling the wood siding and that would be too much.

Given that info does it seem worth pulling the vinyl siding?

In any case if the siding ended an inch above the shingles it would likely be easier to do a good roofing job and there would be less moss growing on the shingles, likely making them last longer. What I do have going for me is that currently there are two layers of shingles on the roof so there may be a little extra room when that is replaced with one layer of shingles. Maybe that will be enough gap to avoid moss. With any luck I will be beyond caring about this roof by the time it needs another layer of shingles.

Is there is some clever way to cut the bottom inch off the siding and move the J channel up without taking the rest of the vinyl siding completely off?

I’m looking for a way to make this into a job so small and straightforward that I have a reasonable chance of being successful.

Thanks for any advice you might be able to give me.
 
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Old 09-17-18, 05:21 PM
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You should remove the vinyl siding in order to install a WRB (housewrap) over the 4x8 siding, behind the vinyl siding. Removing and reinstalling vinyl siding is not hard. Just number the pieces as you take them down.
 
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Old 09-17-18, 07:54 PM
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The wood siding under the vinyl is nailed to a cinder block wall, with an attic on the other side. There are no openings, no way for air to enter the other dwelling. Would the wrap help my roof or protect the wood siding?
 
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Old 09-17-18, 08:13 PM
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A wrb serves many purposes but in this case it is so that your step flashing can either go behind the wrb or so that the step flashing can be taped to the wrb. Vinyl siding is not waterproof so if the siding leaks you don't want the roof to leak just because water got behind the siding. You do realize it's $10 per question, right?

joking... lol
 
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Old 09-18-18, 04:45 AM
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It's worth ten bucks just to see the PigPen icon. Having a place I can go where people answer questions just because they want to be helpful is beyond price.
Thank you very much.
 
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Old 09-18-18, 05:15 AM
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LOL... pig pen rocks.
 
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