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Replacing the shed roof.

 
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sgt.colon



Joined: 27 Jul 2009
Posts: 7380
Location: Just south of north.
PostPosted: Thu Apr 29, 21 4:23 pm    Post subject: Replacing the shed roof. Reply with quote
    

We have a garden shed that is concrete panelled and is 15' x 9' . In winter when it is cold it gets condensated on the inside and the water drips over everything in the shed. So I had an idea. I thought I could take off the existing roof and lay down some osb. Then run some joists, put in some loft insulation, then more osb over the top and cover with roof felt.

Then I had another idea. I could create a living roof. So my question is, can you do them economically? Would I still go osb board, then cover with pond liner, make a frame, throw some soil on top and then decide what to grow up there?

The joists that support the roof at the moment are 9.5cm x 4cm. Would they be strong enough to support a living roof? Would it just be cheaper to go with my first idea?

As always, a couple of photos for your delectation.

Edit:- needed to change joists from inches to cm's.

The shed.



The joists




Thanks.

Last edited by sgt.colon on Thu Apr 29, 21 5:02 pm; edited 1 time in total

tahir



Joined: 28 Oct 2004
Posts: 45672
Location: Essex
PostPosted: Thu Apr 29, 21 4:32 pm    Post subject: Reply with quote
    

The weight is going to be the biggest issue, you'll need to look at the weight per m3 of planting medium and double it to allow for snow/rain.

You don't need soil, and you don't need to plant. You could just put a lightweight aggregate up there and within a few years there'll be plants that will have colonised.

dpack



Joined: 02 Jul 2005
Posts: 46219
Location: yes
PostPosted: Thu Apr 29, 21 4:39 pm    Post subject: Reply with quote
    

re living roof

i do not know

my very strong sticks woven dome was fine with dry frass on a lorry tarp, rain at 2 AM, the dog popped out to see a friend and i used a 3 leg stool to avoid being crushed in my bed

how much water do you need to support if it rains?

mesh, almost no "soil" and plants that like that look nice but are not insulation even if they might sit on that

re dripping seal the top and more ventilation may be your pal

sgt.colon



Joined: 27 Jul 2009
Posts: 7380
Location: Just south of north.
PostPosted: Thu Apr 29, 21 5:07 pm    Post subject: Reply with quote
    

Thanks both. I need to put some real thought into it.

If I went with lightweight aggregate, how deep would it need to be, do you know Tahir? I was looking at the 18mm osb board.

Re insulation DPack, is there anything I could put in the shed, something thin? Headroom (not the guy from the 80's) is going to be an issue if it's too thick.

dpack



Joined: 02 Jul 2005
Posts: 46219
Location: yes
PostPosted: Thu Apr 29, 21 5:39 pm    Post subject: Reply with quote
    

some insulation will make any damp issues worse

seal and ventilate are still my first choice

tahir



Joined: 28 Oct 2004
Posts: 45672
Location: Essex
PostPosted: Thu Apr 29, 21 7:00 pm    Post subject: Reply with quote
    

sgt.colon wrote:
Thanks both. I need to put some real thought into it.

If I went with lightweight aggregate, how deep would it need to be, do you know Tahir? I was looking at the 18mm osb board.

Re insulation DPack, is there anything I could put in the shed, something thin? Headroom (not the guy from the 80's) is going to be an issue if it's too thick.


I'll send you my book on DIY green roofs, PM me your address.

tahir



Joined: 28 Oct 2004
Posts: 45672
Location: Essex
PostPosted: Thu Apr 29, 21 7:03 pm    Post subject: Reply with quote
    

"Compare that to Urbanscape. The green roof solution uses a unique lightweight growing media rather than soil and as a result is less than 8 cm thick and six times lighter than traditional systems weighing only 20 kg/m2 dry or 65 kg/m2 saturated."

From:

https://www.urbanscape-architecture.com/how-much-does-a-green-roof-weigh/

8cm is plenty for sedums and quite a lot of wildflowers

tahir



Joined: 28 Oct 2004
Posts: 45672
Location: Essex
PostPosted: Thu Apr 29, 21 7:04 pm    Post subject: Reply with quote
    

Oh, and the "lightweight growing media" is not unique, you'll find recipes for it, there's probably one in the book

dpack



Joined: 02 Jul 2005
Posts: 46219
Location: yes
PostPosted: Thu Apr 29, 21 7:34 pm    Post subject: Reply with quote
    

"65 kg/m2 saturated."

that determines how strong the beams(or whatever)need to be

3 times the weight when it rains seems reasonable

dpack



Joined: 02 Jul 2005
Posts: 46219
Location: yes
PostPosted: Thu Apr 29, 21 7:41 pm    Post subject: Reply with quote
    

if it is leak proof and ventilated a green roof might be a bonus

thing is unless there is a heat source inside it insulation is probably not much help

tahir



Joined: 28 Oct 2004
Posts: 45672
Location: Essex
PostPosted: Thu Apr 29, 21 8:02 pm    Post subject: Reply with quote
    

Agree no need for insulation

Ty Gwyn



Joined: 22 Sep 2010
Posts: 4613
Location: Lampeter
PostPosted: Thu Apr 29, 21 9:21 pm    Post subject: Reply with quote
    

What is/was the roof covering?
Condensation is the norm with tin roofs,a simple effective solution,would be to strip the roof,pull wire netting tight across the rafters,lay roofing felt and re-sheet,the wire netting to stop the felt sagging between the rafters.

For a living roof,1800`s Western Pioneers,seen many a photo with a steer on the roof grazing,lol.

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