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A Green Roof

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sammo

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Hi - Some time ago we bought a log cabin as a replacement for a single garage (never parked a car in it) - very similar to this... http://dunsterhouse.co.uk/log-cabins/se ... up-sup-400
Last year i got around to insulating the 3 walls - the front wall is mainly windows and doors and i have not yet decided what to do with that wall (advice gratefully received) - anyway the purpose of this thread is this year i am going to insulate the roof. I think I have two options; traditional internal insulation (I like the thin 'space blanket' stuff) or an external "green roof" with planting on... Can the roof take the weight; does anyone know how to calculate this?

Thanks in advance

Sammo
 

=Adam=

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Now in theory I should be able to do this for you seeing as I am studying civil engineering with environmental management, however I would need some info on the timber beams etc... (thickness, length, centres etc)

I love the green roof idea! I think they are very useful and really blend into the environment! One thing that I would say about the green roof is that you really need to ensure that the roof can take the additional weight, as there is one heck of a lot of weight on earth, especially when saturated with water!

I would say that you would need some sort of reinforcement on the roof to make it safe, however I am not an expert, so I would seek some professional advice locally I possible!
 

Mark R

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Hi
First off you need to decide what you want to grow on your roof, if it is a sedum plants then you need circa 80mm of peat like growing medium,40mm drainage layer [that can fill with water!!] and you insulation. If you are after a more natural look then the growing medium goes uap as does the weight. Sadly the native ones do also need maintenance unless you have a goat.

Bauder or Alumasc are able to advise on weight per square metre if that helps


Mark
 

sammo

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Hi
Thanks for the replies - Adam, will send & post some information on the forum. Thanks for the offer of help.

Mark - thinking of the Sedum type - will look at the web site.

Of course i don't have to do the whole roof, but my gut feel is that it's going to be to much weight, and I am going to have to look at the internal alternatives - although the shingles that came with the cabin are very heavy in themselves, and i am assuming that these would be stripped off to accommodate green roof system.


Cheers all

Will let you know what gets decided
 

Cegidfa

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Hello sammo,
As to the insulation, don't forget that the space blanket will require a 25mm gap between it and the roof (and the same for containing the inside heat) to work at all.
It will only stop radiative energy, which helps, but won't stop conducted heat, as it has no real u value/R value. I would think that celotex/Kingspan board would be more effective.
The spaceblanket, fitted properly, will take up 50mm, and I think that 50mm of Kingspan would be the more efficient of the two. Food for thought.

Best wishes...Dick.
 

sammo

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Hi - Dick, after a bit of research I have reached the same conclusion and will be looking at the Kingspan insulation, if I go down the internal route. I have asked a couple of companies some advice about green roof weight; there is one where they indicate it can go straight over the top of a shed roof (over the shingles and all') - all you need is a "root" barrier, which turns out to be either a plastic sheet or pond liner - then over the top of this a fleece to hold some moisture; this seems to be the lightest option.
Have to say I am keen on the green roof idea - as the workshop takes up a lot of garden space...
 
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