Musings on building a workshop and a new machine...

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Originally Posted by Web Goblin

If you are going to build to 2.5mts at one side anyway would you not be as well having a pitch roof? It might not be as much of a slope as you wanted but it would Still be there. The metal roof is not really that noisy and the roof sheets are screwed down on top of the outside sheet of timber anyway.
Photo below (left)shows my workshop roof. The photo on the right shows my nearly complete bike shed with the same type of roof. The roof has the outer sheet of osb, 100mm of poly insulation, then another sheet of osb inside so its well insulated for heat and sound.

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Yes it will be single pitched but I wanted a double pitched roof with a useful void in it, but the expemption won't let me have that and I dont want to go to the hassle of getting permission.
So the 100mm poly insulation is between the roof joists and the OSB screwed top and bottom of the joists? Did you use T&G or the plain stuff? What did you treat the OSB with before attaching the metal covering?

I was looking at using Bitumen-coated corrugated sheet like this:
http://www.wickes.co.uk/content/ebiz...heet_large.jpg

Yes 100mm insulation between the joists with osb top and bottom. I used plain osb screwed down. The grade of the osb is structural I think. It was the one with the better preservative treatment but even so I did give it a couple of coats of creosote or what passes for creosote these days. Seeing as the roof is covered by another waterproof layer you should only need protection from dampness.
My last workshop roof had bitumen coated fiber sheets on it and I really didnt like them. If it is the fiber ones they go soft in really hot weather and hard in really cold weather and after a few years they get very brittle and if you walk on them they break. You need to be really careful when screwing or nailing them down to get the right tension on the fixing so that its not too loose or too tight that it starts to crush the profle and makes it prone to leaks. Also used to have a large tree behind the workshop and in high winds some of the broken off branches punctured the bitumen sheets. You dont get these problems with the metal sheets. Metal stuff can also be repainted after a while to tidy it up again.

Tree's are my problem too... I have a mature chesnut tree approx 3m away on one side and a large laural tree/bush at the back and I'm going to have to cut through a few major roots that lie on the surface. Not sure what impact that will have a) on the tree(s) and b) on the ground swell...

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Originally Posted by irving2008

Tree's are my problem too... I have a mature chesnut tree approx 3m away on one side and a large laural tree/bush at the back and I'm going to have to cut through a few major roots that lie on the surface. Not sure what impact that will have a) on the tree(s) and b) on the ground swell...

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Hmm, we had a youngish (5-10 years) plum tree in the way of where we put the workshop 20x10' shed. The plan was to leave it there, hence why we got 20x10' not 20x12', however surpisingly after cutting lots of bits off my Dad managed to move it so we could have had the extra 2' on the width after all! There's also a mature ash tree pretty close to the end of the workshop, but it turned out there weren't too many roots in the way.

My Dad put insulated plasterboard (like this one), which was just plasterboard with 25mm of foam on the back, covering every wall and the ceiling which certainly made a big difference to the temperature and damp.

Not sure what exactly the roof sheet is, but it's black and corrugated:

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This is the proposed location, marked out with string. As you can see there's a big tree not too far away and if you look carefully you can see the roots (the string bends over the top of one!)

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The roots might cause you a problem but you wont find out till you start digging out the foundation and see how they are growing. Another problem is that the tree roots will continue to grow so could be ok just now but could damage the concrete in the future thats why I removed the tree next to mine, I just knew that it would cause problems so it had to go. I think you might need some expert advice on this one.

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Originally Posted by Web Goblin

The roots might cause you a problem but you wont find out till you start digging out the foundation and see how they are growing. Another problem is that the tree roots will continue to grow so could be ok just now but could damage the concrete in the future thats why I removed the tree next to mine, I just knew that it would cause problems so it had to go. I think you might need some expert advice on this one.

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Yes, trying to find someone...

The current working BOM reckons this 'shed' is near £8k worth of materials :eek: and they say 'materials is only 20% of the job'... err so either I'm very wrong somewhere (been using prices off ebay as a starter) or this 'shed' is going to cost £40k!!!

I know mate, building prices are scary. I completed mine for around £2.5K, size around 7.5 x 3.5 mt. But I did all the work myself with some help from a builder friend of mine who. The only materials I had to buy new was the timber framing and the osb sheets, concrete blocks and the sand. The plastic cladding came from ebay, major bargain it was, garage door company selling off a job lot. The roofing sheets were leftovers from a job at work that were going in the skip and I happened to be in the right place at the time to re-direct them into my trailer. Timber frame idea is easy to build yourself. Drew the whole thing in autocad and split it into sections to build. Once the floor level was complete I transferred the cad drawing for the wall from paper to full scale on the floor and cut and made all the sections there, same for the roof trusses.

The cladding I used was similar to this: Royal Crest Sterling Vinyl Decorative Cladding / Siding 200mm wide x 3.81m Long | eBay

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Originally Posted by irving2008

I've had all sorts of issues with a flat roof on a garage in the past so don't want a repeat of that. The only issue with plastic coated metal roofing is the noise it makes when it rains hard :

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Have you had a look at GRP roofing. I did a roof with a friend of mine as an extension behind his shop. Its uses fibre glass and resin, its easy to put down and has a 30 year life. We didn't put insulation in between the joists, rather OSB3 board over the joists, then 120mm insulation, topped with another layer of OSB3 board, all screwed down with 170mm screws. Planning actually specified which type and size of insulation we needed to use. We had a flat roof with just a rain slope, but it could be installed on a pitch.

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Regarding building the super structure, did you ever watch a program called 'Tommy's ultimate workshop' on Discovery Network. He builds a timber structure on concrete foundations. Its a good example of how you could do most things yourself. Each side of the shed is built on the floor then stood up into place. I did this on a small garden shed I made for my brother. Took me a weekend to complete start to finish. Its not a workshop shed, just a stick all your rubbish in shed. I even fixed the cladding to the neighbouring side before I stood it up into place. Didn't want to go to his side to fix the cladding.

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You have a Selco's builder merchant near you in Cricklewood, go and just have a browse on the materials you will be needing. They have all the equipment for GRp roofing and even have a demonstration video of how to apply it. Its also a talking point when your mates come to see your handy work, lol. I've found they are also the cheapest supplier of timber, and can ask for discount at the checkout.