Mike's Workshop Build (Extension & slates)

[Mike G]

Thanks guys. Yep, weather got pretty bad, and there's more on the way.

 

[Mike G]

I didn't have a lot of time at it today, but made a little progress.

The plan is to have a good amount of loft storage space accessible from inside the workshop. I've decided to have 2 different sections of loft, and 1800 between where the workshop is open to the vaulted roof. This is to enable access to the storage areas, as well as giving me an area of very high headroom if I should ever need it.

After much buggering about because of curvy timbers, I fixed the raised ties with their underside at 2500, enabling me to turn a sheet of ply/ MDF or whatever over inside the workshop without crashing it into the ceiling. Here is one end:



And here is the other, with 2 joists. This also shows a principle tie at plate level...........a lump of 225 x 50 across the little return walls, and spanning the join between the big part of the building and the smaller end. This is fundamental to the roof design of the smaller roof, as you'll see tomorrow:



Here is the view from outside:


This shows more clearly the 2 pairs of rafters which aren't tied by joists, and this is the reason for the hefty ridge beam. If I didn't have a structural ridgebeam here, the walls in that 1800 gap could spread under the load of the roof. However, the strong ridge prevents the top end of the rafters moving, and thus prevents any great outward forces at the eaves. It also allows me to load my loft storage much more than if I had simple trusses, or the usual flimsy ridgebeam.

Here's a question for you. Joist timbers are seldom straight. Builders always sight them, and turn them to put the bow up in the middle. I do the opposite. Why?

Finally, a quick job before I packed up. Marking out the ridge for the small roof. You'll note again that it is a chunky bit of wood. Given what I said above, predict my roof design for the next (small) roof. Here I just sit the ridge in the right position on the wall plate, and mark off the rafter positions (which are above studs). Simple.

 

[the bear]

Mike
I'm v impressed with the rate you work at. This is taking shape so quickly.
Ref the structural ridge beam, I was under the impression they were supposed to be supported by a vertical at each end to transfer the load down to the floor and foundations. Or is that only if its got no ties (joists) across its whole length?

Ref the bows in the joists, is it cause you're from the southern hemisphere?

Mark

 

[Mike G]

Thanks Mark.

Yes, an orthodox structural ridge beam would be supported on posts. Mine is a sort-of hybrid, in that it is supported on complete trusses (by complete, I mean they have tie beams, and thus can't spread). That is why I wasn't concerned about having a scarf joint in the beam. In fact, if it wasn't for the inconvenience of having different rafter lengths, I could have scarfed in a much thinner piece for the short end piece of ridge.

You'll see a more orthodox structural ridge beam (AKA a ridge purlin) tomorrow.

No, the curved-down joists/ ties are not because of where I was born!!

 

[AndyP]

Here's a question for you. Joist timbers are seldom straight. Builders always sight them, and turn them to put the bow up in the middle. I do the opposite. Why?

If the bow was up any weight above the bow would have the affect of straightening the joists thereby pushing the ends out and with it the roof rafters. With the bow below any weight in the "dip" would have the opposite affect and therefore help keep the rafters pulled in.

Least after a morning thinking about this it sounds plausible to me.

edited after a little more thought - andyp

 

[TrimTheKing]

Here's a question for you. Joist timbers are seldom straight. Builders always sight them, and turn them to put the bow up in the middle. I do the opposite. Why?

I haven't a clue, but it's bugging the hell out of me now so you neeeeeeeed to tell me! :eusa-pray:

Cheers
Mark

 

[Halo Jones]

Here's a question for you. Joist timbers are seldom straight. Builders always sight them, and turn them to put the bow up in the middle. I do the opposite. Why?

Are they more likely to straighten as the roof tries to push them out from either side? :eusa-think:

 

[Rod]

Beams normally sag so that's why builders would place it bow up.

If your structure is well designed and supported as it seems to be apart from shrinkage, I cannot see why you've placed it bow down?

Rod

 

[Mike G]

Here's a question for you. Joist timbers are seldom straight. Builders always sight them, and turn them to put the bow up in the middle. I do the opposite. Why?

If the bow was up any weight above the bow would have the affect of straightening the joists thereby pushing the ends out and with it the roof rafters. With the bow below any weight in the "dip" would have the opposite affect and therefore help keep the rafters pulled in.

Least after a morning thinking about this it sounds plausible to me.

edited after a little more thought - andyp

That's it. The rafters are already trying to push the walls apart. If you put the joists bow-up, then any load on them is also trying to push the walls apart. If you place them bow down, the load is pulling the walls in.

That's my theory, anyway, and I'll stick to it. I have never ever seen it done any other way than bow-up on site. I think it's one of those little things which is just passed on without any great thought, and when you see joists sagging, of course you feel that someone has got something wrong, so of course one's initial instinct is to put them bow-up.

 

[AndyP]

I was right!
Mike, you've made my day.

 

[stephen.wood125]

Fantastic progress!

Really enjoying this thread.

Re the downward bow: like all the best solutions it's elegant and seems obvious- when you know!

:text-bravo:

 

[Mike G]

I had half a day at it today, in small segments.........but made reasonable progress.

First, I set out the small roof, as per the big one from a few days ago. A straight piece of wood to check the seat cuts are marked properly:



Next, a batten cut to the length of the span across the plates (note the small length of 150 x 50 acting as a ridgeboard in the geometry):



I then cut 10 rafters to 2 patterns, one long, and one short. Next, the ridge. As before, I want a post up at the gable, so clamped a 100 x 50 into place (this involved moving the diagonal bracing to the inside): To this, I clamped a 150 x 50 to replicate the spacing of the ridgeboard:


I make no great effort to get these plump or central, because the rafter will actually do that for me.

Prop the first pair of rafters in place:





I then took the 150 x 50 away from between the rafter ends, and screwed a bit of scrap across between the two rafter ends. This end of the roof is now ready to accept the ridgeboard:



I then fixed a temporary post at the far end of the roof, to which the other end of the ridgeboard can be clamped:



I should really have taken an intermediate picture, but I was a bit busy getting the ridge into place, then another pair of rafters, which act to locate the ridge at the far end:



Then, as before, just offer up and nail in the rafters. Always do this in pairs (ie don't do one side of the roof, then the other, as you will push your ridgeboard out of alignment). Each pair of rafters is carefully tosh nailed in the right order so as to bring the tops of the rafters to the same height either side of the ridge. After finishing the rafters, a quick check for vertical at the gable then tie it all together with a diagonal brace:



This is what the rear look like, with the big roof overhangs for storage:



Next job. More lining of the inside with OSB. My previous workshop suffered with the OSB bowing and warping, and I decided to leave a few mm between each board this time to see if that would help prevent the problem. It may just have been a dodgy batch last time, or they could have been stored badly. Anyway, gap forming the technical way:



Fully lined to plate level. I decided to fly straight over the hatches and cut them out later, because there is a degree of urgency about finishing this workshop now, and that is a job that can wait:







The acoustics have changed. It sounds like the inside of a drum now!

Finally, just to show that not everything always goes to plan, here is a rafter foot that I noted to be split, and which I marked up to make sure I was extra careful of, before I fixed it with some glue and a screw:

 

[TrimTheKing]

You don't hang around for an ol...Erm, experienced fella do you Mike!

Top job, loving this, and actually contemplating doing my roof myself rather than having someone in to do it!

Keep them coming. :eusa-clap:

Cheers
Mark

 

[Mike G]

actually contemplating doing my roof myself rather than having someone in to do it!

You must Mark. You'll love it.

When it comes time, send me your across plate measurements, and your roof angle, and I'll return a quick drawing showing the exact dimensions for your rafters.

 

[TrimTheKing]

actually contemplating doing my roof myself rather than having someone in to do it!

You must Mark. You'll love it.

When it comes time, send me your across plate measurements, and your roof angle, and I'll return a quick drawing showing the exact dimensions for your rafters.

Thanks Mike, appreciate the offer.

Cheers
Mark

 

[Robert]

Nothing useful to add but I'm enjoying following this rapid build

 

[berncarpenter]

Got to agree that cutting roofs in is very satisfying ,i really enjoy them . Working alone on one is hard work without any scaffolding though Mike , tight as i am even i would use some even if it was only a tower or young man boards .Looking good and nice tidy tight roof

Cheers Bern

 

[AndyP]

I sometimes wish that I could build from scratch having only ever converted existing buildings. I very much doubt that I could achieve what is being done here though.

 

[chataigner]

I sometimes wish that I could build from scratch having only ever converted existing buildings. I very much doubt that I could achieve what is being done here though.

Oh yes, it would be so nice the have vertical walls and 90° corners. All my work has been in VERY old buildings with nothing even remotely square or plumb.

Fantastic progress Mike - I'm watching daily with great interest.

 

[Mike G]

Thanks for the comments, all. Good to know that people are interested in my little shed.

I'm just working out the eaves details, and this evening I will have a go at the gable walls, and maybe start lining the underside of the rooves.

 

[Halo Jones]

Really enjoying the build and from the drawings it looks as if it will be a fantastic looking workshop.

If it isn't too nosy a question can I ask what the rough build cost will be? ie is it 3-5K 5-10K or higher?

The reason I ask is that I really like the design and would like to maybe start negotiations with the purse holder in the near future!

 

[Mike G]

Really enjoying the build and from the drawings it looks as if it will be a fantastic looking workshop.

If it isn't too nosy a question can I ask what the rough build cost will be? ie is it 3-5K 5-10K or higher?

The reason I ask is that I really like the design and would like to maybe start negotiations with the purse holder in the near future!

I doubt it will reach £3000. If it does, it won't exceed it by much. However, I will be using slates reclaimed off the house roof, and the probably re-using a window from the house too. I post all the figures when I've finished.

 

[Steve Maskery]

Hi Mike
Yours looks much classier and generally neater than mine. And I wish my projected expenditure was the same as yours! Smashing job.
S
PS But mine's bigger than your-ors, na, na, na-na, na!

 

[Mike G]

Hi Mike
Yours looks much classier and generally neater than mine. And I wish my projected expenditure was the same as yours! Smashing job.
S
PS But mine's bigger than your-ors, na, na, na-na, na!

Hi Steve.......good to hear from you again. You sound chipper!!

Cheers

Mike

 

[Mike G]

Frustratingly, I've only been able to do the odd hour or two here and there in the last few days, but I got a good run at it today, putting in the best part of 12 hours work.

Details, details.........

It's always the details which take the time. You can make a good dramatic show by getting a few rafters up in an hour or two, but it takes longer to do the eaves details than it did to do the rafters. There are lots of different ways of closing the eaves, and because I want exposed rafter feet I had to come up with something between the rafters. I wanted something square to the top of the boarding, so that I have a good place to finish the boards to under the eaves, rather than just sort of stop somewhere near the felt. This is what I came up with:



Here's a barrow full of bits:



And here they are all screwed together. I kept the screws well in from the ends, and made the pieces over-long, so that they could be trimmed to suit the measured gap between each pair of rafters.



It took ages to trim them all individually to length, hammer them into place, then skew-nail them. Finally, I ran the power plane over the top of them to bring the tops in line with the tops of the rafters:

Before:


After:


Then I quickly did the studwork at the gables, and then took ages fitting 50 x 50's between:



This is the end of the big roof where it meets the smaller roof. This was a pain. Not only does the big tie beam curve in 2 directions, but the width of a stud is more than the width of the rafter plus the width of the tie beam, so the studs didn't actually line up with one of the faces of the beam, overhanging by a nasty 6 or 8mm. Still, I cracked on........



The small gable:



That was the end of the weeks work, and I was away Saturday.

-

Sunday: because of a really early start and not wanting to disturb the tranquility at 7.30, I began with a good tidy up and re-arranging of piles of timber, shifting the OSB near to the workshop. I made a pile of the insulation which will be in use in the next few days, as well as the roof felt etc:



By the time I came to use power tools the place was looking ship-shape. First job was to cut a whole lot of threaded rod "bolts". Actual bolts are expensive, so I buy threaded rod and cut it to length, with 2 nuts. However, there is a catch: if you cut the rod and then try to thread a nut onto it, you'll never succeed. The best answer is to cut it with 2 nuts already on the "bolt", and then you take one off. In unwinding it, the nut cuts through the burrs and mess at the site of the cut, leaving a reasonable thread and giving you a good chance of getting a nut back on without too much of a fight.



The joy of 600 centres on rafters is that you can fit a drill and spade bit between them, and can thus easily drill out for bolts:



Having bolted up all the raised ties (joists), I turned my attention to boarding the gables:



Note the 50 x 50 planted onto the gable, to take the edge of the OSB sheets on the underside of the rafters. Note, too, the batten finishing the nasty little overhang of the studs on the tie beam:





Middle of the afternoon, and the gables are all boarded:

There's a lot more work in those than you'd think, and some of the big sheets were damned awkward to lift into place. It was particularly annoying to have to take some of them up and down 2 or 3 times before I got them right.

Mabel thinks I need a green thing for the next phase of work:



After lots of measuring and thinking, I decided on a strategy for boarding the underside of the rafters. I started with a line just above the joists:



Then, with the help of a temporary batten to support the lower edge, I did the skillings (sloped ceiling below the joists). This involved cutting around the joists, which usually meant 2 or 3 goes at it. No wonder I am so tired now!!



Nearly done:



Finished! Too dark to take a photo outside:



So, lots of fiddly stuff in the last few days, and progress isn't as dramatic as before, but I'm getting very close to felt and battens, and thus being nearly watertight.

 

[TheTiddles]

Too cheap to buy bolts... and I thought I was a cheapskate! Sir, I salute you!

Aidan

 

[Mike G]

Too cheap to buy bolts... and I thought I was a cheapskate! Sir, I salute you!

Aidan

 

[Wizard9999]

Mike

Amazing progress! And loving the fact you already have essential furniture in place, but how well trained is your dog that you can get it to bring you a (green) chair.

Terry.

 

[Mike G]

Thanks Terry. The chair is for spectators. I don't mind them, so long as they come equipped with a cup of tea for me.

 

[Mike G]

Oh bugger!

You silly great clown. Measure how many times before you cut? This is the sloped ceiling lining, cutting around the tie beams. Only 3 of them on this sheet, so getting them in the right place shouldn't have been a huge test.

So, cut an infill piece, and a backing piece, and screw it all together:





It doesn't look too bad in place, but I'll see it every time I walk into the workshop........



I spent a bit of time finishing off the boarding around the inside of the building:



This is the vaulted ceiling over the small end of the 'shop. There will be a 100 x 25 planted along the entire length of the ridge of the building, so the gap will disappear.



This is looking the other way:



I planted any old scraps of batten on the side of the joists so that I could nail through the board below and secure the loose edge:



Scaffold!! :eusa-dance: :shock:



6 inch mineral wool insulation over the main roof:



The felt isn't felt. It is a lightweight breathable sarking material, which looks an awful lot better than the flimsy Tyvek that I've got fed up with in the past. I cut it overlength, and staple it in position. Then sort out the batten spacing (the complication here being that the slates I am going to use are still on another roof, and measuring the batten spacing was not an easy task at all. I hope I've got it right!!):



Blue sarking, blue chalk in my chalk-line............not clever. Can you see the line? It took some peering at, I promise.



The first few battens on:



Most of the main roof done:



Note that I don't nail the battens on the verges, and have left them deliberately over-long, because I am not 100% sure of my verge detail yet, and I don't want to be hauling battens up to cut them, or put undercloaking under them, or whatever.

Called in to dinner, so that's it for the day:

 

[Wizard9999]

Looking very nice, as ever Mike.

One question, if you have scaffolding why did you do the whole roof structure from a ladder?

Terry.

 

[Mike G]

I have scaffolding now. I didn't then. But this was such a small roof that the scaffolding would have been more trouble than it was worth. There would have had to be scaffolding along both eaves, and along the ridgeline, taking up all the flat floor space I used for marking out the frames..........and all for 2 days work. I was quicker without it, especially when you consider the time it takes to erect and dismantle.

However, with felt and battens, until you have actually worked your way sufficiently up the roof to be standing on the roof rather than at the eaves, you have to keep moving along the outside of the building, which would be an absolute pain from a ladder.

 

[Phil]

Mike, that is really looking good.

All the work done by yourself, on your own?

I suppose that if you are 25 and not 65 you can do it.

Cheers
Phil

 

[Mike G]

Mike, that is really looking good.

Thanks Phil. I'm quite pleased too, so far.

All the work done by yourself, on your own?

Yes, although DaveL of this forum gave me a hand to lift 3 of the bigger frames into place.

I suppose that if you are 25 and not 65 you can do it.

I'm 53. I expect to still be able to do stuff like this at 65, but may require more tea to fuel the process!

Edit........actually, I've just remembered I'm 54. Had a birthday recently.

 

[RogerS]

......
I'm 53. I expect to still be able to do stuff like this at 65, but may require more tea to fuel the process!

Edit........actually, I've just remembered I'm 54. Had a birthday recently.

If I can then I'm sure you will be able to as well ! The energy flags towards the end of the day but a pint or two usually gets you back into shape for the next day!

 

[DaveL]

Well I did not do a lot to help, if I were doing this alone, progress would have been a little slower.
After the ladder incident a few years ago I am a bit more wary of climbing about, but I still get into trouble with the LOML for things I do.

 

[Robert]

but I still get into trouble with the LOML for things I do.

I get into trouble for thing I don't do as well

I've been away a few days in Devon as my Mrs wanted to get away from all the decorating etc. that has been a full time activity for so long now. Good to see the workshop build carrying on at the same pace. Watching with interest.

 

[Mike G]

I finished the felt and battens:





Then I did some finishing off inside, getting all the little bits of OSB sorted, putting some 100 x 25 along the ridge line, and as upstands in the "eaves" of the loft storage areas. I also screwed ex 75 x 25 PAR around the entirety of the walls as a skirting board, having first swept and blasted the gaps under the bottom edges of the OSB with the compressor to get everything clean:









Finally, I sprayed a mist coat onto the walls and underside of the roof. I finished, but it was too dark for photos, so here is a WIP:



I had hoped to move in tomorrow (Sunday), but I shan't make it. Monday instead.

 

[Mike G]

Sorry about the lack of progress reports and photos, but my wife has had the camera at school. There will be photos tomorrow. I have partially moved in, and spent today making a pair of sturdy doors. Tomorrow I'll be making an internal shutter for the window. The painting is finished, and I have started fitting shelves etc. and trying to move stuff from my old workshop. it is amazing how much utter rubbish one accumulates over the years.

 

[Rod]

Did you do anymore painting?

I know you are always saying about "too many tools" but two cameras is hardly excessive I think?
Then we wouldn't have to wait so long?

Rod