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Hello Rob, yes, you're quite right. 

 

The problem I highlighted is working with a shallow -angled pitch, at 22.5 degrees. In a 'normal' roof pitch, working up to the soffit and top wall plate is not normally a problem; there's plenty of room. Here the closure angle (still 22.5 degrees) is much more acute, leaving a lot less room for both insulation & air gap. I alluded to the 'Tricky-Dicky  problem earlier, which still hasn't been resolved:- Yet.  Some out of the box thinking, methinks. 

 

I'll be making the first truss today. Although I've made lots of jigs & templates, there is still a lot of capacity to accommodate alterations & improvement available, so we shall see. 

 

Thank you for the post, watch this space!

 

Cheers,

Ian.  

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2 minutes ago, Happy Hippo said:

Don't you think an AA23 Toad would have made a magnificent workshop?

 

It would also have a nice sitting out area when you needed a break and a drink.

 

Hello Richard, yes it would! I did own the Toad over at Blaenavon, but some internal movement at the P&B prompted the sale of the Toad. Luckily, I had bought a significant quantity of 220 x 75 timber for the floor, but I redeployed the asset to the shed project. The earlier photos show the shed spine & joists of the floor, and this is where they have arrived from. 

 

In a way, I have gained a quite good increase in floor space with the change of plan. A Toad has a 16x8 floor area, or 128 square. With the shed, it's nearer to 288 square; a bit of a no-brainer, actually. Plus, it's only up the garden.....

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Thank for the info on the Toad.

 

When we moved into our current property, I  bought a 14 x 10 shed for use as a workshop.  Prior to it being erected, I  put in shuttering and had a reinforced concrete raft poured as a decent base.

 

With the benefit of hindsight,  I would have turned the pad through 90 degrees and had a much larger floor area.

 

Your 288 sq is much more sensible.

 

As an aside the original workshop was torn down when rot set in, and it has been replaced with a better quality building, but alas, still with the same footprint.

 

 

 

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1 hour ago, tomparryharry said:

Hello Rob, yes, you're quite right. 

 

The problem I highlighted is working with a shallow -angled pitch, at 22.5 degrees. In a 'normal' roof pitch, working up to the soffit and top wall plate is not normally a problem; there's plenty of room. Here the closure angle (still 22.5 degrees) is much more acute, leaving a lot less room for both insulation & air gap. I alluded to the 'Tricky-Dicky  problem earlier, which still hasn't been resolved:- Yet.  Some out of the box thinking, methinks. 

 

I'll be making the first truss today. Although I've made lots of jigs & templates, there is still a lot of capacity to accommodate alterations & improvement available, so we shall see. 

 

Thank you for the post, watch this space!

 

Cheers,

Ian.  

You may be trying too hard.  Although it doesn't feature in the official documents, when I converted our garage the Building Control Inspector didn't have any issues with not hitting the insulation target in a few spots as long as there was above target elsewhere.  For example, the walls were single brick with a couple of block pillars on each wall.  The insulation, battens etc. overlayed this to create flush walls which meant having less insulation where each pillar was.  This was balanced by having more insulation than required in the ceiling and floor.

 

I'm not a professional but I'd say that the most important thing is not to break continuity.  It is not unusual to see people roughly cut PIR sheets and slap them in between joists, not paying any heed to the large air gaps at various points which destroy the insulation value.  They need to be a tight fit with no gaps.  You need specific air gaps to prevent rot.  You do not want air flow penetrating the insulation layer(s).

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Posted (edited)

Cheers Rob. 

 

I still think that we'll get 175mm insulation between the joists, paying particular attention to the air gap over the top plate, and into the soffit area. I will try to get in as much ceiling insulation as we can reasonably accommodate. One thing I've considered is a humidity-controlled extraction system, to combat the possibility of rot.  Can't remember if I've mentioned it already, though.....

 

The one thing I need to end up with, is a place of solitude.  The stroke can play strange things on your mind, and that has happened to me.  On that basis, there are times when I just need to get away. It's Ok today, not too warm, but! What about January-February?  It's not much fun brazing the spheres back onto the monkey! That's why I've tried to open up the discussion about this, to generate some informative debate, ideas, and encouragement. I know what this will mean to my euphoria, so I don't see why others can't have or enjoy this, to varying degrees. 

 

Rain has stopped play today, otherwise I'd be outside. Modelling Mojo has stopped, but the euphoric content has vastly compensated whatever I thought I might be experiencing.

 

All of this for a 14xx tank, and an autocoach; who would have thought it?  Ha Ha.

 

Keep safe, folks,

ian.

Edited by tomparryharry
text clean-up.
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Posted (edited)

Hi Ian,

 

I just read the entire thread trying to get an idea of what your roof structure is going to look like (and the eaves detail in particular) but enlightenment eluded me. Have you got any drawings?

 

P.S. Did you insert DPC under your joists?

 

Edited by Harlequin

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Hi Phil. Oh dear, you've caught me out.... No, I'm working off the back of my head....

 

Most of what I've done thus far is stuff for which I've always done. Therefore, centres on 16", or 400mm.  The angle is a 4-12 pitch, or 22.5 degrees. The span is 12'. The upper angle from eaves to apex is approximately 8' which is dead handy for sheets of ply or OSB. The height from floor to wall plate is, will, be 7'.  Overall, the height from floor to apex is 10', plus roof thickness & joist height, so about an extra 10".

 

You're  quite right. I'll get up a drawing this evening. If you can visualise a shallow-angled shed, then you're not far off. Exterior will look strangely similar to some chap in West Devon, but I'm not not going to copy, honest!

 

DPC? Yes, under each joist. 

 

Cheers,

Ian.

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18 minutes ago, tomparryharry said:

I'll get up a drawing this evening

 

All the best drawings and materials lists are on offcuts of plasterboard..:D

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I chalked some critical dimensions on a wall so I wouldn't lose them.  Rendered the wall last week! :fool:

 

Alan

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1 hour ago, chris p bacon said:

 

All the best drawings and materials lists are on offcuts of plasterboard..:D

 

One of my first contracts was a house in Bournemouth, to install some solar thermal panels. I'd written some of the LV wiring on an loft upright, just to remember 'what goes where' . However, I left behind my side cutters. Grrr.... I forgot all about the cutters; bought a new pair. Some years later, I had to return to the house on a service call. Remembering that I'd written it down, I checked to see which temperature probe went where.... "Oooh, look, that's where my cutters went..."

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I found the plumbers pipe cutters 8 years after he did a job, they were left under the floorboards  :rolleyes:

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My late Father lost a good pair of pliers. Many years later he dismantled an old armchair prior to disposing of it. When he found the pliers inside he recalled doing a repair job on it and he had left them inside when replacing the fabric.

 

Those pliers are now part of my own tool kit.

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Not much to show this week. The wood has arrived:-Yippee! That is, if your'e interested in seeing a pile of wood.... Setting down the floorboards over the past 2 weeks has paid dividends, as now I can 'lay-out' for making roof trusses. More patterns will need to be made, just to speed up the process.

 

Sunday is  a 'no work' day. I've got excellent neighbours here, so I always keep it quiet on a Sunday. Monday sees a return to work, hopefully big time. Hopefully some photos, to see where it's going. 

 

Have a great week, and take care.

 

Ian.

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A couple of photos. As usual, not a lot of quality, but progress nonetheless. The laying out of trusses has taken place, and we're about halfway through. Prior to assembly, we had a large pile of pre-cut gussets, all neatly stacked under the stairs. Mrs Smith was soooo pleased...... Still, the pile grows ever smaller. If the weather stays like this, it 'could' be done by the weekend. Next week should see the starting of the walls. All in all, These trussses are massively over-engineered, but the intention is to gain as much insulation as practicably possible.  Still early days however.  

 

Actually, only the one photo. I don't know where the others went..... 

IMAG1374[1].jpg

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One week further on, and I'm happy to say the truss assemblies are made. It's felt a bit strange unscrewing the cleats & jigs from the last 4 weeks, but they have paid dividends in maintaining a degree of accuracy. Now to find a place for these blessed trusses.....

 

The rest of the week should be taken up with making a new set of jigs to make the wall partitions. Sorry! Exterior wall panels! These are multiples of either 4', or 6' long, by 7'6" high. The 4.8 metre length of 5x2" allows 2 cuts at the 7'6" for the stud uprights, and the final top wall plate will arrive at, or about, 8' tall. Hopefully more photos & explanation as we go along. A couple of days-weeks back, Phil Harlequin of this parish asked about the truss assembly set-up, so here it is. The size should allow a 12' clear span from exterior to exterior wall. If it comes out at about 11'9" on the internal,  I shall be well pleased. As  we know, the trusses will come with a 16" centre, so it's all building  standard stuff. 

 

Just another poorly taken photo or two, just to show where we are. 

 

Have a great week, folks!

Ian.

IMAG1389_BURST002_COVER[1].jpg

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Nowt wrong with your photos Ian, they show progress well, which is what they’re supposed to do!

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Hi Ian,

 

I have plans for a shed with a similar width so I'm taking a keen interest in your roof and have some questions.  It looks like 150mm for the tie beam and 100mm for the rafters.  The truss plan  I had in mind would have had the angled pieces as well (sort of W-shape), but I take it you've got information that the single post will be enough.  Is that to do with the 400mm spacing (I was thinking of 600mm)?  Did you have to consider snow-load when you calculated the support and the slope? Finally, is it ply you used for the gussets?  If so what thickness, please?

 

I'm close to the permitted development limit without needing to involve Building Control so I want to be confident that if they take an interest the structure is sound.  We had an extension built with a 45 degree slated roof, boarded with 19mm timber (sarking) and that has 100mm rafters at 600mm centres.

 

Alan

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Posted (edited)
10 hours ago, Buhar said:

Hi Ian,

 

I have plans for a shed with a similar width so I'm taking a keen interest in your roof and have some questions.  It looks like 150mm for the tie beam and 100mm for the rafters.  The truss plan  I had in mind would have had the angled pieces as well (sort of W-shape), but I take it you've got information that the single post will be enough.  Is that to do with the 400mm spacing (I was thinking of 600mm)?  Did you have to consider snow-load when you calculated the support and the slope? Finally, is it ply you used for the gussets?  If so what thickness, please?

 

I'm close to the permitted development limit without needing to involve Building Control so I want to be confident that if they take an interest the structure is sound.  We had an extension built with a 45 degree slated roof, boarded with 19mm timber (sarking) and that has 100mm rafters at 600mm centres.

 

Alan

Hello Alan,

 

Yes, the tie-beam (bottom chord) of the truss is 7x2" C16 timber. This works in at 160x 45mm. The rafter beams, and the centre upright, are made from 5x2" The plywood portions are made from 12mm ply, screwed & glued. As the load is in compression, the ply acts as a side support to the truss proper. 

 

The 'W' angle can be made, and with lighter trusses, certainly advisable.  The 500mm centres is quite common, and I've seen 600mm (2') as well. I plumped for 16" (400mm) as the underlying floor joists are also at that centre. The original 9x3 joists were a recovered asset, so I've just followed on.  The roof angle is (what our American cousins call) a '6-12 pitch', so for every 12" of span, the apex rise 6".   From apex to eaves is under 8', so just right for using boards if required. 

 

I do like a sarked roof; They are normally very strong and long lived. 

 

These trusses are massively over-engineered. The reasoning being is should I need contractors help, then I don't want Frisco Pete and happy posse, saying "Oh, I wouldn't do it like that....." Plus of course, to get in as much insulation as I can. In terms of beam cross-section dimensional size, I'm not too happy with metric sizes in an Imperial situation. If in doubt, go up one. So , 6x2 will be ordered as 160x 45, and things like 4x2 becomes 120x 45. Metric sized stock has a nasty habit of downsizing, becoming 145x45, and 100x45, or more commonly 96x 38, which is well undersized. 

 

If you are not sure, please get advice. The last thing I want to hear  that someone has dropped the building on their pride & joy.  

Edited by tomparryharry
added text.

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Thanks Ian,

 

I have used a structural engineer in the past and my Sketch-up plans for changes to the extension passed muster with him, but he's bloomin' expensive.  I do like over-engineering structures, I've seen enough pictures of roofs bowing or blown off and buildings sinking to be prepared to spend a bit more on timber and time.  Unfortunately, my shed is some way off, got to fish the house first.

 

Alan 

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Your structural engineer should be worth every penny. He'll give you confidence to know you're going the right way. In terms of expense, part of his fee will be his indemnity insurance. Each & every contractor worth his salt will have indemnity insurance. 

 

When you do get going, put some photos up. I'd be interested to see how different your 'take' would be in relation to other people heading the same way.

 

Cheers,

Ian.

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Hi Folks. Apologies for not keeping up regular posts on here, but sometimes events conspire to divert your attention. The last few weeks have been spent making parts of the side walls. These are a nominal 4X2" C24 timber, but in reality, 95x 45mm timber. I did make these sides to accept a 8' board, but when we erected the end wall, it would be too tall.  By way of solution, I trimmed the uprights to 80.5 " which, with the top & bottom rails, comes out at 7' tall. With the trusses to come on top, that brings the shed height down to an overall 10' which is far more acceptable. If the weather holds, and I can get a clear run at it, then I might be able to finish the walls by the weekend.

 

Hope springs eternal, and I've promised myself that I won't buy the new Prairie until the shed is finished,  so the game is afoot! For those metric pedants, about 300-something mm....

 

More sub-standard photos, just to see where it's (still) going. 

 

Cheers,

Ian.

IMAG1391_BURST002[1].jpg

IMAG1392[1].jpg

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Hi Folks. Another couple of days have passed, and the walls are more or less up.  The upper wall plates have been added, and this, together with the top wall plate, provides a register for the trusses. The next couple of days will be taken up with the spirit level, getting them square, and then hopefully, fixing the trusses in place. 

 

The box profile roof has been ordered, with delivery Monday. Once the trusses are on, the roof sarking will begin. 

 

Cheers,

Ian.

IMAG1395_BURST002_COVER[1].jpg

IMAG1394_BURST002_COVER[1].jpg

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Hi Dave. No, just the railway, in 00. It is a place of solitude, where I sometimes need to get some complete isolation. 

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