[Closed] inspired by shed threads, do you think its possible for.....

I've just used twinwall 10mm polycarbonate sheet on a greenhouse. Light weight and easy to work with. The sheets have a male/female edge so you can butt join them. Have a look at polycarbonate button fixings to attach them with.

It's the size, spacing and pitch of the timber that will give you the strength rather than the roofing material.

finished the decking last night, theres nothing else i can do to it now til i sort out more wood for the roof and cladding. spent this morning digging up grass and replacing with gravel so it gives it its own 'area'.

[img] [/img]
that pic maybe shows the end nearest the field a bit better too, with the 3.4m span ive got for the roof beams. looking at it now it just seems ive maybe made it a bit wider than i should 'just cos i could'.

It's the size, spacing and pitch of the timber that will give you the strength rather than the roofing material.

That's looking great.

thanks mate, yep, im pleased with how its going.

next question..... after talking it over with my mate, ive decided to stick with ply for the roof, but thin ply first (4mm) topped with 8mm OSB, and staggered for strength and then that topped with felt.
got a quote for all the ply, plus some decent felt (38kg mineral if that means anything to anyone?) but im unsure about the felt adhesive. i thought id just be tacking it down with clout screws, and then using adhesive on overlaps. reading up on it suggests i should use underlay too??
is this just belt and braces, ive never seen felt plus underlay on any other sheds, so can i get away with my original plan, or do i really need to splash out another £100 or so on underlay? :-/

thanks

oh and also, do i have to spread bitumen/adhesive over the whole roof first or just the overlaps?

clout nails directly into felt through to the joists, or do i use wooden battens to hold the felt down?

thanks

just popped into builders yard on way home from work this morning to look at shiplap and ply. disappointed to see they dont do treated shiplap, id always thought they did, but ill just use another yard for that then.

also a bit dismayed to see just how flimsy 4mm ply is. it was warped and bowing all over the place on their pallets, so thats making me think i should just stick with 12mm ply rather than 4mm ply/8mm OSB and risk a warped inner lining at some point.

would appreciate thoughts on that as its your opinions and invaluable advice thats helping me out on this bad boy 🙂
also answers to above questions re underlay/bitumen/adhesive etc much appreciated.

thanks a lot

When I've done sheds with felt I've never used underlay and just used that black sticky stuff on the overlaps, IANAR 🙂

The thinnest ply I've uses is 9mm, but... It's the wood you screw the ply to that gives it the rigidity. 4mm will be fine if you've got the noggins.

ahhhh balls, forgot bout the noggins. thats more timber needed then 🙂

i assume my only option for noggins is offsetting them to get the screws in yep as i did with the floor? and would i get away with just one set of noggins going across or will i need a couple of rows at a 3.4m span. i feel the answer is going to be 2 rows 🙂

Forgot to check back with this... looking good!

On the polycarbonate subject - are you still planning on using it? If so I can take some pics of the canopy I completed last year - looks similar to that pic on the last page - using 25mm poly. In fact my entire build is spookily similar to yours in essence.

Pics if you want them - I can just send them in a email to save cluttering up your thread. I think I took a few of the build itself showing some fancy cross halving joins.

i assume my only option for noggins is offsetting them to get the screws in yep as i did with the floor? and would i get away with just one set of noggins going across or will i need a couple of rows at a 3.4m span. i feel the answer is going to be 2 rows

Noggins at the end of each sheet and one in the middle would be how I'd do it.

You can get a torch on felt called tecnatorch. Goes on very easy. Used it a few times and had no problems.
Or you could use a edpm rubber roof.

On the polycarbonate subject - are you still planning on using it? If so I can take some pics of the canopy I completed last year - looks similar to that pic on the last page - using 25mm poly. In fact my entire build is spookily similar to yours in essence.

Pics if you want them - I can just send them in a email to save cluttering up your thread. I think I took a few of the build itself showing some fancy cross halving joins.

You can offset them or skew the screws in at 45 degrees on half of them if you want them in line.

Noggins at the end of each sheet and one in the middle would be how I'd do it.

You can get a torch on felt called tecnatorch. Goes on very easy. Used it a few times and had no problems.
Or you could use a edpm rubber roof.

google google googling as usual and had another idea from stuff i saw for sale...... i assume instead of felt i cant use [url= https://www.roofingsuperstore.co.uk/product/black-jack-flashing-trade-100mm-x-10m.html ]this flashing tape[/url] on all the ply joins, and then paint [url= https://www.roofingsuperstore.co.uk/product/black-jack-fast-drying-roof-waterproofer-25-litres.html ]this waterproof coating paint[/url] over all the roof too? as i say, it doesnt matter too much what the top of the roof looks like, it slopes away from view and only the inside is visible. viable alternative or should i really just stick with the felt?

ah ok, yep, 45 degrees may look better to keep em in line. i was going to say that surely all the screws would have to be 45 degrees wouldnt they, but then thought you probably mean to screw in every other noggin first, then 45 degrees for intermediate noggins, yep?

Don't use the paint. The wood will have a certain amount of movement in all weathers and I doubt the paint will move with it and would probably crack over time. Don't hold the felt overlap down with batons as this will just hold moisture and rot.
Do use 12mm external ply or above. Do use noggins but I'd space every 1.22m staggered.

Don't use the paint. The wood will have a certain amount of movement in all weathers and I doubt the paint will move with it and would probably crack over time. Don't hold the felt overlap down with batons as this will just hold moisture and rot.

Do use 12mm external ply or above.

also i have 2 X 4.8m length bits of 2X2 left over so far so was looking at utilising them somewhere. my thoughts at present are to use 2X2 as noggins, save the cost of more 4X2 (joists will be 4X2). ok it means the noggins wont be flush with the joists but as long as they all look the same then am i right in thinking its no big deal? they are only there to stop the joists from bending arent they, which 2X2 will do fine?

Do use noggins but I'd space every 1.22m staggered.

thank you very much.

Personally I'd stagger at 1m intervals and not worry about the join. Structural above asthaetics..
Staggered over 3 rafters so that you land on the join of the ply if your that bothered about looks but people will only look up once when they first visit and will tell you what a brilliant job you've done. After that they'll just get on with doing whatever under it..
Space your rafters at 305 centers over the large span if using 4x2. Put the crown upwards.
The noggins will be to stop the rafters twisting..2x2 won't cut it here
If you want to use the 2x2 up cut at 45deg and put in strategically placed braces in to resist side-loading from the wind.

Space your rafters at 305 centers over the large span if using 4x2.

sorry, i dont understand the rest of your post as i cant imagine in my head what you mean.
staggered over 3 rafters and at 1m intervals? and i also dont know what the crown is. i apologise, youre being very helpful but i just dont understand 😳

EDIT: im also not sure what the diagonal bracing would bring to the party as im thinking the noggins would be resisting wind from the side? i dont spose you could find any google images of what you mean by any of the above could you so i can see it in my head?
thanks a lot 🙂

If you were going to have 3 rafters per board the 1.22m ply joint would span 3 rafters.

Re Diagonal bracing..forget these if you're happy with how far you've sunk the corner posts. What size are they and how deep did you go?

How wide is the opening on the open part..you might need a knee-brace to help support the weight of the roof here..

If you're worried about weight on the ring put coach-bolts through.

[url= &imgrefurl=http%3A%2F%2Fwww.timberframediy.com%2Fchoosing-reference-faces-part-2%2F&docid=TzEPAHAmzZH8hM&tbnid=4wB9uLWN25rxrM%3A&w=800&h=618&bih=512&biw=360&ved=0ahUKEwiP66L68pjPAhXrIcAKHdsfDAYQMwghKAYwBg&iact=mrc&uact=8]crown up[/url]

Re side-/front-loading...sustained loading WILL cause movement...and although the noggins are in place you've only screwed into the end grain of the noggin which is the weakest connection you could make..don't think it will be as strong as a pegged tendon a la ' timber-frame '..overtime the structure could weaken. Any diagonal bracing reduces any movement significantly..
I must admit though I do tend to over-build..

How wide is the opening on the open part..you might need a knee-brace to help support the weight of the roof here.

[img] [/img]

Re Diagonal bracing..forget these if you're happy with how far you've sunk the corner posts. What size are they and how deep did you go?

If you're worried about weight on the ring put coach-bolts through.

re diagonal bracing, i dont really want any wood to go from corner to corner as that removes the access to it doesnt it? i just want it to look nice and open.

crown up

thanks a lot mate

By diagonal bracing I didn't mean corner to corner I meant knee-braces..my fault..
Good luck

thanks.

roof joists completed today. as mentioned before, theyre at 610 spacing so will support each end and halfway along each ply sheet too.
oh and colins guarding it protectively 🙂

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need to do the noggins next, just need to know how to stagger them if you have any advice. at 3.3m depth, and joists halving each ply sheet, i was thinking first side do on the join and halfway, so from the front, set noggins at 4ft and 8ft (easier to work with imperial now as thats how the sheets are measured), then next joist do either just offset by the width of a 4x2, or..... do 4ft and 8ft from the rear as thats probably where the next sheet would be started from to stagger the sheets. that makes the noggins look a bit haphazard tho.

thoughts please?

EDIT: youll notice i also had to stagger the joists on the shed part, thats cos of the framework in the way of a full run, so i decided to do the front joists 'on the join' (as thats on view), and then inside the shed just off the join but i can muck about with extra noggins and whatnot for support in there, it doesnt matter how that looks.

Space the noggins at 610 also for a nice symmetrical pattern..start on the join ..
You should have a ply overhang front and back..

As for the shed part you can sister the rafters where they're staggerd..

Space the noggins at 610 also for a nice symmetrical pattern..start on the join ..

You should have a ply overhang front and back..

As for the shed part you can sister the rafters where they're staggerd..

thanks

would you also use underlay with the felt or is that just belt and braces and not really required? and if underlay [i]is[/i] required, use the proper felt underlay or, i see wickes selling polyester underlay which seems to be a lot cheaper. cheap rubbish tho or better than nothing?

thanks

Personally I wouldn't use underlay.
If you have money for underlay buy a thicker felt.
Overlapping the front will put a drip edge further out. Screw a baton underneath the front/ back edge of ply, fold down ply and tackle, fix a decorative fascia to the batons..

i like that answer, its what i was thinking myself, and hoping itd be ok but expecting people to say "noooo, you need 2 or 3 layers" 🙂

ive been looking at the 38kg mineral stuff, bout £30 a roll, and ill need 4 rolls so still some expense there.

£30 a roll, and ill need 4 rolls so still some expense there.

Woah there, Bald Eagle.

To save me reading back, what size are you covering with that many rolls and where did you look at EPDM prices?

think the structure is 6.7m X 3.4m. so im thinking 1m wide rolls, overlapping a little is gonna take me to needing around 4m width. yes the whole area is maybe just less than 30 sq/m but i cant chop bits off the end and stick em elsewhere, itll take 4 rolls of probably just over 7m length?

EPDM - did a couple of online calculator things, then emailed a couple of places from google. only one of them got back to me with a quote, permaroof uk? quote was £214 for a 6.7 x 3.4 area.

The place I used quotes £182.02 delivered for the same area coverage.

Still quite pricey, I guess, when compared but I've never had felt last particularly long. Maybe when it finally dies you can slip on a bit of rubber membrane then. 🙂

if you've got the noggins.

Noggins 😕
Dont you mean dwangs 😆

Looking very nice by the way , sturdy 8)
Go on. Strengthen the roof and welsh slate it. 8)

The place I used quotes £182.02 delivered for the same area coverage.

Still quite pricey, I guess, when compared but I've never had felt last particularly long.

Go on. Strengthen the roof and welsh slate it.

you may call me a donut here, but i started thinking of something else whilst laid in the bath...... retractable/removable/temporary roof? thought id bring this up here even if its just to be laughed out of court 😀 no harm in thinking outside the box tho is there, and its healthy to think that anythings possible 🙂
i started wondering if its possible to have a cartridge type thing where a canvas/plastic cover gets pulled out when it rains, in a sort of shop-front stylee. either from rear or side.
im not expecting this idea to last long at all, it may not be possible/may not exist/almost certainly be expensive, but i like the thought of it. even something home-made on a roller or somethings. so the gazebos open all the time and the cover is only brought out a) when we have a bbq/party with friends, and b) when its raining. so just 3 or 4 times per year.

feel free to pooh-pooh this or hit me til i see sense again please 🙂

How high is the front off of the ground?

the front is 7ft, sloping down to the rear at 6ft. thats to decking level, then the ground slopes left to right so different height depending.

FWIW ive pretty much talked myself out of the retractable/open roof, think it makes more sense to have a proper roof.

Was thinking you could of put a hinged piece at the front. Ie. If twas 8ft you could of had a hinged 2ft wide piece going across the front so in the down position you'ld have a 6ft opening that you could then lift the hinged piece forming an overhang and an 8ft opening. Clad in cedar shingles.

sadexpunk, I'm jealous. I've just roofed my new shed (thread at some point soon) and was thinking how it was pretty good then I see this. If I tried something that size I wouldn't have anywhere to park the car.

I roofed mine with standard shed felt but then I could do the whole lot in one run as it's a long narrow roof and used the bitumen felt adhesive. I used a flashband on the top edge as it joins onto a brick wall and I didn't want to faff with melting stuff. I would have liked to have used the torch on stuff but the budget was spent a while ago.

Did you find treated shiplap? I had a quick look but it worked out about twice times the price of the untreated stuff. Mine is going to end up painted anyway so wasn't too fussed.

Was thinking you could of put a hinged piece at the front. Ie. If twas 8ft you could of had a hinged 2ft wide piece going across the front so in the down position you'ld have a 6ft opening that you could then lift the hinged piece forming an overhang and an 8ft opening. Clad in cedar shingles.

Did you find treated shiplap? I had a quick look but it worked out about twice times the price of the untreated stuff.

Mine is going to end up painted anyway so wasn't too fussed

Re my post..it was a variation on you roller-awning idea

what place is that mate? and does it include adhesive and any fittings?

This place : http://www.rubba-seal.co.uk/

But no, I forgot to add the cost of the adhesive. That'll be another £20, sir. And no edging either, though a wood is a viable alternative.

Just ignore me...

Wood rots fastest where it goes in the ground. Your uprights will go first (after many years) so I wouldn't worry too much about the rest.

been reading up on tanalised wood, and it generally says because its been pressure treated it doesnt need any further treatment. now i dont intend to just leave it without further treatment, but it does suggest itd be a better option for if i do become a bit lazy. obviously nearly every end will have been cut to fit somewhere, so i do intend to go over it all with some ronseal 5yr protection or somethings when its all finished, plus some non-slip decking oil.

thanks

End-grain sealer for the cut edges. Your wood will start silvering down after 6 months to a year whether it's tanalised or not. You can prevent this with a uv protect oil from Osmo ( yearly ). If your timber stays out of sustained contact with moisture it won't rot for a very long time so you could, for instance, use un- tanalised shiplap and then oil or paint. DON'T, I repeat, DON'T buy kiln-dried shiplap and go home and fit it immediately. Let it acclimatise, leave it in the open part under the roof before fitting. If you have a dry warm week you'll need to fit loosely. Ie. Fit the first one, rest the next on top and lift off slightly (1-2mm) and fix. This will allow for expansion due to moisture.

rightyo, thanks. is end sealer different/betterer than 5yr preservative then? should i get both? FWIW i dont mind wood silvering with time, thats not a bad thing is it? just dont want it to rot/split/warp.
and no, i havent actually seen anything 'kiln-dried' so i shouldnt make that mistake, everything ive looked at has been tanalised.

raining yesterday so popped round to see me mate who said i could nick some of his woodburner logs. took a few logs of different sizes, sliced em a few inches thick and stuck em under the decking for the er.... rustic look 🙂

[img] [/img]
then had a tough day today, although i dont seem to have got much done. twas the noggins today and they went fine. spaced the first row to match the join in ply sheets, adjusting 2" for front overhang. in retrospect im not sure i should have maybe left a little more as i forgot im going to put a facing board up too, but no matter, done now, 2" is probs ok.

its times like this you realise you should have worked things out a bit better, as when i got to shed end, the front of the shed frame was just slightly in the way of perfect noggin spacing. id just plopped the shed front where it looked ok, if id thought about the roof i could have come an inch or two forward and id have had a nice beam to nail a ply sheet to. durrr.

anyways, had the afternoon left plus a bit of surplus timber so i thought id attempt tymbians suggestion of knee braces, see how they looked.
did the first one and....
[img] [/img]
bit savage innit 🙂 decided itd look better smaller, so cut em down again, then realised im gonna be struggling at the ends. double mitre where the corners meet, and wouldnt you know it, the chop saw wouldnt quite fit 4x2 in at 45 degrees so had to do the corners best i could at probably 43 degrees or somethings. thats a lot to be out and it was leaving a big gap so i spent ages rubbing the faces against brickwork, walls, anything rough to try and file away the excess wood so the corners could meet up.
used a bit of creative licence and er....'reformed' the wood a little with a lump hammer 😀
before

[img] [/img]

after

[img] [/img]

oh yep forgot, i also realised they looked a bit crap with a sharp V shape, so sawed the bottoms flat, i think it makes em look a bit better.
again, before and after below....

[img] [/img]

[img] [/img]

so thats my day, sorry its a bit pic heavy but thought the pics would describe my day better than words.

cheers

EDIT: still not sure bout them braces. im perfectly willing to take em down if everyone thinks they look crap, i await comments from you chaps plus wife and friends.....

EDIT EDIT: the more i look at em, the more i think i should have made life easier for myself by screwing the braces to the [i]inside[/i] of the ring beam, so i could screw em directly into the posts, and then they wouldnt have to meet outside the posts. probs look better too. b*ll*cks. ah well, a wasted afternoon maybe. wotcha all reckon?

NO idea which is the better solution from an engineering perspective but I like them. Good work that man.