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banditthedog

leafy vines on roof: insulation or problem?

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I live in a very moderate southern California climate with an average rainfall of only 15 inches (38cm) / year. My roof is asphalt shingle and the pitch is 1/3. In two places I have vines growing up walls and then spreading out on the roof. The vines lie directly on the shingles and cover sizable areas. The vines do not adhere to the roof - as ivy would - but are held in place by gravity and friction.

My questions are:

1. Do the vines impede water shedding and so promote roof failure? I haven't had any leaks and the vines have been there for years.

2. Are the vines shortening the life of the roof somehow or actually prolonging it?

3. Do the vines have any significant insulation value?

4. What other concerns might I have?

Thanks.

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I live in a very moderate southern California climate with an average rainfall of only 15 inches (38cm) / year. My roof is asphalt shingle and the pitch is 1/3. In two places I have vines growing up walls and then spreading out on the roof. The vines lie directly on the shingles and cover sizable areas. The vines do not adhere to the roof - as ivy would - but are held in place by gravity and friction.

My questions are:

1. Do the vines impede water shedding and so promote roof failure? I haven't had any leaks and the vines have been there for years.

2. Are the vines shortening the life of the roof somehow or actually prolonging it?

3. Do the vines have any significant insulation value?

4. What other concerns might I have?

Thanks.

Depends hugely on the types of vines.And your roofing material.

Yes, the vines will be holding some water, but if the roof is structurally OK that may not matter, particularly if you don't get much rain.

Can't tell how the vines will affect the roof of the life - we don't have asphalt shingle as a roofing material here in Australia. Also, it would depend on the vines.

Yes - the vines will be adding significantly to the insulation value of the roof. They keep the heat down by providing shade, AND as an evaporative cooling system as they transpire moisture.

If you don't need to worry about the roof rusting/rotting, I'd leave them.

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On the loading, generally wind load is the highest load and this will be in excess of the vines anyway. On a low pitched roof it can sometimes be light traffic load. Your vines would weigh less than either of these cases I expect.

Just don't walk on your roof in the same place as the vines. ;)

If the vines were actually attaching themselves to your roof with roots between shingles I would start to worry about wind load as the vines could cause some of your shingles to lift as they catch the wind on the windward sode of your roof and once a few go allowing the wind to get under your roof increasing pressure inside and uplift on the leeward side of your roof, this can happen like night before last;

Storm brings deluge

Monday August 22, 2011 - 11:49 EST

A storm which passed over Perth and south-west Western Australia overnight has dumped heavy rain and caused some minor damage.

The State Emergency Service (SES) says a building lost its roof in Port Kennedy.

Of course you don't need vines for that to happen but it is not going to help if they are attached. In your case given they are not attached in such an event you would expect them to just blow off I would imagine?

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Although more environmental, I'd think that the leafy vines may be more of a problem - but that's just my opinion. I'd worry about the life of the roof and damage that the vines may cause to the roof. You may also have to maintain the vines to ensure that they don't do that, which may have to be regular maintenance.

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Honestly this thread means nothing if you don't know what sort of vine is being discussed.

There are so many different creepers and climbers out there, and each of them has a different method of attaching or not attaching, growth patterns, water retention, biomass etc.

Also asphalt shingle can be virtually impenetrable, sort of like a single huge layer of roof covering - very hard for a vine to get 'between' the shingles, as they are not at all like wood shingles other than in name. It's not a kind of roofing I have seen in Aust, only in the US. Roof shape and guttering (or lack of it) conventions are quite different over there, too. All these things make a big difference to the usefulness of an answer.

As a hugely simplistic example,a glory vine could potentially be a helpful shade plant. Ivy, on the other hand, could literally bring your house down.

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Possum-in-Gutter.jpg?3222Myna-Nest.jpg?8690

So have any of these guys made a home on the roof since?

I thought of one advantage of having the vines on the roof. At least you will not have to install roof anchors. :thumbup:

Just tie off on the thickest branch up there.  :wheelchair:

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