Author Topic: Shed Roof  (Read 1092 times)

Shed Roof
« on: May 07, 2019, 09:19:30 am »
Right, Shedxperts of yacf - Bring me your wisdom.

I have inherited a decent sized shed with my new dwelling. The first thing I noticed was that water was pissing in every time it rained, the roof materials were sodden and there was considerable mould growth on the walls inside.

I stripped the old felt off in December and made a temporary covering with a big sheet of DPC. Much to my delight, the roof timber has recovered quite well and is now fully dry. I have replaced a load of the shiplap boards on the rear that were rotten and given it a thorough drink of cuprinol. The shed is worth another turn.

The current roof structure is a series of boards about 100mm wide by 10mm thick. They are anything but level with one another and there is some bowing in the very middle of the roof. My idea is to attach some big sheets over the top and felt over them instead.

To Ply or to OSB? And then what thickness? I don't want to add too much weight, so I was leaning towards 5mm ply, but i'm not sure it'll be stiff enough.

Then onto the felt. Any old felt? Nail or glue-on? Any other membranes underneath?

Over to you. Any ideas welcome. I don't want it to be a massive job.

Re: Shed Roof
« Reply #1 on: May 07, 2019, 09:24:44 am »
Why felt? I'd buy corrugated sheet and use that instead, much longer lasting.

5mm ply (exterior grade) will be good enough if you're laying it over the existing boards.
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #2 on: May 07, 2019, 09:30:38 am »
My dad has some corrugated tin i'm sure he wouldn't miss, but i'd be a bit concerned about it being noisy (?). Also, how does one seal the ends?

Re: Shed Roof
« Reply #3 on: May 07, 2019, 09:31:25 am »
I don't think I would use felt ever again.  I have reroofed my 2 sheds in the last 3 or 4 years and I have used Onduline bitumised corrugated sheets available from Wickes and others https://www.wickes.co.uk/search?text=onduline  It is a joy to work with.  On one shed I measured carefully and pre-drilled holes for screws (I prefer decking screws to nails), on the other I was not fussy.  This meant I could align fixings with the roof support timbers.  In your case you might find you can get away without ply or anything else.  Some of my ship lap boards on my less important shed suffered with water splashing back and rotting them, so I fitted some Onduline sheets vertically (an approved method) to protect them.

Re: Shed Roof
« Reply #4 on: May 07, 2019, 09:35:44 am »
Some of my ship lap boards on my less important shed suffered with water splashing back and rotting them, so I fitted some Onduline sheets vertically (an approved method) to protect them.

The back wall of the shed is about 2 feet from a tall breeze-block wall, so I assume that water splash back combined with a breezeless corner is probably an issue there too.

Re: Shed Roof
« Reply #5 on: May 07, 2019, 09:38:36 am »
The bitumen corruagted sheets look the ticket.

I shed* have mentioned above, It's a single-span sloping roof. No apex.

*Typo - but leaving that in! ;D

Re: Shed Roof
« Reply #6 on: May 07, 2019, 11:09:38 am »
Consider also EPDM rubber sheet if you can get hold of it from your local shed place. Made by Firestone and has an alleged 50 year life. Unaffected by UV. Uses a vulcanising adhesive if need to lap. Now widely used for extension flat roofs. Corrugated roofing has purpose made foam inserts for the eaves and ridge cappings are available
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Re: Shed Roof
« Reply #7 on: May 07, 2019, 11:20:48 am »
I’ve got some left over board from when I had my shed done - it’s that reconstituted wood. Any use?

Re: Shed Roof
« Reply #8 on: May 07, 2019, 11:38:24 am »
My dad has some corrugated tin i'm sure he wouldn't miss, but i'd be a bit concerned about it being noisy (?). Also, how does one seal the ends?

As has now been posted by others, I was referring to the bitumen type corrugated roofing. I have a gutter and water butt attached to my shed to catch the run-off, no need to seal the ends as it's laid over the previous felting I did, which was still intact when I put on the corrugated stuff.
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #9 on: May 07, 2019, 11:52:59 am »
I’ve got some left over board from when I had my shed done - it’s that reconstituted wood. Any use?

Cheers Paul, but i'm going to go the corrugated sheet route. At most i'll need some batons underneath.

Re: Shed Roof
« Reply #10 on: May 07, 2019, 12:16:12 pm »
Top Tip: Remember to drill the fixings through the peaks of the corrugation, not the troughs. (No, I didn't, but I nearly did!)
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #11 on: May 07, 2019, 12:31:57 pm »
I watched the Onduline vid, but would have thought to go through the troughs if left to my own devices.

Also interesting that they use nails over screws. I'd better get more accurate with a hammer before i do this...

Re: Shed Roof
« Reply #12 on: May 07, 2019, 12:38:47 pm »
I watched the Onduline vid, but would have thought to go through the troughs if left to my own devices.

Also interesting that they use nails over screws. I'd better get more accurate with a hammer before i do this...

I used something like these...

https://www.screwfix.com/p/hardened-steel-roofing-screws-8-x-75mm-20-pack/79532
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #13 on: May 07, 2019, 02:55:50 pm »
Onduline folk, what do you do with the edges?

The prices all seemed very reasonable until I added the verge strips.

EDIT: found the answer. They are flexible enough that you can screw the overlap into the side. Phew

Re: Shed Roof
« Reply #14 on: May 07, 2019, 03:05:11 pm »
What Onduline suggest is that you end up with a "down" slope over the side edge and bend it down and nail it to the barge board that you've put there for that purpose... it's image 14 in the Onduline Quick Fixing Guide, but I can't work out how to copy and paste the image

Oh, and Wickes sell these Onduline screws (as well as all the other stuff).

https://www.wickes.co.uk/Onduline-Roofing-Black-Screws-60mm---Pack-of-100/p/207693
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #15 on: May 07, 2019, 03:41:29 pm »
EDIT: found the answer. They are flexible enough that you can screw the overlap into the side. Phew
Which is what I did.  Hint - heat from a hot air gun helps which means that black roofing is the preferred colour because the black bitumen would show through if overheating the green.

Re: Shed Roof
« Reply #16 on: May 07, 2019, 03:50:56 pm »
Already sketched it up on AutoCAD and ordered all the bits. The weekend can't come soon enough. Thanks chaps!  ;D

Re: Shed Roof
« Reply #17 on: May 10, 2019, 07:55:25 am »
it's image 14 in the Onduline Quick Fixing Guide, but I can't work out how to copy and paste the image

Try the Windows Snipping Tool?

Re: Shed Roof
« Reply #18 on: May 10, 2019, 09:05:57 am »
Tried that, it didn't want to snip from a pdf, and by then Peat had the answer.  :)
We are making a New World (Paul Nash, 1918)

Re: Shed Roof
« Reply #19 on: May 11, 2019, 08:19:43 am »
It's SHED DAY, everyone.

Onduline already measured up and cut, some holes drilled. Today is going to be special.

This stuff stinks to high heaven.  :sick: Had it in my car for a day (delivered to work) and was getting pretty queasy.

guidon

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Re: Shed Roof
« Reply #20 on: May 11, 2019, 09:54:05 am »
go for it!

Re: Shed Roof
« Reply #21 on: May 13, 2019, 08:20:33 am »
Well, all rather uneventful in the end. In a good way. Onduline is ridiculously easy to work with.

After finishing on Sat, I was treated to a sudden heavy downpour - so i rushed to the shed and reveled in the lack of water making it's way into the shed.

Just need to modify the guttering a bit now. The concentration of the corrugations seems to throw the water past the catchment of the gutter. Hey ho.

Thanks for the advice. 

Re: Shed Roof
« Reply #22 on: May 13, 2019, 09:31:46 am »
Tried that, it didn't want to snip from a pdf, and by then Peat had the answer.  :)


.....you probably didn't, as it is a screen scrape that doesn't care what program.

<Shift><Windows Key><S> brings up the snipping tool

Another Onduline fan here, although I used Onduvilla on my shed, replacing felt shingles.

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Re: Shed Roof
« Reply #23 on: June 02, 2019, 06:10:27 pm »
Another onduline shed fan here.
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